diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
new file mode 100644
index 0000000..7b43022
--- /dev/null
+++ b/Modules/_io/_iomodule.c
@@ -0,0 +1,735 @@
+/*
+    An implementation of the new I/O lib as defined by PEP 3116 - "New I/O"
+    
+    Classes defined here: UnsupportedOperation, BlockingIOError.
+    Functions defined here: open().
+    
+    Mostly written by Amaury Forgeot d'Arc
+*/
+
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+#include "structmember.h"
+#include "_iomodule.h"
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif /* HAVE_SYS_TYPES_H */
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif /* HAVE_SYS_STAT_H */
+
+
+/* Various interned strings */
+
+PyObject *_PyIO_str_close;
+PyObject *_PyIO_str_closed;
+PyObject *_PyIO_str_decode;
+PyObject *_PyIO_str_encode;
+PyObject *_PyIO_str_fileno;
+PyObject *_PyIO_str_flush;
+PyObject *_PyIO_str_getstate;
+PyObject *_PyIO_str_isatty;
+PyObject *_PyIO_str_newlines;
+PyObject *_PyIO_str_nl;
+PyObject *_PyIO_str_read;
+PyObject *_PyIO_str_read1;
+PyObject *_PyIO_str_readable;
+PyObject *_PyIO_str_readinto;
+PyObject *_PyIO_str_readline;
+PyObject *_PyIO_str_reset;
+PyObject *_PyIO_str_seek;
+PyObject *_PyIO_str_seekable;
+PyObject *_PyIO_str_setstate;
+PyObject *_PyIO_str_tell;
+PyObject *_PyIO_str_truncate;
+PyObject *_PyIO_str_writable;
+PyObject *_PyIO_str_write;
+
+PyObject *_PyIO_empty_str;
+PyObject *_PyIO_empty_bytes;
+PyObject *_PyIO_zero;
+
+
+PyDoc_STRVAR(module_doc,
+"The io module provides the Python interfaces to stream handling. The\n"
+"builtin open function is defined in this module.\n"
+"\n"
+"At the top of the I/O hierarchy is the abstract base class IOBase. It\n"
+"defines the basic interface to a stream. Note, however, that there is no\n"
+"seperation between reading and writing to streams; implementations are\n"
+"allowed to throw an IOError if they do not support a given operation.\n"
+"\n"
+"Extending IOBase is RawIOBase which deals simply with the reading and\n"
+"writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide\n"
+"an interface to OS files.\n"
+"\n"
+"BufferedIOBase deals with buffering on a raw byte stream (RawIOBase). Its\n"
+"subclasses, BufferedWriter, BufferedReader, and BufferedRWPair buffer\n"
+"streams that are readable, writable, and both respectively.\n"
+"BufferedRandom provides a buffered interface to random access\n"
+"streams. BytesIO is a simple stream of in-memory bytes.\n"
+"\n"
+"Another IOBase subclass, TextIOBase, deals with the encoding and decoding\n"
+"of streams into text. TextIOWrapper, which extends it, is a buffered text\n"
+"interface to a buffered raw stream (`BufferedIOBase`). Finally, StringIO\n"
+"is a in-memory stream for text.\n"
+"\n"
+"Argument names are not part of the specification, and only the arguments\n"
+"of open() are intended to be used as keyword arguments.\n"
+"\n"
+"data:\n"
+"\n"
+"DEFAULT_BUFFER_SIZE\n"
+"\n"
+"   An int containing the default buffer size used by the module's buffered\n"
+"   I/O classes. open() uses the file's blksize (as obtained by os.stat) if\n"
+"   possible.\n"
+    );
+
+
+/*
+ * BlockingIOError extends IOError
+ */
+
+static int
+blockingioerror_init(PyBlockingIOErrorObject *self, PyObject *args,
+                     PyObject *kwds)
+{
+    PyObject *myerrno = NULL, *strerror = NULL;
+    PyObject *baseargs = NULL;
+    Py_ssize_t written = 0;
+
+    assert(PyTuple_Check(args));
+
+    self->written = 0;
+    if (!PyArg_ParseTuple(args, "OO|n:BlockingIOError",
+                          &myerrno, &strerror, &written))
+        return -1;
+
+    baseargs = PyTuple_Pack(2, myerrno, strerror);
+    if (baseargs == NULL)
+        return -1;
+    /* This will take care of initializing of myerrno and strerror members */
+    if (((PyTypeObject *)PyExc_IOError)->tp_init(
+                (PyObject *)self, baseargs, kwds) == -1) {
+        Py_DECREF(baseargs);
+        return -1;
+    }
+    Py_DECREF(baseargs);
+
+    self->written = written;
+    return 0;
+}
+
+static PyMemberDef blockingioerror_members[] = {
+    {"characters_written", T_PYSSIZET, offsetof(PyBlockingIOErrorObject, written), 0},
+    {NULL}  /* Sentinel */
+};
+
+static PyTypeObject _PyExc_BlockingIOError = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "BlockingIOError", /*tp_name*/
+    sizeof(PyBlockingIOErrorObject), /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    0,                          /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    PyDoc_STR("Exception raised when I/O would block "
+              "on a non-blocking I/O stream"), /* tp_doc */
+    0,                          /* tp_traverse */
+    0,                          /* tp_clear */
+    0,                          /* tp_richcompare */
+    0,                          /* tp_weaklistoffset */
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    0,                          /* tp_methods */
+    blockingioerror_members,    /* tp_members */
+    0,                          /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    0,                          /* tp_dictoffset */
+    (initproc)blockingioerror_init, /* tp_init */
+    0,                          /* tp_alloc */
+    0,                          /* tp_new */
+};
+PyObject *PyExc_BlockingIOError = (PyObject *)&_PyExc_BlockingIOError;
+
+
+/*
+ * The main open() function
+ */
+PyDoc_STRVAR(open_doc,
+"Open file and return a stream.  Raise IOError upon failure.\n"
+"\n"
+"file is either a text or byte string giving the name (and the path\n"
+"if the file isn't in the current working directory) of the file to\n"
+"be opened or an integer file descriptor of the file to be\n"
+"wrapped. (If a file descriptor is given, it is closed when the\n"
+"returned I/O object is closed, unless closefd is set to False.)\n"
+"\n"
+"mode is an optional string that specifies the mode in which the file\n"
+"is opened. It defaults to 'r' which means open for reading in text\n"
+"mode.  Other common values are 'w' for writing (truncating the file if\n"
+"it already exists), and 'a' for appending (which on some Unix systems,\n"
+"means that all writes append to the end of the file regardless of the\n"
+"current seek position). In text mode, if encoding is not specified the\n"
+"encoding used is platform dependent. (For reading and writing raw\n"
+"bytes use binary mode and leave encoding unspecified.) The available\n"
+"modes are:\n"
+"\n"
+"========= ===============================================================\n"
+"Character Meaning\n"
+"--------- ---------------------------------------------------------------\n"
+"'r'       open for reading (default)\n"
+"'w'       open for writing, truncating the file first\n"
+"'a'       open for writing, appending to the end of the file if it exists\n"
+"'b'       binary mode\n"
+"'t'       text mode (default)\n"
+"'+'       open a disk file for updating (reading and writing)\n"
+"'U'       universal newline mode (for backwards compatibility; unneeded\n"
+"          for new code)\n"
+"========= ===============================================================\n"
+"\n"
+"The default mode is 'rt' (open for reading text). For binary random\n"
+"access, the mode 'w+b' opens and truncates the file to 0 bytes, while\n"
+"'r+b' opens the file without truncation.\n"
+"\n"
+"Python distinguishes between files opened in binary and text modes,\n"
+"even when the underlying operating system doesn't. Files opened in\n"
+"binary mode (appending 'b' to the mode argument) return contents as\n"
+"bytes objects without any decoding. In text mode (the default, or when\n"
+"'t' is appended to the mode argument), the contents of the file are\n"
+"returned as strings, the bytes having been first decoded using a\n"
+"platform-dependent encoding or using the specified encoding if given.\n"
+"\n"
+"buffering is an optional integer used to set the buffering policy. By\n"
+"default full buffering is on. Pass 0 to switch buffering off (only\n"
+"allowed in binary mode), 1 to set line buffering, and an integer > 1\n"
+"for full buffering.\n"
+"\n"
+"encoding is the name of the encoding used to decode or encode the\n"
+"file. This should only be used in text mode. The default encoding is\n"
+"platform dependent, but any encoding supported by Python can be\n"
+"passed.  See the codecs module for the list of supported encodings.\n"
+"\n"
+"errors is an optional string that specifies how encoding errors are to\n"
+"be handled---this argument should not be used in binary mode. Pass\n"
+"'strict' to raise a ValueError exception if there is an encoding error\n"
+"(the default of None has the same effect), or pass 'ignore' to ignore\n"
+"errors. (Note that ignoring encoding errors can lead to data loss.)\n"
+"See the documentation for codecs.register for a list of the permitted\n"
+"encoding error strings.\n"
+"\n"
+"newline controls how universal newlines works (it only applies to text\n"
+"mode). It can be None, '', '\\n', '\\r', and '\\r\\n'.  It works as\n"
+"follows:\n"
+"\n"
+"* On input, if newline is None, universal newlines mode is\n"
+"  enabled. Lines in the input can end in '\\n', '\\r', or '\\r\\n', and\n"
+"  these are translated into '\\n' before being returned to the\n"
+"  caller. If it is '', universal newline mode is enabled, but line\n"
+"  endings are returned to the caller untranslated. If it has any of\n"
+"  the other legal values, input lines are only terminated by the given\n"
+"  string, and the line ending is returned to the caller untranslated.\n"
+"\n"
+"* On output, if newline is None, any '\\n' characters written are\n"
+"  translated to the system default line separator, os.linesep. If\n"
+"  newline is '', no translation takes place. If newline is any of the\n"
+"  other legal values, any '\\n' characters written are translated to\n"
+"  the given string.\n"
+"\n"
+"If closefd is False, the underlying file descriptor will be kept open\n"
+"when the file is closed. This does not work when a file name is given\n"
+"and must be True in that case.\n"
+"\n"
+"open() returns a file object whose type depends on the mode, and\n"
+"through which the standard file operations such as reading and writing\n"
+"are performed. When open() is used to open a file in a text mode ('w',\n"
+"'r', 'wt', 'rt', etc.), it returns a TextIOWrapper. When used to open\n"
+"a file in a binary mode, the returned class varies: in read binary\n"
+"mode, it returns a BufferedReader; in write binary and append binary\n"
+"modes, it returns a BufferedWriter, and in read/write mode, it returns\n"
+"a BufferedRandom.\n"
+"\n"
+"It is also possible to use a string or bytearray as a file for both\n"
+"reading and writing. For strings StringIO can be used like a file\n"
+"opened in a text mode, and for bytes a BytesIO can be used like a file\n"
+"opened in a binary mode.\n"
+    );
+
+static PyObject *
+io_open(PyObject *self, PyObject *args, PyObject *kwds)
+{
+    char *kwlist[] = {"file", "mode", "buffering",
+                      "encoding", "errors", "newline",
+                      "closefd", NULL};
+    PyObject *file;
+    char *mode = "r";
+    int buffering = -1, closefd = 1;
+    char *encoding = NULL, *errors = NULL, *newline = NULL;
+    unsigned i;
+
+    int reading = 0, writing = 0, appending = 0, updating = 0;
+    int text = 0, binary = 0, universal = 0;
+
+    char rawmode[5], *m;
+    int line_buffering, isatty;
+
+    PyObject *raw, *modeobj = NULL, *buffer = NULL, *wrapper = NULL;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|sizzzi:open", kwlist,
+                                     &file, &mode, &buffering,
+                                     &encoding, &errors, &newline,
+                                     &closefd)) {
+        return NULL;
+    }
+
+    if (!PyUnicode_Check(file) &&
+	!PyBytes_Check(file) &&
+	!PyNumber_Check(file)) {
+        PyObject *repr = PyObject_Repr(file);
+        if (repr != NULL) {
+            PyErr_Format(PyExc_TypeError, "invalid file: %s",
+                         PyString_AS_STRING(repr));
+            Py_DECREF(repr);
+        }
+        return NULL;
+    }
+
+    /* Decode mode */
+    for (i = 0; i < strlen(mode); i++) {
+        char c = mode[i];
+
+        switch (c) {
+        case 'r':
+            reading = 1;
+            break;
+        case 'w':
+            writing = 1;
+            break;
+        case 'a':
+            appending = 1;
+            break;
+        case '+':
+            updating = 1;
+            break;
+        case 't':
+            text = 1;
+            break;
+        case 'b':
+            binary = 1;
+            break;
+        case 'U':
+            universal = 1;
+            reading = 1;
+            break;
+        default:
+            goto invalid_mode;
+        }
+
+        /* c must not be duplicated */
+        if (strchr(mode+i+1, c)) {
+          invalid_mode:
+            PyErr_Format(PyExc_ValueError, "invalid mode: '%s'", mode);
+            return NULL;
+        }
+
+    }
+
+    m = rawmode;
+    if (reading)   *(m++) = 'r';
+    if (writing)   *(m++) = 'w';
+    if (appending) *(m++) = 'a';
+    if (updating)  *(m++) = '+';
+    *m = '\0';
+
+    /* Parameters validation */
+    if (universal) {
+        if (writing || appending) {
+            PyErr_SetString(PyExc_ValueError,
+                            "can't use U and writing mode at once");
+            return NULL;
+        }
+        reading = 1;
+    }
+
+    if (text && binary) {
+        PyErr_SetString(PyExc_ValueError,
+                        "can't have text and binary mode at once");
+        return NULL;
+    }
+
+    if (reading + writing + appending > 1) {
+        PyErr_SetString(PyExc_ValueError,
+                        "must have exactly one of read/write/append mode");
+        return NULL;
+    }
+
+    if (binary && encoding != NULL) {
+        PyErr_SetString(PyExc_ValueError,
+                        "binary mode doesn't take an encoding argument");
+        return NULL;
+    }
+
+    if (binary && errors != NULL) {
+        PyErr_SetString(PyExc_ValueError,
+                        "binary mode doesn't take an errors argument");
+        return NULL;
+    }
+
+    if (binary && newline != NULL) {
+        PyErr_SetString(PyExc_ValueError,
+                        "binary mode doesn't take a newline argument");
+        return NULL;
+    }
+
+    /* Create the Raw file stream */
+    raw = PyObject_CallFunction((PyObject *)&PyFileIO_Type,
+				"Osi", file, rawmode, closefd);
+    if (raw == NULL)
+        return NULL;
+
+    modeobj = PyUnicode_FromString(mode);
+    if (modeobj == NULL)
+        goto error;
+
+    /* buffering */
+    {
+        PyObject *res = PyObject_CallMethod(raw, "isatty", NULL);
+        if (res == NULL)
+            goto error;
+        isatty = PyLong_AsLong(res);
+        Py_DECREF(res);
+        if (isatty == -1 && PyErr_Occurred())
+            goto error;
+    }
+
+    if (buffering == 1 || (buffering < 0 && isatty)) {
+        buffering = -1;
+        line_buffering = 1;
+    }
+    else
+        line_buffering = 0;
+
+    if (buffering < 0) {
+        buffering = DEFAULT_BUFFER_SIZE;
+#ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
+        {
+            struct stat st;
+            long fileno;
+            PyObject *res = PyObject_CallMethod(raw, "fileno", NULL);
+            if (res == NULL)
+                goto error;
+
+            fileno = PyInt_AsLong(res);
+            Py_DECREF(res);
+            if (fileno == -1 && PyErr_Occurred())
+                goto error;
+
+            if (fstat(fileno, &st) >= 0)
+                buffering = st.st_blksize;
+        }
+#endif
+    }
+    if (buffering < 0) {
+        PyErr_SetString(PyExc_ValueError,
+                        "invalid buffering size");
+        goto error;
+    }
+
+    /* if not buffering, returns the raw file object */
+    if (buffering == 0) {
+        if (!binary) {
+            PyErr_SetString(PyExc_ValueError,
+                            "can't have unbuffered text I/O");
+            goto error;
+        }
+
+        Py_DECREF(modeobj);
+        return raw;
+    }
+
+    /* wraps into a buffered file */
+    {
+        PyObject *Buffered_class;
+
+        if (updating)
+            Buffered_class = (PyObject *)&PyBufferedRandom_Type;
+        else if (writing || appending)
+            Buffered_class = (PyObject *)&PyBufferedWriter_Type;
+        else if (reading)
+            Buffered_class = (PyObject *)&PyBufferedReader_Type;
+        else {
+            PyErr_Format(PyExc_ValueError,
+                         "unknown mode: '%s'", mode);
+            goto error;
+        }
+
+        buffer = PyObject_CallFunction(Buffered_class, "Oi", raw, buffering);
+    }
+    Py_CLEAR(raw);
+    if (buffer == NULL)
+        goto error;
+
+
+    /* if binary, returns the buffered file */
+    if (binary) {
+        Py_DECREF(modeobj);
+        return buffer;
+    }
+
+    /* wraps into a TextIOWrapper */
+    wrapper = PyObject_CallFunction((PyObject *)&PyTextIOWrapper_Type,
+				    "Osssi",
+				    buffer,
+				    encoding, errors, newline,
+				    line_buffering);
+    Py_CLEAR(buffer);
+    if (wrapper == NULL)
+        goto error;
+
+    if (PyObject_SetAttrString(wrapper, "mode", modeobj) < 0)
+        goto error;
+    Py_DECREF(modeobj);
+    return wrapper;
+
+  error:
+    Py_XDECREF(raw);
+    Py_XDECREF(modeobj);
+    Py_XDECREF(buffer);
+    Py_XDECREF(wrapper);
+    return NULL;
+}
+
+/*
+ * Private helpers for the io module.
+ */
+
+Py_off_t
+PyNumber_AsOff_t(PyObject *item, PyObject *err)
+{
+    Py_off_t result;
+    PyObject *runerr;
+    PyObject *value = PyNumber_Index(item);
+    if (value == NULL)
+        return -1;
+
+    if (PyInt_Check(value)) {
+        /* We assume a long always fits in a Py_off_t... */
+        result = (Py_off_t) PyInt_AS_LONG(value);
+        goto finish;
+    }
+
+    /* We're done if PyLong_AsSsize_t() returns without error. */
+    result = PyLong_AsOff_t(value);
+    if (result != -1 || !(runerr = PyErr_Occurred()))
+        goto finish;
+
+    /* Error handling code -- only manage OverflowError differently */
+    if (!PyErr_GivenExceptionMatches(runerr, PyExc_OverflowError))
+        goto finish;
+
+    PyErr_Clear();
+    /* If no error-handling desired then the default clipping
+       is sufficient.
+     */
+    if (!err) {
+        assert(PyLong_Check(value));
+        /* Whether or not it is less than or equal to
+           zero is determined by the sign of ob_size
+        */
+        if (_PyLong_Sign(value) < 0)
+            result = PY_OFF_T_MIN;
+        else
+            result = PY_OFF_T_MAX;
+    }
+    else {
+        /* Otherwise replace the error with caller's error object. */
+        PyErr_Format(err,
+                     "cannot fit '%.200s' into an offset-sized integer",
+                     item->ob_type->tp_name);
+    }
+
+ finish:
+    Py_DECREF(value);
+    return result;
+}
+
+
+/*
+ * Module definition
+ */
+
+PyObject *_PyIO_os_module = NULL;
+PyObject *_PyIO_locale_module = NULL;
+PyObject *_PyIO_unsupported_operation = NULL;
+
+static PyMethodDef module_methods[] = {
+    {"open", (PyCFunction)io_open, METH_VARARGS|METH_KEYWORDS, open_doc},
+    {NULL, NULL}
+};
+
+PyMODINIT_FUNC
+init_io(void)
+{
+    PyObject *m = Py_InitModule4("_io", module_methods,
+                                 module_doc, NULL, PYTHON_API_VERSION);
+    if (m == NULL)
+        return;
+
+    /* put os in the module state */
+    _PyIO_os_module = PyImport_ImportModule("os");
+    if (_PyIO_os_module == NULL)
+        goto fail;
+
+#define ADD_TYPE(type, name) \
+    if (PyType_Ready(type) < 0) \
+        goto fail; \
+    Py_INCREF(type); \
+    if (PyModule_AddObject(m, name, (PyObject *)type) < 0) {  \
+        Py_DECREF(type); \
+        goto fail; \
+    }
+
+    /* DEFAULT_BUFFER_SIZE */
+    if (PyModule_AddIntMacro(m, DEFAULT_BUFFER_SIZE) < 0)
+        goto fail;
+
+    /* UnsupportedOperation inherits from ValueError and IOError */
+    _PyIO_unsupported_operation = PyObject_CallFunction(
+        (PyObject *)&PyType_Type, "s(OO){}",
+        "UnsupportedOperation", PyExc_ValueError, PyExc_IOError);
+    if (_PyIO_unsupported_operation == NULL)
+        goto fail;
+    Py_INCREF(_PyIO_unsupported_operation);
+    if (PyModule_AddObject(m, "UnsupportedOperation",
+                           _PyIO_unsupported_operation) < 0)
+        goto fail;
+
+    /* BlockingIOError */
+    _PyExc_BlockingIOError.tp_base = (PyTypeObject *) PyExc_IOError;
+    ADD_TYPE(&_PyExc_BlockingIOError, "BlockingIOError");
+
+    /* Concrete base types of the IO ABCs.
+       (the ABCs themselves are declared through inheritance in io.py)
+    */
+    ADD_TYPE(&PyIOBase_Type, "_IOBase");
+    ADD_TYPE(&PyRawIOBase_Type, "_RawIOBase");
+    ADD_TYPE(&PyBufferedIOBase_Type, "_BufferedIOBase");
+    ADD_TYPE(&PyTextIOBase_Type, "_TextIOBase");
+
+    /* Implementation of concrete IO objects. */
+    /* FileIO */
+    PyFileIO_Type.tp_base = &PyRawIOBase_Type;
+    ADD_TYPE(&PyFileIO_Type, "FileIO");
+
+    /* BytesIO */
+    PyBytesIO_Type.tp_base = &PyBufferedIOBase_Type;
+    ADD_TYPE(&PyBytesIO_Type, "BytesIO");
+
+    /* StringIO */
+    PyStringIO_Type.tp_base = &PyTextIOBase_Type;
+    ADD_TYPE(&PyStringIO_Type, "StringIO");
+
+    /* BufferedReader */
+    PyBufferedReader_Type.tp_base = &PyBufferedIOBase_Type;
+    ADD_TYPE(&PyBufferedReader_Type, "BufferedReader");
+
+    /* BufferedWriter */
+    PyBufferedWriter_Type.tp_base = &PyBufferedIOBase_Type;
+    ADD_TYPE(&PyBufferedWriter_Type, "BufferedWriter");
+
+    /* BufferedRWPair */
+    PyBufferedRWPair_Type.tp_base = &PyBufferedIOBase_Type;
+    ADD_TYPE(&PyBufferedRWPair_Type, "BufferedRWPair");
+
+    /* BufferedRandom */
+    PyBufferedRandom_Type.tp_base = &PyBufferedIOBase_Type;
+    ADD_TYPE(&PyBufferedRandom_Type, "BufferedRandom");
+
+    /* TextIOWrapper */
+    PyTextIOWrapper_Type.tp_base = &PyTextIOBase_Type;
+    ADD_TYPE(&PyTextIOWrapper_Type, "TextIOWrapper");
+
+    /* IncrementalNewlineDecoder */
+    ADD_TYPE(&PyIncrementalNewlineDecoder_Type, "IncrementalNewlineDecoder");
+
+    /* Interned strings */
+    if (!(_PyIO_str_close = PyString_InternFromString("close")))
+        goto fail;
+    if (!(_PyIO_str_closed = PyString_InternFromString("closed")))
+        goto fail;
+    if (!(_PyIO_str_decode = PyString_InternFromString("decode")))
+        goto fail;
+    if (!(_PyIO_str_encode = PyString_InternFromString("encode")))
+        goto fail;
+    if (!(_PyIO_str_fileno = PyString_InternFromString("fileno")))
+        goto fail;
+    if (!(_PyIO_str_flush = PyString_InternFromString("flush")))
+        goto fail;
+    if (!(_PyIO_str_getstate = PyString_InternFromString("getstate")))
+        goto fail;
+    if (!(_PyIO_str_isatty = PyString_InternFromString("isatty")))
+        goto fail;
+    if (!(_PyIO_str_newlines = PyString_InternFromString("newlines")))
+        goto fail;
+    if (!(_PyIO_str_nl = PyString_InternFromString("\n")))
+        goto fail;
+    if (!(_PyIO_str_read = PyString_InternFromString("read")))
+        goto fail;
+    if (!(_PyIO_str_read1 = PyString_InternFromString("read1")))
+        goto fail;
+    if (!(_PyIO_str_readable = PyString_InternFromString("readable")))
+        goto fail;
+    if (!(_PyIO_str_readinto = PyString_InternFromString("readinto")))
+        goto fail;
+    if (!(_PyIO_str_readline = PyString_InternFromString("readline")))
+        goto fail;
+    if (!(_PyIO_str_reset = PyString_InternFromString("reset")))
+        goto fail;
+    if (!(_PyIO_str_seek = PyString_InternFromString("seek")))
+        goto fail;
+    if (!(_PyIO_str_seekable = PyString_InternFromString("seekable")))
+        goto fail;
+    if (!(_PyIO_str_setstate = PyString_InternFromString("setstate")))
+        goto fail;
+    if (!(_PyIO_str_tell = PyString_InternFromString("tell")))
+        goto fail;
+    if (!(_PyIO_str_truncate = PyString_InternFromString("truncate")))
+        goto fail;
+    if (!(_PyIO_str_write = PyString_InternFromString("write")))
+        goto fail;
+    if (!(_PyIO_str_writable = PyString_InternFromString("writable")))
+        goto fail;
+    
+    if (!(_PyIO_empty_str = PyUnicode_FromStringAndSize(NULL, 0)))
+        goto fail;
+    if (!(_PyIO_empty_bytes = PyBytes_FromStringAndSize(NULL, 0)))
+        goto fail;
+    if (!(_PyIO_zero = PyLong_FromLong(0L)))
+        goto fail;
+
+    return;
+
+  fail:
+    Py_CLEAR(_PyIO_os_module);
+    Py_CLEAR(_PyIO_unsupported_operation);
+    Py_DECREF(m);
+}
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
new file mode 100644
index 0000000..e220ec1
--- /dev/null
+++ b/Modules/_io/_iomodule.h
@@ -0,0 +1,146 @@
+/*
+ * Declarations shared between the different parts of the io module
+ */
+
+/* ABCs */
+extern PyTypeObject PyIOBase_Type;
+extern PyTypeObject PyRawIOBase_Type;
+extern PyTypeObject PyBufferedIOBase_Type;
+extern PyTypeObject PyTextIOBase_Type;
+
+/* Concrete classes */
+extern PyTypeObject PyFileIO_Type;
+extern PyTypeObject PyBytesIO_Type;
+extern PyTypeObject PyStringIO_Type;
+extern PyTypeObject PyBufferedReader_Type;
+extern PyTypeObject PyBufferedWriter_Type;
+extern PyTypeObject PyBufferedRWPair_Type;
+extern PyTypeObject PyBufferedRandom_Type;
+extern PyTypeObject PyTextIOWrapper_Type;
+extern PyTypeObject PyIncrementalNewlineDecoder_Type;
+
+/* These functions are used as METH_NOARGS methods, are normally called
+ * with args=NULL, and return a new reference.
+ * BUT when args=Py_True is passed, they return a borrowed reference.
+ */
+extern PyObject* _PyIOBase_check_readable(PyObject *self, PyObject *args);
+extern PyObject* _PyIOBase_check_writable(PyObject *self, PyObject *args);
+extern PyObject* _PyIOBase_check_seekable(PyObject *self, PyObject *args);
+extern PyObject* _PyIOBase_check_closed(PyObject *self, PyObject *args);
+
+/* Helper for finalization.
+   This function will revive an object ready to be deallocated and try to
+   close() it. It returns 0 if the object can be destroyed, or -1 if it
+   is alive again. */
+extern int _PyIOBase_finalize(PyObject *self);
+
+/* Returns true if the given FileIO object is closed.
+   Doesn't check the argument type, so be careful! */
+extern int _PyFileIO_closed(PyObject *self);
+
+/* Shortcut to the core of the IncrementalNewlineDecoder.decode method */
+extern PyObject *_PyIncrementalNewlineDecoder_decode(
+    PyObject *self, PyObject *input, int final);
+
+/* Finds the first line ending between `start` and `end`.
+   If found, returns the index after the line ending and doesn't touch
+   `*consumed`.
+   If not found, returns -1 and sets `*consumed` to the number of characters
+   which can be safely put aside until another search.
+   
+   NOTE: for performance reasons, `end` must point to a NUL character ('\0'). 
+   Otherwise, the function will scan further and return garbage. */
+extern Py_ssize_t _PyIO_find_line_ending(
+    int translated, int universal, PyObject *readnl,
+    Py_UNICODE *start, Py_UNICODE *end, Py_ssize_t *consumed);
+
+
+#define DEFAULT_BUFFER_SIZE (8 * 1024)  /* bytes */
+
+typedef struct {
+    /* This is the equivalent of PyException_HEAD in 3.x */
+    PyObject_HEAD
+    PyObject *dict;
+    PyObject *args;
+    PyObject *message;
+
+    PyObject *myerrno;
+    PyObject *strerror;
+    PyObject *filename; /* Not used, but part of the IOError object */
+    Py_ssize_t written;
+} PyBlockingIOErrorObject;
+PyAPI_DATA(PyObject *) PyExc_BlockingIOError;
+
+/*
+ * Offset type for positioning.
+ */
+
+#if defined(MS_WIN64) || defined(MS_WINDOWS)
+
+/* Windows uses long long for offsets */
+typedef PY_LONG_LONG Py_off_t;
+# define PyLong_AsOff_t     PyLong_AsLongLong
+# define PyLong_FromOff_t   PyLong_FromLongLong
+# define PY_OFF_T_MAX       PY_LLONG_MAX
+# define PY_OFF_T_MIN       PY_LLONG_MIN
+
+#else
+
+/* Other platforms use off_t */
+typedef off_t Py_off_t;
+#if (SIZEOF_OFF_T == SIZEOF_SIZE_T)
+# define PyLong_AsOff_t     PyLong_AsSsize_t
+# define PyLong_FromOff_t   PyLong_FromSsize_t
+# define PY_OFF_T_MAX       PY_SSIZE_T_MAX
+# define PY_OFF_T_MIN       PY_SSIZE_T_MIN
+#elif (SIZEOF_OFF_T == SIZEOF_LONG_LONG)
+# define PyLong_AsOff_t     PyLong_AsLongLong
+# define PyLong_FromOff_t   PyLong_FromLongLong
+# define PY_OFF_T_MAX       PY_LLONG_MAX
+# define PY_OFF_T_MIN       PY_LLONG_MIN
+#elif (SIZEOF_OFF_T == SIZEOF_LONG)
+# define PyLong_AsOff_t     PyLong_AsLong
+# define PyLong_FromOff_t   PyLong_FromLong
+# define PY_OFF_T_MAX       LONG_MAX
+# define PY_OFF_T_MIN       LONG_MIN
+#else
+# error off_t does not match either size_t, long, or long long!
+#endif
+
+#endif
+
+extern Py_off_t PyNumber_AsOff_t(PyObject *item, PyObject *err);
+
+/* Implementation details */
+
+extern PyObject *_PyIO_os_module;
+extern PyObject *_PyIO_locale_module;
+extern PyObject *_PyIO_unsupported_operation;
+
+extern PyObject *_PyIO_str_close;
+extern PyObject *_PyIO_str_closed;
+extern PyObject *_PyIO_str_decode;
+extern PyObject *_PyIO_str_encode;
+extern PyObject *_PyIO_str_fileno;
+extern PyObject *_PyIO_str_flush;
+extern PyObject *_PyIO_str_getstate;
+extern PyObject *_PyIO_str_isatty;
+extern PyObject *_PyIO_str_newlines;
+extern PyObject *_PyIO_str_nl;
+extern PyObject *_PyIO_str_read;
+extern PyObject *_PyIO_str_read1;
+extern PyObject *_PyIO_str_readable;
+extern PyObject *_PyIO_str_readinto;
+extern PyObject *_PyIO_str_readline;
+extern PyObject *_PyIO_str_reset;
+extern PyObject *_PyIO_str_seek;
+extern PyObject *_PyIO_str_seekable;
+extern PyObject *_PyIO_str_setstate;
+extern PyObject *_PyIO_str_tell;
+extern PyObject *_PyIO_str_truncate;
+extern PyObject *_PyIO_str_writable;
+extern PyObject *_PyIO_str_write;
+
+extern PyObject *_PyIO_empty_str;
+extern PyObject *_PyIO_empty_bytes;
+extern PyObject *_PyIO_zero;
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
new file mode 100644
index 0000000..554e113
--- /dev/null
+++ b/Modules/_io/bufferedio.c
@@ -0,0 +1,2289 @@
+/*
+    An implementation of Buffered I/O as defined by PEP 3116 - "New I/O"
+    
+    Classes defined here: BufferedIOBase, BufferedReader, BufferedWriter,
+    BufferedRandom.
+    
+    Written by Amaury Forgeot d'Arc and Antoine Pitrou
+*/
+
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+#include "structmember.h"
+#include "pythread.h"
+#include "_iomodule.h"
+
+/*
+ * BufferedIOBase class, inherits from IOBase.
+ */
+PyDoc_STRVAR(bufferediobase_doc,
+    "Base class for buffered IO objects.\n"
+    "\n"
+    "The main difference with RawIOBase is that the read() method\n"
+    "supports omitting the size argument, and does not have a default\n"
+    "implementation that defers to readinto().\n"
+    "\n"
+    "In addition, read(), readinto() and write() may raise\n"
+    "BlockingIOError if the underlying raw stream is in non-blocking\n"
+    "mode and not ready; unlike their raw counterparts, they will never\n"
+    "return None.\n"
+    "\n"
+    "A typical implementation should not inherit from a RawIOBase\n"
+    "implementation, but wrap one.\n"
+    );
+
+static PyObject *
+bufferediobase_readinto(PyObject *self, PyObject *args)
+{
+    Py_buffer buf;
+    Py_ssize_t len;
+    PyObject *data;
+
+    if (!PyArg_ParseTuple(args, "w*:readinto", &buf)) {
+        return NULL;
+    }
+
+    data = PyObject_CallMethod(self, "read", "n", buf.len);
+    if (data == NULL)
+        goto error;
+
+    if (!PyBytes_Check(data)) {
+        Py_DECREF(data);
+        PyErr_SetString(PyExc_TypeError, "read() should return bytes");
+        goto error;
+    }
+
+    len = Py_SIZE(data);
+    memcpy(buf.buf, PyBytes_AS_STRING(data), len);
+
+    PyBuffer_Release(&buf);
+    Py_DECREF(data);
+
+    return PyLong_FromSsize_t(len);
+
+  error:
+    PyBuffer_Release(&buf);
+    return NULL;
+}
+
+static PyObject *
+bufferediobase_unsupported(const char *message)
+{
+    PyErr_SetString(_PyIO_unsupported_operation, message);
+    return NULL;
+}
+
+PyDoc_STRVAR(bufferediobase_detach_doc,
+    "Disconnect this buffer from its underlying raw stream and return it.\n"
+    "\n"
+    "After the raw stream has been detached, the buffer is in an unusable\n"
+    "state.\n");
+
+static PyObject *
+bufferediobase_detach(PyObject *self)
+{
+    return bufferediobase_unsupported("detach");
+}
+
+PyDoc_STRVAR(bufferediobase_read_doc,
+    "Read and return up to n bytes.\n"
+    "\n"
+    "If the argument is omitted, None, or negative, reads and\n"
+    "returns all data until EOF.\n"
+    "\n"
+    "If the argument is positive, and the underlying raw stream is\n"
+    "not 'interactive', multiple raw reads may be issued to satisfy\n"
+    "the byte count (unless EOF is reached first).  But for\n"
+    "interactive raw streams (as well as sockets and pipes), at most\n"
+    "one raw read will be issued, and a short result does not imply\n"
+    "that EOF is imminent.\n"
+    "\n"
+    "Returns an empty bytes object on EOF.\n"
+    "\n"
+    "Returns None if the underlying raw stream was open in non-blocking\n"
+    "mode and no data is available at the moment.\n");
+
+static PyObject *
+bufferediobase_read(PyObject *self, PyObject *args)
+{
+    return bufferediobase_unsupported("read");
+}
+
+PyDoc_STRVAR(bufferediobase_read1_doc,
+    "Read and return up to n bytes, with at most one read() call\n"
+    "to the underlying raw stream. A short result does not imply\n"
+    "that EOF is imminent.\n"
+    "\n"
+    "Returns an empty bytes object on EOF.\n");
+
+static PyObject *
+bufferediobase_read1(PyObject *self, PyObject *args)
+{
+    return bufferediobase_unsupported("read1");
+}
+
+PyDoc_STRVAR(bufferediobase_write_doc,
+    "Write the given buffer to the IO stream.\n"
+    "\n"
+    "Returns the number of bytes written, which is never less than\n"
+    "len(b).\n"
+    "\n"
+    "Raises BlockingIOError if the buffer is full and the\n"
+    "underlying raw stream cannot accept more data at the moment.\n");
+
+static PyObject *
+bufferediobase_write(PyObject *self, PyObject *args)
+{
+    return bufferediobase_unsupported("write");
+}
+
+
+static PyMethodDef bufferediobase_methods[] = {
+    {"detach", (PyCFunction)bufferediobase_detach, METH_NOARGS, bufferediobase_detach_doc},
+    {"read", bufferediobase_read, METH_VARARGS, bufferediobase_read_doc},
+    {"read1", bufferediobase_read1, METH_VARARGS, bufferediobase_read1_doc},
+    {"readinto", bufferediobase_readinto, METH_VARARGS, NULL},
+    {"write", bufferediobase_write, METH_VARARGS, bufferediobase_write_doc},
+    {NULL, NULL}
+};
+
+PyTypeObject PyBufferedIOBase_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io._BufferedIOBase",      /*tp_name*/
+    0,                          /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    0,                          /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
+    bufferediobase_doc,         /* tp_doc */
+    0,                          /* tp_traverse */
+    0,                          /* tp_clear */
+    0,                          /* tp_richcompare */
+    0,                          /* tp_weaklistoffset */
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    bufferediobase_methods,     /* tp_methods */
+    0,                          /* tp_members */
+    0,                          /* tp_getset */
+    &PyIOBase_Type,             /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    0,                          /* tp_dictoffset */
+    0,                          /* tp_init */
+    0,                          /* tp_alloc */
+    0,                          /* tp_new */
+};
+
+
+typedef struct {
+    PyObject_HEAD
+
+    PyObject *raw;
+    int ok;    /* Initialized? */
+    int detached;
+    int readable;
+    int writable;
+    
+    /* True if this is a vanilla Buffered object (rather than a user derived
+       class) *and* the raw stream is a vanilla FileIO object. */
+    int fast_closed_checks;
+
+    /* Absolute position inside the raw stream (-1 if unknown). */
+    Py_off_t abs_pos;
+
+    /* A static buffer of size `buffer_size` */
+    char *buffer;
+    /* Current logical position in the buffer. */
+    Py_off_t pos;
+    /* Position of the raw stream in the buffer. */
+    Py_off_t raw_pos;
+
+    /* Just after the last buffered byte in the buffer, or -1 if the buffer
+       isn't ready for reading. */
+    Py_off_t read_end;
+
+    /* Just after the last byte actually written */
+    Py_off_t write_pos;
+    /* Just after the last byte waiting to be written, or -1 if the buffer
+       isn't ready for writing. */
+    Py_off_t write_end;
+
+#ifdef WITH_THREAD
+    PyThread_type_lock lock;
+#endif
+
+    Py_ssize_t buffer_size;
+    Py_ssize_t buffer_mask;
+
+    PyObject *dict;
+    PyObject *weakreflist;
+} buffered;
+
+/*
+    Implementation notes:
+    
+    * BufferedReader, BufferedWriter and BufferedRandom try to share most
+      methods (this is helped by the members `readable` and `writable`, which
+      are initialized in the respective constructors)
+    * They also share a single buffer for reading and writing. This enables
+      interleaved reads and writes without flushing. It also makes the logic
+      a bit trickier to get right.
+    * The absolute position of the raw stream is cached, if possible, in the
+      `abs_pos` member. It must be updated every time an operation is done
+      on the raw stream. If not sure, it can be reinitialized by calling
+      _buffered_raw_tell(), which queries the raw stream (_buffered_raw_seek()
+      also does it). To read it, use RAW_TELL().
+    * Three helpers, _bufferedreader_raw_read, _bufferedwriter_raw_write and
+      _bufferedwriter_flush_unlocked do a lot of useful housekeeping.
+
+    NOTE: we should try to maintain block alignment of reads and writes to the
+    raw stream (according to the buffer size), but for now it is only done
+    in read() and friends.
+    
+*/
+
+/* These macros protect the buffered object against concurrent operations. */
+
+#ifdef WITH_THREAD
+#define ENTER_BUFFERED(self) \
+    Py_BEGIN_ALLOW_THREADS \
+    PyThread_acquire_lock(self->lock, 1); \
+    Py_END_ALLOW_THREADS
+
+#define LEAVE_BUFFERED(self) \
+    PyThread_release_lock(self->lock);
+#else
+#define ENTER_BUFFERED(self)
+#define LEAVE_BUFFERED(self)
+#endif
+
+#define CHECK_INITIALIZED(self) \
+    if (self->ok <= 0) { \
+        if (self->detached) { \
+            PyErr_SetString(PyExc_ValueError, \
+                 "raw stream has been detached"); \
+        } else { \
+            PyErr_SetString(PyExc_ValueError, \
+                "I/O operation on uninitialized object"); \
+        } \
+        return NULL; \
+    }
+
+#define CHECK_INITIALIZED_INT(self) \
+    if (self->ok <= 0) { \
+        if (self->detached) { \
+            PyErr_SetString(PyExc_ValueError, \
+                 "raw stream has been detached"); \
+        } else { \
+            PyErr_SetString(PyExc_ValueError, \
+                "I/O operation on uninitialized object"); \
+        } \
+        return -1; \
+    }
+
+#define IS_CLOSED(self) \
+    (self->fast_closed_checks \
+     ? _PyFileIO_closed(self->raw) \
+     : buffered_closed(self))
+
+#define CHECK_CLOSED(self, error_msg) \
+    if (IS_CLOSED(self)) { \
+        PyErr_SetString(PyExc_ValueError, error_msg); \
+        return NULL; \
+    }
+
+
+#define VALID_READ_BUFFER(self) \
+    (self->readable && self->read_end != -1)
+
+#define VALID_WRITE_BUFFER(self) \
+    (self->writable && self->write_end != -1)
+
+#define ADJUST_POSITION(self, _new_pos) \
+    do { \
+        self->pos = _new_pos; \
+        if (VALID_READ_BUFFER(self) && self->read_end < self->pos) \
+            self->read_end = self->pos; \
+    } while(0)
+
+#define READAHEAD(self) \
+    ((self->readable && VALID_READ_BUFFER(self)) \
+        ? (self->read_end - self->pos) : 0)
+
+#define RAW_OFFSET(self) \
+    (((VALID_READ_BUFFER(self) || VALID_WRITE_BUFFER(self)) \
+        && self->raw_pos >= 0) ? self->raw_pos - self->pos : 0)
+
+#define RAW_TELL(self) \
+    (self->abs_pos != -1 ? self->abs_pos : _buffered_raw_tell(self))
+
+#define MINUS_LAST_BLOCK(self, size) \
+    (self->buffer_mask ? \
+        (size & ~self->buffer_mask) : \
+        (self->buffer_size * (size / self->buffer_size)))
+
+
+static void
+buffered_dealloc(buffered *self)
+{
+    if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
+        return;
+    _PyObject_GC_UNTRACK(self);
+    self->ok = 0;
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *)self);
+    Py_CLEAR(self->raw);
+    if (self->buffer) {
+        PyMem_Free(self->buffer);
+        self->buffer = NULL;
+    }
+#ifdef WITH_THREAD
+    if (self->lock) {
+        PyThread_free_lock(self->lock);
+        self->lock = NULL;
+    }
+#endif
+    Py_CLEAR(self->dict);
+    Py_TYPE(self)->tp_free((PyObject *)self);
+}
+
+static int
+buffered_traverse(buffered *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->raw);
+    Py_VISIT(self->dict);
+    return 0;
+}
+
+static int
+buffered_clear(buffered *self)
+{
+    if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
+        return -1;
+    self->ok = 0;
+    Py_CLEAR(self->raw);
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+/*
+ * _BufferedIOMixin methods
+ * This is not a class, just a collection of methods that will be reused
+ * by BufferedReader and BufferedWriter
+ */
+
+/* Flush and close */
+
+static PyObject *
+buffered_simple_flush(buffered *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodObjArgs(self->raw, _PyIO_str_flush, NULL);
+}
+
+static int
+buffered_closed(buffered *self)
+{
+    int closed;
+    PyObject *res;
+    CHECK_INITIALIZED_INT(self)
+    res = PyObject_GetAttr(self->raw, _PyIO_str_closed);
+    if (res == NULL)
+        return -1;
+    closed = PyObject_IsTrue(res);
+    Py_DECREF(res);
+    return closed;
+}
+
+static PyObject *
+buffered_closed_get(buffered *self, void *context)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_GetAttr(self->raw, _PyIO_str_closed);
+}
+
+static PyObject *
+buffered_close(buffered *self, PyObject *args)
+{
+    PyObject *res = NULL;
+    int r;
+
+    CHECK_INITIALIZED(self)
+    ENTER_BUFFERED(self)
+
+    r = buffered_closed(self);
+    if (r < 0)
+        goto end;
+    if (r > 0) {
+        res = Py_None;
+        Py_INCREF(res);
+        goto end;
+    }
+    /* flush() will most probably re-take the lock, so drop it first */
+    LEAVE_BUFFERED(self)
+    res = PyObject_CallMethodObjArgs((PyObject *)self, _PyIO_str_flush, NULL);
+    ENTER_BUFFERED(self)
+    if (res == NULL) {
+        /* If flush() fails, just give up */
+        if (PyErr_ExceptionMatches(PyExc_IOError))
+            PyErr_Clear();
+        else
+            goto end;
+    }
+    Py_XDECREF(res);
+
+    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_close, NULL);
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+/* detach */
+
+static PyObject *
+buffered_detach(buffered *self, PyObject *args)
+{
+    PyObject *raw, *res;
+    CHECK_INITIALIZED(self)
+    res = PyObject_CallMethodObjArgs((PyObject *)self, _PyIO_str_flush, NULL);
+    if (res == NULL)
+        return NULL;
+    Py_DECREF(res);
+    raw = self->raw;
+    self->raw = NULL;
+    self->detached = 1;
+    self->ok = 0;
+    return raw;
+}
+
+/* Inquiries */
+
+static PyObject *
+buffered_seekable(buffered *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodObjArgs(self->raw, _PyIO_str_seekable, NULL);
+}
+
+static PyObject *
+buffered_readable(buffered *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodObjArgs(self->raw, _PyIO_str_readable, NULL);
+}
+
+static PyObject *
+buffered_writable(buffered *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodObjArgs(self->raw, _PyIO_str_writable, NULL);
+}
+
+static PyObject *
+buffered_name_get(buffered *self, void *context)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_GetAttrString(self->raw, "name");
+}
+
+static PyObject *
+buffered_mode_get(buffered *self, void *context)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_GetAttrString(self->raw, "mode");
+}
+
+/* Lower-level APIs */
+
+static PyObject *
+buffered_fileno(buffered *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodObjArgs(self->raw, _PyIO_str_fileno, NULL);
+}
+
+static PyObject *
+buffered_isatty(buffered *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self)
+    return PyObject_CallMethodObjArgs(self->raw, _PyIO_str_isatty, NULL);
+}
+
+
+/* Forward decls */
+static PyObject *
+_bufferedwriter_flush_unlocked(buffered *, int);
+static Py_ssize_t
+_bufferedreader_fill_buffer(buffered *self);
+static void
+_bufferedreader_reset_buf(buffered *self);
+static void
+_bufferedwriter_reset_buf(buffered *self);
+static PyObject *
+_bufferedreader_peek_unlocked(buffered *self, Py_ssize_t);
+static PyObject *
+_bufferedreader_read_all(buffered *self);
+static PyObject *
+_bufferedreader_read_fast(buffered *self, Py_ssize_t);
+static PyObject *
+_bufferedreader_read_generic(buffered *self, Py_ssize_t);
+
+
+/*
+ * Helpers
+ */
+
+/* Returns the address of the `written` member if a BlockingIOError was
+   raised, NULL otherwise. The error is always re-raised. */
+static Py_ssize_t *
+_buffered_check_blocking_error(void)
+{
+    PyObject *t, *v, *tb;
+    PyBlockingIOErrorObject *err;
+
+    PyErr_Fetch(&t, &v, &tb);
+    if (v == NULL || !PyErr_GivenExceptionMatches(v, PyExc_BlockingIOError)) {
+        PyErr_Restore(t, v, tb);
+        return NULL;
+    }
+    err = (PyBlockingIOErrorObject *) v;
+    /* TODO: sanity check (err->written >= 0) */
+    PyErr_Restore(t, v, tb);
+    return &err->written;
+}
+
+static Py_off_t
+_buffered_raw_tell(buffered *self)
+{
+    Py_off_t n;
+    PyObject *res;
+    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_tell, NULL);
+    if (res == NULL)
+        return -1;
+    n = PyNumber_AsOff_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0) {
+        if (!PyErr_Occurred())
+            PyErr_Format(PyExc_IOError,
+                         "Raw stream returned invalid position %zd", n);
+        return -1;
+    }
+    self->abs_pos = n;
+    return n;
+}
+
+static Py_off_t
+_buffered_raw_seek(buffered *self, Py_off_t target, int whence)
+{
+    PyObject *res, *posobj, *whenceobj;
+    Py_off_t n;
+
+    posobj = PyLong_FromOff_t(target);
+    if (posobj == NULL)
+        return -1;
+    whenceobj = PyLong_FromLong(whence);
+    if (whenceobj == NULL) {
+        Py_DECREF(posobj);
+        return -1;
+    }
+    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_seek,
+                                     posobj, whenceobj, NULL);
+    Py_DECREF(posobj);
+    Py_DECREF(whenceobj);
+    if (res == NULL)
+        return -1;
+    n = PyNumber_AsOff_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0) {
+        if (!PyErr_Occurred())
+            PyErr_Format(PyExc_IOError,
+                         "Raw stream returned invalid position %zd", n);
+        return -1;
+    }
+    self->abs_pos = n;
+    return n;
+}
+
+static int
+_buffered_init(buffered *self)
+{
+    Py_ssize_t n;
+    if (self->buffer_size <= 0) {
+        PyErr_SetString(PyExc_ValueError,
+            "buffer size must be strictly positive");
+        return -1;
+    }
+    if (self->buffer)
+        PyMem_Free(self->buffer);
+    self->buffer = PyMem_Malloc(self->buffer_size);
+    if (self->buffer == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+#ifdef WITH_THREAD
+    self->lock = PyThread_allocate_lock();
+    if (self->lock == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "can't allocate read lock");
+        return -1;
+    }
+#endif
+    /* Find out whether buffer_size is a power of 2 */
+    /* XXX is this optimization useful? */
+    for (n = self->buffer_size - 1; n & 1; n >>= 1)
+        ;
+    if (n == 0)
+        self->buffer_mask = self->buffer_size - 1;
+    else
+        self->buffer_mask = 0;
+    if (_buffered_raw_tell(self) == -1)
+        PyErr_Clear();
+    return 0;
+}
+
+/*
+ * Shared methods and wrappers
+ */
+
+static PyObject *
+buffered_flush(buffered *self, PyObject *args)
+{
+    PyObject *res;
+
+    CHECK_INITIALIZED(self)
+    CHECK_CLOSED(self, "flush of closed file")
+
+    ENTER_BUFFERED(self)
+    res = _bufferedwriter_flush_unlocked(self, 0);
+    if (res != NULL && self->readable) {
+        /* Rewind the raw stream so that its position corresponds to
+           the current logical position. */
+        Py_off_t n;
+        n = _buffered_raw_seek(self, -RAW_OFFSET(self), 1);
+        if (n == -1)
+            Py_CLEAR(res);
+        _bufferedreader_reset_buf(self);
+    }
+    LEAVE_BUFFERED(self)
+
+    return res;
+}
+
+static PyObject *
+buffered_peek(buffered *self, PyObject *args)
+{
+    Py_ssize_t n = 0;
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "|n:peek", &n)) {
+        return NULL;
+    }
+
+    ENTER_BUFFERED(self)
+
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self, 1);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+    res = _bufferedreader_peek_unlocked(self, n);
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+static PyObject *
+buffered_read(buffered *self, PyObject *args)
+{
+    Py_ssize_t n = -1;
+    PyObject *res;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "|n:read", &n)) {
+        return NULL;
+    }
+    if (n < -1) {
+        PyErr_SetString(PyExc_ValueError,
+                        "read length must be positive or -1");
+        return NULL;
+    }
+
+    CHECK_CLOSED(self, "read of closed file")
+
+    if (n == -1) {
+        /* The number of bytes is unspecified, read until the end of stream */
+        ENTER_BUFFERED(self)
+        res = _bufferedreader_read_all(self);
+        LEAVE_BUFFERED(self)
+    }
+    else {
+        res = _bufferedreader_read_fast(self, n);
+        if (res == Py_None) {
+            Py_DECREF(res);
+            ENTER_BUFFERED(self)
+            res = _bufferedreader_read_generic(self, n);
+            LEAVE_BUFFERED(self)
+        }
+    }
+
+    return res;
+}
+
+static PyObject *
+buffered_read1(buffered *self, PyObject *args)
+{
+    Py_ssize_t n, have, r;
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "n:read1", &n)) {
+        return NULL;
+    }
+
+    if (n < 0) {
+        PyErr_SetString(PyExc_ValueError,
+                        "read length must be positive");
+        return NULL;
+    }
+    if (n == 0)
+        return PyBytes_FromStringAndSize(NULL, 0);
+
+    ENTER_BUFFERED(self)
+    
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self, 1);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+
+    /* Return up to n bytes.  If at least one byte is buffered, we
+       only return buffered bytes.  Otherwise, we do one raw read. */
+
+    /* XXX: this mimicks the io.py implementation but is probably wrong.
+       If we need to read from the raw stream, then we could actually read
+       all `n` bytes asked by the caller (and possibly more, so as to fill
+       our buffer for the next reads). */
+
+    have = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (have > 0) {
+        if (n > have)
+            n = have;
+        res = PyBytes_FromStringAndSize(self->buffer + self->pos, n);
+        if (res == NULL)
+            goto end;
+        self->pos += n;
+        goto end;
+    }
+
+    /* Fill the buffer from the raw stream, and copy it to the result. */
+    _bufferedreader_reset_buf(self);
+    r = _bufferedreader_fill_buffer(self);
+    if (r == -1)
+        goto end;
+    if (r == -2)
+        r = 0;
+    if (n > r)
+        n = r;
+    res = PyBytes_FromStringAndSize(self->buffer, n);
+    if (res == NULL)
+        goto end;
+    self->pos = n;
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+static PyObject *
+buffered_readinto(buffered *self, PyObject *args)
+{
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    
+    /* TODO: use raw.readinto() instead! */
+    if (self->writable) {
+        ENTER_BUFFERED(self)
+        res = _bufferedwriter_flush_unlocked(self, 0);
+        LEAVE_BUFFERED(self)
+        if (res == NULL)
+            goto end;
+        Py_DECREF(res);
+    }
+    res = bufferediobase_readinto((PyObject *)self, args);
+
+end:
+    return res;
+}
+
+static PyObject *
+_buffered_readline(buffered *self, Py_ssize_t limit)
+{
+    PyObject *res = NULL;
+    PyObject *chunks = NULL;
+    Py_ssize_t n, written = 0;
+    const char *start, *s, *end;
+
+    CHECK_CLOSED(self, "readline of closed file")
+
+    /* First, try to find a line in the buffer. This can run unlocked because
+       the calls to the C API are simple enough that they can't trigger
+       any thread switch. */
+    n = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (limit >= 0 && n > limit)
+        n = limit;
+    start = self->buffer + self->pos;
+    s = memchr(start, '\n', n);
+    if (s != NULL) {
+        res = PyBytes_FromStringAndSize(start, s - start + 1);
+        if (res != NULL)
+            self->pos += s - start + 1;
+        goto end_unlocked;
+    }
+    if (n == limit) {
+        res = PyBytes_FromStringAndSize(start, n);
+        if (res != NULL)
+            self->pos += n;
+        goto end_unlocked;
+    }
+
+    ENTER_BUFFERED(self)
+
+    /* Now we try to get some more from the raw stream */
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self, 1);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+    chunks = PyList_New(0);
+    if (chunks == NULL)
+        goto end;
+    if (n > 0) {
+        res = PyBytes_FromStringAndSize(start, n);
+        if (res == NULL)
+            goto end;
+        if (PyList_Append(chunks, res) < 0) {
+            Py_CLEAR(res);
+            goto end;
+        }
+        Py_CLEAR(res);
+        written += n;
+        if (limit >= 0)
+            limit -= n;
+    }
+
+    for (;;) {
+        _bufferedreader_reset_buf(self);
+        n = _bufferedreader_fill_buffer(self);
+        if (n == -1)
+            goto end;
+        if (n <= 0)
+            break;
+        if (limit >= 0 && n > limit)
+            n = limit;
+        start = self->buffer;
+        end = start + n;
+        s = start;
+        while (s < end) {
+            if (*s++ == '\n') {
+                res = PyBytes_FromStringAndSize(start, s - start);
+                if (res == NULL)
+                    goto end;
+                self->pos = s - start;
+                goto found;
+            }
+        }
+        res = PyBytes_FromStringAndSize(start, n);
+        if (res == NULL)
+            goto end;
+        if (n == limit) {
+            self->pos = n;
+            break;
+        }
+        if (PyList_Append(chunks, res) < 0) {
+            Py_CLEAR(res);
+            goto end;
+        }
+        Py_CLEAR(res);
+        written += n;
+        if (limit >= 0)
+            limit -= n;
+    }
+found:
+    if (res != NULL && PyList_Append(chunks, res) < 0) {
+        Py_CLEAR(res);
+        goto end;
+    }
+    Py_CLEAR(res);
+    res = _PyBytes_Join(_PyIO_empty_bytes, chunks);
+
+end:
+    LEAVE_BUFFERED(self)
+end_unlocked:
+    Py_XDECREF(chunks);
+    return res;
+}
+
+static PyObject *
+buffered_readline(buffered *self, PyObject *args)
+{
+    PyObject *limitobj = NULL;
+    Py_ssize_t limit = -1;
+
+    CHECK_INITIALIZED(self)
+
+    if (!PyArg_ParseTuple(args, "|O:readline", &limitobj)) {
+        return NULL;
+    }
+    if (limitobj) {
+        if (!PyNumber_Check(limitobj)) {
+            PyErr_Format(PyExc_TypeError,
+                         "integer argument expected, got '%.200s'",
+                         Py_TYPE(limitobj)->tp_name);
+            return NULL;
+        }
+        limit = PyNumber_AsSsize_t(limitobj, PyExc_OverflowError);
+        if (limit == -1 && PyErr_Occurred())
+            return NULL;
+    }
+    return _buffered_readline(self, limit);
+}
+
+
+static PyObject *
+buffered_tell(buffered *self, PyObject *args)
+{
+    Py_off_t pos;
+
+    CHECK_INITIALIZED(self)
+    pos = _buffered_raw_tell(self);
+    if (pos == -1)
+        return NULL;
+    pos -= RAW_OFFSET(self);
+    /* TODO: sanity check (pos >= 0) */
+    return PyLong_FromOff_t(pos);
+}
+
+static PyObject *
+buffered_seek(buffered *self, PyObject *args)
+{
+    Py_off_t target, n;
+    int whence = 0;
+    PyObject *targetobj, *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "O|i:seek", &targetobj, &whence)) {
+        return NULL;
+    }
+    if (whence < 0 || whence > 2) {
+        PyErr_Format(PyExc_ValueError,
+                     "whence must be between 0 and 2, not %d", whence);
+        return NULL;
+    }
+
+    CHECK_CLOSED(self, "seek of closed file")
+
+    target = PyNumber_AsOff_t(targetobj, PyExc_ValueError);
+    if (target == -1 && PyErr_Occurred())
+        return NULL;
+
+    if (whence != 2 && self->readable) {
+        Py_off_t current, avail;
+        /* Check if seeking leaves us inside the current buffer,
+           so as to return quickly if possible. Also, we needn't take the
+           lock in this fast path.
+           Don't know how to do that when whence == 2, though. */
+        /* NOTE: RAW_TELL() can release the GIL but the object is in a stable
+           state at this point. */
+        current = RAW_TELL(self);
+        avail = READAHEAD(self);
+        if (avail > 0) {
+            Py_off_t offset;
+            if (whence == 0)
+                offset = target - (current - RAW_OFFSET(self));
+            else
+                offset = target;
+            if (offset >= -self->pos && offset <= avail) {
+                self->pos += offset;
+                return PyLong_FromOff_t(current - avail + offset);
+            }
+        }
+    }
+
+    ENTER_BUFFERED(self)
+
+    /* Fallback: invoke raw seek() method and clear buffer */
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self, 0);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+        _bufferedwriter_reset_buf(self);
+    }
+
+    /* TODO: align on block boundary and read buffer if needed? */
+    if (whence == 1)
+        target -= RAW_OFFSET(self);
+    n = _buffered_raw_seek(self, target, whence);
+    if (n == -1)
+        goto end;
+    self->raw_pos = -1;
+    res = PyLong_FromOff_t(n);
+    if (res != NULL && self->readable)
+        _bufferedreader_reset_buf(self);
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+static PyObject *
+buffered_truncate(buffered *self, PyObject *args)
+{
+    PyObject *pos = Py_None;
+    PyObject *res = NULL;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "|O:truncate", &pos)) {
+        return NULL;
+    }
+
+    ENTER_BUFFERED(self)
+
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self, 0);
+        if (res == NULL)
+            goto end;
+        Py_CLEAR(res);
+    }
+    if (self->readable) {
+        if (pos == Py_None) {
+            /* Rewind the raw stream so that its position corresponds to
+               the current logical position. */
+            if (_buffered_raw_seek(self, -RAW_OFFSET(self), 1) == -1)
+                goto end;
+        }
+        _bufferedreader_reset_buf(self);
+    }
+    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_truncate, pos, NULL);
+    if (res == NULL)
+        goto end;
+    /* Reset cached position */
+    if (_buffered_raw_tell(self) == -1)
+        PyErr_Clear();
+
+end:
+    LEAVE_BUFFERED(self)
+    return res;
+}
+
+static PyObject *
+buffered_iternext(buffered *self)
+{
+    PyObject *line;
+    PyTypeObject *tp;
+
+    CHECK_INITIALIZED(self);
+
+    tp = Py_TYPE(self);
+    if (tp == &PyBufferedReader_Type ||
+        tp == &PyBufferedRandom_Type) {
+        /* Skip method call overhead for speed */
+        line = _buffered_readline(self, -1);
+    }
+    else {
+        line = PyObject_CallMethodObjArgs((PyObject *)self,
+                                           _PyIO_str_readline, NULL);
+        if (line && !PyBytes_Check(line)) {
+            PyErr_Format(PyExc_IOError,
+                         "readline() should have returned a bytes object, "
+                         "not '%.200s'", Py_TYPE(line)->tp_name);
+            Py_DECREF(line);
+            return NULL;
+        }
+    }
+
+    if (line == NULL)
+        return NULL;
+
+    if (PyBytes_GET_SIZE(line) == 0) {
+        /* Reached EOF or would have blocked */
+        Py_DECREF(line);
+        return NULL;
+    }
+
+    return line;
+}
+
+static PyObject *
+buffered_repr(buffered *self)
+{
+    PyObject *nameobj, *res;
+
+    nameobj = PyObject_GetAttrString((PyObject *) self, "name");
+    if (nameobj == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_AttributeError))
+            PyErr_Clear();
+        else
+            return NULL;
+        res = PyString_FromFormat("<%s>", Py_TYPE(self)->tp_name);
+    }
+    else {
+        PyObject *repr = PyObject_Repr(nameobj);
+        Py_DECREF(nameobj);
+        if (repr == NULL)
+            return NULL;
+        res = PyString_FromFormat("<%s name=%s>",
+                                   Py_TYPE(self)->tp_name,
+                                   PyString_AS_STRING(repr));
+        Py_DECREF(repr);
+    }
+    return res;
+}
+
+/*
+ * class BufferedReader
+ */
+
+PyDoc_STRVAR(bufferedreader_doc,
+             "Create a new buffered reader using the given readable raw IO object.");
+
+static void _bufferedreader_reset_buf(buffered *self)
+{
+    self->read_end = -1;
+}
+
+static int
+bufferedreader_init(buffered *self, PyObject *args, PyObject *kwds)
+{
+    char *kwlist[] = {"raw", "buffer_size", NULL};
+    Py_ssize_t buffer_size = DEFAULT_BUFFER_SIZE;
+    PyObject *raw;
+
+    self->ok = 0;
+    self->detached = 0;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|n:BufferedReader", kwlist,
+                                     &raw, &buffer_size)) {
+        return -1;
+    }
+
+    if (_PyIOBase_check_readable(raw, Py_True) == NULL)
+        return -1;
+
+    Py_CLEAR(self->raw);
+    Py_INCREF(raw);
+    self->raw = raw;
+    self->buffer_size = buffer_size;
+    self->readable = 1;
+    self->writable = 0;
+
+    if (_buffered_init(self) < 0)
+        return -1;
+    _bufferedreader_reset_buf(self);
+
+    self->fast_closed_checks = (Py_TYPE(self) == &PyBufferedReader_Type &&
+                                Py_TYPE(raw) == &PyFileIO_Type);
+
+    self->ok = 1;
+    return 0;
+}
+
+static Py_ssize_t
+_bufferedreader_raw_read(buffered *self, char *start, Py_ssize_t len)
+{
+    Py_buffer buf;
+    PyObject *memobj, *res;
+    Py_ssize_t n;
+    /* NOTE: the buffer needn't be released as its object is NULL. */
+    if (PyBuffer_FillInfo(&buf, NULL, start, len, 0, PyBUF_CONTIG) == -1)
+        return -1;
+    memobj = PyMemoryView_FromBuffer(&buf);
+    if (memobj == NULL)
+        return -1;
+    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_readinto, memobj, NULL);
+    Py_DECREF(memobj);
+    if (res == NULL)
+        return -1;
+    if (res == Py_None) {
+        /* Non-blocking stream would have blocked. Special return code! */
+        Py_DECREF(res);
+        return -2;
+    }
+    n = PyNumber_AsSsize_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0 || n > len) {
+        PyErr_Format(PyExc_IOError,
+                     "raw readinto() returned invalid length %zd "
+                     "(should have been between 0 and %zd)", n, len);
+        return -1;
+    }
+    if (n > 0 && self->abs_pos != -1)
+        self->abs_pos += n;
+    return n;
+}
+
+static Py_ssize_t
+_bufferedreader_fill_buffer(buffered *self)
+{
+    Py_ssize_t start, len, n;
+    if (VALID_READ_BUFFER(self))
+        start = Py_SAFE_DOWNCAST(self->read_end, Py_off_t, Py_ssize_t);
+    else
+        start = 0;
+    len = self->buffer_size - start;
+    n = _bufferedreader_raw_read(self, self->buffer + start, len);
+    if (n <= 0)
+        return n;
+    self->read_end = start + n;
+    self->raw_pos = start + n;
+    return n;
+}
+
+static PyObject *
+_bufferedreader_read_all(buffered *self)
+{
+    Py_ssize_t current_size;
+    PyObject *res, *data = NULL;
+    PyObject *chunks = PyList_New(0);
+
+    if (chunks == NULL)
+        return NULL;
+
+    /* First copy what we have in the current buffer. */
+    current_size = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (current_size) {
+        data = PyBytes_FromStringAndSize(
+            self->buffer + self->pos, current_size);
+        if (data == NULL) {
+            Py_DECREF(chunks);
+            return NULL;
+        }
+    }
+    _bufferedreader_reset_buf(self);
+    /* We're going past the buffer's bounds, flush it */
+    if (self->writable) {
+        res = _bufferedwriter_flush_unlocked(self, 1);
+        if (res == NULL) {
+            Py_DECREF(chunks);
+            return NULL;
+        }
+        Py_CLEAR(res);
+    }
+    while (1) {
+        if (data) {
+            if (PyList_Append(chunks, data) < 0) {
+                Py_DECREF(data);
+                Py_DECREF(chunks);
+                return NULL;
+            }
+            Py_DECREF(data);
+        }
+
+        /* Read until EOF or until read() would block. */
+        data = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_read, NULL);
+        if (data == NULL) {
+            Py_DECREF(chunks);
+            return NULL;
+        }
+        if (data != Py_None && !PyBytes_Check(data)) {
+            Py_DECREF(data);
+            Py_DECREF(chunks);
+            PyErr_SetString(PyExc_TypeError, "read() should return bytes");
+            return NULL;
+        }
+        if (data == Py_None || PyBytes_GET_SIZE(data) == 0) {
+            if (current_size == 0) {
+                Py_DECREF(chunks);
+                return data;
+            }
+            else {
+                res = _PyBytes_Join(_PyIO_empty_bytes, chunks);
+                Py_DECREF(data);
+                Py_DECREF(chunks);
+                return res;
+            }
+        }
+        current_size += PyBytes_GET_SIZE(data);
+        if (self->abs_pos != -1)
+            self->abs_pos += PyBytes_GET_SIZE(data);
+    }
+}
+
+/* Read n bytes from the buffer if it can, otherwise return None.
+   This function is simple enough that it can run unlocked. */
+static PyObject *
+_bufferedreader_read_fast(buffered *self, Py_ssize_t n)
+{
+    Py_ssize_t current_size;
+
+    current_size = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (n <= current_size) {
+        /* Fast path: the data to read is fully buffered. */
+        PyObject *res = PyBytes_FromStringAndSize(self->buffer + self->pos, n);
+        if (res != NULL)
+            self->pos += n;
+        return res;
+    }
+    Py_RETURN_NONE;
+}
+
+/* Generic read function: read from the stream until enough bytes are read,
+ * or until an EOF occurs or until read() would block.
+ */
+static PyObject *
+_bufferedreader_read_generic(buffered *self, Py_ssize_t n)
+{
+    PyObject *res = NULL;
+    Py_ssize_t current_size, remaining, written;
+    char *out;
+
+    current_size = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    if (n <= current_size)
+        return _bufferedreader_read_fast(self, n);
+
+    res = PyBytes_FromStringAndSize(NULL, n);
+    if (res == NULL)
+        goto error;
+    out = PyBytes_AS_STRING(res);
+    remaining = n;
+    written = 0;
+    if (current_size > 0) {
+        memcpy(out, self->buffer + self->pos, current_size);
+        remaining -= current_size;
+        written += current_size;
+    }
+    _bufferedreader_reset_buf(self);
+    while (remaining > 0) {
+        /* We want to read a whole block at the end into buffer.
+           If we had readv() we could do this in one pass. */
+        Py_ssize_t r = MINUS_LAST_BLOCK(self, remaining);
+        if (r == 0)
+            break;
+        r = _bufferedreader_raw_read(self, out + written, r);
+        if (r == -1)
+            goto error;
+        if (r == 0 || r == -2) {
+            /* EOF occurred or read() would block. */
+            if (r == 0 || written > 0) {
+                if (_PyBytes_Resize(&res, written))
+                    goto error;
+                return res;
+            }
+            Py_DECREF(res);
+            Py_INCREF(Py_None);
+            return Py_None;
+        }
+        remaining -= r;
+        written += r;
+    }
+    assert(remaining <= self->buffer_size);
+    self->pos = 0;
+    self->raw_pos = 0;
+    self->read_end = 0;
+    while (self->read_end < self->buffer_size) {
+        Py_ssize_t r = _bufferedreader_fill_buffer(self);
+        if (r == -1)
+            goto error;
+        if (r == 0 || r == -2) {
+            /* EOF occurred or read() would block. */
+            if (r == 0 || written > 0) {
+                if (_PyBytes_Resize(&res, written))
+                    goto error;
+                return res;
+            }
+            Py_DECREF(res);
+            Py_INCREF(Py_None);
+            return Py_None;
+        }
+        if (remaining > r) {
+            memcpy(out + written, self->buffer + self->pos, r);
+            written += r;
+            self->pos += r;
+            remaining -= r;
+        }
+        else if (remaining > 0) {
+            memcpy(out + written, self->buffer + self->pos, remaining);
+            written += remaining;
+            self->pos += remaining;
+            remaining = 0;
+        }
+        if (remaining == 0)
+            break;
+    }
+
+    return res;
+
+error:
+    Py_XDECREF(res);
+    return NULL;
+}
+
+static PyObject *
+_bufferedreader_peek_unlocked(buffered *self, Py_ssize_t n)
+{
+    Py_ssize_t have, r;
+
+    have = Py_SAFE_DOWNCAST(READAHEAD(self), Py_off_t, Py_ssize_t);
+    /* Constraints:
+       1. we don't want to advance the file position.
+       2. we don't want to lose block alignment, so we can't shift the buffer
+          to make some place.
+       Therefore, we either return `have` bytes (if > 0), or a full buffer.
+    */
+    if (have > 0) {
+        return PyBytes_FromStringAndSize(self->buffer + self->pos, have);
+    }
+
+    /* Fill the buffer from the raw stream, and copy it to the result. */
+    _bufferedreader_reset_buf(self);
+    r = _bufferedreader_fill_buffer(self);
+    if (r == -1)
+        return NULL;
+    if (r == -2)
+        r = 0;
+    self->pos = 0;
+    return PyBytes_FromStringAndSize(self->buffer, r);
+}
+
+static PyMethodDef bufferedreader_methods[] = {
+    /* BufferedIOMixin methods */
+    {"detach", (PyCFunction)buffered_detach, METH_NOARGS},
+    {"flush", (PyCFunction)buffered_simple_flush, METH_NOARGS},
+    {"close", (PyCFunction)buffered_close, METH_NOARGS},
+    {"seekable", (PyCFunction)buffered_seekable, METH_NOARGS},
+    {"readable", (PyCFunction)buffered_readable, METH_NOARGS},
+    {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
+    {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
+    {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
+
+    {"read", (PyCFunction)buffered_read, METH_VARARGS},
+    {"peek", (PyCFunction)buffered_peek, METH_VARARGS},
+    {"read1", (PyCFunction)buffered_read1, METH_VARARGS},
+    {"readline", (PyCFunction)buffered_readline, METH_VARARGS},
+    {"seek", (PyCFunction)buffered_seek, METH_VARARGS},
+    {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
+    {"truncate", (PyCFunction)buffered_truncate, METH_VARARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedreader_members[] = {
+    {"raw", T_OBJECT, offsetof(buffered, raw), 0},
+    {NULL}
+};
+
+static PyGetSetDef bufferedreader_getset[] = {
+    {"closed", (getter)buffered_closed_get, NULL, NULL},
+    {"name", (getter)buffered_name_get, NULL, NULL},
+    {"mode", (getter)buffered_mode_get, NULL, NULL},
+    {NULL}
+};
+
+
+PyTypeObject PyBufferedReader_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.BufferedReader",       /*tp_name*/
+    sizeof(buffered),           /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)buffered_dealloc,     /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    (reprfunc)buffered_repr,    /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+            | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+    bufferedreader_doc,         /* tp_doc */
+    (traverseproc)buffered_traverse, /* tp_traverse */
+    (inquiry)buffered_clear,    /* tp_clear */
+    0,                          /* tp_richcompare */
+    offsetof(buffered, weakreflist), /*tp_weaklistoffset*/
+    0,                          /* tp_iter */
+    (iternextfunc)buffered_iternext, /* tp_iternext */
+    bufferedreader_methods,     /* tp_methods */
+    bufferedreader_members,     /* tp_members */
+    bufferedreader_getset,      /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    offsetof(buffered, dict), /* tp_dictoffset */
+    (initproc)bufferedreader_init, /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};
+
+
+
+static int
+complain_about_max_buffer_size(void)
+{
+    if (PyErr_WarnEx(PyExc_DeprecationWarning,
+                     "max_buffer_size is deprecated", 1) < 0)
+        return 0;
+    return 1;
+}
+
+/*
+ * class BufferedWriter
+ */
+PyDoc_STRVAR(bufferedwriter_doc,
+    "A buffer for a writeable sequential RawIO object.\n"
+    "\n"
+    "The constructor creates a BufferedWriter for the given writeable raw\n"
+    "stream. If the buffer_size is not given, it defaults to\n"
+    "DEFAULT_BUFFER_SIZE. max_buffer_size isn't used anymore.\n"
+    );
+
+static void
+_bufferedwriter_reset_buf(buffered *self)
+{
+    self->write_pos = 0;
+    self->write_end = -1;
+}
+
+static int
+bufferedwriter_init(buffered *self, PyObject *args, PyObject *kwds)
+{
+    /* TODO: properly deprecate max_buffer_size */
+    char *kwlist[] = {"raw", "buffer_size", "max_buffer_size", NULL};
+    Py_ssize_t buffer_size = DEFAULT_BUFFER_SIZE;
+    Py_ssize_t max_buffer_size = -234;
+    PyObject *raw;
+
+    self->ok = 0;
+    self->detached = 0;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|nn:BufferedReader", kwlist,
+                                     &raw, &buffer_size, &max_buffer_size)) {
+        return -1;
+    }
+
+    if (max_buffer_size != -234 && !complain_about_max_buffer_size())
+        return -1;
+
+    if (_PyIOBase_check_writable(raw, Py_True) == NULL)
+        return -1;
+
+    Py_CLEAR(self->raw);
+    Py_INCREF(raw);
+    self->raw = raw;
+    self->readable = 0;
+    self->writable = 1;
+
+    self->buffer_size = buffer_size;
+    if (_buffered_init(self) < 0)
+        return -1;
+    _bufferedwriter_reset_buf(self);
+    self->pos = 0;
+
+    self->fast_closed_checks = (Py_TYPE(self) == &PyBufferedWriter_Type &&
+                                Py_TYPE(raw) == &PyFileIO_Type);
+
+    self->ok = 1;
+    return 0;
+}
+
+static Py_ssize_t
+_bufferedwriter_raw_write(buffered *self, char *start, Py_ssize_t len)
+{
+    Py_buffer buf;
+    PyObject *memobj, *res;
+    Py_ssize_t n;
+    /* NOTE: the buffer needn't be released as its object is NULL. */
+    if (PyBuffer_FillInfo(&buf, NULL, start, len, 1, PyBUF_CONTIG_RO) == -1)
+        return -1;
+    memobj = PyMemoryView_FromBuffer(&buf);
+    if (memobj == NULL)
+        return -1;
+    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_write, memobj, NULL);
+    Py_DECREF(memobj);
+    if (res == NULL)
+        return -1;
+    n = PyNumber_AsSsize_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n < 0 || n > len) {
+        PyErr_Format(PyExc_IOError,
+                     "raw write() returned invalid length %zd "
+                     "(should have been between 0 and %zd)", n, len);
+        return -1;
+    }
+    if (n > 0 && self->abs_pos != -1)
+        self->abs_pos += n;
+    return n;
+}
+
+/* `restore_pos` is 1 if we need to restore the raw stream position at
+   the end, 0 otherwise. */
+static PyObject *
+_bufferedwriter_flush_unlocked(buffered *self, int restore_pos)
+{
+    Py_ssize_t written = 0;
+    Py_off_t n, rewind;
+
+    if (!VALID_WRITE_BUFFER(self) || self->write_pos == self->write_end)
+        goto end;
+    /* First, rewind */
+    rewind = RAW_OFFSET(self) + (self->pos - self->write_pos);
+    if (rewind != 0) {
+        n = _buffered_raw_seek(self, -rewind, 1);
+        if (n < 0) {
+            goto error;
+        }
+        self->raw_pos -= rewind;
+    }
+    while (self->write_pos < self->write_end) {
+        n = _bufferedwriter_raw_write(self,
+            self->buffer + self->write_pos,
+            Py_SAFE_DOWNCAST(self->write_end - self->write_pos,
+                             Py_off_t, Py_ssize_t));
+        if (n == -1) {
+            Py_ssize_t *w = _buffered_check_blocking_error();
+            if (w == NULL)
+                goto error;
+            self->write_pos += *w;
+            self->raw_pos = self->write_pos;
+            written += *w;
+            *w = written;
+            /* Already re-raised */
+            goto error;
+        }
+        self->write_pos += n;
+        self->raw_pos = self->write_pos;
+        written += Py_SAFE_DOWNCAST(n, Py_off_t, Py_ssize_t);
+    }
+
+    if (restore_pos) {
+        Py_off_t forward = rewind - written;
+        if (forward != 0) {
+            n = _buffered_raw_seek(self, forward, 1);
+            if (n < 0) {
+                goto error;
+            }
+            self->raw_pos += forward;
+        }
+    }
+    _bufferedwriter_reset_buf(self);
+
+end:
+    Py_RETURN_NONE;
+
+error:
+    return NULL;
+}
+
+static PyObject *
+bufferedwriter_write(buffered *self, PyObject *args)
+{
+    PyObject *res = NULL;
+    Py_buffer buf;
+    Py_ssize_t written, avail, remaining, n;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "s*:write", &buf)) {
+        return NULL;
+    }
+
+    if (IS_CLOSED(self)) {
+        PyErr_SetString(PyExc_ValueError, "write to closed file");
+        PyBuffer_Release(&buf);
+        return NULL;
+    }
+
+    ENTER_BUFFERED(self)
+
+    /* Fast path: the data to write can be fully buffered. */
+    if (!VALID_READ_BUFFER(self) && !VALID_WRITE_BUFFER(self)) {
+        self->pos = 0;
+        self->raw_pos = 0;
+    }
+    avail = Py_SAFE_DOWNCAST(self->buffer_size - self->pos, Py_off_t, Py_ssize_t);
+    if (buf.len <= avail) {
+        memcpy(self->buffer + self->pos, buf.buf, buf.len);
+        if (!VALID_WRITE_BUFFER(self)) {
+            self->write_pos = self->pos;
+        }
+        ADJUST_POSITION(self, self->pos + buf.len);
+        if (self->pos > self->write_end)
+            self->write_end = self->pos;
+        written = buf.len;
+        goto end;
+    }
+
+    /* First write the current buffer */
+    res = _bufferedwriter_flush_unlocked(self, 0);
+    if (res == NULL) {
+        Py_ssize_t *w = _buffered_check_blocking_error();
+        if (w == NULL)
+            goto error;
+        if (self->readable)
+            _bufferedreader_reset_buf(self);
+        /* Make some place by shifting the buffer. */
+        assert(VALID_WRITE_BUFFER(self));
+        memmove(self->buffer, self->buffer + self->write_pos,
+                Py_SAFE_DOWNCAST(self->write_end - self->write_pos,
+                                 Py_off_t, Py_ssize_t));
+        self->write_end -= self->write_pos;
+        self->raw_pos -= self->write_pos;
+        self->pos -= self->write_pos;
+        self->write_pos = 0;
+        avail = Py_SAFE_DOWNCAST(self->buffer_size - self->write_end,
+                                 Py_off_t, Py_ssize_t);
+        if (buf.len <= avail) {
+            /* Everything can be buffered */
+            PyErr_Clear();
+            memcpy(self->buffer + self->write_end, buf.buf, buf.len);
+            self->write_end += buf.len;
+            written = buf.len;
+            goto end;
+        }
+        /* Buffer as much as possible. */
+        memcpy(self->buffer + self->write_end, buf.buf, avail);
+        self->write_end += avail;
+        /* Already re-raised */
+        *w = avail;
+        goto error;
+    }
+    Py_CLEAR(res);
+
+    /* Then write buf itself. At this point the buffer has been emptied. */
+    remaining = buf.len;
+    written = 0;
+    while (remaining > self->buffer_size) {
+        n = _bufferedwriter_raw_write(
+            self, (char *) buf.buf + written, buf.len - written);
+        if (n == -1) {
+            Py_ssize_t *w = _buffered_check_blocking_error();
+            if (w == NULL)
+                goto error;
+            written += *w;
+            remaining -= *w;
+            if (remaining > self->buffer_size) {
+                /* Can't buffer everything, still buffer as much as possible */
+                memcpy(self->buffer,
+                       (char *) buf.buf + written, self->buffer_size);
+                self->raw_pos = 0;
+                ADJUST_POSITION(self, self->buffer_size);
+                self->write_end = self->buffer_size;
+                *w = written + self->buffer_size;
+                /* Already re-raised */
+                goto error;
+            }
+            PyErr_Clear();
+            break;
+        }
+        written += n;
+        remaining -= n;
+    }
+    if (self->readable)
+        _bufferedreader_reset_buf(self);
+    if (remaining > 0) {
+        memcpy(self->buffer, (char *) buf.buf + written, remaining);
+        written += remaining;
+    }
+    self->write_pos = 0;
+    /* TODO: sanity check (remaining >= 0) */
+    self->write_end = remaining;
+    ADJUST_POSITION(self, remaining);
+    self->raw_pos = 0;
+
+end:
+    res = PyLong_FromSsize_t(written);
+
+error:
+    LEAVE_BUFFERED(self)
+    PyBuffer_Release(&buf);
+    return res;
+}
+
+static PyMethodDef bufferedwriter_methods[] = {
+    /* BufferedIOMixin methods */
+    {"close", (PyCFunction)buffered_close, METH_NOARGS},
+    {"detach", (PyCFunction)buffered_detach, METH_NOARGS},
+    {"seekable", (PyCFunction)buffered_seekable, METH_NOARGS},
+    {"readable", (PyCFunction)buffered_readable, METH_NOARGS},
+    {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
+    {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
+    {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
+
+    {"write", (PyCFunction)bufferedwriter_write, METH_VARARGS},
+    {"truncate", (PyCFunction)buffered_truncate, METH_VARARGS},
+    {"flush", (PyCFunction)buffered_flush, METH_NOARGS},
+    {"seek", (PyCFunction)buffered_seek, METH_VARARGS},
+    {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedwriter_members[] = {
+    {"raw", T_OBJECT, offsetof(buffered, raw), 0},
+    {NULL}
+};
+
+static PyGetSetDef bufferedwriter_getset[] = {
+    {"closed", (getter)buffered_closed_get, NULL, NULL},
+    {"name", (getter)buffered_name_get, NULL, NULL},
+    {"mode", (getter)buffered_mode_get, NULL, NULL},
+    {NULL}
+};
+
+
+PyTypeObject PyBufferedWriter_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.BufferedWriter",       /*tp_name*/
+    sizeof(buffered),           /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)buffered_dealloc,     /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    (reprfunc)buffered_repr,    /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
+    bufferedwriter_doc,         /* tp_doc */
+    (traverseproc)buffered_traverse, /* tp_traverse */
+    (inquiry)buffered_clear,    /* tp_clear */
+    0,                          /* tp_richcompare */
+    offsetof(buffered, weakreflist), /*tp_weaklistoffset*/
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    bufferedwriter_methods,     /* tp_methods */
+    bufferedwriter_members,     /* tp_members */
+    bufferedwriter_getset,      /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    offsetof(buffered, dict),   /* tp_dictoffset */
+    (initproc)bufferedwriter_init, /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};
+
+
+
+/*
+ * BufferedRWPair
+ */
+
+PyDoc_STRVAR(bufferedrwpair_doc,
+    "A buffered reader and writer object together.\n"
+    "\n"
+    "A buffered reader object and buffered writer object put together to\n"
+    "form a sequential IO object that can read and write. This is typically\n"
+    "used with a socket or two-way pipe.\n"
+    "\n"
+    "reader and writer are RawIOBase objects that are readable and\n"
+    "writeable respectively. If the buffer_size is omitted it defaults to\n"
+    "DEFAULT_BUFFER_SIZE.\n"
+    );
+
+/* XXX The usefulness of this (compared to having two separate IO objects) is
+ * questionable.
+ */
+
+typedef struct {
+    PyObject_HEAD
+    buffered *reader;
+    buffered *writer;
+    PyObject *dict;
+    PyObject *weakreflist;
+} rwpair;
+
+static int
+bufferedrwpair_init(rwpair *self, PyObject *args, PyObject *kwds)
+{
+    PyObject *reader, *writer;
+    Py_ssize_t buffer_size = DEFAULT_BUFFER_SIZE;
+    Py_ssize_t max_buffer_size = -234;
+
+    if (!PyArg_ParseTuple(args, "OO|nn:BufferedRWPair", &reader, &writer,
+                          &buffer_size, &max_buffer_size)) {
+        return -1;
+    }
+
+    if (max_buffer_size != -234 && !complain_about_max_buffer_size())
+        return -1;
+
+    if (_PyIOBase_check_readable(reader, Py_True) == NULL)
+        return -1;
+    if (_PyIOBase_check_writable(writer, Py_True) == NULL)
+        return -1;
+
+    self->reader = (buffered *) PyObject_CallFunction(
+            (PyObject *) &PyBufferedReader_Type, "On", reader, buffer_size);
+    if (self->reader == NULL)
+        return -1;
+
+    self->writer = (buffered *) PyObject_CallFunction(
+            (PyObject *) &PyBufferedWriter_Type, "On", writer, buffer_size);
+    if (self->writer == NULL) {
+        Py_CLEAR(self->reader);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+bufferedrwpair_traverse(rwpair *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->dict);
+    return 0;
+}
+
+static int
+bufferedrwpair_clear(rwpair *self)
+{
+    Py_CLEAR(self->reader);
+    Py_CLEAR(self->writer);
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+static void
+bufferedrwpair_dealloc(rwpair *self)
+{
+    _PyObject_GC_UNTRACK(self);
+    Py_CLEAR(self->reader);
+    Py_CLEAR(self->writer);
+    Py_CLEAR(self->dict);
+    Py_TYPE(self)->tp_free((PyObject *) self);
+}
+
+static PyObject *
+_forward_call(buffered *self, const char *name, PyObject *args)
+{
+    PyObject *func = PyObject_GetAttrString((PyObject *)self, name);
+    PyObject *ret;
+
+    if (func == NULL) {
+        PyErr_SetString(PyExc_AttributeError, name);
+        return NULL;
+    }
+
+    ret = PyObject_CallObject(func, args);
+    Py_DECREF(func);
+    return ret;
+}
+
+static PyObject *
+bufferedrwpair_read(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, "read", args);
+}
+
+static PyObject *
+bufferedrwpair_peek(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, "peek", args);
+}
+
+static PyObject *
+bufferedrwpair_read1(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, "read1", args);
+}
+
+static PyObject *
+bufferedrwpair_readinto(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, "readinto", args);
+}
+
+static PyObject *
+bufferedrwpair_write(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->writer, "write", args);
+}
+
+static PyObject *
+bufferedrwpair_flush(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->writer, "flush", args);
+}
+
+static PyObject *
+bufferedrwpair_readable(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->reader, "readable", args);
+}
+
+static PyObject *
+bufferedrwpair_writable(rwpair *self, PyObject *args)
+{
+    return _forward_call(self->writer, "writable", args);
+}
+
+static PyObject *
+bufferedrwpair_close(rwpair *self, PyObject *args)
+{
+    PyObject *ret = _forward_call(self->writer, "close", args);
+    if (ret == NULL)
+        return NULL;
+    Py_DECREF(ret);
+
+    return _forward_call(self->reader, "close", args);
+}
+
+static PyObject *
+bufferedrwpair_isatty(rwpair *self, PyObject *args)
+{
+    PyObject *ret = _forward_call(self->writer, "isatty", args);
+
+    if (ret != Py_False) {
+        /* either True or exception */
+        return ret;
+    }
+    Py_DECREF(ret);
+
+    return _forward_call(self->reader, "isatty", args);
+}
+
+static PyObject *
+bufferedrwpair_closed_get(rwpair *self, void *context)
+{
+    return PyObject_GetAttr((PyObject *) self->writer, _PyIO_str_closed);
+}
+
+static PyMethodDef bufferedrwpair_methods[] = {
+    {"read", (PyCFunction)bufferedrwpair_read, METH_VARARGS},
+    {"peek", (PyCFunction)bufferedrwpair_peek, METH_VARARGS},
+    {"read1", (PyCFunction)bufferedrwpair_read1, METH_VARARGS},
+    {"readinto", (PyCFunction)bufferedrwpair_readinto, METH_VARARGS},
+
+    {"write", (PyCFunction)bufferedrwpair_write, METH_VARARGS},
+    {"flush", (PyCFunction)bufferedrwpair_flush, METH_NOARGS},
+
+    {"readable", (PyCFunction)bufferedrwpair_readable, METH_NOARGS},
+    {"writable", (PyCFunction)bufferedrwpair_writable, METH_NOARGS},
+
+    {"close", (PyCFunction)bufferedrwpair_close, METH_NOARGS},
+    {"isatty", (PyCFunction)bufferedrwpair_isatty, METH_NOARGS},
+
+    {NULL, NULL}
+};
+
+static PyGetSetDef bufferedrwpair_getset[] = {
+    {"closed", (getter)bufferedrwpair_closed_get, NULL, NULL},
+    {NULL}
+};
+
+PyTypeObject PyBufferedRWPair_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.BufferedRWPair",       /*tp_name*/
+    sizeof(rwpair),            /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)bufferedrwpair_dealloc,     /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+        | Py_TPFLAGS_HAVE_GC,   /* tp_flags */
+    bufferedrwpair_doc,         /* tp_doc */
+    (traverseproc)bufferedrwpair_traverse, /* tp_traverse */
+    (inquiry)bufferedrwpair_clear, /* tp_clear */
+    0,                          /* tp_richcompare */
+    offsetof(rwpair, weakreflist), /*tp_weaklistoffset*/
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    bufferedrwpair_methods,     /* tp_methods */
+    0,                          /* tp_members */
+    bufferedrwpair_getset,      /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    offsetof(rwpair, dict),     /* tp_dictoffset */
+    (initproc)bufferedrwpair_init, /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};
+
+
+
+/*
+ * BufferedRandom
+ */
+
+PyDoc_STRVAR(bufferedrandom_doc,
+    "A buffered interface to random access streams.\n"
+    "\n"
+    "The constructor creates a reader and writer for a seekable stream,\n"
+    "raw, given in the first argument. If the buffer_size is omitted it\n"
+    "defaults to DEFAULT_BUFFER_SIZE. max_buffer_size isn't used anymore.\n"
+    );
+
+static int
+bufferedrandom_init(buffered *self, PyObject *args, PyObject *kwds)
+{
+    char *kwlist[] = {"raw", "buffer_size", "max_buffer_size", NULL};
+    Py_ssize_t buffer_size = DEFAULT_BUFFER_SIZE;
+    Py_ssize_t max_buffer_size = -234;
+    PyObject *raw;
+
+    self->ok = 0;
+    self->detached = 0;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|nn:BufferedReader", kwlist,
+                                     &raw, &buffer_size, &max_buffer_size)) {
+        return -1;
+    }
+
+    if (max_buffer_size != -234 && !complain_about_max_buffer_size())
+        return -1;
+
+    if (_PyIOBase_check_seekable(raw, Py_True) == NULL)
+        return -1;
+    if (_PyIOBase_check_readable(raw, Py_True) == NULL)
+        return -1;
+    if (_PyIOBase_check_writable(raw, Py_True) == NULL)
+        return -1;
+
+    Py_CLEAR(self->raw);
+    Py_INCREF(raw);
+    self->raw = raw;
+    self->buffer_size = buffer_size;
+    self->readable = 1;
+    self->writable = 1;
+
+    if (_buffered_init(self) < 0)
+        return -1;
+    _bufferedreader_reset_buf(self);
+    _bufferedwriter_reset_buf(self);
+    self->pos = 0;
+
+    self->fast_closed_checks = (Py_TYPE(self) == &PyBufferedRandom_Type &&
+                                Py_TYPE(raw) == &PyFileIO_Type);
+
+    self->ok = 1;
+    return 0;
+}
+
+static PyMethodDef bufferedrandom_methods[] = {
+    /* BufferedIOMixin methods */
+    {"close", (PyCFunction)buffered_close, METH_NOARGS},
+    {"detach", (PyCFunction)buffered_detach, METH_NOARGS},
+    {"seekable", (PyCFunction)buffered_seekable, METH_NOARGS},
+    {"readable", (PyCFunction)buffered_readable, METH_NOARGS},
+    {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
+    {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
+    {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
+
+    {"flush", (PyCFunction)buffered_flush, METH_NOARGS},
+
+    {"seek", (PyCFunction)buffered_seek, METH_VARARGS},
+    {"tell", (PyCFunction)buffered_tell, METH_NOARGS},
+    {"truncate", (PyCFunction)buffered_truncate, METH_VARARGS},
+    {"read", (PyCFunction)buffered_read, METH_VARARGS},
+    {"read1", (PyCFunction)buffered_read1, METH_VARARGS},
+    {"readinto", (PyCFunction)buffered_readinto, METH_VARARGS},
+    {"readline", (PyCFunction)buffered_readline, METH_VARARGS},
+    {"peek", (PyCFunction)buffered_peek, METH_VARARGS},
+    {"write", (PyCFunction)bufferedwriter_write, METH_VARARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef bufferedrandom_members[] = {
+    {"raw", T_OBJECT, offsetof(buffered, raw), 0},
+    {NULL}
+};
+
+static PyGetSetDef bufferedrandom_getset[] = {
+    {"closed", (getter)buffered_closed_get, NULL, NULL},
+    {"name", (getter)buffered_name_get, NULL, NULL},
+    {"mode", (getter)buffered_mode_get, NULL, NULL},
+    {NULL}
+};
+
+
+PyTypeObject PyBufferedRandom_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.BufferedRandom",       /*tp_name*/
+    sizeof(buffered),           /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)buffered_dealloc,     /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    (reprfunc)buffered_repr,    /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
+    bufferedrandom_doc,         /* tp_doc */
+    (traverseproc)buffered_traverse, /* tp_traverse */
+    (inquiry)buffered_clear,    /* tp_clear */
+    0,                          /* tp_richcompare */
+    offsetof(buffered, weakreflist), /*tp_weaklistoffset*/
+    0,                          /* tp_iter */
+    (iternextfunc)buffered_iternext, /* tp_iternext */
+    bufferedrandom_methods,     /* tp_methods */
+    bufferedrandom_members,     /* tp_members */
+    bufferedrandom_getset,      /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /*tp_dict*/
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    offsetof(buffered, dict), /*tp_dictoffset*/
+    (initproc)bufferedrandom_init, /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};
+
diff --git a/Modules/_bytesio.c b/Modules/_io/bytesio.c
similarity index 81%
rename from Modules/_bytesio.c
rename to Modules/_io/bytesio.c
index c5c14b3..ed2f7cc 100644
--- a/Modules/_bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -1,4 +1,6 @@
 #include "Python.h"
+#include "structmember.h"       /* for offsetof() */
+#include "_iomodule.h"
 
 typedef struct {
     PyObject_HEAD
@@ -6,7 +8,9 @@
     Py_ssize_t pos;
     Py_ssize_t string_size;
     size_t buf_size;
-} BytesIOObject;
+    PyObject *dict;
+    PyObject *weakreflist;
+} bytesio;
 
 #define CHECK_CLOSED(self)                                  \
     if ((self)->buf == NULL) {                              \
@@ -19,7 +23,7 @@
    object. Returns the length between the current position to the
    next newline character. */
 static Py_ssize_t
-get_line(BytesIOObject *self, char **output)
+get_line(bytesio *self, char **output)
 {
     char *n;
     const char *str_end;
@@ -52,7 +56,7 @@
    The caller should ensure that the 'size' argument is non-negative.  Returns
    0 on success, -1 otherwise. */
 static int
-resize_buffer(BytesIOObject *self, size_t size)
+resize_buffer(bytesio *self, size_t size)
 {
     /* Here, unsigned types are used to avoid dealing with signed integer
        overflow, which is undefined in C. */
@@ -104,7 +108,7 @@
 /* Internal routine for writing a string of bytes to the buffer of a BytesIO
    object. Returns the number of bytes wrote, or -1 on error. */
 static Py_ssize_t
-write_bytes(BytesIOObject *self, const char *bytes, Py_ssize_t len)
+write_bytes(bytesio *self, const char *bytes, Py_ssize_t len)
 {
     assert(self->buf != NULL);
     assert(self->pos >= 0);
@@ -142,17 +146,19 @@
 }
 
 static PyObject *
-bytesio_get_closed(BytesIOObject *self)
+bytesio_get_closed(bytesio *self)
 {
-    if (self->buf == NULL)
+    if (self->buf == NULL) {
         Py_RETURN_TRUE;
-    else
+    }
+    else {
         Py_RETURN_FALSE;
+    }
 }
 
 /* Generic getter for the writable, readable and seekable properties */
 static PyObject *
-return_true(BytesIOObject *self)
+return_true(bytesio *self)
 {
     Py_RETURN_TRUE;
 }
@@ -161,7 +167,7 @@
 "flush() -> None.  Does nothing.");
 
 static PyObject *
-bytesio_flush(BytesIOObject *self)
+bytesio_flush(bytesio *self)
 {
     Py_RETURN_NONE;
 }
@@ -172,10 +178,10 @@
 "Retrieve the entire contents of the BytesIO object.");
 
 static PyObject *
-bytesio_getvalue(BytesIOObject *self)
+bytesio_getvalue(bytesio *self)
 {
     CHECK_CLOSED(self);
-    return PyString_FromStringAndSize(self->buf, self->string_size);
+    return PyBytes_FromStringAndSize(self->buf, self->string_size);
 }
 
 PyDoc_STRVAR(isatty_doc,
@@ -185,7 +191,7 @@
 "to a tty-like device.");
 
 static PyObject *
-bytesio_isatty(BytesIOObject *self)
+bytesio_isatty(bytesio *self)
 {
     CHECK_CLOSED(self);
     Py_RETURN_FALSE;
@@ -195,10 +201,10 @@
 "tell() -> current file position, an integer\n");
 
 static PyObject *
-bytesio_tell(BytesIOObject *self)
+bytesio_tell(bytesio *self)
 {
     CHECK_CLOSED(self);
-    return PyInt_FromSsize_t(self->pos);
+    return PyLong_FromSsize_t(self->pos);
 }
 
 PyDoc_STRVAR(read_doc,
@@ -208,7 +214,7 @@
 "Return an empty string at EOF.");
 
 static PyObject *
-bytesio_read(BytesIOObject *self, PyObject *args)
+bytesio_read(bytesio *self, PyObject *args)
 {
     Py_ssize_t size, n;
     char *output;
@@ -219,8 +225,8 @@
     if (!PyArg_ParseTuple(args, "|O:read", &arg))
         return NULL;
 
-    if (PyInt_Check(arg)) {
-        size = PyInt_AsSsize_t(arg);
+    if (PyNumber_Check(arg)) {
+        size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
         if (size == -1 && PyErr_Occurred())
             return NULL;
     }
@@ -246,7 +252,7 @@
     output = self->buf + self->pos;
     self->pos += size;
 
-    return PyString_FromStringAndSize(output, size);
+    return PyBytes_FromStringAndSize(output, size);
 }
 
 
@@ -257,7 +263,7 @@
 "Return an empty string at EOF.");
 
 static PyObject *
-bytesio_read1(BytesIOObject *self, PyObject *n)
+bytesio_read1(bytesio *self, PyObject *n)
 {
     PyObject *arg, *res;
 
@@ -277,7 +283,7 @@
 "Return an empty string at EOF.\n");
 
 static PyObject *
-bytesio_readline(BytesIOObject *self, PyObject *args)
+bytesio_readline(bytesio *self, PyObject *args)
 {
     Py_ssize_t size, n;
     char *output;
@@ -288,8 +294,8 @@
     if (!PyArg_ParseTuple(args, "|O:readline", &arg))
         return NULL;
 
-    if (PyInt_Check(arg)) {
-        size = PyInt_AsSsize_t(arg);
+    if (PyNumber_Check(arg)) {
+        size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
         if (size == -1 && PyErr_Occurred())
             return NULL;
     }
@@ -311,7 +317,7 @@
         self->pos -= size;
     }
 
-    return PyString_FromStringAndSize(output, n);
+    return PyBytes_FromStringAndSize(output, n);
 }
 
 PyDoc_STRVAR(readlines_doc,
@@ -322,7 +328,7 @@
 "total number of bytes in the lines returned.\n");
 
 static PyObject *
-bytesio_readlines(BytesIOObject *self, PyObject *args)
+bytesio_readlines(bytesio *self, PyObject *args)
 {
     Py_ssize_t maxsize, size, n;
     PyObject *result, *line;
@@ -334,8 +340,8 @@
     if (!PyArg_ParseTuple(args, "|O:readlines", &arg))
         return NULL;
 
-    if (PyInt_Check(arg)) {
-        maxsize = PyInt_AsSsize_t(arg);
+    if (PyNumber_Check(arg)) {
+        maxsize = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
         if (maxsize == -1 && PyErr_Occurred())
             return NULL;
     }
@@ -355,7 +361,7 @@
         return NULL;
 
     while ((n = get_line(self, &output)) != 0) {
-        line = PyString_FromStringAndSize(output, n);
+        line = PyBytes_FromStringAndSize(output, n);
         if (!line)
             goto on_error;
         if (PyList_Append(result, line) == -1) {
@@ -381,25 +387,27 @@
 "is set not to block as has no data to read.");
 
 static PyObject *
-bytesio_readinto(BytesIOObject *self, PyObject *buffer)
+bytesio_readinto(bytesio *self, PyObject *args)
 {
-    void *raw_buffer;
+    Py_buffer buf;
     Py_ssize_t len;
 
     CHECK_CLOSED(self);
 
-    if (PyObject_AsWriteBuffer(buffer, &raw_buffer, &len) == -1)
+    if (!PyArg_ParseTuple(args, "w*", &buf))
         return NULL;
 
+    len = buf.len;
     if (self->pos + len > self->string_size)
         len = self->string_size - self->pos;
 
-    memcpy(raw_buffer, self->buf + self->pos, len);
+    memcpy(buf.buf, self->buf + self->pos, len);
     assert(self->pos + len < PY_SSIZE_T_MAX);
     assert(len >= 0);
     self->pos += len;
 
-    return PyInt_FromSsize_t(len);
+    PyBuffer_Release(&buf);
+    return PyLong_FromSsize_t(len);
 }
 
 PyDoc_STRVAR(truncate_doc,
@@ -409,7 +417,7 @@
 "Returns the new size.  Imply an absolute seek to the position size.");
 
 static PyObject *
-bytesio_truncate(BytesIOObject *self, PyObject *args)
+bytesio_truncate(bytesio *self, PyObject *args)
 {
     Py_ssize_t size;
     PyObject *arg = Py_None;
@@ -419,8 +427,8 @@
     if (!PyArg_ParseTuple(args, "|O:truncate", &arg))
         return NULL;
 
-    if (PyInt_Check(arg)) {
-        size = PyInt_AsSsize_t(arg);
+    if (PyNumber_Check(arg)) {
+        size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
         if (size == -1 && PyErr_Occurred())
             return NULL;
     }
@@ -447,11 +455,11 @@
     }
     self->pos = size;
 
-    return PyInt_FromSsize_t(size);
+    return PyLong_FromSsize_t(size);
 }
 
 static PyObject *
-bytesio_iternext(BytesIOObject *self)
+bytesio_iternext(bytesio *self)
 {
     char *next;
     Py_ssize_t n;
@@ -463,7 +471,7 @@
     if (!next || n == 0)
         return NULL;
 
-    return PyString_FromStringAndSize(next, n);
+    return PyBytes_FromStringAndSize(next, n);
 }
 
 PyDoc_STRVAR(seek_doc,
@@ -476,27 +484,21 @@
 "Returns the new absolute position.");
 
 static PyObject *
-bytesio_seek(BytesIOObject *self, PyObject *args)
+bytesio_seek(bytesio *self, PyObject *args)
 {
-    PyObject *pos_obj, *mode_obj;
+    PyObject *posobj;
     Py_ssize_t pos;
     int mode = 0;
 
     CHECK_CLOSED(self);
 
-    /* Special-case for 2.x to prevent floats from passing through.
-       This only needed to make a test in test_io succeed. */
-    if (!PyArg_UnpackTuple(args, "seek", 1, 2, &pos_obj, &mode_obj))
-        return NULL;
-    if (PyFloat_Check(pos_obj)) {
-        PyErr_SetString(PyExc_TypeError,
-                        "position argument must be an integer");
-        return NULL;
-    }
-
-    if (!PyArg_ParseTuple(args, "n|i:seek", &pos, &mode))
+    if (!PyArg_ParseTuple(args, "O|i:seek", &posobj, &mode))
         return NULL;
 
+    pos = PyNumber_AsSsize_t(posobj, PyExc_OverflowError);
+    if (pos == -1 && PyErr_Occurred())
+        return NULL;
+    
     if (pos < 0 && mode == 0) {
         PyErr_Format(PyExc_ValueError,
                      "negative seek value %zd", pos);
@@ -532,7 +534,7 @@
         pos = 0;
     self->pos = pos;
 
-    return PyInt_FromSsize_t(self->pos);
+    return PyLong_FromSsize_t(self->pos);
 }
 
 PyDoc_STRVAR(write_doc,
@@ -541,31 +543,24 @@
 "Return the number of bytes written.");
 
 static PyObject *
-bytesio_write(BytesIOObject *self, PyObject *obj)
+bytesio_write(bytesio *self, PyObject *obj)
 {
-    const char *bytes;
-    Py_ssize_t size;
     Py_ssize_t n = 0;
+    Py_buffer buf;
+    PyObject *result = NULL;
 
     CHECK_CLOSED(self);
 
-    /* Special-case in 2.x to prevent unicode objects to pass through. */
-    if (PyUnicode_Check(obj)) {
-	    PyErr_SetString(PyExc_TypeError,
-                        "expecting a bytes object, got unicode");
-        return NULL;
-    }
-
-    if (PyObject_AsReadBuffer(obj, (void *)&bytes, &size) < 0)
+    if (PyObject_GetBuffer(obj, &buf, PyBUF_CONTIG_RO) < 0)
         return NULL;
 
-    if (size != 0) {
-        n = write_bytes(self, bytes, size);
-        if (n < 0)
-            return NULL;
-    }
+    if (buf.len != 0)
+        n = write_bytes(self, buf.buf, buf.len);
+    if (n >= 0)
+        result = PyLong_FromSsize_t(n);
 
-    return PyInt_FromSsize_t(n);
+    PyBuffer_Release(&buf);
+    return result;
 }
 
 PyDoc_STRVAR(writelines_doc,
@@ -576,7 +571,7 @@
 "each string.");
 
 static PyObject *
-bytesio_writelines(BytesIOObject *self, PyObject *v)
+bytesio_writelines(bytesio *self, PyObject *v)
 {
     PyObject *it, *item;
     PyObject *ret;
@@ -609,7 +604,7 @@
 "close() -> None.  Disable all I/O operations.");
 
 static PyObject *
-bytesio_close(BytesIOObject *self)
+bytesio_close(bytesio *self)
 {
     if (self->buf != NULL) {
         PyMem_Free(self->buf);
@@ -619,22 +614,23 @@
 }
 
 static void
-bytesio_dealloc(BytesIOObject *self)
+bytesio_dealloc(bytesio *self)
 {
     if (self->buf != NULL) {
         PyMem_Free(self->buf);
         self->buf = NULL;
     }
+    Py_TYPE(self)->tp_clear((PyObject *)self);
     Py_TYPE(self)->tp_free(self);
 }
 
 static PyObject *
 bytesio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
-    BytesIOObject *self;
+    bytesio *self;
 
     assert(type != NULL && type->tp_alloc != NULL);
-    self = (BytesIOObject *)type->tp_alloc(type, 0);
+    self = (bytesio *)type->tp_alloc(type, 0);
     if (self == NULL)
         return NULL;
 
@@ -651,7 +647,7 @@
 }
 
 static int
-bytesio_init(BytesIOObject *self, PyObject *args, PyObject *kwds)
+bytesio_init(bytesio *self, PyObject *args, PyObject *kwds)
 {
     PyObject *initvalue = NULL;
 
@@ -674,10 +670,28 @@
     return 0;
 }
 
+static int
+bytesio_traverse(bytesio *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->dict);
+    Py_VISIT(self->weakreflist);
+    return 0;
+}
+
+static int
+bytesio_clear(bytesio *self)
+{
+    Py_CLEAR(self->dict);
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *)self);
+    return 0;
+}
+
+
 static PyGetSetDef bytesio_getsetlist[] = {
     {"closed",  (getter)bytesio_get_closed, NULL,
      "True if the file is closed."},
-    {0},            /* sentinel */
+    {NULL},            /* sentinel */
 };
 
 static struct PyMethodDef bytesio_methods[] = {
@@ -691,7 +705,7 @@
     {"write",      (PyCFunction)bytesio_write,      METH_O, write_doc},
     {"writelines", (PyCFunction)bytesio_writelines, METH_O, writelines_doc},
     {"read1",      (PyCFunction)bytesio_read1,      METH_O, read1_doc},
-    {"readinto",   (PyCFunction)bytesio_readinto,   METH_O, readinto_doc},
+    {"readinto",   (PyCFunction)bytesio_readinto,   METH_VARARGS, readinto_doc},
     {"readline",   (PyCFunction)bytesio_readline,   METH_VARARGS, readline_doc},
     {"readlines",  (PyCFunction)bytesio_readlines,  METH_VARARGS, readlines_doc},
     {"read",       (PyCFunction)bytesio_read,       METH_VARARGS, read_doc},
@@ -707,16 +721,16 @@
 "Create a buffered I/O implementation using an in-memory bytes\n"
 "buffer, ready for reading and writing.");
 
-static PyTypeObject BytesIO_Type = {
+PyTypeObject PyBytesIO_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
-    "_bytesio._BytesIO",                       /*tp_name*/
-    sizeof(BytesIOObject),                     /*tp_basicsize*/
+    "_io.BytesIO",                             /*tp_name*/
+    sizeof(bytesio),                     /*tp_basicsize*/
     0,                                         /*tp_itemsize*/
     (destructor)bytesio_dealloc,               /*tp_dealloc*/
     0,                                         /*tp_print*/
     0,                                         /*tp_getattr*/
     0,                                         /*tp_setattr*/
-    0,                                         /*tp_compare*/
+    0,                                         /*tp_reserved*/
     0,                                         /*tp_repr*/
     0,                                         /*tp_as_number*/
     0,                                         /*tp_as_sequence*/
@@ -727,12 +741,13 @@
     0,                                         /*tp_getattro*/
     0,                                         /*tp_setattro*/
     0,                                         /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
+    Py_TPFLAGS_HAVE_GC,                        /*tp_flags*/
     bytesio_doc,                               /*tp_doc*/
-    0,                                         /*tp_traverse*/
-    0,                                         /*tp_clear*/
+    (traverseproc)bytesio_traverse,            /*tp_traverse*/
+    (inquiry)bytesio_clear,                    /*tp_clear*/
     0,                                         /*tp_richcompare*/
-    0,                                         /*tp_weaklistoffset*/
+    offsetof(bytesio, weakreflist),      /*tp_weaklistoffset*/
     PyObject_SelfIter,                         /*tp_iter*/
     (iternextfunc)bytesio_iternext,            /*tp_iternext*/
     bytesio_methods,                           /*tp_methods*/
@@ -742,22 +757,8 @@
     0,                                         /*tp_dict*/
     0,                                         /*tp_descr_get*/
     0,                                         /*tp_descr_set*/
-    0,                                         /*tp_dictoffset*/
+    offsetof(bytesio, dict),             /*tp_dictoffset*/
     (initproc)bytesio_init,                    /*tp_init*/
     0,                                         /*tp_alloc*/
     bytesio_new,                               /*tp_new*/
 };
-
-PyMODINIT_FUNC
-init_bytesio(void)
-{
-    PyObject *m;
-
-    if (PyType_Ready(&BytesIO_Type) < 0)
-        return;
-    m = Py_InitModule("_bytesio", NULL);
-    if (m == NULL)
-        return;
-    Py_INCREF(&BytesIO_Type);
-    PyModule_AddObject(m, "_BytesIO", (PyObject *)&BytesIO_Type);
-}
diff --git a/Modules/_fileio.c b/Modules/_io/fileio.c
similarity index 71%
rename from Modules/_fileio.c
rename to Modules/_io/fileio.c
index efe0855..917ad63 100644
--- a/Modules/_fileio.c
+++ b/Modules/_io/fileio.c
@@ -6,6 +6,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stddef.h> /* For offsetof */
+#include "_iomodule.h"
 
 /*
  * Known likely problems:
@@ -27,6 +28,20 @@
 #include <windows.h>
 #endif
 
+#if BUFSIZ < (8*1024)
+#define SMALLCHUNK (8*1024)
+#elif (BUFSIZ >= (2 << 25))
+#error "unreasonable BUFSIZ > 64MB defined"
+#else
+#define SMALLCHUNK BUFSIZ
+#endif
+
+#if SIZEOF_INT < 4
+#define BIGCHUNK  (512 * 32)
+#else
+#define BIGCHUNK  (512 * 1024)
+#endif
+
 typedef struct {
 	PyObject_HEAD
 	int fd;
@@ -35,55 +50,76 @@
 	int seekable : 2; /* -1 means unknown */
 	int closefd : 1;
 	PyObject *weakreflist;
-} PyFileIOObject;
+	PyObject *dict;
+} fileio;
 
 PyTypeObject PyFileIO_Type;
 
 #define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
 
+int
+_PyFileIO_closed(PyObject *self)
+{
+	return ((fileio *)self)->fd < 0;
+}
+
 static PyObject *
 portable_lseek(int fd, PyObject *posobj, int whence);
 
-/* Returns 0 on success, errno (which is < 0) on failure. */
+static PyObject *portable_lseek(int fd, PyObject *posobj, int whence);
+
+/* Returns 0 on success, -1 with exception set on failure. */
 static int
-internal_close(PyFileIOObject *self)
+internal_close(fileio *self)
 {
+	int err = 0;
 	int save_errno = 0;
 	if (self->fd >= 0) {
 		int fd = self->fd;
 		self->fd = -1;
-		Py_BEGIN_ALLOW_THREADS
-		if (close(fd) < 0)
+		/* fd is accessible and someone else may have closed it */
+		if (_PyVerify_fd(fd)) {
+			Py_BEGIN_ALLOW_THREADS
+			err = close(fd);
+			if (err < 0)
+				save_errno = errno;
+			Py_END_ALLOW_THREADS
+		} else {
 			save_errno = errno;
-		Py_END_ALLOW_THREADS
+			err = -1;
+		}
 	}
-	return save_errno;
+	if (err < 0) {
+		errno = save_errno;
+		PyErr_SetFromErrno(PyExc_IOError);
+		return -1;
+	}
+	return 0;
 }
 
 static PyObject *
-fileio_close(PyFileIOObject *self)
+fileio_close(fileio *self)
 {
 	if (!self->closefd) {
 		self->fd = -1;
 		Py_RETURN_NONE;
 	}
 	errno = internal_close(self);
-	if (errno < 0) {
-		PyErr_SetFromErrno(PyExc_IOError);
+	if (errno < 0)
 		return NULL;
-	}
 
-	Py_RETURN_NONE;
+	return PyObject_CallMethod((PyObject*)&PyRawIOBase_Type,
+				   "close", "O", self);
 }
 
 static PyObject *
-fileio_new(PyTypeObject *type, PyObject *args, PyObject *kews)
+fileio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
-	PyFileIOObject *self;
+	fileio *self;
 
 	assert(type != NULL && type->tp_alloc != NULL);
 
-	self = (PyFileIOObject *) type->tp_alloc(type, 0);
+	self = (fileio *) type->tp_alloc(type, 0);
 	if (self != NULL) {
 		self->fd = -1;
 		self->readable = 0;
@@ -101,7 +137,7 @@
    directories, so we need a check.  */
 
 static int
-dircheck(PyFileIOObject* self, char *name)
+dircheck(fileio* self, const char *name)
 {
 #if defined(HAVE_FSTAT) && defined(S_IFDIR) && defined(EISDIR)
 	struct stat buf;
@@ -110,7 +146,8 @@
 	if (fstat(self->fd, &buf) == 0 && S_ISDIR(buf.st_mode)) {
 		char *msg = strerror(EISDIR);
 		PyObject *exc;
-		internal_close(self);
+		if (internal_close(self))
+			return -1;
 
 		exc = PyObject_CallFunction(PyExc_IOError, "(iss)",
 					    EISDIR, msg, name);
@@ -144,9 +181,10 @@
 static int
 fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
 {
-	PyFileIOObject *self = (PyFileIOObject *) oself;
+	fileio *self = (fileio *) oself;
 	static char *kwlist[] = {"file", "mode", "closefd", NULL};
-	char *name = NULL;
+	const char *name = NULL;
+	PyObject *nameobj, *stringobj = NULL;
 	char *mode = "r";
 	char *s;
 #ifdef MS_WINDOWS
@@ -165,42 +203,59 @@
 			return -1;
 	}
 
-	if (PyArg_ParseTupleAndKeywords(args, kwds, "i|si:fileio",
-					kwlist, &fd, &mode, &closefd)) {
-		if (fd < 0) {
+	if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|si:fileio",
+					 kwlist, &nameobj, &mode, &closefd))
+		return -1;
+
+	if (PyFloat_Check(nameobj)) {
+		PyErr_SetString(PyExc_TypeError,
+				"integer argument expected, got float");
+		return -1;
+	}
+
+	fd = PyLong_AsLong(nameobj);
+	if (fd < 0) {
+		if (!PyErr_Occurred()) {
 			PyErr_SetString(PyExc_ValueError,
 					"Negative filedescriptor");
 			return -1;
 		}
-		if (check_fd(fd))
-			return -1;
-	}
-	else {
 		PyErr_Clear();
+	}
 
 #ifdef MS_WINDOWS
-	    if (GetVersion() < 0x80000000) {
+	if (GetVersion() < 0x80000000) {
 		/* On NT, so wide API available */
-		PyObject *po;
-		if (PyArg_ParseTupleAndKeywords(args, kwds, "U|si:fileio",
-						kwlist, &po, &mode, &closefd)
-						) {
-			widename = PyUnicode_AS_UNICODE(po);
-		} else {
-			/* Drop the argument parsing error as narrow
-			   strings are also valid. */
-			PyErr_Clear();
-		}
-	    }
-	    if (widename == NULL)
+		if (PyUnicode_Check(nameobj))
+			widename = PyUnicode_AS_UNICODE(nameobj);
+	}
+	if (widename == NULL)
 #endif
-	    {
-		if (!PyArg_ParseTupleAndKeywords(args, kwds, "et|si:fileio",
-						 kwlist,
-						 Py_FileSystemDefaultEncoding,
-						 &name, &mode, &closefd))
-			return -1;
-	    }
+	if (fd < 0)
+	{
+		if (PyBytes_Check(nameobj) || PyByteArray_Check(nameobj)) {
+			Py_ssize_t namelen;
+			if (PyObject_AsCharBuffer(nameobj, &name, &namelen) < 0)
+				return -1;
+		}
+		else {
+			PyObject *u = PyUnicode_FromObject(nameobj);
+
+			if (u == NULL)
+				return -1;
+
+			stringobj = PyUnicode_AsEncodedString(
+				u, Py_FileSystemDefaultEncoding, "surrogateescape");
+			Py_DECREF(u);
+			if (stringobj == NULL)
+				return -1;
+			if (!PyBytes_Check(stringobj)) {
+				PyErr_SetString(PyExc_TypeError,
+						"encoder failed to return bytes");
+				goto error;
+			}
+			name = PyBytes_AS_STRING(stringobj);
+		}
 	}
 
 	s = mode;
@@ -266,6 +321,8 @@
 #endif
 
 	if (fd >= 0) {
+		if (check_fd(fd))
+			goto error;
 		self->fd = fd;
 		self->closefd = closefd;
 	}
@@ -299,6 +356,9 @@
 			goto error;
 	}
 
+	if (PyObject_SetAttrString((PyObject *)self, "name", nameobj) < 0)
+		goto error;
+
 	if (append) {
 		/* For consistent behaviour, we explicitly seek to the
 		   end of file (otherwise, it might be done only on the
@@ -315,24 +375,33 @@
 	ret = -1;
 
  done:
-	PyMem_Free(name);
+	Py_CLEAR(stringobj);
 	return ret;
 }
 
-static void
-fileio_dealloc(PyFileIOObject *self)
+static int
+fileio_traverse(fileio *self, visitproc visit, void *arg)
 {
+	Py_VISIT(self->dict);
+	return 0;
+}
+
+static int
+fileio_clear(fileio *self)
+{
+	Py_CLEAR(self->dict);
+	return 0;
+}
+
+static void
+fileio_dealloc(fileio *self)
+{
+	if (_PyIOBase_finalize((PyObject *) self) < 0)
+		return;
+	_PyObject_GC_UNTRACK(self);
 	if (self->weakreflist != NULL)
 		PyObject_ClearWeakRefs((PyObject *) self);
-
-	if (self->fd >= 0 && self->closefd) {
-		errno = internal_close(self);
-		if (errno < 0) {
-			PySys_WriteStderr("close failed: [Errno %d] %s\n",
-                                          errno, strerror(errno));
-		}
-	}
-
+	Py_CLEAR(self->dict);
 	Py_TYPE(self)->tp_free((PyObject *)self);
 }
 
@@ -351,7 +420,7 @@
 }
 
 static PyObject *
-fileio_fileno(PyFileIOObject *self)
+fileio_fileno(fileio *self)
 {
 	if (self->fd < 0)
 		return err_closed();
@@ -359,7 +428,7 @@
 }
 
 static PyObject *
-fileio_readable(PyFileIOObject *self)
+fileio_readable(fileio *self)
 {
 	if (self->fd < 0)
 		return err_closed();
@@ -367,7 +436,7 @@
 }
 
 static PyObject *
-fileio_writable(PyFileIOObject *self)
+fileio_writable(fileio *self)
 {
 	if (self->fd < 0)
 		return err_closed();
@@ -375,25 +444,25 @@
 }
 
 static PyObject *
-fileio_seekable(PyFileIOObject *self)
+fileio_seekable(fileio *self)
 {
 	if (self->fd < 0)
 		return err_closed();
 	if (self->seekable < 0) {
-		int ret;
-		Py_BEGIN_ALLOW_THREADS
-		ret = lseek(self->fd, 0, SEEK_CUR);
-		Py_END_ALLOW_THREADS
-		if (ret < 0)
+		PyObject *pos = portable_lseek(self->fd, NULL, SEEK_CUR);
+		if (pos == NULL) {
+			PyErr_Clear();
 			self->seekable = 0;
-		else
+		} else {
+			Py_DECREF(pos);
 			self->seekable = 1;
+		}
 	}
 	return PyBool_FromLong((long) self->seekable);
 }
 
 static PyObject *
-fileio_readinto(PyFileIOObject *self, PyObject *args)
+fileio_readinto(fileio *self, PyObject *args)
 {
 	Py_buffer pbuf;
 	Py_ssize_t n;
@@ -406,10 +475,13 @@
 	if (!PyArg_ParseTuple(args, "w*", &pbuf))
 		return NULL;
 
-	Py_BEGIN_ALLOW_THREADS
-	errno = 0;
-	n = read(self->fd, pbuf.buf, pbuf.len);
-	Py_END_ALLOW_THREADS
+	if (_PyVerify_fd(self->fd)) {
+		Py_BEGIN_ALLOW_THREADS
+		errno = 0;
+		n = read(self->fd, pbuf.buf, pbuf.len);
+		Py_END_ALLOW_THREADS
+	} else
+		n = -1;
 	PyBuffer_Release(&pbuf);
 	if (n < 0) {
 		if (errno == EAGAIN)
@@ -421,23 +493,62 @@
 	return PyLong_FromSsize_t(n);
 }
 
-#define DEFAULT_BUFFER_SIZE (8*1024)
+static size_t
+new_buffersize(fileio *self, size_t currentsize)
+{
+#ifdef HAVE_FSTAT
+	off_t pos, end;
+	struct stat st;
+	if (fstat(self->fd, &st) == 0) {
+		end = st.st_size;
+		pos = lseek(self->fd, 0L, SEEK_CUR);
+		/* Files claiming a size smaller than SMALLCHUNK may
+		   actually be streaming pseudo-files. In this case, we
+		   apply the more aggressive algorithm below.
+		*/
+		if (end >= SMALLCHUNK && end >= pos && pos >= 0) {
+			/* Add 1 so if the file were to grow we'd notice. */
+			return currentsize + end - pos + 1;
+		}
+	}
+#endif
+	if (currentsize > SMALLCHUNK) {
+		/* Keep doubling until we reach BIGCHUNK;
+		   then keep adding BIGCHUNK. */
+		if (currentsize <= BIGCHUNK)
+			return currentsize + currentsize;
+		else
+			return currentsize + BIGCHUNK;
+	}
+	return currentsize + SMALLCHUNK;
+}
 
 static PyObject *
-fileio_readall(PyFileIOObject *self)
+fileio_readall(fileio *self)
 {
 	PyObject *result;
 	Py_ssize_t total = 0;
 	int n;
 
-	result = PyString_FromStringAndSize(NULL, DEFAULT_BUFFER_SIZE);
+	if (!_PyVerify_fd(self->fd))
+		return PyErr_SetFromErrno(PyExc_IOError);
+
+	result = PyBytes_FromStringAndSize(NULL, SMALLCHUNK);
 	if (result == NULL)
 		return NULL;
 
 	while (1) {
-		Py_ssize_t newsize = total + DEFAULT_BUFFER_SIZE;
-		if (PyString_GET_SIZE(result) < newsize) {
-			if (_PyString_Resize(&result, newsize) < 0) {
+		size_t newsize = new_buffersize(self, total);
+		if (newsize > PY_SSIZE_T_MAX || newsize <= 0) {
+			PyErr_SetString(PyExc_OverflowError,
+				"unbounded read returned more bytes "
+				"than a Python string can hold ");
+			Py_DECREF(result);
+			return NULL;
+		}
+
+		if (PyBytes_GET_SIZE(result) < (Py_ssize_t)newsize) {
+			if (_PyBytes_Resize(&result, newsize) < 0) {
 				if (total == 0) {
 					Py_DECREF(result);
 					return NULL;
@@ -449,7 +560,7 @@
 		Py_BEGIN_ALLOW_THREADS
 		errno = 0;
 		n = read(self->fd,
-			 PyString_AS_STRING(result) + total,
+			 PyBytes_AS_STRING(result) + total,
 			 newsize - total);
 		Py_END_ALLOW_THREADS
 		if (n == 0)
@@ -468,8 +579,8 @@
 		total += n;
 	}
 
-	if (PyString_GET_SIZE(result) > total) {
-		if (_PyString_Resize(&result, total) < 0) {
+	if (PyBytes_GET_SIZE(result) > total) {
+		if (_PyBytes_Resize(&result, total) < 0) {
 			/* This should never happen, but just in case */
 			Py_DECREF(result);
 			return NULL;
@@ -479,7 +590,7 @@
 }
 
 static PyObject *
-fileio_read(PyFileIOObject *self, PyObject *args)
+fileio_read(fileio *self, PyObject *args)
 {
 	char *ptr;
 	Py_ssize_t n;
@@ -498,17 +609,21 @@
 		return fileio_readall(self);
 	}
 
-	bytes = PyString_FromStringAndSize(NULL, size);
+	bytes = PyBytes_FromStringAndSize(NULL, size);
 	if (bytes == NULL)
 		return NULL;
-	ptr = PyString_AS_STRING(bytes);
+	ptr = PyBytes_AS_STRING(bytes);
 
-	Py_BEGIN_ALLOW_THREADS
-	errno = 0;
-	n = read(self->fd, ptr, size);
-	Py_END_ALLOW_THREADS
+	if (_PyVerify_fd(self->fd)) {
+		Py_BEGIN_ALLOW_THREADS
+		errno = 0;
+		n = read(self->fd, ptr, size);
+		Py_END_ALLOW_THREADS
+	} else
+		n = -1;
 
 	if (n < 0) {
+		Py_DECREF(bytes);
 		if (errno == EAGAIN)
 			Py_RETURN_NONE;
 		PyErr_SetFromErrno(PyExc_IOError);
@@ -516,7 +631,7 @@
 	}
 
 	if (n != size) {
-		if (_PyString_Resize(&bytes, n) < 0) {
+		if (_PyBytes_Resize(&bytes, n) < 0) {
 			Py_DECREF(bytes);
 			return NULL;
 		}
@@ -526,7 +641,7 @@
 }
 
 static PyObject *
-fileio_write(PyFileIOObject *self, PyObject *args)
+fileio_write(fileio *self, PyObject *args)
 {
 	Py_buffer pbuf;
 	Py_ssize_t n;
@@ -539,10 +654,13 @@
 	if (!PyArg_ParseTuple(args, "s*", &pbuf))
 		return NULL;
 
-	Py_BEGIN_ALLOW_THREADS
-	errno = 0;
-	n = write(self->fd, pbuf.buf, pbuf.len);
-	Py_END_ALLOW_THREADS
+	if (_PyVerify_fd(self->fd)) {
+		Py_BEGIN_ALLOW_THREADS
+		errno = 0;
+		n = write(self->fd, pbuf.buf, pbuf.len);
+		Py_END_ALLOW_THREADS
+	} else
+		n = -1;
 
 	PyBuffer_Release(&pbuf);
 
@@ -558,12 +676,6 @@
 
 /* XXX Windows support below is likely incomplete */
 
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
-typedef PY_LONG_LONG Py_off_t;
-#else
-typedef off_t Py_off_t;
-#endif
-
 /* Cribbed from posix_lseek() */
 static PyObject *
 portable_lseek(int fd, PyObject *posobj, int whence)
@@ -601,13 +713,16 @@
 			return NULL;
 	}
 
-	Py_BEGIN_ALLOW_THREADS
+	if (_PyVerify_fd(fd)) {
+		Py_BEGIN_ALLOW_THREADS
 #if defined(MS_WIN64) || defined(MS_WINDOWS)
-	res = _lseeki64(fd, pos, whence);
+		res = _lseeki64(fd, pos, whence);
 #else
-	res = lseek(fd, pos, whence);
+		res = lseek(fd, pos, whence);
 #endif
-	Py_END_ALLOW_THREADS
+		Py_END_ALLOW_THREADS
+	} else
+		res = -1;
 	if (res < 0)
 		return PyErr_SetFromErrno(PyExc_IOError);
 
@@ -619,7 +734,7 @@
 }
 
 static PyObject *
-fileio_seek(PyFileIOObject *self, PyObject *args)
+fileio_seek(fileio *self, PyObject *args)
 {
 	PyObject *posobj;
 	int whence = 0;
@@ -634,7 +749,7 @@
 }
 
 static PyObject *
-fileio_tell(PyFileIOObject *self, PyObject *args)
+fileio_tell(fileio *self, PyObject *args)
 {
 	if (self->fd < 0)
 		return err_closed();
@@ -644,7 +759,7 @@
 
 #ifdef HAVE_FTRUNCATE
 static PyObject *
-fileio_truncate(PyFileIOObject *self, PyObject *args)
+fileio_truncate(fileio *self, PyObject *args)
 {
 	PyObject *posobj = NULL;
 	Py_off_t pos;
@@ -670,13 +785,15 @@
 		/* Move to the position to be truncated. */
                 posobj = portable_lseek(fd, posobj, 0);
         }
+	if (posobj == NULL)
+		return NULL;
 
 #if defined(HAVE_LARGEFILE_SUPPORT)
 	pos = PyLong_AsLongLong(posobj);
 #else
 	pos = PyLong_AsLong(posobj);
 #endif
-	if (PyErr_Occurred())
+	if (pos == -1 && PyErr_Occurred())
 		return NULL;
 
 #ifdef MS_WINDOWS
@@ -714,7 +831,7 @@
 #endif
 
 static char *
-mode_string(PyFileIOObject *self)
+mode_string(fileio *self)
 {
 	if (self->readable) {
 		if (self->writable)
@@ -727,17 +844,37 @@
 }
 
 static PyObject *
-fileio_repr(PyFileIOObject *self)
+fileio_repr(fileio *self)
 {
-        if (self->fd < 0)
-		return PyString_FromFormat("_fileio._FileIO(-1)");
+	PyObject *nameobj, *res;
 
-	return PyString_FromFormat("_fileio._FileIO(%d, '%s')",
-				   self->fd, mode_string(self));
+        if (self->fd < 0)
+		return PyString_FromFormat("<_io.FileIO [closed]>");
+
+	nameobj = PyObject_GetAttrString((PyObject *) self, "name");
+	if (nameobj == NULL) {
+		if (PyErr_ExceptionMatches(PyExc_AttributeError))
+			PyErr_Clear();
+		else
+			return NULL;
+		res = PyString_FromFormat("<_io.FileIO fd=%d mode='%s'>",
+					   self->fd, mode_string(self));
+	}
+	else {
+		PyObject *repr = PyObject_Repr(nameobj);
+		Py_DECREF(nameobj);
+		if (repr == NULL)
+			return NULL;
+		res = PyString_FromFormat("<_io.FileIO name=%s mode='%s'>",
+					   PyString_AS_STRING(repr),
+					   mode_string(self));
+		Py_DECREF(repr);
+	}
+	return res;
 }
 
 static PyObject *
-fileio_isatty(PyFileIOObject *self)
+fileio_isatty(fileio *self)
 {
 	long res;
 
@@ -806,7 +943,7 @@
 "tell() -> int.	 Current file position");
 
 PyDoc_STRVAR(readinto_doc,
-"readinto() -> Undocumented.  Don't use this; it may go away.");
+"readinto() -> Same as RawIOBase.readinto().");
 
 PyDoc_STRVAR(close_doc,
 "close() -> None.  Close the file.\n"
@@ -848,21 +985,21 @@
 /* 'closed' and 'mode' are attributes for backwards compatibility reasons. */
 
 static PyObject *
-get_closed(PyFileIOObject *self, void *closure)
+get_closed(fileio *self, void *closure)
 {
 	return PyBool_FromLong((long)(self->fd < 0));
 }
 
 static PyObject *
-get_closefd(PyFileIOObject *self, void *closure)
+get_closefd(fileio *self, void *closure)
 {
 	return PyBool_FromLong((long)(self->closefd));
 }
 
 static PyObject *
-get_mode(PyFileIOObject *self, void *closure)
+get_mode(fileio *self, void *closure)
 {
-	return PyString_FromString(mode_string(self));
+	return PyUnicode_FromString(mode_string(self));
 }
 
 static PyGetSetDef fileio_getsetlist[] = {
@@ -870,19 +1007,19 @@
 	{"closefd", (getter)get_closefd, NULL, 
 		"True if the file descriptor will be closed"},
 	{"mode", (getter)get_mode, NULL, "String giving the file mode"},
-	{0},
+	{NULL},
 };
 
 PyTypeObject PyFileIO_Type = {
 	PyVarObject_HEAD_INIT(NULL, 0)
-	"_FileIO",
-	sizeof(PyFileIOObject),
+	"_io.FileIO",
+	sizeof(fileio),
 	0,
 	(destructor)fileio_dealloc,		/* tp_dealloc */
 	0,					/* tp_print */
 	0,					/* tp_getattr */
 	0,					/* tp_setattr */
-	0,					/* tp_compare */
+	0,					/* tp_reserved */
 	(reprfunc)fileio_repr,			/* tp_repr */
 	0,					/* tp_as_number */
 	0,					/* tp_as_sequence */
@@ -893,12 +1030,13 @@
 	PyObject_GenericGetAttr,		/* tp_getattro */
 	0,					/* tp_setattro */
 	0,					/* tp_as_buffer */
-	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
+	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+			| Py_TPFLAGS_HAVE_GC,	/* tp_flags */
 	fileio_doc,				/* tp_doc */
-	0,					/* tp_traverse */
-	0,					/* tp_clear */
+	(traverseproc)fileio_traverse,		/* tp_traverse */
+	(inquiry)fileio_clear,			/* tp_clear */
 	0,					/* tp_richcompare */
-	offsetof(PyFileIOObject, weakreflist),	/* tp_weaklistoffset */
+	offsetof(fileio, weakreflist),	/* tp_weaklistoffset */
 	0,					/* tp_iter */
 	0,					/* tp_iternext */
 	fileio_methods,				/* tp_methods */
@@ -908,28 +1046,9 @@
 	0,					/* tp_dict */
 	0,					/* tp_descr_get */
 	0,					/* tp_descr_set */
-	0,					/* tp_dictoffset */
+	offsetof(fileio, dict),         /* tp_dictoffset */
 	fileio_init,				/* tp_init */
 	PyType_GenericAlloc,			/* tp_alloc */
 	fileio_new,				/* tp_new */
-	PyObject_Del,				/* tp_free */
+	PyObject_GC_Del,			/* tp_free */
 };
-
-static PyMethodDef module_methods[] = {
-	{NULL, NULL}
-};
-
-PyMODINIT_FUNC
-init_fileio(void)
-{
-	PyObject *m;	/* a module object */
-
-	m = Py_InitModule3("_fileio", module_methods,
-			   "Fast implementation of io.FileIO.");
-	if (m == NULL)
-		return;
-	if (PyType_Ready(&PyFileIO_Type) < 0)
-		return;
-	Py_INCREF(&PyFileIO_Type);
-	PyModule_AddObject(m, "_FileIO", (PyObject *) &PyFileIO_Type);
-}
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
new file mode 100644
index 0000000..38080f7
--- /dev/null
+++ b/Modules/_io/iobase.c
@@ -0,0 +1,894 @@
+/*
+    An implementation of the I/O abstract base classes hierarchy
+    as defined by PEP 3116 - "New I/O"
+    
+    Classes defined here: IOBase, RawIOBase.
+    
+    Written by Amaury Forgeot d'Arc and Antoine Pitrou
+*/
+
+
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+#include "structmember.h"
+#include "_iomodule.h"
+
+/*
+ * IOBase class, an abstract class
+ */
+
+typedef struct {
+    PyObject_HEAD
+    
+    PyObject *dict;
+    PyObject *weakreflist;
+} iobase;
+
+PyDoc_STRVAR(iobase_doc,
+    "The abstract base class for all I/O classes, acting on streams of\n"
+    "bytes. There is no public constructor.\n"
+    "\n"
+    "This class provides dummy implementations for many methods that\n"
+    "derived classes can override selectively; the default implementations\n"
+    "represent a file that cannot be read, written or seeked.\n"
+    "\n"
+    "Even though IOBase does not declare read, readinto, or write because\n"
+    "their signatures will vary, implementations and clients should\n"
+    "consider those methods part of the interface. Also, implementations\n"
+    "may raise a IOError when operations they do not support are called.\n"
+    "\n"
+    "The basic type used for binary data read from or written to a file is\n"
+    "bytes. bytearrays are accepted too, and in some cases (such as\n"
+    "readinto) needed. Text I/O classes work with str data.\n"
+    "\n"
+    "Note that calling any method (even inquiries) on a closed stream is\n"
+    "undefined. Implementations may raise IOError in this case.\n"
+    "\n"
+    "IOBase (and its subclasses) support the iterator protocol, meaning\n"
+    "that an IOBase object can be iterated over yielding the lines in a\n"
+    "stream.\n"
+    "\n"
+    "IOBase also supports the :keyword:`with` statement. In this example,\n"
+    "fp is closed after the suite of the with statment is complete:\n"
+    "\n"
+    "with open('spam.txt', 'r') as fp:\n"
+    "    fp.write('Spam and eggs!')\n");
+
+/* Use this macro whenever you want to check the internal `closed` status
+   of the IOBase object rather than the virtual `closed` attribute as returned
+   by whatever subclass. */
+
+#define IS_CLOSED(self) \
+    PyObject_HasAttrString(self, "__IOBase_closed")
+
+/* Internal methods */
+static PyObject *
+iobase_unsupported(const char *message)
+{
+    PyErr_SetString(_PyIO_unsupported_operation, message);
+    return NULL;
+}
+
+/* Positionning */
+
+PyDoc_STRVAR(iobase_seek_doc,
+    "Change stream position.\n"
+    "\n"
+    "Change the stream position to byte offset offset. offset is\n"
+    "interpreted relative to the position indicated by whence.  Values\n"
+    "for whence are:\n"
+    "\n"
+    "* 0 -- start of stream (the default); offset should be zero or positive\n"
+    "* 1 -- current stream position; offset may be negative\n"
+    "* 2 -- end of stream; offset is usually negative\n"
+    "\n"
+    "Return the new absolute position.");
+
+static PyObject *
+iobase_seek(PyObject *self, PyObject *args)
+{
+    return iobase_unsupported("seek");
+}
+
+PyDoc_STRVAR(iobase_tell_doc,
+             "Return current stream position.");
+
+static PyObject *
+iobase_tell(PyObject *self, PyObject *args)
+{
+    return PyObject_CallMethod(self, "seek", "ii", 0, 1);
+}
+
+PyDoc_STRVAR(iobase_truncate_doc,
+    "Truncate file to size bytes.\n"
+    "\n"
+    "Size defaults to the current IO position as reported by tell().  Return\n"
+    "the new size.");
+
+static PyObject *
+iobase_truncate(PyObject *self, PyObject *args)
+{
+    return iobase_unsupported("truncate");
+}
+
+/* Flush and close methods */
+
+PyDoc_STRVAR(iobase_flush_doc,
+    "Flush write buffers, if applicable.\n"
+    "\n"
+    "This is not implemented for read-only and non-blocking streams.\n");
+
+static PyObject *
+iobase_flush(PyObject *self, PyObject *args)
+{
+    /* XXX Should this return the number of bytes written??? */
+    if (IS_CLOSED(self)) {
+        PyErr_SetString(PyExc_ValueError, "I/O operation on closed file.");
+        return NULL;
+    }
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(iobase_close_doc,
+    "Flush and close the IO object.\n"
+    "\n"
+    "This method has no effect if the file is already closed.\n");
+
+static int
+iobase_closed(PyObject *self)
+{
+    PyObject *res;
+    int closed;
+    /* This gets the derived attribute, which is *not* __IOBase_closed
+       in most cases! */
+    res = PyObject_GetAttr(self, _PyIO_str_closed);
+    if (res == NULL)
+        return 0;
+    closed = PyObject_IsTrue(res);
+    Py_DECREF(res);
+    return closed;
+}
+
+static PyObject *
+iobase_closed_get(PyObject *self, void *context)
+{
+    return PyBool_FromLong(IS_CLOSED(self));
+}
+
+PyObject *
+_PyIOBase_check_closed(PyObject *self, PyObject *args)
+{
+    if (iobase_closed(self)) {
+        PyErr_SetString(PyExc_ValueError, "I/O operation on closed file.");
+        return NULL;
+    }
+    if (args == Py_True)
+        return Py_None;
+    else
+        Py_RETURN_NONE;
+}
+
+/* XXX: IOBase thinks it has to maintain its own internal state in
+   `__IOBase_closed` and call flush() by itself, but it is redundant with
+   whatever behaviour a non-trivial derived class will implement. */
+
+static PyObject *
+iobase_close(PyObject *self, PyObject *args)
+{
+    PyObject *res;
+
+    if (IS_CLOSED(self))
+        Py_RETURN_NONE;
+
+    res = PyObject_CallMethodObjArgs(self, _PyIO_str_flush, NULL);
+    PyObject_SetAttrString(self, "__IOBase_closed", Py_True);
+    if (res == NULL) {
+        /* If flush() fails, just give up */
+        if (PyErr_ExceptionMatches(PyExc_IOError))
+            PyErr_Clear();
+        else
+            return NULL;
+    }
+    Py_XDECREF(res);
+    Py_RETURN_NONE;
+}
+
+/* Finalization and garbage collection support */
+
+int
+_PyIOBase_finalize(PyObject *self)
+{
+    PyObject *res;
+    PyObject *tp, *v, *tb;
+    int closed = 1;
+    int is_zombie;
+
+    /* If _PyIOBase_finalize() is called from a destructor, we need to
+       resurrect the object as calling close() can invoke arbitrary code. */
+    is_zombie = (Py_REFCNT(self) == 0);
+    if (is_zombie) {
+        ++Py_REFCNT(self);
+    }
+    PyErr_Fetch(&tp, &v, &tb);
+    /* If `closed` doesn't exist or can't be evaluated as bool, then the
+       object is probably in an unusable state, so ignore. */
+    res = PyObject_GetAttr(self, _PyIO_str_closed);
+    if (res == NULL)
+        PyErr_Clear();
+    else {
+        closed = PyObject_IsTrue(res);
+        Py_DECREF(res);
+        if (closed == -1)
+            PyErr_Clear();
+    }
+    if (closed == 0) {
+        res = PyObject_CallMethodObjArgs((PyObject *) self, _PyIO_str_close,
+                                          NULL);
+        /* Silencing I/O errors is bad, but printing spurious tracebacks is
+           equally as bad, and potentially more frequent (because of
+           shutdown issues). */
+        if (res == NULL)
+            PyErr_Clear();
+        else
+            Py_DECREF(res);
+    }
+    PyErr_Restore(tp, v, tb);
+    if (is_zombie) {
+        if (--Py_REFCNT(self) != 0) {
+            /* The object lives again. The following code is taken from
+               slot_tp_del in typeobject.c. */
+            Py_ssize_t refcnt = Py_REFCNT(self);
+            _Py_NewReference(self);
+            Py_REFCNT(self) = refcnt;
+            /* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
+             * we need to undo that. */
+            _Py_DEC_REFTOTAL;
+            /* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
+             * chain, so no more to do there.
+             * If COUNT_ALLOCS, the original decref bumped tp_frees, and
+             * _Py_NewReference bumped tp_allocs:  both of those need to be
+             * undone.
+             */
+#ifdef COUNT_ALLOCS
+            --Py_TYPE(self)->tp_frees;
+            --Py_TYPE(self)->tp_allocs;
+#endif
+            return -1;
+        }
+    }
+    return 0;
+}
+
+static int
+iobase_traverse(iobase *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->dict);
+    return 0;
+}
+
+static int
+iobase_clear(iobase *self)
+{
+    if (_PyIOBase_finalize((PyObject *) self) < 0)
+        return -1;
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+/* Destructor */
+
+static void
+iobase_dealloc(iobase *self)
+{
+    /* NOTE: since IOBaseObject has its own dict, Python-defined attributes
+       are still available here for close() to use.
+       However, if the derived class declares a __slots__, those slots are
+       already gone.
+    */
+    if (_PyIOBase_finalize((PyObject *) self) < 0) {
+        /* When called from a heap type's dealloc, the type will be
+           decref'ed on return (see e.g. subtype_dealloc in typeobject.c). */
+        if (PyType_HasFeature(Py_TYPE(self), Py_TPFLAGS_HEAPTYPE))
+            Py_INCREF(Py_TYPE(self));
+        return;
+    }
+    _PyObject_GC_UNTRACK(self);
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *) self);
+    Py_CLEAR(self->dict);
+    Py_TYPE(self)->tp_free((PyObject *) self);
+}
+
+/* Inquiry methods */
+
+PyDoc_STRVAR(iobase_seekable_doc,
+    "Return whether object supports random access.\n"
+    "\n"
+    "If False, seek(), tell() and truncate() will raise IOError.\n"
+    "This method may need to do a test seek().");
+
+static PyObject *
+iobase_seekable(PyObject *self, PyObject *args)
+{
+    Py_RETURN_FALSE;
+}
+
+PyObject *
+_PyIOBase_check_seekable(PyObject *self, PyObject *args)
+{
+    PyObject *res  = PyObject_CallMethodObjArgs(self, _PyIO_str_seekable, NULL);
+    if (res == NULL)
+        return NULL;
+    if (res != Py_True) {
+        Py_CLEAR(res);
+        PyErr_SetString(PyExc_IOError, "File or stream is not seekable.");
+        return NULL;
+    }
+    if (args == Py_True) {
+        Py_DECREF(res);
+    }
+    return res;
+}
+
+PyDoc_STRVAR(iobase_readable_doc,
+    "Return whether object was opened for reading.\n"
+    "\n"
+    "If False, read() will raise IOError.");
+
+static PyObject *
+iobase_readable(PyObject *self, PyObject *args)
+{
+    Py_RETURN_FALSE;
+}
+
+/* May be called with any object */
+PyObject *
+_PyIOBase_check_readable(PyObject *self, PyObject *args)
+{
+    PyObject *res  = PyObject_CallMethodObjArgs(self, _PyIO_str_readable, NULL);
+    if (res == NULL)
+        return NULL;
+    if (res != Py_True) {
+        Py_CLEAR(res);
+        PyErr_SetString(PyExc_IOError, "File or stream is not readable.");
+        return NULL;
+    }
+    if (args == Py_True) {
+        Py_DECREF(res);
+    }
+    return res;
+}
+
+PyDoc_STRVAR(iobase_writable_doc,
+    "Return whether object was opened for writing.\n"
+    "\n"
+    "If False, read() will raise IOError.");
+
+static PyObject *
+iobase_writable(PyObject *self, PyObject *args)
+{
+    Py_RETURN_FALSE;
+}
+
+/* May be called with any object */
+PyObject *
+_PyIOBase_check_writable(PyObject *self, PyObject *args)
+{
+    PyObject *res  = PyObject_CallMethodObjArgs(self, _PyIO_str_writable, NULL);
+    if (res == NULL)
+        return NULL;
+    if (res != Py_True) {
+        Py_CLEAR(res);
+        PyErr_SetString(PyExc_IOError, "File or stream is not writable.");
+        return NULL;
+    }
+    if (args == Py_True) {
+        Py_DECREF(res);
+    }
+    return res;
+}
+
+/* Context manager */
+
+static PyObject *
+iobase_enter(PyObject *self, PyObject *args)
+{
+    if (_PyIOBase_check_closed(self, Py_True) == NULL)
+        return NULL;
+
+    Py_INCREF(self);
+    return self;
+}
+
+static PyObject *
+iobase_exit(PyObject *self, PyObject *args)
+{
+    return PyObject_CallMethodObjArgs(self, _PyIO_str_close, NULL);
+}
+
+/* Lower-level APIs */
+
+/* XXX Should these be present even if unimplemented? */
+
+PyDoc_STRVAR(iobase_fileno_doc,
+    "Returns underlying file descriptor if one exists.\n"
+    "\n"
+    "An IOError is raised if the IO object does not use a file descriptor.\n");
+
+static PyObject *
+iobase_fileno(PyObject *self, PyObject *args)
+{
+    return iobase_unsupported("fileno");
+}
+
+PyDoc_STRVAR(iobase_isatty_doc,
+    "Return whether this is an 'interactive' stream.\n"
+    "\n"
+    "Return False if it can't be determined.\n");
+
+static PyObject *
+iobase_isatty(PyObject *self, PyObject *args)
+{
+    if (_PyIOBase_check_closed(self, Py_True) == NULL)
+        return NULL;
+    Py_RETURN_FALSE;
+}
+
+/* Readline(s) and writelines */
+
+PyDoc_STRVAR(iobase_readline_doc,
+    "Read and return a line from the stream.\n"
+    "\n"
+    "If limit is specified, at most limit bytes will be read.\n"
+    "\n"
+    "The line terminator is always b'\n' for binary files; for text\n"
+    "files, the newlines argument to open can be used to select the line\n"
+    "terminator(s) recognized.\n");
+
+static PyObject *
+iobase_readline(PyObject *self, PyObject *args)
+{
+    /* For backwards compatibility, a (slowish) readline(). */
+
+    Py_ssize_t limit = -1;
+    int has_peek = 0;
+    PyObject *buffer, *result;
+    Py_ssize_t old_size = -1;
+
+    if (!PyArg_ParseTuple(args, "|n:readline", &limit)) {
+        return NULL;
+    }
+
+    if (PyObject_HasAttrString(self, "peek"))
+        has_peek = 1;
+
+    buffer = PyByteArray_FromStringAndSize(NULL, 0);
+    if (buffer == NULL)
+        return NULL;
+
+    while (limit < 0 || Py_SIZE(buffer) < limit) {
+        Py_ssize_t nreadahead = 1;
+        PyObject *b;
+
+        if (has_peek) {
+            PyObject *readahead = PyObject_CallMethod(self, "peek", "i", 1);
+            if (readahead == NULL)
+                goto fail;
+            if (!PyBytes_Check(readahead)) {
+                PyErr_Format(PyExc_IOError,
+                             "peek() should have returned a bytes object, "
+                             "not '%.200s'", Py_TYPE(readahead)->tp_name);
+                Py_DECREF(readahead);
+                goto fail;
+            }
+            if (PyBytes_GET_SIZE(readahead) > 0) {
+                Py_ssize_t n = 0;
+                const char *buf = PyBytes_AS_STRING(readahead);
+                if (limit >= 0) {
+                    do {
+                        if (n >= PyBytes_GET_SIZE(readahead) || n >= limit)
+                            break;
+                        if (buf[n++] == '\n')
+                            break;
+                    } while (1);
+                }
+                else {
+                    do {
+                        if (n >= PyBytes_GET_SIZE(readahead))
+                            break;
+                        if (buf[n++] == '\n')
+                            break;
+                    } while (1);
+                }
+                nreadahead = n;
+            }
+            Py_DECREF(readahead);
+        }
+
+        b = PyObject_CallMethod(self, "read", "n", nreadahead);
+        if (b == NULL)
+            goto fail;
+        if (!PyBytes_Check(b)) {
+            PyErr_Format(PyExc_IOError,
+                         "read() should have returned a bytes object, "
+                         "not '%.200s'", Py_TYPE(b)->tp_name);
+            Py_DECREF(b);
+            goto fail;
+        }
+        if (PyBytes_GET_SIZE(b) == 0) {
+            Py_DECREF(b);
+            break;
+        }
+
+        old_size = PyByteArray_GET_SIZE(buffer);
+        PyByteArray_Resize(buffer, old_size + PyBytes_GET_SIZE(b));
+        memcpy(PyByteArray_AS_STRING(buffer) + old_size,
+               PyBytes_AS_STRING(b), PyBytes_GET_SIZE(b));
+
+        Py_DECREF(b);
+
+        if (PyByteArray_AS_STRING(buffer)[PyByteArray_GET_SIZE(buffer) - 1] == '\n')
+            break;
+    }
+
+    result = PyBytes_FromStringAndSize(PyByteArray_AS_STRING(buffer),
+                                       PyByteArray_GET_SIZE(buffer));
+    Py_DECREF(buffer);
+    return result;
+  fail:
+    Py_DECREF(buffer);
+    return NULL;
+}
+
+static PyObject *
+iobase_iter(PyObject *self)
+{
+    if (_PyIOBase_check_closed(self, Py_True) == NULL)
+        return NULL;
+
+    Py_INCREF(self);
+    return self;
+}
+
+static PyObject *
+iobase_iternext(PyObject *self)
+{
+    PyObject *line = PyObject_CallMethodObjArgs(self, _PyIO_str_readline, NULL);
+
+    if (line == NULL)
+        return NULL;
+
+    if (PyObject_Size(line) == 0) {
+        Py_DECREF(line);
+        return NULL;
+    }
+
+    return line;
+}
+
+PyDoc_STRVAR(iobase_readlines_doc,
+    "Return a list of lines from the stream.\n"
+    "\n"
+    "hint can be specified to control the number of lines read: no more\n"
+    "lines will be read if the total size (in bytes/characters) of all\n"
+    "lines so far exceeds hint.");
+
+static PyObject *
+iobase_readlines(PyObject *self, PyObject *args)
+{
+    Py_ssize_t hint = -1, length = 0;
+    PyObject *hintobj = Py_None, *result;
+
+    if (!PyArg_ParseTuple(args, "|O:readlines", &hintobj)) {
+        return NULL;
+    }
+    if (hintobj != Py_None) {
+        hint = PyNumber_AsSsize_t(hintobj, PyExc_ValueError);
+        if (hint == -1 && PyErr_Occurred())
+            return NULL;
+    }
+
+    result = PyList_New(0);
+    if (result == NULL)
+        return NULL;
+
+    if (hint <= 0) {
+        /* XXX special-casing this made sense in the Python version in order
+           to remove the bytecode interpretation overhead, but it could
+           probably be removed here. */
+        PyObject *ret = PyObject_CallMethod(result, "extend", "O", self);
+        if (ret == NULL) {
+            Py_DECREF(result);
+            return NULL;
+        }
+        Py_DECREF(ret);
+        return result;
+    }
+
+    while (1) {
+        PyObject *line = PyIter_Next(self);
+        if (line == NULL) {
+            if (PyErr_Occurred()) {
+                Py_DECREF(result);
+                return NULL;
+            }
+            else
+                break; /* StopIteration raised */
+        }
+
+        if (PyList_Append(result, line) < 0) {
+            Py_DECREF(line);
+            Py_DECREF(result);
+            return NULL;
+        }
+        length += PyObject_Size(line);
+        Py_DECREF(line);
+
+        if (length > hint)
+            break;
+    }
+    return result;
+}
+
+static PyObject *
+iobase_writelines(PyObject *self, PyObject *args)
+{
+    PyObject *lines, *iter, *res;
+
+    if (!PyArg_ParseTuple(args, "O:writelines", &lines)) {
+        return NULL;
+    }
+
+    if (_PyIOBase_check_closed(self, Py_True) == NULL)
+        return NULL;
+
+    iter = PyObject_GetIter(lines);
+    if (iter == NULL)
+        return NULL;
+
+    while (1) {
+        PyObject *line = PyIter_Next(iter);
+        if (line == NULL) {
+            if (PyErr_Occurred()) {
+                Py_DECREF(iter);
+                return NULL;
+            }
+            else
+                break; /* Stop Iteration */
+        }
+
+        res = PyObject_CallMethodObjArgs(self, _PyIO_str_write, line, NULL);
+        Py_DECREF(line);
+        if (res == NULL) {
+            Py_DECREF(iter);
+            return NULL;
+        }
+        Py_DECREF(res);
+    }
+    Py_DECREF(iter);
+    Py_RETURN_NONE;
+}
+
+static PyMethodDef iobase_methods[] = {
+    {"seek", iobase_seek, METH_VARARGS, iobase_seek_doc},
+    {"tell", iobase_tell, METH_NOARGS, iobase_tell_doc},
+    {"truncate", iobase_truncate, METH_VARARGS, iobase_truncate_doc},
+    {"flush", iobase_flush, METH_NOARGS, iobase_flush_doc},
+    {"close", iobase_close, METH_NOARGS, iobase_close_doc},
+
+    {"seekable", iobase_seekable, METH_NOARGS, iobase_seekable_doc},
+    {"readable", iobase_readable, METH_NOARGS, iobase_readable_doc},
+    {"writable", iobase_writable, METH_NOARGS, iobase_writable_doc},
+
+    {"_checkClosed",   _PyIOBase_check_closed, METH_NOARGS},
+    {"_checkSeekable", _PyIOBase_check_seekable, METH_NOARGS},
+    {"_checkReadable", _PyIOBase_check_readable, METH_NOARGS},
+    {"_checkWritable", _PyIOBase_check_writable, METH_NOARGS},
+
+    {"fileno", iobase_fileno, METH_NOARGS, iobase_fileno_doc},
+    {"isatty", iobase_isatty, METH_NOARGS, iobase_isatty_doc},
+
+    {"__enter__", iobase_enter, METH_NOARGS},
+    {"__exit__", iobase_exit, METH_VARARGS},
+
+    {"readline", iobase_readline, METH_VARARGS, iobase_readline_doc},
+    {"readlines", iobase_readlines, METH_VARARGS, iobase_readlines_doc},
+    {"writelines", iobase_writelines, METH_VARARGS},
+
+    {NULL, NULL}
+};
+
+static PyGetSetDef iobase_getset[] = {
+    {"closed", (getter)iobase_closed_get, NULL, NULL},
+    {NULL}
+};
+
+
+PyTypeObject PyIOBase_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io._IOBase",              /*tp_name*/
+    sizeof(iobase),             /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)iobase_dealloc, /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
+    iobase_doc,                 /* tp_doc */
+    (traverseproc)iobase_traverse, /* tp_traverse */
+    (inquiry)iobase_clear,      /* tp_clear */
+    0,                          /* tp_richcompare */
+    offsetof(iobase, weakreflist), /* tp_weaklistoffset */
+    iobase_iter,                /* tp_iter */
+    iobase_iternext,            /* tp_iternext */
+    iobase_methods,             /* tp_methods */
+    0,                          /* tp_members */
+    iobase_getset,              /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    offsetof(iobase, dict),     /* tp_dictoffset */
+    0,                          /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};
+
+
+/*
+ * RawIOBase class, Inherits from IOBase.
+ */
+PyDoc_STRVAR(rawiobase_doc,
+             "Base class for raw binary I/O.");
+
+/*
+ * The read() method is implemented by calling readinto(); derived classes
+ * that want to support read() only need to implement readinto() as a
+ * primitive operation.  In general, readinto() can be more efficient than
+ * read().
+ *
+ * (It would be tempting to also provide an implementation of readinto() in
+ * terms of read(), in case the latter is a more suitable primitive operation,
+ * but that would lead to nasty recursion in case a subclass doesn't implement
+ * either.)
+*/
+
+static PyObject *
+rawiobase_read(PyObject *self, PyObject *args)
+{
+    Py_ssize_t n = -1;
+    PyObject *b, *res;
+
+    if (!PyArg_ParseTuple(args, "|n:read", &n)) {
+        return NULL;
+    }
+
+    if (n < 0)
+        return PyObject_CallMethod(self, "readall", NULL);
+
+    /* TODO: allocate a bytes object directly instead and manually construct
+       a writable memoryview pointing to it. */
+    b = PyByteArray_FromStringAndSize(NULL, n);
+    if (b == NULL)
+        return NULL;
+
+    res = PyObject_CallMethodObjArgs(self, _PyIO_str_readinto, b, NULL);
+    if (res == NULL) {
+        Py_DECREF(b);
+        return NULL;
+    }
+
+    n = PyNumber_AsSsize_t(res, PyExc_ValueError);
+    Py_DECREF(res);
+    if (n == -1 && PyErr_Occurred()) {
+        Py_DECREF(b);
+        return NULL;
+    }
+
+    res = PyBytes_FromStringAndSize(PyByteArray_AsString(b), n);
+    Py_DECREF(b);
+    return res;
+}
+
+
+PyDoc_STRVAR(rawiobase_readall_doc,
+             "Read until EOF, using multiple read() call.");
+
+static PyObject *
+rawiobase_readall(PyObject *self, PyObject *args)
+{
+    int r;
+    PyObject *chunks = PyList_New(0);
+    PyObject *result;
+    
+    if (chunks == NULL)
+        return NULL;
+
+    while (1) {
+        PyObject *data = PyObject_CallMethod(self, "read",
+                                             "i", DEFAULT_BUFFER_SIZE);
+        if (!data) {
+            Py_DECREF(chunks);
+            return NULL;
+        }
+        if (!PyBytes_Check(data)) {
+            Py_DECREF(chunks);
+            Py_DECREF(data);
+            PyErr_SetString(PyExc_TypeError, "read() should return bytes");
+            return NULL;
+        }
+        if (PyBytes_GET_SIZE(data) == 0) {
+            /* EOF */
+            Py_DECREF(data);
+            break;
+        }
+        r = PyList_Append(chunks, data);
+        Py_DECREF(data);
+        if (r < 0) {
+            Py_DECREF(chunks);
+            return NULL;
+        }
+    }
+    result = _PyBytes_Join(_PyIO_empty_bytes, chunks);
+    Py_DECREF(chunks);
+    return result;
+}
+
+static PyMethodDef rawiobase_methods[] = {
+    {"read", rawiobase_read, METH_VARARGS},
+    {"readall", rawiobase_readall, METH_NOARGS, rawiobase_readall_doc},
+    {NULL, NULL}
+};
+
+PyTypeObject PyRawIOBase_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io._RawIOBase",                /*tp_name*/
+    0,                          /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    0,                          /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
+    rawiobase_doc,              /* tp_doc */
+    0,                          /* tp_traverse */
+    0,                          /* tp_clear */
+    0,                          /* tp_richcompare */
+    0,                          /* tp_weaklistoffset */
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    rawiobase_methods,          /* tp_methods */
+    0,                          /* tp_members */
+    0,                          /* tp_getset */
+    &PyIOBase_Type,             /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    0,                          /* tp_dictoffset */
+    0,                          /* tp_init */
+    0,                          /* tp_alloc */
+    0,                          /* tp_new */
+};
diff --git a/Modules/_io/stringio.c b/Modules/_io/stringio.c
new file mode 100644
index 0000000..b602ee8
--- /dev/null
+++ b/Modules/_io/stringio.c
@@ -0,0 +1,756 @@
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+#include "structmember.h"
+#include "_iomodule.h"
+
+/* Implementation note: the buffer is always at least one character longer
+   than the enclosed string, for proper functioning of _PyIO_find_line_ending.
+*/
+
+typedef struct {
+    PyObject_HEAD
+    Py_UNICODE *buf;
+    Py_ssize_t pos;
+    Py_ssize_t string_size;
+    size_t buf_size;
+
+    char ok; /* initialized? */
+    char closed;
+    char readuniversal;
+    char readtranslate;
+    PyObject *decoder;
+    PyObject *readnl;
+    PyObject *writenl;
+    
+    PyObject *dict;
+    PyObject *weakreflist;
+} stringio;
+
+#define CHECK_INITIALIZED(self) \
+    if (self->ok <= 0) { \
+        PyErr_SetString(PyExc_ValueError, \
+            "I/O operation on uninitialized object"); \
+        return NULL; \
+    }
+
+#define CHECK_CLOSED(self) \
+    if (self->closed) { \
+        PyErr_SetString(PyExc_ValueError, \
+            "I/O operation on closed file"); \
+        return NULL; \
+    }
+
+PyDoc_STRVAR(stringio_doc,
+    "Text I/O implementation using an in-memory buffer.\n"
+    "\n"
+    "The initial_value argument sets the value of object.  The newline\n"
+    "argument is like the one of TextIOWrapper's constructor.");
+
+
+/* Internal routine for changing the size, in terms of characters, of the
+   buffer of StringIO objects.  The caller should ensure that the 'size'
+   argument is non-negative.  Returns 0 on success, -1 otherwise. */
+static int
+resize_buffer(stringio *self, size_t size)
+{
+    /* Here, unsigned types are used to avoid dealing with signed integer
+       overflow, which is undefined in C. */
+    size_t alloc = self->buf_size;
+    Py_UNICODE *new_buf = NULL;
+
+    assert(self->buf != NULL);
+
+    /* Reserve one more char for line ending detection. */
+    size = size + 1;
+    /* For simplicity, stay in the range of the signed type. Anyway, Python
+       doesn't allow strings to be longer than this. */
+    if (size > PY_SSIZE_T_MAX)
+        goto overflow;
+
+    if (size < alloc / 2) {
+        /* Major downsize; resize down to exact size. */
+        alloc = size + 1;
+    }
+    else if (size < alloc) {
+        /* Within allocated size; quick exit */
+        return 0;
+    }
+    else if (size <= alloc * 1.125) {
+        /* Moderate upsize; overallocate similar to list_resize() */
+        alloc = size + (size >> 3) + (size < 9 ? 3 : 6);
+    }
+    else {
+        /* Major upsize; resize up to exact size */
+        alloc = size + 1;
+    }
+
+    if (alloc > ((size_t)-1) / sizeof(Py_UNICODE))
+        goto overflow;
+    new_buf = (Py_UNICODE *)PyMem_Realloc(self->buf,
+                                          alloc * sizeof(Py_UNICODE));
+    if (new_buf == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+    self->buf_size = alloc;
+    self->buf = new_buf;
+
+    return 0;
+
+  overflow:
+    PyErr_SetString(PyExc_OverflowError,
+                    "new buffer size too large");
+    return -1;
+}
+
+/* Internal routine for writing a whole PyUnicode object to the buffer of a
+   StringIO object. Returns 0 on success, or -1 on error. */
+static Py_ssize_t
+write_str(stringio *self, PyObject *obj)
+{
+    Py_UNICODE *str;
+    Py_ssize_t len;
+    PyObject *decoded = NULL;
+    assert(self->buf != NULL);
+    assert(self->pos >= 0);
+
+    if (self->decoder != NULL) {
+        decoded = _PyIncrementalNewlineDecoder_decode(
+            self->decoder, obj, 1 /* always final */);
+    }
+    else {
+        decoded = obj;
+        Py_INCREF(decoded);
+    }
+    if (self->writenl) {
+        PyObject *translated = PyUnicode_Replace(
+            decoded, _PyIO_str_nl, self->writenl, -1);
+        Py_DECREF(decoded);
+        decoded = translated;
+    }
+    if (decoded == NULL)
+        return -1;
+
+    assert(PyUnicode_Check(decoded));
+    str = PyUnicode_AS_UNICODE(decoded);
+    len = PyUnicode_GET_SIZE(decoded);
+
+    assert(len >= 0);
+
+    /* This overflow check is not strictly necessary. However, it avoids us to
+       deal with funky things like comparing an unsigned and a signed
+       integer. */
+    if (self->pos > PY_SSIZE_T_MAX - len) {
+        PyErr_SetString(PyExc_OverflowError,
+                        "new position too large");
+        goto fail;
+    }
+    if (self->pos + len > self->string_size) {
+        if (resize_buffer(self, self->pos + len) < 0)
+            goto fail;
+    }
+
+    if (self->pos > self->string_size) {
+        /* In case of overseek, pad with null bytes the buffer region between
+           the end of stream and the current position.
+
+          0   lo      string_size                           hi
+          |   |<---used--->|<----------available----------->|
+          |   |            <--to pad-->|<---to write--->    |
+          0   buf                   positon
+
+        */
+        memset(self->buf + self->string_size, '\0',
+               (self->pos - self->string_size) * sizeof(Py_UNICODE));
+    }
+
+    /* Copy the data to the internal buffer, overwriting some of the
+       existing data if self->pos < self->string_size. */
+    memcpy(self->buf + self->pos, str, len * sizeof(Py_UNICODE));
+    self->pos += len;
+
+    /* Set the new length of the internal string if it has changed. */
+    if (self->string_size < self->pos) {
+        self->string_size = self->pos;
+    }
+
+    Py_DECREF(decoded);
+    return 0;
+
+fail:
+    Py_XDECREF(decoded);
+    return -1;
+}
+
+PyDoc_STRVAR(stringio_getvalue_doc,
+    "Retrieve the entire contents of the object.");
+
+static PyObject *
+stringio_getvalue(stringio *self)
+{
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+    return PyUnicode_FromUnicode(self->buf, self->string_size);
+}
+
+PyDoc_STRVAR(stringio_tell_doc,
+    "Tell the current file position.");
+
+static PyObject *
+stringio_tell(stringio *self)
+{
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+    return PyLong_FromSsize_t(self->pos);
+}
+
+PyDoc_STRVAR(stringio_read_doc,
+    "Read at most n characters, returned as a string.\n"
+    "\n"
+    "If the argument is negative or omitted, read until EOF\n"
+    "is reached. Return an empty string at EOF.\n");
+
+static PyObject *
+stringio_read(stringio *self, PyObject *args)
+{
+    Py_ssize_t size, n;
+    Py_UNICODE *output;
+    PyObject *arg = Py_None;
+
+    CHECK_INITIALIZED(self);
+    if (!PyArg_ParseTuple(args, "|O:read", &arg))
+        return NULL;
+    CHECK_CLOSED(self);
+
+    if (PyNumber_Check(arg)) {
+        size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
+        if (size == -1 && PyErr_Occurred())
+            return NULL;
+    }
+    else if (arg == Py_None) {
+        /* Read until EOF is reached, by default. */
+        size = -1;
+    }
+    else {
+        PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
+                     Py_TYPE(arg)->tp_name);
+        return NULL;
+    }
+
+    /* adjust invalid sizes */
+    n = self->string_size - self->pos;
+    if (size < 0 || size > n) {
+        size = n;
+        if (size < 0)
+            size = 0;
+    }
+
+    output = self->buf + self->pos;
+    self->pos += size;
+    return PyUnicode_FromUnicode(output, size);
+}
+
+/* Internal helper, used by stringio_readline and stringio_iternext */
+static PyObject *
+_stringio_readline(stringio *self, Py_ssize_t limit)
+{
+    Py_UNICODE *start, *end, old_char;
+    Py_ssize_t len, consumed;
+
+    /* In case of overseek, return the empty string */
+    if (self->pos >= self->string_size)
+        return PyUnicode_FromString("");
+
+    start = self->buf + self->pos;
+    if (limit < 0 || limit > self->string_size - self->pos)
+        limit = self->string_size - self->pos;
+
+    end = start + limit;
+    old_char = *end;
+    *end = '\0';
+    len = _PyIO_find_line_ending(
+        self->readtranslate, self->readuniversal, self->readnl,
+        start, end, &consumed);
+    *end = old_char;
+    /* If we haven't found any line ending, we just return everything
+       (`consumed` is ignored). */
+    if (len < 0)
+        len = limit;
+    self->pos += len;
+    return PyUnicode_FromUnicode(start, len);
+}
+
+PyDoc_STRVAR(stringio_readline_doc,
+    "Read until newline or EOF.\n"
+    "\n"
+    "Returns an empty string if EOF is hit immediately.\n");
+
+static PyObject *
+stringio_readline(stringio *self, PyObject *args)
+{
+    PyObject *arg = Py_None;
+    Py_ssize_t limit = -1;
+
+    CHECK_INITIALIZED(self);
+    if (!PyArg_ParseTuple(args, "|O:readline", &arg))
+        return NULL;
+    CHECK_CLOSED(self);
+
+    if (PyNumber_Check(arg)) {
+        limit = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
+        if (limit == -1 && PyErr_Occurred())
+            return NULL;
+    }
+    else if (arg != Py_None) {
+        PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
+                     Py_TYPE(arg)->tp_name);
+        return NULL;
+    }
+    return _stringio_readline(self, limit);
+}
+
+static PyObject *
+stringio_iternext(stringio *self)
+{
+    PyObject *line;
+
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+
+    if (Py_TYPE(self) == &PyStringIO_Type) {
+        /* Skip method call overhead for speed */
+        line = _stringio_readline(self, -1);
+    }
+    else {
+        /* XXX is subclassing StringIO really supported? */
+        line = PyObject_CallMethodObjArgs((PyObject *)self,
+                                           _PyIO_str_readline, NULL);
+        if (line && !PyUnicode_Check(line)) {
+            PyErr_Format(PyExc_IOError,
+                         "readline() should have returned an str object, "
+                         "not '%.200s'", Py_TYPE(line)->tp_name);
+            Py_DECREF(line);
+            return NULL;
+        }
+    }
+
+    if (line == NULL)
+        return NULL;
+
+    if (PyUnicode_GET_SIZE(line) == 0) {
+        /* Reached EOF */
+        Py_DECREF(line);
+        return NULL;
+    }
+
+    return line;
+}
+
+PyDoc_STRVAR(stringio_truncate_doc,
+    "Truncate size to pos.\n"
+    "\n"
+    "The pos argument defaults to the current file position, as\n"
+    "returned by tell().  Imply an absolute seek to pos.\n"
+    "Returns the new absolute position.\n");
+
+static PyObject *
+stringio_truncate(stringio *self, PyObject *args)
+{
+    Py_ssize_t size;
+    PyObject *arg = Py_None;
+
+    CHECK_INITIALIZED(self);
+    if (!PyArg_ParseTuple(args, "|O:truncate", &arg))
+        return NULL;
+    CHECK_CLOSED(self);
+
+    if (PyNumber_Check(arg)) {
+        size = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
+        if (size == -1 && PyErr_Occurred())
+            return NULL;
+    }
+    else if (arg == Py_None) {
+        /* Truncate to current position if no argument is passed. */
+        size = self->pos;
+    }
+    else {
+        PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
+                     Py_TYPE(arg)->tp_name);
+        return NULL;
+    }
+
+    if (size < 0) {
+        PyErr_Format(PyExc_ValueError,
+                     "Negative size value %zd", size);
+        return NULL;
+    }
+
+    if (size < self->string_size) {
+        if (resize_buffer(self, size) < 0)
+            return NULL;
+        self->string_size = size;
+    }
+    self->pos = size;
+
+    return PyLong_FromSsize_t(size);
+}
+
+PyDoc_STRVAR(stringio_seek_doc,
+    "Change stream position.\n"
+    "\n"
+    "Seek to character offset pos relative to position indicated by whence:\n"
+    "    0  Start of stream (the default).  pos should be >= 0;\n"
+    "    1  Current position - pos must be 0;\n"
+    "    2  End of stream - pos must be 0.\n"
+    "Returns the new absolute position.\n");
+
+static PyObject *
+stringio_seek(stringio *self, PyObject *args)
+{
+    PyObject *posobj;
+    Py_ssize_t pos;
+    int mode = 0;
+
+    CHECK_INITIALIZED(self);
+    if (!PyArg_ParseTuple(args, "O|i:seek", &posobj, &mode))
+        return NULL;
+
+    pos = PyNumber_AsSsize_t(posobj, PyExc_OverflowError);
+    if (pos == -1 && PyErr_Occurred())
+        return NULL;
+    
+    CHECK_CLOSED(self);
+
+    if (mode != 0 && mode != 1 && mode != 2) {
+        PyErr_Format(PyExc_ValueError,
+                     "Invalid whence (%i, should be 0, 1 or 2)", mode);
+        return NULL;
+    }
+    else if (pos < 0 && mode == 0) {
+        PyErr_Format(PyExc_ValueError,
+                     "Negative seek position %zd", pos);
+        return NULL;
+    }
+    else if (mode != 0 && pos != 0) {
+        PyErr_SetString(PyExc_IOError,
+                        "Can't do nonzero cur-relative seeks");
+        return NULL;
+    }
+
+    /* mode 0: offset relative to beginning of the string.
+       mode 1: no change to current position.
+       mode 2: change position to end of file. */
+    if (mode == 1) {
+        pos = self->pos;
+    }
+    else if (mode == 2) {
+        pos = self->string_size;
+    }
+
+    self->pos = pos;
+
+    return PyLong_FromSsize_t(self->pos);
+}
+
+PyDoc_STRVAR(stringio_write_doc,
+    "Write string to file.\n"
+    "\n"
+    "Returns the number of characters written, which is always equal to\n"
+    "the length of the string.\n");
+
+static PyObject *
+stringio_write(stringio *self, PyObject *obj)
+{
+    Py_ssize_t size;
+
+    CHECK_INITIALIZED(self);
+    if (!PyUnicode_Check(obj)) {
+        PyErr_Format(PyExc_TypeError, "string argument expected, got '%s'",
+                     Py_TYPE(obj)->tp_name);
+        return NULL;
+    }
+    CHECK_CLOSED(self);
+    size = PyUnicode_GET_SIZE(obj);
+
+    if (size > 0 && write_str(self, obj) < 0)
+        return NULL;
+
+    return PyLong_FromSsize_t(size);
+}
+
+PyDoc_STRVAR(stringio_close_doc,
+    "Close the IO object. Attempting any further operation after the\n"
+    "object is closed will raise a ValueError.\n"
+    "\n"
+    "This method has no effect if the file is already closed.\n");
+
+static PyObject *
+stringio_close(stringio *self)
+{
+    self->closed = 1;
+    /* Free up some memory */
+    if (resize_buffer(self, 0) < 0)
+        return NULL;
+    Py_CLEAR(self->readnl);
+    Py_CLEAR(self->writenl);
+    Py_CLEAR(self->decoder);
+    Py_RETURN_NONE;
+}
+
+static int
+stringio_traverse(stringio *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->dict);
+    return 0;
+}
+
+static int
+stringio_clear(stringio *self)
+{
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+static void
+stringio_dealloc(stringio *self)
+{
+    _PyObject_GC_UNTRACK(self);
+    Py_CLEAR(self->readnl);
+    Py_CLEAR(self->writenl);
+    Py_CLEAR(self->decoder);
+    if (self->buf)
+        PyMem_Free(self->buf);
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *) self);
+    Py_TYPE(self)->tp_free(self);
+}
+
+static PyObject *
+stringio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    stringio *self;
+
+    assert(type != NULL && type->tp_alloc != NULL);
+    self = (stringio *)type->tp_alloc(type, 0);
+    if (self == NULL)
+        return NULL;
+
+    self->string_size = 0;
+    self->pos = 0;
+    self->buf_size = 0;
+    self->buf = (Py_UNICODE *)PyMem_Malloc(0);
+    if (self->buf == NULL) {
+        Py_DECREF(self);
+        return PyErr_NoMemory();
+    }
+
+    return (PyObject *)self;
+}
+
+static int
+stringio_init(stringio *self, PyObject *args, PyObject *kwds)
+{
+    char *kwlist[] = {"initial_value", "newline", NULL};
+    PyObject *value = NULL;
+    char *newline = "\n";
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|Oz:__init__", kwlist,
+                                     &value, &newline))
+        return -1;
+
+    if (newline && newline[0] != '\0'
+        && !(newline[0] == '\n' && newline[1] == '\0')
+        && !(newline[0] == '\r' && newline[1] == '\0')
+        && !(newline[0] == '\r' && newline[1] == '\n' && newline[2] == '\0')) {
+        PyErr_Format(PyExc_ValueError,
+                     "illegal newline value: %s", newline);
+        return -1;
+    }
+    if (value && value != Py_None && !PyUnicode_Check(value)) {
+        PyErr_Format(PyExc_ValueError,
+                     "initial_value must be str or None, not %.200s",
+                     Py_TYPE(value)->tp_name);
+        return -1;
+    }
+
+    self->ok = 0;
+
+    Py_CLEAR(self->readnl);
+    Py_CLEAR(self->writenl);
+    Py_CLEAR(self->decoder);
+
+    if (newline) {
+        self->readnl = PyString_FromString(newline);
+        if (self->readnl == NULL)
+            return -1;
+    }
+    self->readuniversal = (newline == NULL || newline[0] == '\0');
+    self->readtranslate = (newline == NULL);
+    /* If newline == "", we don't translate anything.
+       If newline == "\n" or newline == None, we translate to "\n", which is
+       a no-op.
+       (for newline == None, TextIOWrapper translates to os.sepline, but it
+       is pointless for StringIO)
+    */
+    if (newline != NULL && newline[0] == '\r') {
+        self->writenl = PyUnicode_FromString(newline);
+    }
+
+    if (self->readuniversal) {
+        self->decoder = PyObject_CallFunction(
+            (PyObject *)&PyIncrementalNewlineDecoder_Type,
+            "Oi", Py_None, (int) self->readtranslate);
+        if (self->decoder == NULL)
+            return -1;
+    }
+
+    /* Now everything is set up, resize buffer to size of initial value,
+       and copy it */
+    self->string_size = 0;
+    if (value && value != Py_None) {
+        Py_ssize_t len = PyUnicode_GetSize(value);
+        /* This is a heuristic, for newline translation might change
+           the string length. */
+        if (resize_buffer(self, len) < 0)
+            return -1;
+        self->pos = 0;
+        if (write_str(self, value) < 0)
+            return -1;
+    }
+    else {
+        if (resize_buffer(self, 0) < 0)
+            return -1;
+    }
+    self->pos = 0;
+
+    self->closed = 0;
+    self->ok = 1;
+    return 0;
+}
+
+/* Properties and pseudo-properties */
+static PyObject *
+stringio_seekable(stringio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    Py_RETURN_TRUE;
+}
+
+static PyObject *
+stringio_readable(stringio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    Py_RETURN_TRUE;
+}
+
+static PyObject *
+stringio_writable(stringio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    Py_RETURN_TRUE;
+}
+
+static PyObject *
+stringio_buffer(stringio *self, void *context)
+{
+    PyErr_SetString(_PyIO_unsupported_operation,
+                    "buffer attribute is unsupported on type StringIO");
+    return NULL;
+}
+
+static PyObject *
+stringio_closed(stringio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    return PyBool_FromLong(self->closed);
+}
+
+static PyObject *
+stringio_line_buffering(stringio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+    Py_RETURN_FALSE;
+}
+
+static PyObject *
+stringio_newlines(stringio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+    if (self->decoder == NULL)
+        Py_RETURN_NONE;
+    return PyObject_GetAttr(self->decoder, _PyIO_str_newlines);
+}
+
+static struct PyMethodDef stringio_methods[] = {
+    {"close",    (PyCFunction)stringio_close,    METH_NOARGS,  stringio_close_doc},
+    {"getvalue", (PyCFunction)stringio_getvalue, METH_VARARGS, stringio_getvalue_doc},
+    {"read",     (PyCFunction)stringio_read,     METH_VARARGS, stringio_read_doc},
+    {"readline", (PyCFunction)stringio_readline, METH_VARARGS, stringio_readline_doc},
+    {"tell",     (PyCFunction)stringio_tell,     METH_NOARGS,  stringio_tell_doc},
+    {"truncate", (PyCFunction)stringio_truncate, METH_VARARGS, stringio_truncate_doc},
+    {"seek",     (PyCFunction)stringio_seek,     METH_VARARGS, stringio_seek_doc},
+    {"write",    (PyCFunction)stringio_write,    METH_O,       stringio_write_doc},
+    
+    {"seekable", (PyCFunction)stringio_seekable, METH_NOARGS},
+    {"readable", (PyCFunction)stringio_readable, METH_NOARGS},
+    {"writable", (PyCFunction)stringio_writable, METH_NOARGS},
+    {NULL, NULL}        /* sentinel */
+};
+
+static PyGetSetDef stringio_getset[] = {
+    {"closed",         (getter)stringio_closed,         NULL, NULL},
+    {"newlines",       (getter)stringio_newlines,       NULL, NULL},
+    /*  (following comments straight off of the original Python wrapper:)
+        XXX Cruft to support the TextIOWrapper API. This would only
+        be meaningful if StringIO supported the buffer attribute.
+        Hopefully, a better solution, than adding these pseudo-attributes,
+        will be found.
+    */
+    {"buffer",         (getter)stringio_buffer,         NULL, NULL},
+    {"line_buffering", (getter)stringio_line_buffering, NULL, NULL},
+    {NULL}
+};
+
+PyTypeObject PyStringIO_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.StringIO",                            /*tp_name*/
+    sizeof(stringio),                    /*tp_basicsize*/
+    0,                                         /*tp_itemsize*/
+    (destructor)stringio_dealloc,              /*tp_dealloc*/
+    0,                                         /*tp_print*/
+    0,                                         /*tp_getattr*/
+    0,                                         /*tp_setattr*/
+    0,                                         /*tp_reserved*/
+    0,                                         /*tp_repr*/
+    0,                                         /*tp_as_number*/
+    0,                                         /*tp_as_sequence*/
+    0,                                         /*tp_as_mapping*/
+    0,                                         /*tp_hash*/
+    0,                                         /*tp_call*/
+    0,                                         /*tp_str*/
+    0,                                         /*tp_getattro*/
+    0,                                         /*tp_setattro*/
+    0,                                         /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+                       | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
+    stringio_doc,                              /*tp_doc*/
+    (traverseproc)stringio_traverse,           /*tp_traverse*/
+    (inquiry)stringio_clear,                   /*tp_clear*/
+    0,                                         /*tp_richcompare*/
+    offsetof(stringio, weakreflist),            /*tp_weaklistoffset*/
+    0,                                         /*tp_iter*/
+    (iternextfunc)stringio_iternext,           /*tp_iternext*/
+    stringio_methods,                          /*tp_methods*/
+    0,                                         /*tp_members*/
+    stringio_getset,                           /*tp_getset*/
+    0,                                         /*tp_base*/
+    0,                                         /*tp_dict*/
+    0,                                         /*tp_descr_get*/
+    0,                                         /*tp_descr_set*/
+    offsetof(stringio, dict),                  /*tp_dictoffset*/
+    (initproc)stringio_init,                   /*tp_init*/
+    0,                                         /*tp_alloc*/
+    stringio_new,                              /*tp_new*/
+};
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
new file mode 100644
index 0000000..c129303
--- /dev/null
+++ b/Modules/_io/textio.c
@@ -0,0 +1,2606 @@
+/*
+    An implementation of Text I/O as defined by PEP 3116 - "New I/O"
+
+    Classes defined here: TextIOBase, IncrementalNewlineDecoder, TextIOWrapper.
+
+    Written by Amaury Forgeot d'Arc and Antoine Pitrou
+*/
+
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+#include "structmember.h"
+#include "_iomodule.h"
+
+/* TextIOBase */
+
+PyDoc_STRVAR(textiobase_doc,
+    "Base class for text I/O.\n"
+    "\n"
+    "This class provides a character and line based interface to stream\n"
+    "I/O. There is no readinto method because Python's character strings\n"
+    "are immutable. There is no public constructor.\n"
+    );
+
+static PyObject *
+_unsupported(const char *message)
+{
+    PyErr_SetString(_PyIO_unsupported_operation, message);
+    return NULL;
+}
+
+PyDoc_STRVAR(textiobase_detach_doc,
+    "Separate the underlying buffer from the TextIOBase and return it.\n"
+    "\n"
+    "After the underlying buffer has been detached, the TextIO is in an\n"
+    "unusable state.\n"
+    );
+
+static PyObject *
+textiobase_detach(PyObject *self)
+{
+    return _unsupported("detach");
+}
+
+PyDoc_STRVAR(textiobase_read_doc,
+    "Read at most n characters from stream.\n"
+    "\n"
+    "Read from underlying buffer until we have n characters or we hit EOF.\n"
+    "If n is negative or omitted, read until EOF.\n"
+    );
+
+static PyObject *
+textiobase_read(PyObject *self, PyObject *args)
+{
+    return _unsupported("read");
+}
+
+PyDoc_STRVAR(textiobase_readline_doc,
+    "Read until newline or EOF.\n"
+    "\n"
+    "Returns an empty string if EOF is hit immediately.\n"
+    );
+
+static PyObject *
+textiobase_readline(PyObject *self, PyObject *args)
+{
+    return _unsupported("readline");
+}
+
+PyDoc_STRVAR(textiobase_write_doc,
+    "Write string to stream.\n"
+    "Returns the number of characters written (which is always equal to\n"
+    "the length of the string).\n"
+    );
+
+static PyObject *
+textiobase_write(PyObject *self, PyObject *args)
+{
+    return _unsupported("write");
+}
+
+PyDoc_STRVAR(textiobase_encoding_doc,
+    "Encoding of the text stream.\n"
+    "\n"
+    "Subclasses should override.\n"
+    );
+
+static PyObject *
+textiobase_encoding_get(PyObject *self, void *context)
+{
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(textiobase_newlines_doc,
+    "Line endings translated so far.\n"
+    "\n"
+    "Only line endings translated during reading are considered.\n"
+    "\n"
+    "Subclasses should override.\n"
+    );
+
+static PyObject *
+textiobase_newlines_get(PyObject *self, void *context)
+{
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(textiobase_errors_doc,
+    "The error setting of the decoder or encoder.\n"
+    "\n"
+    "Subclasses should override.\n"
+    );
+
+static PyObject *
+textiobase_errors_get(PyObject *self, void *context)
+{
+    Py_RETURN_NONE;
+}
+
+
+static PyMethodDef textiobase_methods[] = {
+    {"detach", (PyCFunction)textiobase_detach, METH_NOARGS, textiobase_detach_doc},
+    {"read", textiobase_read, METH_VARARGS, textiobase_read_doc},
+    {"readline", textiobase_readline, METH_VARARGS, textiobase_readline_doc},
+    {"write", textiobase_write, METH_VARARGS, textiobase_write_doc},
+    {NULL, NULL}
+};
+
+static PyGetSetDef textiobase_getset[] = {
+    {"encoding", (getter)textiobase_encoding_get, NULL, textiobase_encoding_doc},
+    {"newlines", (getter)textiobase_newlines_get, NULL, textiobase_newlines_doc},
+    {"errors", (getter)textiobase_errors_get, NULL, textiobase_errors_doc},
+    {NULL}
+};
+
+PyTypeObject PyTextIOBase_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io._TextIOBase",          /*tp_name*/
+    0,                          /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    0,                          /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
+    textiobase_doc,             /* tp_doc */
+    0,                          /* tp_traverse */
+    0,                          /* tp_clear */
+    0,                          /* tp_richcompare */
+    0,                          /* tp_weaklistoffset */
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    textiobase_methods,         /* tp_methods */
+    0,                          /* tp_members */
+    textiobase_getset,          /* tp_getset */
+    &PyIOBase_Type,             /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    0,                          /* tp_dictoffset */
+    0,                          /* tp_init */
+    0,                          /* tp_alloc */
+    0,                          /* tp_new */
+};
+
+
+/* IncrementalNewlineDecoder */
+
+PyDoc_STRVAR(incrementalnewlinedecoder_doc,
+    "Codec used when reading a file in universal newlines mode.  It wraps\n"
+    "another incremental decoder, translating \\r\\n and \\r into \\n.  It also\n"
+    "records the types of newlines encountered.  When used with\n"
+    "translate=False, it ensures that the newline sequence is returned in\n"
+    "one piece. When used with decoder=None, it expects unicode strings as\n"
+    "decode input and translates newlines without first invoking an external\n"
+    "decoder.\n"
+    );
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *decoder;
+    PyObject *errors;
+    int pendingcr:1;
+    int translate:1;
+    unsigned int seennl:3;
+} nldecoder_object;
+
+static int
+incrementalnewlinedecoder_init(nldecoder_object *self,
+                               PyObject *args, PyObject *kwds)
+{
+    PyObject *decoder;
+    int translate;
+    PyObject *errors = NULL;
+    char *kwlist[] = {"decoder", "translate", "errors", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "Oi|O:IncrementalNewlineDecoder",
+                                     kwlist, &decoder, &translate, &errors))
+        return -1;
+
+    self->decoder = decoder;
+    Py_INCREF(decoder);
+
+    if (errors == NULL) {
+        self->errors = PyUnicode_FromString("strict");
+        if (self->errors == NULL)
+            return -1;
+    }
+    else {
+        Py_INCREF(errors);
+        self->errors = errors;
+    }
+
+    self->translate = translate;
+    self->seennl = 0;
+    self->pendingcr = 0;
+
+    return 0;
+}
+
+static void
+incrementalnewlinedecoder_dealloc(nldecoder_object *self)
+{
+    Py_CLEAR(self->decoder);
+    Py_CLEAR(self->errors);
+    Py_TYPE(self)->tp_free((PyObject *)self);
+}
+
+#define SEEN_CR   1
+#define SEEN_LF   2
+#define SEEN_CRLF 4
+#define SEEN_ALL (SEEN_CR | SEEN_LF | SEEN_CRLF)
+
+PyObject *
+_PyIncrementalNewlineDecoder_decode(PyObject *_self,
+                                    PyObject *input, int final)
+{
+    PyObject *output;
+    Py_ssize_t output_len;
+    nldecoder_object *self = (nldecoder_object *) _self;
+
+    if (self->decoder == NULL) {
+        PyErr_SetString(PyExc_ValueError,
+                        "IncrementalNewlineDecoder.__init__ not called");
+        return NULL;
+    }
+
+    /* decode input (with the eventual \r from a previous pass) */
+    if (self->decoder != Py_None) {
+        output = PyObject_CallMethodObjArgs(self->decoder,
+            _PyIO_str_decode, input, final ? Py_True : Py_False, NULL);
+    }
+    else {
+        output = input;
+        Py_INCREF(output);
+    }
+
+    if (output == NULL)
+        return NULL;
+
+    if (!PyUnicode_Check(output)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "decoder should return a string result");
+        goto error;
+    }
+
+    output_len = PyUnicode_GET_SIZE(output);
+    if (self->pendingcr && (final || output_len > 0)) {
+        Py_UNICODE *out;
+        PyObject *modified = PyUnicode_FromUnicode(NULL, output_len + 1);
+        if (modified == NULL)
+            goto error;
+        out = PyUnicode_AS_UNICODE(modified);
+        out[0] = '\r';
+        memcpy(out + 1, PyUnicode_AS_UNICODE(output),
+               output_len * sizeof(Py_UNICODE));
+        Py_DECREF(output);
+        output = modified;
+        self->pendingcr = 0;
+        output_len++;
+    }
+
+    /* retain last \r even when not translating data:
+     * then readline() is sure to get \r\n in one pass
+     */
+    if (!final) {
+        if (output_len > 0
+            && PyUnicode_AS_UNICODE(output)[output_len - 1] == '\r') {
+
+            if (Py_REFCNT(output) == 1) {
+                if (PyUnicode_Resize(&output, output_len - 1) < 0)
+                    goto error;
+            }
+            else {
+                PyObject *modified = PyUnicode_FromUnicode(
+                    PyUnicode_AS_UNICODE(output),
+                    output_len - 1);
+                if (modified == NULL)
+                    goto error;
+                Py_DECREF(output);
+                output = modified;
+            }
+            self->pendingcr = 1;
+        }
+    }
+
+    /* Record which newlines are read and do newline translation if desired,
+       all in one pass. */
+    {
+        Py_UNICODE *in_str;
+        Py_ssize_t len;
+        int seennl = self->seennl;
+        int only_lf = 0;
+
+        in_str = PyUnicode_AS_UNICODE(output);
+        len = PyUnicode_GET_SIZE(output);
+
+        if (len == 0)
+            return output;
+
+        /* If, up to now, newlines are consistently \n, do a quick check
+           for the \r *byte* with the libc's optimized memchr.
+           */
+        if (seennl == SEEN_LF || seennl == 0) {
+            only_lf = (memchr(in_str, '\r', len * sizeof(Py_UNICODE)) == NULL);
+        }
+
+        if (only_lf) {
+            /* If not already seen, quick scan for a possible "\n" character.
+               (there's nothing else to be done, even when in translation mode)
+            */
+            if (seennl == 0 &&
+                memchr(in_str, '\n', len * sizeof(Py_UNICODE)) != NULL) {
+                Py_UNICODE *s, *end;
+                s = in_str;
+                end = in_str + len;
+                for (;;) {
+                    Py_UNICODE c;
+                    /* Fast loop for non-control characters */
+                    while (*s > '\n')
+                        s++;
+                    c = *s++;
+                    if (c == '\n') {
+                        seennl |= SEEN_LF;
+                        break;
+                    }
+                    if (s > end)
+                        break;
+                }
+            }
+            /* Finished: we have scanned for newlines, and none of them
+               need translating */
+        }
+        else if (!self->translate) {
+            Py_UNICODE *s, *end;
+            /* We have already seen all newline types, no need to scan again */
+            if (seennl == SEEN_ALL)
+                goto endscan;
+            s = in_str;
+            end = in_str + len;
+            for (;;) {
+                Py_UNICODE c;
+                /* Fast loop for non-control characters */
+                while (*s > '\r')
+                    s++;
+                c = *s++;
+                if (c == '\n')
+                    seennl |= SEEN_LF;
+                else if (c == '\r') {
+                    if (*s == '\n') {
+                        seennl |= SEEN_CRLF;
+                        s++;
+                    }
+                    else
+                        seennl |= SEEN_CR;
+                }
+                if (s > end)
+                    break;
+                if (seennl == SEEN_ALL)
+                    break;
+            }
+        endscan:
+            ;
+        }
+        else {
+            PyObject *translated = NULL;
+            Py_UNICODE *out_str;
+            Py_UNICODE *in, *out, *end;
+            if (Py_REFCNT(output) != 1) {
+                /* We could try to optimize this so that we only do a copy
+                   when there is something to translate. On the other hand,
+                   most decoders should only output non-shared strings, i.e.
+                   translation is done in place. */
+                translated = PyUnicode_FromUnicode(NULL, len);
+                if (translated == NULL)
+                    goto error;
+                assert(Py_REFCNT(translated) == 1);
+                memcpy(PyUnicode_AS_UNICODE(translated),
+                       PyUnicode_AS_UNICODE(output),
+                       len * sizeof(Py_UNICODE));
+            }
+            else {
+                translated = output;
+            }
+            out_str = PyUnicode_AS_UNICODE(translated);
+            in = in_str;
+            out = out_str;
+            end = in_str + len;
+            for (;;) {
+                Py_UNICODE c;
+                /* Fast loop for non-control characters */
+                while ((c = *in++) > '\r')
+                    *out++ = c;
+                if (c == '\n') {
+                    *out++ = c;
+                    seennl |= SEEN_LF;
+                    continue;
+                }
+                if (c == '\r') {
+                    if (*in == '\n') {
+                        in++;
+                        seennl |= SEEN_CRLF;
+                    }
+                    else
+                        seennl |= SEEN_CR;
+                    *out++ = '\n';
+                    continue;
+                }
+                if (in > end)
+                    break;
+                *out++ = c;
+            }
+            if (translated != output) {
+                Py_DECREF(output);
+                output = translated;
+            }
+            if (out - out_str != len) {
+                if (PyUnicode_Resize(&output, out - out_str) < 0)
+                    goto error;
+            }
+        }
+        self->seennl |= seennl;
+    }
+
+    return output;
+
+  error:
+    Py_DECREF(output);
+    return NULL;
+}
+
+static PyObject *
+incrementalnewlinedecoder_decode(nldecoder_object *self,
+                                 PyObject *args, PyObject *kwds)
+{
+    char *kwlist[] = {"input", "final", NULL};
+    PyObject *input;
+    int final = 0;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|i:IncrementalNewlineDecoder",
+                                     kwlist, &input, &final))
+        return NULL;
+    return _PyIncrementalNewlineDecoder_decode((PyObject *) self, input, final);
+}
+
+static PyObject *
+incrementalnewlinedecoder_getstate(nldecoder_object *self, PyObject *args)
+{
+    PyObject *buffer;
+    unsigned PY_LONG_LONG flag;
+
+    if (self->decoder != Py_None) {
+        PyObject *state = PyObject_CallMethodObjArgs(self->decoder,
+           _PyIO_str_getstate, NULL);
+        if (state == NULL)
+            return NULL;
+        if (!PyArg_Parse(state, "(OK)", &buffer, &flag)) {
+            Py_DECREF(state);
+            return NULL;
+        }
+        Py_INCREF(buffer);
+        Py_DECREF(state);
+    }
+    else {
+        buffer = PyBytes_FromString("");
+        flag = 0;
+    }
+    flag <<= 1;
+    if (self->pendingcr)
+        flag |= 1;
+    return Py_BuildValue("NK", buffer, flag);
+}
+
+static PyObject *
+incrementalnewlinedecoder_setstate(nldecoder_object *self, PyObject *state)
+{
+    PyObject *buffer;
+    unsigned PY_LONG_LONG flag;
+
+    if (!PyArg_Parse(state, "(OK)", &buffer, &flag))
+        return NULL;
+
+    self->pendingcr = (int) flag & 1;
+    flag >>= 1;
+
+    if (self->decoder != Py_None)
+        return PyObject_CallMethod(self->decoder,
+                                   "setstate", "((OK))", buffer, flag);
+    else
+        Py_RETURN_NONE;
+}
+
+static PyObject *
+incrementalnewlinedecoder_reset(nldecoder_object *self, PyObject *args)
+{
+    self->seennl = 0;
+    self->pendingcr = 0;
+    if (self->decoder != Py_None)
+        return PyObject_CallMethodObjArgs(self->decoder, _PyIO_str_reset, NULL);
+    else
+        Py_RETURN_NONE;
+}
+
+static PyObject *
+incrementalnewlinedecoder_newlines_get(nldecoder_object *self, void *context)
+{
+    switch (self->seennl) {
+    case SEEN_CR:
+        return PyUnicode_FromString("\r");
+    case SEEN_LF:
+        return PyUnicode_FromString("\n");
+    case SEEN_CRLF:
+        return PyUnicode_FromString("\r\n");
+    case SEEN_CR | SEEN_LF:
+        return Py_BuildValue("ss", "\r", "\n");
+    case SEEN_CR | SEEN_CRLF:
+        return Py_BuildValue("ss", "\r", "\r\n");
+    case SEEN_LF | SEEN_CRLF:
+        return Py_BuildValue("ss", "\n", "\r\n");
+    case SEEN_CR | SEEN_LF | SEEN_CRLF:
+        return Py_BuildValue("sss", "\r", "\n", "\r\n");
+    default:
+        Py_RETURN_NONE;
+   }
+
+}
+
+
+static PyMethodDef incrementalnewlinedecoder_methods[] = {
+    {"decode", (PyCFunction)incrementalnewlinedecoder_decode, METH_VARARGS|METH_KEYWORDS},
+    {"getstate", (PyCFunction)incrementalnewlinedecoder_getstate, METH_NOARGS},
+    {"setstate", (PyCFunction)incrementalnewlinedecoder_setstate, METH_O},
+    {"reset", (PyCFunction)incrementalnewlinedecoder_reset, METH_NOARGS},
+    {NULL}
+};
+
+static PyGetSetDef incrementalnewlinedecoder_getset[] = {
+    {"newlines", (getter)incrementalnewlinedecoder_newlines_get, NULL, NULL},
+    {NULL}
+};
+
+PyTypeObject PyIncrementalNewlineDecoder_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.IncrementalNewlineDecoder", /*tp_name*/
+    sizeof(nldecoder_object), /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)incrementalnewlinedecoder_dealloc, /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare */
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
+    incrementalnewlinedecoder_doc,          /* tp_doc */
+    0,                          /* tp_traverse */
+    0,                          /* tp_clear */
+    0,                          /* tp_richcompare */
+    0,                          /*tp_weaklistoffset*/
+    0,                          /* tp_iter */
+    0,                          /* tp_iternext */
+    incrementalnewlinedecoder_methods, /* tp_methods */
+    0,                          /* tp_members */
+    incrementalnewlinedecoder_getset, /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    0,                          /* tp_dictoffset */
+    (initproc)incrementalnewlinedecoder_init, /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};
+
+
+/* TextIOWrapper */
+
+PyDoc_STRVAR(textiowrapper_doc,
+    "Character and line based layer over a BufferedIOBase object, buffer.\n"
+    "\n"
+    "encoding gives the name of the encoding that the stream will be\n"
+    "decoded or encoded with. It defaults to locale.getpreferredencoding.\n"
+    "\n"
+    "errors determines the strictness of encoding and decoding (see the\n"
+    "codecs.register) and defaults to \"strict\".\n"
+    "\n"
+    "newline can be None, '', '\\n', '\\r', or '\\r\\n'.  It controls the\n"
+    "handling of line endings. If it is None, universal newlines is\n"
+    "enabled.  With this enabled, on input, the lines endings '\\n', '\\r',\n"
+    "or '\\r\\n' are translated to '\\n' before being returned to the\n"
+    "caller. Conversely, on output, '\\n' is translated to the system\n"
+    "default line seperator, os.linesep. If newline is any other of its\n"
+    "legal values, that newline becomes the newline when the file is read\n"
+    "and it is returned untranslated. On output, '\\n' is converted to the\n"
+    "newline.\n"
+    "\n"
+    "If line_buffering is True, a call to flush is implied when a call to\n"
+    "write contains a newline character."
+    );
+
+typedef PyObject *
+        (*encodefunc_t)(PyObject *, PyObject *);
+
+typedef struct
+{
+    PyObject_HEAD
+    int ok; /* initialized? */
+    int detached;
+    Py_ssize_t chunk_size;
+    PyObject *buffer;
+    PyObject *encoding;
+    PyObject *encoder;
+    PyObject *decoder;
+    PyObject *readnl;
+    PyObject *errors;
+    const char *writenl; /* utf-8 encoded, NULL stands for \n */
+    char line_buffering;
+    char readuniversal;
+    char readtranslate;
+    char writetranslate;
+    char seekable;
+    char telling;
+    /* Specialized encoding func (see below) */
+    encodefunc_t encodefunc;
+    /* Whether or not it's the start of the stream */
+    char encoding_start_of_stream;
+
+    /* Reads and writes are internally buffered in order to speed things up.
+       However, any read will first flush the write buffer if itsn't empty.
+
+       Please also note that text to be written is first encoded before being
+       buffered. This is necessary so that encoding errors are immediately
+       reported to the caller, but it unfortunately means that the
+       IncrementalEncoder (whose encode() method is always written in Python)
+       becomes a bottleneck for small writes.
+    */
+    PyObject *decoded_chars;       /* buffer for text returned from decoder */
+    Py_ssize_t decoded_chars_used; /* offset into _decoded_chars for read() */
+    PyObject *pending_bytes;       /* list of bytes objects waiting to be
+                                      written, or NULL */
+    Py_ssize_t pending_bytes_count;
+    PyObject *snapshot;
+    /* snapshot is either None, or a tuple (dec_flags, next_input) where
+     * dec_flags is the second (integer) item of the decoder state and
+     * next_input is the chunk of input bytes that comes next after the
+     * snapshot point.  We use this to reconstruct decoder states in tell().
+     */
+
+    /* Cache raw object if it's a FileIO object */
+    PyObject *raw;
+
+    PyObject *weakreflist;
+    PyObject *dict;
+} textio;
+
+
+/* A couple of specialized cases in order to bypass the slow incremental
+   encoding methods for the most popular encodings. */
+
+static PyObject *
+ascii_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeASCII(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors));
+}
+
+static PyObject *
+utf16be_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeUTF16(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors), 1);
+}
+
+static PyObject *
+utf16le_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeUTF16(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors), -1);
+}
+
+static PyObject *
+utf16_encode(textio *self, PyObject *text)
+{
+    if (!self->encoding_start_of_stream) {
+        /* Skip the BOM and use native byte ordering */
+#if defined(WORDS_BIGENDIAN)
+        return utf16be_encode(self, text);
+#else
+        return utf16le_encode(self, text);
+#endif
+    }
+    return PyUnicode_EncodeUTF16(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors), 0);
+}
+
+static PyObject *
+utf32be_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeUTF32(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors), 1);
+}
+
+static PyObject *
+utf32le_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeUTF32(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors), -1);
+}
+
+static PyObject *
+utf32_encode(textio *self, PyObject *text)
+{
+    if (!self->encoding_start_of_stream) {
+        /* Skip the BOM and use native byte ordering */
+#if defined(WORDS_BIGENDIAN)
+        return utf32be_encode(self, text);
+#else
+        return utf32le_encode(self, text);
+#endif
+    }
+    return PyUnicode_EncodeUTF32(PyUnicode_AS_UNICODE(text),
+                                 PyUnicode_GET_SIZE(text),
+                                 PyBytes_AS_STRING(self->errors), 0);
+}
+
+static PyObject *
+utf8_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeUTF8(PyUnicode_AS_UNICODE(text),
+                                PyUnicode_GET_SIZE(text),
+                                PyBytes_AS_STRING(self->errors));
+}
+
+static PyObject *
+latin1_encode(textio *self, PyObject *text)
+{
+    return PyUnicode_EncodeLatin1(PyUnicode_AS_UNICODE(text),
+                                  PyUnicode_GET_SIZE(text),
+                                  PyBytes_AS_STRING(self->errors));
+}
+
+/* Map normalized encoding names onto the specialized encoding funcs */
+
+typedef struct {
+    const char *name;
+    encodefunc_t encodefunc;
+} encodefuncentry;
+
+static encodefuncentry encodefuncs[] = {
+    {"ascii",       (encodefunc_t) ascii_encode},
+    {"iso8859-1",   (encodefunc_t) latin1_encode},
+    {"utf-8",       (encodefunc_t) utf8_encode},
+    {"utf-16-be",   (encodefunc_t) utf16be_encode},
+    {"utf-16-le",   (encodefunc_t) utf16le_encode},
+    {"utf-16",      (encodefunc_t) utf16_encode},
+    {"utf-32-be",   (encodefunc_t) utf32be_encode},
+    {"utf-32-le",   (encodefunc_t) utf32le_encode},
+    {"utf-32",      (encodefunc_t) utf32_encode},
+    {NULL, NULL}
+};
+
+
+static int
+textiowrapper_init(textio *self, PyObject *args, PyObject *kwds)
+{
+    char *kwlist[] = {"buffer", "encoding", "errors",
+                      "newline", "line_buffering",
+                      NULL};
+    PyObject *buffer, *raw;
+    char *encoding = NULL;
+    char *errors = NULL;
+    char *newline = NULL;
+    int line_buffering = 0;
+
+    PyObject *res;
+    int r;
+
+    self->ok = 0;
+    self->detached = 0;
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|zzzi:fileio",
+                                     kwlist, &buffer, &encoding, &errors,
+                                     &newline, &line_buffering))
+        return -1;
+
+    if (newline && newline[0] != '\0'
+        && !(newline[0] == '\n' && newline[1] == '\0')
+        && !(newline[0] == '\r' && newline[1] == '\0')
+        && !(newline[0] == '\r' && newline[1] == '\n' && newline[2] == '\0')) {
+        PyErr_Format(PyExc_ValueError,
+                     "illegal newline value: %s", newline);
+        return -1;
+    }
+
+    Py_CLEAR(self->buffer);
+    Py_CLEAR(self->encoding);
+    Py_CLEAR(self->encoder);
+    Py_CLEAR(self->decoder);
+    Py_CLEAR(self->readnl);
+    Py_CLEAR(self->decoded_chars);
+    Py_CLEAR(self->pending_bytes);
+    Py_CLEAR(self->snapshot);
+    Py_CLEAR(self->errors);
+    Py_CLEAR(self->raw);
+    self->decoded_chars_used = 0;
+    self->pending_bytes_count = 0;
+    self->encodefunc = NULL;
+    self->writenl = NULL;
+
+    if (encoding == NULL && self->encoding == NULL) {
+        if (_PyIO_locale_module == NULL) {
+            _PyIO_locale_module = PyImport_ImportModule("locale");
+            if (_PyIO_locale_module == NULL)
+                goto catch_ImportError;
+            else
+                goto use_locale;
+        }
+        else {
+          use_locale:
+            self->encoding = PyObject_CallMethod(
+                _PyIO_locale_module, "getpreferredencoding", NULL);
+            if (self->encoding == NULL) {
+              catch_ImportError:
+                /*
+                 Importing locale can raise a ImportError because of
+                 _functools, and locale.getpreferredencoding can raise a
+                 ImportError if _locale is not available.  These will happen
+                 during module building.
+                */
+                if (PyErr_ExceptionMatches(PyExc_ImportError)) {
+                    PyErr_Clear();
+                    self->encoding = PyString_FromString("ascii");
+                }
+                else
+                    goto error;
+            }
+            else if (!PyString_Check(self->encoding))
+                Py_CLEAR(self->encoding);
+        }
+    }
+    if (self->encoding != NULL)
+        encoding = PyString_AsString(self->encoding);
+    else if (encoding != NULL) {
+        self->encoding = PyString_FromString(encoding);
+        if (self->encoding == NULL)
+            goto error;
+    }
+    else {
+        PyErr_SetString(PyExc_IOError,
+                        "could not determine default encoding");
+    }
+
+    if (errors == NULL)
+        errors = "strict";
+    self->errors = PyBytes_FromString(errors);
+    if (self->errors == NULL)
+        goto error;
+
+    self->chunk_size = 8192;
+    self->readuniversal = (newline == NULL || newline[0] == '\0');
+    self->line_buffering = line_buffering;
+    self->readtranslate = (newline == NULL);
+    if (newline) {
+        self->readnl = PyString_FromString(newline);
+        if (self->readnl == NULL)
+            return -1;
+    }
+    self->writetranslate = (newline == NULL || newline[0] != '\0');
+    if (!self->readuniversal && self->writetranslate) {
+        self->writenl = PyString_AsString(self->readnl);
+        if (!strcmp(self->writenl, "\n"))
+            self->writenl = NULL;
+    }
+#ifdef MS_WINDOWS
+    else
+        self->writenl = "\r\n";
+#endif
+
+    /* Build the decoder object */
+    res = PyObject_CallMethod(buffer, "readable", NULL);
+    if (res == NULL)
+        goto error;
+    r = PyObject_IsTrue(res);
+    Py_DECREF(res);
+    if (r == -1)
+        goto error;
+    if (r == 1) {
+        self->decoder = PyCodec_IncrementalDecoder(
+            encoding, errors);
+        if (self->decoder == NULL)
+            goto error;
+
+        if (self->readuniversal) {
+            PyObject *incrementalDecoder = PyObject_CallFunction(
+                (PyObject *)&PyIncrementalNewlineDecoder_Type,
+                "Oi", self->decoder, (int)self->readtranslate);
+            if (incrementalDecoder == NULL)
+                goto error;
+            Py_CLEAR(self->decoder);
+            self->decoder = incrementalDecoder;
+        }
+    }
+
+    /* Build the encoder object */
+    res = PyObject_CallMethod(buffer, "writable", NULL);
+    if (res == NULL)
+        goto error;
+    r = PyObject_IsTrue(res);
+    Py_DECREF(res);
+    if (r == -1)
+        goto error;
+    if (r == 1) {
+        PyObject *ci;
+        self->encoder = PyCodec_IncrementalEncoder(
+            encoding, errors);
+        if (self->encoder == NULL)
+            goto error;
+        /* Get the normalized named of the codec */
+        ci = _PyCodec_Lookup(encoding);
+        if (ci == NULL)
+            goto error;
+        res = PyObject_GetAttrString(ci, "name");
+        Py_DECREF(ci);
+        if (res == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_AttributeError))
+                PyErr_Clear();
+            else
+                goto error;
+        }
+        else if (PyString_Check(res)) {
+            encodefuncentry *e = encodefuncs;
+            while (e->name != NULL) {
+                if (!strcmp(PyString_AS_STRING(res), e->name)) {
+                    self->encodefunc = e->encodefunc;
+                    break;
+                }
+                e++;
+            }
+        }
+        Py_XDECREF(res);
+    }
+
+    self->buffer = buffer;
+    Py_INCREF(buffer);
+
+    if (Py_TYPE(buffer) == &PyBufferedReader_Type ||
+        Py_TYPE(buffer) == &PyBufferedWriter_Type ||
+        Py_TYPE(buffer) == &PyBufferedRandom_Type) {
+        raw = PyObject_GetAttrString(buffer, "raw");
+        /* Cache the raw FileIO object to speed up 'closed' checks */
+        if (raw == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_AttributeError))
+                PyErr_Clear();
+            else
+                goto error;
+        }
+        else if (Py_TYPE(raw) == &PyFileIO_Type)
+            self->raw = raw;
+        else
+            Py_DECREF(raw);
+    }
+
+    res = PyObject_CallMethod(buffer, "seekable", NULL);
+    if (res == NULL)
+        goto error;
+    self->seekable = self->telling = PyObject_IsTrue(res);
+    Py_DECREF(res);
+
+    self->encoding_start_of_stream = 0;
+    if (self->seekable && self->encoder) {
+        PyObject *cookieObj;
+        int cmp;
+
+        self->encoding_start_of_stream = 1;
+
+        cookieObj = PyObject_CallMethodObjArgs(buffer, _PyIO_str_tell, NULL);
+        if (cookieObj == NULL)
+            goto error;
+
+        cmp = PyObject_RichCompareBool(cookieObj, _PyIO_zero, Py_EQ);
+        Py_DECREF(cookieObj);
+        if (cmp < 0) {
+            goto error;
+        }
+
+        if (cmp == 0) {
+            self->encoding_start_of_stream = 0;
+            res = PyObject_CallMethodObjArgs(self->encoder, _PyIO_str_setstate,
+                                             _PyIO_zero, NULL);
+            if (res == NULL)
+                goto error;
+            Py_DECREF(res);
+        }
+    }
+
+    self->ok = 1;
+    return 0;
+
+  error:
+    return -1;
+}
+
+static int
+_textiowrapper_clear(textio *self)
+{
+    if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
+        return -1;
+    self->ok = 0;
+    Py_CLEAR(self->buffer);
+    Py_CLEAR(self->encoding);
+    Py_CLEAR(self->encoder);
+    Py_CLEAR(self->decoder);
+    Py_CLEAR(self->readnl);
+    Py_CLEAR(self->decoded_chars);
+    Py_CLEAR(self->pending_bytes);
+    Py_CLEAR(self->snapshot);
+    Py_CLEAR(self->errors);
+    Py_CLEAR(self->raw);
+    return 0;
+}
+
+static void
+textiowrapper_dealloc(textio *self)
+{
+    if (_textiowrapper_clear(self) < 0)
+        return;
+    _PyObject_GC_UNTRACK(self);
+    if (self->weakreflist != NULL)
+        PyObject_ClearWeakRefs((PyObject *)self);
+    Py_CLEAR(self->dict);
+    Py_TYPE(self)->tp_free((PyObject *)self);
+}
+
+static int
+textiowrapper_traverse(textio *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->buffer);
+    Py_VISIT(self->encoding);
+    Py_VISIT(self->encoder);
+    Py_VISIT(self->decoder);
+    Py_VISIT(self->readnl);
+    Py_VISIT(self->decoded_chars);
+    Py_VISIT(self->pending_bytes);
+    Py_VISIT(self->snapshot);
+    Py_VISIT(self->errors);
+    Py_VISIT(self->raw);
+
+    Py_VISIT(self->dict);
+    return 0;
+}
+
+static int
+textiowrapper_clear(textio *self)
+{
+    if (_textiowrapper_clear(self) < 0)
+        return -1;
+    Py_CLEAR(self->dict);
+    return 0;
+}
+
+static PyObject *
+textiowrapper_closed_get(textio *self, void *context);
+
+/* This macro takes some shortcuts to make the common case faster. */
+#define CHECK_CLOSED(self) \
+    do { \
+        int r; \
+        PyObject *_res; \
+        if (Py_TYPE(self) == &PyTextIOWrapper_Type) { \
+            if (self->raw != NULL) \
+                r = _PyFileIO_closed(self->raw); \
+            else { \
+                _res = textiowrapper_closed_get(self, NULL); \
+                if (_res == NULL) \
+                    return NULL; \
+                r = PyObject_IsTrue(_res); \
+                Py_DECREF(_res); \
+                if (r < 0) \
+                    return NULL; \
+            } \
+            if (r > 0) { \
+                PyErr_SetString(PyExc_ValueError, \
+                                "I/O operation on closed file."); \
+                return NULL; \
+            } \
+        } \
+        else if (_PyIOBase_check_closed((PyObject *)self, Py_True) == NULL) \
+            return NULL; \
+    } while (0)
+
+#define CHECK_INITIALIZED(self) \
+    if (self->ok <= 0) { \
+        if (self->detached) { \
+            PyErr_SetString(PyExc_ValueError, \
+                 "underlying buffer has been detached"); \
+        } else {                                   \
+            PyErr_SetString(PyExc_ValueError, \
+                "I/O operation on uninitialized object"); \
+        } \
+        return NULL; \
+    }
+
+#define CHECK_INITIALIZED_INT(self) \
+    if (self->ok <= 0) { \
+        if (self->detached) { \
+            PyErr_SetString(PyExc_ValueError, \
+                 "underlying buffer has been detached"); \
+        } else {                                   \
+            PyErr_SetString(PyExc_ValueError, \
+                "I/O operation on uninitialized object"); \
+        } \
+        return -1; \
+    }
+
+
+static PyObject *
+textiowrapper_detach(textio *self)
+{
+    PyObject *buffer, *res;
+    CHECK_INITIALIZED(self);
+    res = PyObject_CallMethodObjArgs((PyObject *)self, _PyIO_str_flush, NULL);
+    if (res == NULL)
+        return NULL;
+    Py_DECREF(res);
+    buffer = self->buffer;
+    self->buffer = NULL;
+    self->detached = 1;
+    self->ok = 0;
+    return buffer;
+}
+
+Py_LOCAL_INLINE(const Py_UNICODE *)
+findchar(const Py_UNICODE *s, Py_ssize_t size, Py_UNICODE ch)
+{
+    /* like wcschr, but doesn't stop at NULL characters */
+    while (size-- > 0) {
+        if (*s == ch)
+            return s;
+        s++;
+    }
+    return NULL;
+}
+
+/* Flush the internal write buffer. This doesn't explicitly flush the
+   underlying buffered object, though. */
+static int
+_textiowrapper_writeflush(textio *self)
+{
+    PyObject *b, *ret;
+
+    if (self->pending_bytes == NULL)
+        return 0;
+    b = _PyBytes_Join(_PyIO_empty_bytes, self->pending_bytes);
+    if (b == NULL)
+        return -1;
+    ret = PyObject_CallMethodObjArgs(self->buffer,
+                                     _PyIO_str_write, b, NULL);
+    Py_DECREF(b);
+    if (ret == NULL)
+        return -1;
+    Py_DECREF(ret);
+    Py_CLEAR(self->pending_bytes);
+    self->pending_bytes_count = 0;
+    return 0;
+}
+
+static PyObject *
+textiowrapper_write(textio *self, PyObject *args)
+{
+    PyObject *ret;
+    PyObject *text; /* owned reference */
+    PyObject *b;
+    Py_ssize_t textlen;
+    int haslf = 0;
+    int needflush = 0;
+
+    CHECK_INITIALIZED(self);
+
+    if (!PyArg_ParseTuple(args, "U:write", &text)) {
+        return NULL;
+    }
+
+    CHECK_CLOSED(self);
+
+    if (self->encoder == NULL) {
+        PyErr_SetString(PyExc_IOError, "not writable");
+        return NULL;
+    }
+
+    Py_INCREF(text);
+
+    textlen = PyUnicode_GetSize(text);
+
+    if ((self->writetranslate && self->writenl != NULL) || self->line_buffering)
+        if (findchar(PyUnicode_AS_UNICODE(text),
+                     PyUnicode_GET_SIZE(text), '\n'))
+            haslf = 1;
+
+    if (haslf && self->writetranslate && self->writenl != NULL) {
+        PyObject *newtext = PyObject_CallMethod(
+            text, "replace", "ss", "\n", self->writenl);
+        Py_DECREF(text);
+        if (newtext == NULL)
+            return NULL;
+        text = newtext;
+    }
+
+    if (self->line_buffering &&
+        (haslf ||
+         findchar(PyUnicode_AS_UNICODE(text),
+                  PyUnicode_GET_SIZE(text), '\r')))
+        needflush = 1;
+
+    /* XXX What if we were just reading? */
+    if (self->encodefunc != NULL) {
+        b = (*self->encodefunc)((PyObject *) self, text);
+        self->encoding_start_of_stream = 0;
+    }
+    else
+        b = PyObject_CallMethodObjArgs(self->encoder,
+                                       _PyIO_str_encode, text, NULL);
+    Py_DECREF(text);
+    if (b == NULL)
+        return NULL;
+
+    if (self->pending_bytes == NULL) {
+        self->pending_bytes = PyList_New(0);
+        if (self->pending_bytes == NULL) {
+            Py_DECREF(b);
+            return NULL;
+        }
+        self->pending_bytes_count = 0;
+    }
+    if (PyList_Append(self->pending_bytes, b) < 0) {
+        Py_DECREF(b);
+        return NULL;
+    }
+    self->pending_bytes_count += PyBytes_GET_SIZE(b);
+    Py_DECREF(b);
+    if (self->pending_bytes_count > self->chunk_size || needflush) {
+        if (_textiowrapper_writeflush(self) < 0)
+            return NULL;
+    }
+
+    if (needflush) {
+        ret = PyObject_CallMethodObjArgs(self->buffer, _PyIO_str_flush, NULL);
+        if (ret == NULL)
+            return NULL;
+        Py_DECREF(ret);
+    }
+
+    Py_CLEAR(self->snapshot);
+
+    if (self->decoder) {
+        ret = PyObject_CallMethod(self->decoder, "reset", NULL);
+        if (ret == NULL)
+            return NULL;
+        Py_DECREF(ret);
+    }
+
+    return PyLong_FromSsize_t(textlen);
+}
+
+/* Steal a reference to chars and store it in the decoded_char buffer;
+ */
+static void
+textiowrapper_set_decoded_chars(textio *self, PyObject *chars)
+{
+    Py_CLEAR(self->decoded_chars);
+    self->decoded_chars = chars;
+    self->decoded_chars_used = 0;
+}
+
+static PyObject *
+textiowrapper_get_decoded_chars(textio *self, Py_ssize_t n)
+{
+    PyObject *chars;
+    Py_ssize_t avail;
+
+    if (self->decoded_chars == NULL)
+        return PyUnicode_FromStringAndSize(NULL, 0);
+
+    avail = (PyUnicode_GET_SIZE(self->decoded_chars)
+             - self->decoded_chars_used);
+
+    assert(avail >= 0);
+
+    if (n < 0 || n > avail)
+        n = avail;
+
+    if (self->decoded_chars_used > 0 || n < avail) {
+        chars = PyUnicode_FromUnicode(
+            PyUnicode_AS_UNICODE(self->decoded_chars)
+            + self->decoded_chars_used, n);
+        if (chars == NULL)
+            return NULL;
+    }
+    else {
+        chars = self->decoded_chars;
+        Py_INCREF(chars);
+    }
+
+    self->decoded_chars_used += n;
+    return chars;
+}
+
+/* Read and decode the next chunk of data from the BufferedReader.
+ */
+static int
+textiowrapper_read_chunk(textio *self)
+{
+    PyObject *dec_buffer = NULL;
+    PyObject *dec_flags = NULL;
+    PyObject *input_chunk = NULL;
+    PyObject *decoded_chars, *chunk_size;
+    int eof;
+
+    /* The return value is True unless EOF was reached.  The decoded string is
+     * placed in self._decoded_chars (replacing its previous value).  The
+     * entire input chunk is sent to the decoder, though some of it may remain
+     * buffered in the decoder, yet to be converted.
+     */
+
+    if (self->decoder == NULL) {
+        PyErr_SetString(PyExc_IOError, "not readable");
+        return -1;
+    }
+
+    if (self->telling) {
+        /* To prepare for tell(), we need to snapshot a point in the file
+         * where the decoder's input buffer is empty.
+         */
+
+        PyObject *state = PyObject_CallMethodObjArgs(self->decoder,
+                                                     _PyIO_str_getstate, NULL);
+        if (state == NULL)
+            return -1;
+        /* Given this, we know there was a valid snapshot point
+         * len(dec_buffer) bytes ago with decoder state (b'', dec_flags).
+         */
+        if (PyArg_Parse(state, "(OO)", &dec_buffer, &dec_flags) < 0) {
+            Py_DECREF(state);
+            return -1;
+        }
+        Py_INCREF(dec_buffer);
+        Py_INCREF(dec_flags);
+        Py_DECREF(state);
+    }
+
+    /* Read a chunk, decode it, and put the result in self._decoded_chars. */
+    chunk_size = PyLong_FromSsize_t(self->chunk_size);
+    if (chunk_size == NULL)
+        goto fail;
+    input_chunk = PyObject_CallMethodObjArgs(self->buffer,
+        _PyIO_str_read1, chunk_size, NULL);
+    Py_DECREF(chunk_size);
+    if (input_chunk == NULL)
+        goto fail;
+    assert(PyBytes_Check(input_chunk));
+
+    eof = (PyBytes_Size(input_chunk) == 0);
+
+    if (Py_TYPE(self->decoder) == &PyIncrementalNewlineDecoder_Type) {
+        decoded_chars = _PyIncrementalNewlineDecoder_decode(
+            self->decoder, input_chunk, eof);
+    }
+    else {
+        decoded_chars = PyObject_CallMethodObjArgs(self->decoder,
+            _PyIO_str_decode, input_chunk, eof ? Py_True : Py_False, NULL);
+    }
+
+    /* TODO sanity check: isinstance(decoded_chars, unicode) */
+    if (decoded_chars == NULL)
+        goto fail;
+    textiowrapper_set_decoded_chars(self, decoded_chars);
+    if (PyUnicode_GET_SIZE(decoded_chars) > 0)
+        eof = 0;
+
+    if (self->telling) {
+        /* At the snapshot point, len(dec_buffer) bytes before the read, the
+         * next input to be decoded is dec_buffer + input_chunk.
+         */
+        PyObject *next_input = PyNumber_Add(dec_buffer, input_chunk);
+        if (next_input == NULL)
+            goto fail;
+        assert (PyBytes_Check(next_input));
+        Py_DECREF(dec_buffer);
+        Py_CLEAR(self->snapshot);
+        self->snapshot = Py_BuildValue("NN", dec_flags, next_input);
+    }
+    Py_DECREF(input_chunk);
+
+    return (eof == 0);
+
+  fail:
+    Py_XDECREF(dec_buffer);
+    Py_XDECREF(dec_flags);
+    Py_XDECREF(input_chunk);
+    return -1;
+}
+
+static PyObject *
+textiowrapper_read(textio *self, PyObject *args)
+{
+    Py_ssize_t n = -1;
+    PyObject *result = NULL, *chunks = NULL;
+
+    CHECK_INITIALIZED(self);
+
+    if (!PyArg_ParseTuple(args, "|n:read", &n))
+        return NULL;
+
+    CHECK_CLOSED(self);
+
+    if (self->decoder == NULL) {
+        PyErr_SetString(PyExc_IOError, "not readable");
+        return NULL;
+    }
+
+    if (_textiowrapper_writeflush(self) < 0)
+        return NULL;
+
+    if (n < 0) {
+        /* Read everything */
+        PyObject *bytes = PyObject_CallMethod(self->buffer, "read", NULL);
+        PyObject *decoded, *final;
+        if (bytes == NULL)
+            goto fail;
+        decoded = PyObject_CallMethodObjArgs(self->decoder, _PyIO_str_decode,
+                                             bytes, Py_True, NULL);
+        Py_DECREF(bytes);
+        if (decoded == NULL)
+            goto fail;
+
+        result = textiowrapper_get_decoded_chars(self, -1);
+
+        if (result == NULL) {
+            Py_DECREF(decoded);
+            return NULL;
+        }
+
+        final = PyUnicode_Concat(result, decoded);
+        Py_DECREF(result);
+        Py_DECREF(decoded);
+        if (final == NULL)
+            goto fail;
+
+        Py_CLEAR(self->snapshot);
+        return final;
+    }
+    else {
+        int res = 1;
+        Py_ssize_t remaining = n;
+
+        result = textiowrapper_get_decoded_chars(self, n);
+        if (result == NULL)
+            goto fail;
+        remaining -= PyUnicode_GET_SIZE(result);
+
+        /* Keep reading chunks until we have n characters to return */
+        while (remaining > 0) {
+            res = textiowrapper_read_chunk(self);
+            if (res < 0)
+                goto fail;
+            if (res == 0)  /* EOF */
+                break;
+            if (chunks == NULL) {
+                chunks = PyList_New(0);
+                if (chunks == NULL)
+                    goto fail;
+            }
+            if (PyList_Append(chunks, result) < 0)
+                goto fail;
+            Py_DECREF(result);
+            result = textiowrapper_get_decoded_chars(self, remaining);
+            if (result == NULL)
+                goto fail;
+            remaining -= PyUnicode_GET_SIZE(result);
+        }
+        if (chunks != NULL) {
+            if (result != NULL && PyList_Append(chunks, result) < 0)
+                goto fail;
+            Py_CLEAR(result);
+            result = PyUnicode_Join(_PyIO_empty_str, chunks);
+            if (result == NULL)
+                goto fail;
+            Py_CLEAR(chunks);
+        }
+        return result;
+    }
+  fail:
+    Py_XDECREF(result);
+    Py_XDECREF(chunks);
+    return NULL;
+}
+
+
+/* NOTE: `end` must point to the real end of the Py_UNICODE storage,
+   that is to the NUL character. Otherwise the function will produce
+   incorrect results. */
+static Py_UNICODE *
+find_control_char(Py_UNICODE *start, Py_UNICODE *end, Py_UNICODE ch)
+{
+    Py_UNICODE *s = start;
+    for (;;) {
+        while (*s > ch)
+            s++;
+        if (*s == ch)
+            return s;
+        if (s == end)
+            return NULL;
+        s++;
+    }
+}
+
+Py_ssize_t
+_PyIO_find_line_ending(
+    int translated, int universal, PyObject *readnl,
+    Py_UNICODE *start, Py_UNICODE *end, Py_ssize_t *consumed)
+{
+    Py_ssize_t len = end - start;
+
+    if (translated) {
+        /* Newlines are already translated, only search for \n */
+        Py_UNICODE *pos = find_control_char(start, end, '\n');
+        if (pos != NULL)
+            return pos - start + 1;
+        else {
+            *consumed = len;
+            return -1;
+        }
+    }
+    else if (universal) {
+        /* Universal newline search. Find any of \r, \r\n, \n
+         * The decoder ensures that \r\n are not split in two pieces
+         */
+        Py_UNICODE *s = start;
+        for (;;) {
+            Py_UNICODE ch;
+            /* Fast path for non-control chars. The loop always ends
+               since the Py_UNICODE storage is NUL-terminated. */
+            while (*s > '\r')
+                s++;
+            if (s >= end) {
+                *consumed = len;
+                return -1;
+            }
+            ch = *s++;
+            if (ch == '\n')
+                return s - start;
+            if (ch == '\r') {
+                if (*s == '\n')
+                    return s - start + 1;
+                else
+                    return s - start;
+            }
+        }
+    }
+    else {
+        /* Non-universal mode. */
+        Py_ssize_t readnl_len = PyString_GET_SIZE(readnl);
+        unsigned char *nl = (unsigned char *) PyString_AS_STRING(readnl);
+        if (readnl_len == 1) {
+            Py_UNICODE *pos = find_control_char(start, end, nl[0]);
+            if (pos != NULL)
+                return pos - start + 1;
+            *consumed = len;
+            return -1;
+        }
+        else {
+            Py_UNICODE *s = start;
+            Py_UNICODE *e = end - readnl_len + 1;
+            Py_UNICODE *pos;
+            if (e < s)
+                e = s;
+            while (s < e) {
+                Py_ssize_t i;
+                Py_UNICODE *pos = find_control_char(s, end, nl[0]);
+                if (pos == NULL || pos >= e)
+                    break;
+                for (i = 1; i < readnl_len; i++) {
+                    if (pos[i] != nl[i])
+                        break;
+                }
+                if (i == readnl_len)
+                    return pos - start + readnl_len;
+                s = pos + 1;
+            }
+            pos = find_control_char(e, end, nl[0]);
+            if (pos == NULL)
+                *consumed = len;
+            else
+                *consumed = pos - start;
+            return -1;
+        }
+    }
+}
+
+static PyObject *
+_textiowrapper_readline(textio *self, Py_ssize_t limit)
+{
+    PyObject *line = NULL, *chunks = NULL, *remaining = NULL;
+    Py_ssize_t start, endpos, chunked, offset_to_buffer;
+    int res;
+
+    CHECK_CLOSED(self);
+
+    if (_textiowrapper_writeflush(self) < 0)
+        return NULL;
+
+    chunked = 0;
+
+    while (1) {
+        Py_UNICODE *ptr;
+        Py_ssize_t line_len;
+        Py_ssize_t consumed = 0;
+
+        /* First, get some data if necessary */
+        res = 1;
+        while (!self->decoded_chars ||
+               !PyUnicode_GET_SIZE(self->decoded_chars)) {
+            res = textiowrapper_read_chunk(self);
+            if (res < 0)
+                goto error;
+            if (res == 0)
+                break;
+        }
+        if (res == 0) {
+            /* end of file */
+            textiowrapper_set_decoded_chars(self, NULL);
+            Py_CLEAR(self->snapshot);
+            start = endpos = offset_to_buffer = 0;
+            break;
+        }
+
+        if (remaining == NULL) {
+            line = self->decoded_chars;
+            start = self->decoded_chars_used;
+            offset_to_buffer = 0;
+            Py_INCREF(line);
+        }
+        else {
+            assert(self->decoded_chars_used == 0);
+            line = PyUnicode_Concat(remaining, self->decoded_chars);
+            start = 0;
+            offset_to_buffer = PyUnicode_GET_SIZE(remaining);
+            Py_CLEAR(remaining);
+            if (line == NULL)
+                goto error;
+        }
+
+        ptr = PyUnicode_AS_UNICODE(line);
+        line_len = PyUnicode_GET_SIZE(line);
+
+        endpos = _PyIO_find_line_ending(
+            self->readtranslate, self->readuniversal, self->readnl,
+            ptr + start, ptr + line_len, &consumed);
+        if (endpos >= 0) {
+            endpos += start;
+            if (limit >= 0 && (endpos - start) + chunked >= limit)
+                endpos = start + limit - chunked;
+            break;
+        }
+
+        /* We can put aside up to `endpos` */
+        endpos = consumed + start;
+        if (limit >= 0 && (endpos - start) + chunked >= limit) {
+            /* Didn't find line ending, but reached length limit */
+            endpos = start + limit - chunked;
+            break;
+        }
+
+        if (endpos > start) {
+            /* No line ending seen yet - put aside current data */
+            PyObject *s;
+            if (chunks == NULL) {
+                chunks = PyList_New(0);
+                if (chunks == NULL)
+                    goto error;
+            }
+            s = PyUnicode_FromUnicode(ptr + start, endpos - start);
+            if (s == NULL)
+                goto error;
+            if (PyList_Append(chunks, s) < 0) {
+                Py_DECREF(s);
+                goto error;
+            }
+            chunked += PyUnicode_GET_SIZE(s);
+            Py_DECREF(s);
+        }
+        /* There may be some remaining bytes we'll have to prepend to the
+           next chunk of data */
+        if (endpos < line_len) {
+            remaining = PyUnicode_FromUnicode(
+                    ptr + endpos, line_len - endpos);
+            if (remaining == NULL)
+                goto error;
+        }
+        Py_CLEAR(line);
+        /* We have consumed the buffer */
+        textiowrapper_set_decoded_chars(self, NULL);
+    }
+
+    if (line != NULL) {
+        /* Our line ends in the current buffer */
+        self->decoded_chars_used = endpos - offset_to_buffer;
+        if (start > 0 || endpos < PyUnicode_GET_SIZE(line)) {
+            if (start == 0 && Py_REFCNT(line) == 1) {
+                if (PyUnicode_Resize(&line, endpos) < 0)
+                    goto error;
+            }
+            else {
+                PyObject *s = PyUnicode_FromUnicode(
+                        PyUnicode_AS_UNICODE(line) + start, endpos - start);
+                Py_CLEAR(line);
+                if (s == NULL)
+                    goto error;
+                line = s;
+            }
+        }
+    }
+    if (remaining != NULL) {
+        if (chunks == NULL) {
+            chunks = PyList_New(0);
+            if (chunks == NULL)
+                goto error;
+        }
+        if (PyList_Append(chunks, remaining) < 0)
+            goto error;
+        Py_CLEAR(remaining);
+    }
+    if (chunks != NULL) {
+        if (line != NULL && PyList_Append(chunks, line) < 0)
+            goto error;
+        Py_CLEAR(line);
+        line = PyUnicode_Join(_PyIO_empty_str, chunks);
+        if (line == NULL)
+            goto error;
+        Py_DECREF(chunks);
+    }
+    if (line == NULL)
+        line = PyUnicode_FromStringAndSize(NULL, 0);
+
+    return line;
+
+  error:
+    Py_XDECREF(chunks);
+    Py_XDECREF(remaining);
+    Py_XDECREF(line);
+    return NULL;
+}
+
+static PyObject *
+textiowrapper_readline(textio *self, PyObject *args)
+{
+    PyObject *limitobj = NULL;
+    Py_ssize_t limit = -1;
+
+    CHECK_INITIALIZED(self);
+    if (!PyArg_ParseTuple(args, "|O:readline", &limitobj)) {
+        return NULL;
+    }
+    if (limitobj) {
+        if (!PyNumber_Check(limitobj)) {
+            PyErr_Format(PyExc_TypeError,
+                         "integer argument expected, got '%.200s'",
+                         Py_TYPE(limitobj)->tp_name);
+            return NULL;
+        }
+        limit = PyNumber_AsSsize_t(limitobj, PyExc_OverflowError);
+        if (limit == -1 && PyErr_Occurred())
+            return NULL;
+    }
+    return _textiowrapper_readline(self, limit);
+}
+
+/* Seek and Tell */
+
+typedef struct {
+    Py_off_t start_pos;
+    int dec_flags;
+    int bytes_to_feed;
+    int chars_to_skip;
+    char need_eof;
+} cookie_type;
+
+/*
+   To speed up cookie packing/unpacking, we store the fields in a temporary
+   string and call _PyLong_FromByteArray() or _PyLong_AsByteArray (resp.).
+   The following macros define at which offsets in the intermediary byte
+   string the various CookieStruct fields will be stored.
+ */
+
+#define COOKIE_BUF_LEN      (sizeof(Py_off_t) + 3 * sizeof(int) + sizeof(char))
+
+#if defined(WORDS_BIGENDIAN)
+
+# define IS_LITTLE_ENDIAN   0
+
+/* We want the least significant byte of start_pos to also be the least
+   significant byte of the cookie, which means that in big-endian mode we
+   must copy the fields in reverse order. */
+
+# define OFF_START_POS      (sizeof(char) + 3 * sizeof(int))
+# define OFF_DEC_FLAGS      (sizeof(char) + 2 * sizeof(int))
+# define OFF_BYTES_TO_FEED  (sizeof(char) + sizeof(int))
+# define OFF_CHARS_TO_SKIP  (sizeof(char))
+# define OFF_NEED_EOF       0
+
+#else
+
+# define IS_LITTLE_ENDIAN   1
+
+/* Little-endian mode: the least significant byte of start_pos will
+   naturally end up the least significant byte of the cookie. */
+
+# define OFF_START_POS      0
+# define OFF_DEC_FLAGS      (sizeof(Py_off_t))
+# define OFF_BYTES_TO_FEED  (sizeof(Py_off_t) + sizeof(int))
+# define OFF_CHARS_TO_SKIP  (sizeof(Py_off_t) + 2 * sizeof(int))
+# define OFF_NEED_EOF       (sizeof(Py_off_t) + 3 * sizeof(int))
+
+#endif
+
+static int
+textiowrapper_parse_cookie(cookie_type *cookie, PyObject *cookieObj)
+{
+    unsigned char buffer[COOKIE_BUF_LEN];
+    PyLongObject *cookieLong = (PyLongObject *)PyNumber_Long(cookieObj);
+    if (cookieLong == NULL)
+        return -1;
+
+    if (_PyLong_AsByteArray(cookieLong, buffer, sizeof(buffer),
+                            IS_LITTLE_ENDIAN, 0) < 0) {
+        Py_DECREF(cookieLong);
+        return -1;
+    }
+    Py_DECREF(cookieLong);
+
+    memcpy(&cookie->start_pos, buffer + OFF_START_POS, sizeof(cookie->start_pos));
+    memcpy(&cookie->dec_flags, buffer + OFF_DEC_FLAGS, sizeof(cookie->dec_flags));
+    memcpy(&cookie->bytes_to_feed, buffer + OFF_BYTES_TO_FEED, sizeof(cookie->bytes_to_feed));
+    memcpy(&cookie->chars_to_skip, buffer + OFF_CHARS_TO_SKIP, sizeof(cookie->chars_to_skip));
+    memcpy(&cookie->need_eof, buffer + OFF_NEED_EOF, sizeof(cookie->need_eof));
+
+    return 0;
+}
+
+static PyObject *
+textiowrapper_build_cookie(cookie_type *cookie)
+{
+    unsigned char buffer[COOKIE_BUF_LEN];
+
+    memcpy(buffer + OFF_START_POS, &cookie->start_pos, sizeof(cookie->start_pos));
+    memcpy(buffer + OFF_DEC_FLAGS, &cookie->dec_flags, sizeof(cookie->dec_flags));
+    memcpy(buffer + OFF_BYTES_TO_FEED, &cookie->bytes_to_feed, sizeof(cookie->bytes_to_feed));
+    memcpy(buffer + OFF_CHARS_TO_SKIP, &cookie->chars_to_skip, sizeof(cookie->chars_to_skip));
+    memcpy(buffer + OFF_NEED_EOF, &cookie->need_eof, sizeof(cookie->need_eof));
+
+    return _PyLong_FromByteArray(buffer, sizeof(buffer), IS_LITTLE_ENDIAN, 0);
+}
+#undef IS_LITTLE_ENDIAN
+
+static int
+_textiowrapper_decoder_setstate(textio *self, cookie_type *cookie)
+{
+    PyObject *res;
+    /* When seeking to the start of the stream, we call decoder.reset()
+       rather than decoder.getstate().
+       This is for a few decoders such as utf-16 for which the state value
+       at start is not (b"", 0) but e.g. (b"", 2) (meaning, in the case of
+       utf-16, that we are expecting a BOM).
+    */
+    if (cookie->start_pos == 0 && cookie->dec_flags == 0)
+        res = PyObject_CallMethodObjArgs(self->decoder, _PyIO_str_reset, NULL);
+    else
+        res = PyObject_CallMethod(self->decoder, "setstate",
+                                  "((si))", "", cookie->dec_flags);
+    if (res == NULL)
+        return -1;
+    Py_DECREF(res);
+    return 0;
+}
+
+static int
+_textiowrapper_encoder_setstate(textio *self, cookie_type *cookie)
+{
+    PyObject *res;
+    /* Same as _textiowrapper_decoder_setstate() above. */
+    if (cookie->start_pos == 0 && cookie->dec_flags == 0) {
+        res = PyObject_CallMethodObjArgs(self->encoder, _PyIO_str_reset, NULL);
+        self->encoding_start_of_stream = 1;
+    }
+    else {
+        res = PyObject_CallMethodObjArgs(self->encoder, _PyIO_str_setstate,
+                                         _PyIO_zero, NULL);
+        self->encoding_start_of_stream = 0;
+    }
+    if (res == NULL)
+        return -1;
+    Py_DECREF(res);
+    return 0;
+}
+
+static PyObject *
+textiowrapper_seek(textio *self, PyObject *args)
+{
+    PyObject *cookieObj, *posobj;
+    cookie_type cookie;
+    int whence = 0;
+    PyObject *res;
+    int cmp;
+
+    CHECK_INITIALIZED(self);
+
+    if (!PyArg_ParseTuple(args, "O|i:seek", &cookieObj, &whence))
+        return NULL;
+    CHECK_CLOSED(self);
+
+    Py_INCREF(cookieObj);
+
+    if (!self->seekable) {
+        PyErr_SetString(PyExc_IOError,
+                        "underlying stream is not seekable");
+        goto fail;
+    }
+
+    if (whence == 1) {
+        /* seek relative to current position */
+        cmp = PyObject_RichCompareBool(cookieObj, _PyIO_zero, Py_EQ);
+        if (cmp < 0)
+            goto fail;
+
+        if (cmp == 0) {
+            PyErr_SetString(PyExc_IOError,
+                            "can't do nonzero cur-relative seeks");
+            goto fail;
+        }
+
+        /* Seeking to the current position should attempt to
+         * sync the underlying buffer with the current position.
+         */
+        Py_DECREF(cookieObj);
+        cookieObj = PyObject_CallMethod((PyObject *)self, "tell", NULL);
+        if (cookieObj == NULL)
+            goto fail;
+    }
+    else if (whence == 2) {
+        /* seek relative to end of file */
+
+        cmp = PyObject_RichCompareBool(cookieObj, _PyIO_zero, Py_EQ);
+        if (cmp < 0)
+            goto fail;
+
+        if (cmp == 0) {
+            PyErr_SetString(PyExc_IOError,
+                            "can't do nonzero end-relative seeks");
+            goto fail;
+        }
+
+        res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
+        if (res == NULL)
+            goto fail;
+        Py_DECREF(res);
+
+        textiowrapper_set_decoded_chars(self, NULL);
+        Py_CLEAR(self->snapshot);
+        if (self->decoder) {
+            res = PyObject_CallMethod(self->decoder, "reset", NULL);
+            if (res == NULL)
+                goto fail;
+            Py_DECREF(res);
+        }
+
+        res = PyObject_CallMethod(self->buffer, "seek", "ii", 0, 2);
+        Py_XDECREF(cookieObj);
+        return res;
+    }
+    else if (whence != 0) {
+        PyErr_Format(PyExc_ValueError,
+                     "invalid whence (%d, should be 0, 1 or 2)", whence);
+        goto fail;
+    }
+
+    cmp = PyObject_RichCompareBool(cookieObj, _PyIO_zero, Py_LT);
+    if (cmp < 0)
+        goto fail;
+
+    if (cmp == 1) {
+        PyObject *repr = PyObject_Repr(cookieObj);
+        if (repr != NULL) {
+            PyErr_Format(PyExc_ValueError,
+                         "negative seek position %s",
+                         PyString_AS_STRING(repr));
+            Py_DECREF(repr);
+        }
+        goto fail;
+    }
+
+    res = PyObject_CallMethodObjArgs((PyObject *)self, _PyIO_str_flush, NULL);
+    if (res == NULL)
+        goto fail;
+    Py_DECREF(res);
+
+    /* The strategy of seek() is to go back to the safe start point
+     * and replay the effect of read(chars_to_skip) from there.
+     */
+    if (textiowrapper_parse_cookie(&cookie, cookieObj) < 0)
+        goto fail;
+
+    /* Seek back to the safe start point. */
+    posobj = PyLong_FromOff_t(cookie.start_pos);
+    if (posobj == NULL)
+        goto fail;
+    res = PyObject_CallMethodObjArgs(self->buffer,
+                                     _PyIO_str_seek, posobj, NULL);
+    Py_DECREF(posobj);
+    if (res == NULL)
+        goto fail;
+    Py_DECREF(res);
+
+    textiowrapper_set_decoded_chars(self, NULL);
+    Py_CLEAR(self->snapshot);
+
+    /* Restore the decoder to its state from the safe start point. */
+    if (self->decoder) {
+        if (_textiowrapper_decoder_setstate(self, &cookie) < 0)
+            goto fail;
+    }
+
+    if (cookie.chars_to_skip) {
+        /* Just like _read_chunk, feed the decoder and save a snapshot. */
+        PyObject *input_chunk = PyObject_CallMethod(
+            self->buffer, "read", "i", cookie.bytes_to_feed);
+        PyObject *decoded;
+
+        if (input_chunk == NULL)
+            goto fail;
+
+        assert (PyBytes_Check(input_chunk));
+
+        self->snapshot = Py_BuildValue("iN", cookie.dec_flags, input_chunk);
+        if (self->snapshot == NULL) {
+            Py_DECREF(input_chunk);
+            goto fail;
+        }
+
+        decoded = PyObject_CallMethod(self->decoder, "decode",
+                                      "Oi", input_chunk, (int)cookie.need_eof);
+
+        if (decoded == NULL)
+            goto fail;
+
+        textiowrapper_set_decoded_chars(self, decoded);
+
+        /* Skip chars_to_skip of the decoded characters. */
+        if (PyUnicode_GetSize(self->decoded_chars) < cookie.chars_to_skip) {
+            PyErr_SetString(PyExc_IOError, "can't restore logical file position");
+            goto fail;
+        }
+        self->decoded_chars_used = cookie.chars_to_skip;
+    }
+    else {
+        self->snapshot = Py_BuildValue("is", cookie.dec_flags, "");
+        if (self->snapshot == NULL)
+            goto fail;
+    }
+
+    /* Finally, reset the encoder (merely useful for proper BOM handling) */
+    if (self->encoder) {
+        if (_textiowrapper_encoder_setstate(self, &cookie) < 0)
+            goto fail;
+    }
+    return cookieObj;
+  fail:
+    Py_XDECREF(cookieObj);
+    return NULL;
+
+}
+
+static PyObject *
+textiowrapper_tell(textio *self, PyObject *args)
+{
+    PyObject *res;
+    PyObject *posobj = NULL;
+    cookie_type cookie = {0,0,0,0,0};
+    PyObject *next_input;
+    Py_ssize_t chars_to_skip, chars_decoded;
+    PyObject *saved_state = NULL;
+    char *input, *input_end;
+
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+
+    if (!self->seekable) {
+        PyErr_SetString(PyExc_IOError,
+                        "underlying stream is not seekable");
+        goto fail;
+    }
+    if (!self->telling) {
+        PyErr_SetString(PyExc_IOError,
+                        "telling position disabled by next() call");
+        goto fail;
+    }
+
+    if (_textiowrapper_writeflush(self) < 0)
+        return NULL;
+    res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
+    if (res == NULL)
+        goto fail;
+    Py_DECREF(res);
+
+    posobj = PyObject_CallMethod(self->buffer, "tell", NULL);
+    if (posobj == NULL)
+        goto fail;
+
+    if (self->decoder == NULL || self->snapshot == NULL) {
+        assert (self->decoded_chars == NULL || PyUnicode_GetSize(self->decoded_chars) == 0);
+        return posobj;
+    }
+
+#if defined(HAVE_LARGEFILE_SUPPORT)
+    cookie.start_pos = PyLong_AsLongLong(posobj);
+#else
+    cookie.start_pos = PyLong_AsLong(posobj);
+#endif
+    if (PyErr_Occurred())
+        goto fail;
+
+    /* Skip backward to the snapshot point (see _read_chunk). */
+    if (!PyArg_Parse(self->snapshot, "(iO)", &cookie.dec_flags, &next_input))
+        goto fail;
+
+    assert (PyBytes_Check(next_input));
+
+    cookie.start_pos -= PyBytes_GET_SIZE(next_input);
+
+    /* How many decoded characters have been used up since the snapshot? */
+    if (self->decoded_chars_used == 0)  {
+        /* We haven't moved from the snapshot point. */
+        Py_DECREF(posobj);
+        return textiowrapper_build_cookie(&cookie);
+    }
+
+    chars_to_skip = self->decoded_chars_used;
+
+    /* Starting from the snapshot position, we will walk the decoder
+     * forward until it gives us enough decoded characters.
+     */
+    saved_state = PyObject_CallMethodObjArgs(self->decoder,
+                                             _PyIO_str_getstate, NULL);
+    if (saved_state == NULL)
+        goto fail;
+
+    /* Note our initial start point. */
+    if (_textiowrapper_decoder_setstate(self, &cookie) < 0)
+        goto fail;
+
+    /* Feed the decoder one byte at a time.  As we go, note the
+     * nearest "safe start point" before the current location
+     * (a point where the decoder has nothing buffered, so seek()
+     * can safely start from there and advance to this location).
+     */
+    chars_decoded = 0;
+    input = PyBytes_AS_STRING(next_input);
+    input_end = input + PyBytes_GET_SIZE(next_input);
+    while (input < input_end) {
+        PyObject *state;
+        char *dec_buffer;
+        Py_ssize_t dec_buffer_len;
+        int dec_flags;
+
+        PyObject *decoded = PyObject_CallMethod(
+            self->decoder, "decode", "s#", input, 1);
+        if (decoded == NULL)
+            goto fail;
+        assert (PyUnicode_Check(decoded));
+        chars_decoded += PyUnicode_GET_SIZE(decoded);
+        Py_DECREF(decoded);
+
+        cookie.bytes_to_feed += 1;
+
+        state = PyObject_CallMethodObjArgs(self->decoder,
+                                           _PyIO_str_getstate, NULL);
+        if (state == NULL)
+            goto fail;
+        if (!PyArg_Parse(state, "(s#i)", &dec_buffer, &dec_buffer_len, &dec_flags)) {
+            Py_DECREF(state);
+            goto fail;
+        }
+        Py_DECREF(state);
+
+        if (dec_buffer_len == 0 && chars_decoded <= chars_to_skip) {
+            /* Decoder buffer is empty, so this is a safe start point. */
+            cookie.start_pos += cookie.bytes_to_feed;
+            chars_to_skip -= chars_decoded;
+            cookie.dec_flags = dec_flags;
+            cookie.bytes_to_feed = 0;
+            chars_decoded = 0;
+        }
+        if (chars_decoded >= chars_to_skip)
+            break;
+        input++;
+    }
+    if (input == input_end) {
+        /* We didn't get enough decoded data; signal EOF to get more. */
+        PyObject *decoded = PyObject_CallMethod(
+            self->decoder, "decode", "si", "", /* final = */ 1);
+        if (decoded == NULL)
+            goto fail;
+        assert (PyUnicode_Check(decoded));
+        chars_decoded += PyUnicode_GET_SIZE(decoded);
+        Py_DECREF(decoded);
+        cookie.need_eof = 1;
+
+        if (chars_decoded < chars_to_skip) {
+            PyErr_SetString(PyExc_IOError,
+                            "can't reconstruct logical file position");
+            goto fail;
+        }
+    }
+
+    /* finally */
+    Py_XDECREF(posobj);
+    res = PyObject_CallMethod(self->decoder, "setstate", "(O)", saved_state);
+    Py_DECREF(saved_state);
+    if (res == NULL)
+        return NULL;
+    Py_DECREF(res);
+
+    /* The returned cookie corresponds to the last safe start point. */
+    cookie.chars_to_skip = Py_SAFE_DOWNCAST(chars_to_skip, Py_ssize_t, int);
+    return textiowrapper_build_cookie(&cookie);
+
+  fail:
+    Py_XDECREF(posobj);
+    if (saved_state) {
+        PyObject *type, *value, *traceback;
+        PyErr_Fetch(&type, &value, &traceback);
+
+        res = PyObject_CallMethod(self->decoder, "setstate", "(O)", saved_state);
+        Py_DECREF(saved_state);
+        if (res == NULL)
+            return NULL;
+        Py_DECREF(res);
+
+        PyErr_Restore(type, value, traceback);
+    }
+    return NULL;
+}
+
+static PyObject *
+textiowrapper_truncate(textio *self, PyObject *args)
+{
+    PyObject *pos = Py_None;
+    PyObject *res;
+
+    CHECK_INITIALIZED(self)
+    if (!PyArg_ParseTuple(args, "|O:truncate", &pos)) {
+        return NULL;
+    }
+
+    res = PyObject_CallMethodObjArgs((PyObject *) self, _PyIO_str_flush, NULL);
+    if (res == NULL)
+        return NULL;
+    Py_DECREF(res);
+
+    if (pos != Py_None) {
+        res = PyObject_CallMethodObjArgs((PyObject *) self,
+                                          _PyIO_str_seek, pos, NULL);
+        if (res == NULL)
+            return NULL;
+        Py_DECREF(res);
+    }
+
+    return PyObject_CallMethodObjArgs(self->buffer, _PyIO_str_truncate, NULL);
+}
+
+static PyObject *
+textiowrapper_repr(textio *self)
+{
+    PyObject *nameobj, *res;
+    PyObject *namerepr = NULL, *encrepr = NULL;
+
+    CHECK_INITIALIZED(self);
+
+    nameobj = PyObject_GetAttrString((PyObject *) self, "name");
+    if (nameobj == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_AttributeError))
+            PyErr_Clear();
+        else
+            goto error;
+        encrepr = PyObject_Repr(self->encoding);
+        res = PyString_FromFormat("<_io.TextIOWrapper encoding=%s>",
+                                   PyString_AS_STRING(encrepr));
+    }
+    else {
+        encrepr = PyObject_Repr(self->encoding);
+        namerepr = PyObject_Repr(nameobj);
+        res = PyString_FromFormat("<_io.TextIOWrapper name=%s encoding=%s>",
+                                   PyString_AS_STRING(namerepr),
+                                   PyString_AS_STRING(encrepr));
+        Py_DECREF(nameobj);
+    }
+    Py_XDECREF(namerepr);
+    Py_XDECREF(encrepr);
+    return res;
+
+error:
+    Py_XDECREF(namerepr);
+    Py_XDECREF(encrepr);
+    return NULL;
+}
+
+
+/* Inquiries */
+
+static PyObject *
+textiowrapper_fileno(textio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_CallMethod(self->buffer, "fileno", NULL);
+}
+
+static PyObject *
+textiowrapper_seekable(textio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_CallMethod(self->buffer, "seekable", NULL);
+}
+
+static PyObject *
+textiowrapper_readable(textio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_CallMethod(self->buffer, "readable", NULL);
+}
+
+static PyObject *
+textiowrapper_writable(textio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_CallMethod(self->buffer, "writable", NULL);
+}
+
+static PyObject *
+textiowrapper_isatty(textio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_CallMethod(self->buffer, "isatty", NULL);
+}
+
+static PyObject *
+textiowrapper_flush(textio *self, PyObject *args)
+{
+    CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
+    self->telling = self->seekable;
+    if (_textiowrapper_writeflush(self) < 0)
+        return NULL;
+    return PyObject_CallMethod(self->buffer, "flush", NULL);
+}
+
+static PyObject *
+textiowrapper_close(textio *self, PyObject *args)
+{
+    PyObject *res;
+    CHECK_INITIALIZED(self);
+    res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
+    if (res == NULL) {
+        /* If flush() fails, just give up */
+        PyErr_Clear();
+    }
+    else
+        Py_DECREF(res);
+
+    return PyObject_CallMethod(self->buffer, "close", NULL);
+}
+
+static PyObject *
+textiowrapper_iternext(textio *self)
+{
+    PyObject *line;
+
+    CHECK_INITIALIZED(self);
+
+    self->telling = 0;
+    if (Py_TYPE(self) == &PyTextIOWrapper_Type) {
+        /* Skip method call overhead for speed */
+        line = _textiowrapper_readline(self, -1);
+    }
+    else {
+        line = PyObject_CallMethodObjArgs((PyObject *)self,
+                                           _PyIO_str_readline, NULL);
+        if (line && !PyUnicode_Check(line)) {
+            PyErr_Format(PyExc_IOError,
+                         "readline() should have returned an str object, "
+                         "not '%.200s'", Py_TYPE(line)->tp_name);
+            Py_DECREF(line);
+            return NULL;
+        }
+    }
+
+    if (line == NULL)
+        return NULL;
+
+    if (PyUnicode_GET_SIZE(line) == 0) {
+        /* Reached EOF or would have blocked */
+        Py_DECREF(line);
+        Py_CLEAR(self->snapshot);
+        self->telling = self->seekable;
+        return NULL;
+    }
+
+    return line;
+}
+
+static PyObject *
+textiowrapper_name_get(textio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_GetAttrString(self->buffer, "name");
+}
+
+static PyObject *
+textiowrapper_closed_get(textio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    return PyObject_GetAttr(self->buffer, _PyIO_str_closed);
+}
+
+static PyObject *
+textiowrapper_newlines_get(textio *self, void *context)
+{
+    PyObject *res;
+    CHECK_INITIALIZED(self);
+    if (self->decoder == NULL)
+        Py_RETURN_NONE;
+    res = PyObject_GetAttr(self->decoder, _PyIO_str_newlines);
+    if (res == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
+            PyErr_Clear();
+            Py_RETURN_NONE;
+        }
+        else {
+            return NULL;
+        }
+    }
+    return res;
+}
+
+static PyObject *
+textiowrapper_errors_get(textio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    Py_INCREF(self->errors);
+    return self->errors;
+}
+
+static PyObject *
+textiowrapper_chunk_size_get(textio *self, void *context)
+{
+    CHECK_INITIALIZED(self);
+    return PyLong_FromSsize_t(self->chunk_size);
+}
+
+static int
+textiowrapper_chunk_size_set(textio *self, PyObject *arg, void *context)
+{
+    Py_ssize_t n;
+    CHECK_INITIALIZED_INT(self);
+    n = PyNumber_AsSsize_t(arg, PyExc_TypeError);
+    if (n == -1 && PyErr_Occurred())
+        return -1;
+    if (n <= 0) {
+        PyErr_SetString(PyExc_ValueError,
+                        "a strictly positive integer is required");
+        return -1;
+    }
+    self->chunk_size = n;
+    return 0;
+}
+
+static PyMethodDef textiowrapper_methods[] = {
+    {"detach", (PyCFunction)textiowrapper_detach, METH_NOARGS},
+    {"write", (PyCFunction)textiowrapper_write, METH_VARARGS},
+    {"read", (PyCFunction)textiowrapper_read, METH_VARARGS},
+    {"readline", (PyCFunction)textiowrapper_readline, METH_VARARGS},
+    {"flush", (PyCFunction)textiowrapper_flush, METH_NOARGS},
+    {"close", (PyCFunction)textiowrapper_close, METH_NOARGS},
+
+    {"fileno", (PyCFunction)textiowrapper_fileno, METH_NOARGS},
+    {"seekable", (PyCFunction)textiowrapper_seekable, METH_NOARGS},
+    {"readable", (PyCFunction)textiowrapper_readable, METH_NOARGS},
+    {"writable", (PyCFunction)textiowrapper_writable, METH_NOARGS},
+    {"isatty", (PyCFunction)textiowrapper_isatty, METH_NOARGS},
+
+    {"seek", (PyCFunction)textiowrapper_seek, METH_VARARGS},
+    {"tell", (PyCFunction)textiowrapper_tell, METH_NOARGS},
+    {"truncate", (PyCFunction)textiowrapper_truncate, METH_VARARGS},
+    {NULL, NULL}
+};
+
+static PyMemberDef textiowrapper_members[] = {
+    {"encoding", T_OBJECT, offsetof(textio, encoding), READONLY},
+    {"buffer", T_OBJECT, offsetof(textio, buffer), READONLY},
+    {"line_buffering", T_BOOL, offsetof(textio, line_buffering), READONLY},
+    {NULL}
+};
+
+static PyGetSetDef textiowrapper_getset[] = {
+    {"name", (getter)textiowrapper_name_get, NULL, NULL},
+    {"closed", (getter)textiowrapper_closed_get, NULL, NULL},
+/*    {"mode", (getter)TextIOWrapper_mode_get, NULL, NULL},
+*/
+    {"newlines", (getter)textiowrapper_newlines_get, NULL, NULL},
+    {"errors", (getter)textiowrapper_errors_get, NULL, NULL},
+    {"_CHUNK_SIZE", (getter)textiowrapper_chunk_size_get,
+                    (setter)textiowrapper_chunk_size_set, NULL},
+    {NULL}
+};
+
+PyTypeObject PyTextIOWrapper_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_io.TextIOWrapper",        /*tp_name*/
+    sizeof(textio), /*tp_basicsize*/
+    0,                          /*tp_itemsize*/
+    (destructor)textiowrapper_dealloc, /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tps_etattr*/
+    0,                          /*tp_compare */
+    (reprfunc)textiowrapper_repr,/*tp_repr*/
+    0,                          /*tp_as_number*/
+    0,                          /*tp_as_sequence*/
+    0,                          /*tp_as_mapping*/
+    0,                          /*tp_hash */
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
+            | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+    textiowrapper_doc,          /* tp_doc */
+    (traverseproc)textiowrapper_traverse, /* tp_traverse */
+    (inquiry)textiowrapper_clear, /* tp_clear */
+    0,                          /* tp_richcompare */
+    offsetof(textio, weakreflist), /*tp_weaklistoffset*/
+    0,                          /* tp_iter */
+    (iternextfunc)textiowrapper_iternext, /* tp_iternext */
+    textiowrapper_methods,      /* tp_methods */
+    textiowrapper_members,      /* tp_members */
+    textiowrapper_getset,       /* tp_getset */
+    0,                          /* tp_base */
+    0,                          /* tp_dict */
+    0,                          /* tp_descr_get */
+    0,                          /* tp_descr_set */
+    offsetof(textio, dict), /*tp_dictoffset*/
+    (initproc)textiowrapper_init, /* tp_init */
+    0,                          /* tp_alloc */
+    PyType_GenericNew,          /* tp_new */
+};