Added fast alternate io.BytesIO implementation and its test suite.
Removed old test suite for StringIO.
Modified truncate() to imply a seek to given argument value.
diff --git a/Modules/_bytesio.c b/Modules/_bytesio.c
new file mode 100644
index 0000000..00cb06b
--- /dev/null
+++ b/Modules/_bytesio.c
@@ -0,0 +1,744 @@
+#include "Python.h"
+
+typedef struct {
+ PyObject_HEAD
+ char *buf;
+ Py_ssize_t pos;
+ Py_ssize_t string_size;
+ size_t buf_size;
+} BytesIOObject;
+
+#define CHECK_CLOSED(self) \
+ if ((self)->buf == NULL) { \
+ PyErr_SetString(PyExc_ValueError, \
+ "I/O operation on closed file."); \
+ return NULL; \
+ }
+
+/* Internal routine to get a line from the buffer of a BytesIO
+ object. Returns the length between the current position to the
+ next newline character. */
+static Py_ssize_t
+get_line(BytesIOObject *self, char **output)
+{
+ char *n;
+ const char *str_end;
+ Py_ssize_t len;
+
+ assert(self->buf != NULL);
+
+ /* Move to the end of the line, up to the end of the string, s. */
+ str_end = self->buf + self->string_size;
+ for (n = self->buf + self->pos;
+ n < str_end && *n != '\n';
+ n++);
+
+ /* Skip the newline character */
+ if (n < str_end)
+ n++;
+
+ /* Get the length from the current position to the end of the line. */
+ len = n - (self->buf + self->pos);
+ *output = self->buf + self->pos;
+
+ assert(len >= 0);
+ assert(self->pos < PY_SSIZE_T_MAX - len);
+ self->pos += len;
+
+ return len;
+}
+
+/* Internal routine for changing the size of the buffer of BytesIO objects.
+ 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)
+{
+ /* Here, unsigned types are used to avoid dealing with signed integer
+ overflow, which is undefined in C. */
+ size_t alloc = self->buf_size;
+ char *new_buf = NULL;
+
+ assert(self->buf != NULL);
+
+ /* 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(char))
+ goto overflow;
+ new_buf = (char *)PyMem_Realloc(self->buf, alloc * sizeof(char));
+ 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 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)
+{
+ assert(self->buf != NULL);
+ assert(self->pos >= 0);
+ 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");
+ return -1;
+ }
+ if (self->pos + len > self->buf_size) {
+ if (resize_buffer(self, self->pos + len) < 0)
+ return -1;
+ }
+
+ 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 position
+ */
+ memset(self->buf + self->string_size, '\0',
+ (self->pos - self->string_size) * sizeof(char));
+ }
+
+ /* Copy the data to the internal buffer, overwriting some of the existing
+ data if self->pos < self->string_size. */
+ memcpy(self->buf + self->pos, bytes, len);
+ 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;
+ }
+
+ return len;
+}
+
+static PyObject *
+bytesio_get_closed(BytesIOObject *self)
+{
+ if (self->buf == NULL)
+ Py_RETURN_TRUE;
+ else
+ Py_RETURN_FALSE;
+}
+
+/* Generic getter for the writable, readable and seekable properties */
+static PyObject *
+return_true(BytesIOObject *self)
+{
+ Py_RETURN_TRUE;
+}
+
+PyDoc_STRVAR(flush_doc,
+"flush() -> None. Does nothing.");
+
+static PyObject *
+bytesio_flush(BytesIOObject *self)
+{
+ Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(getval_doc,
+"getvalue() -> string.\n"
+"\n"
+"Retrieve the entire contents of the BytesIO object.");
+
+static PyObject *
+bytesio_getvalue(BytesIOObject *self)
+{
+ CHECK_CLOSED(self);
+ return PyString_FromStringAndSize(self->buf, self->string_size);
+}
+
+PyDoc_STRVAR(isatty_doc,
+"isatty() -> False.\n"
+"\n"
+"Always returns False since BytesIO objects are not connected\n"
+"to a tty-like device.");
+
+static PyObject *
+bytesio_isatty(BytesIOObject *self)
+{
+ CHECK_CLOSED(self);
+ Py_RETURN_FALSE;
+}
+
+PyDoc_STRVAR(tell_doc,
+"tell() -> current file position, an integer\n");
+
+static PyObject *
+bytesio_tell(BytesIOObject *self)
+{
+ CHECK_CLOSED(self);
+ return PyLong_FromSsize_t(self->pos);
+}
+
+PyDoc_STRVAR(read_doc,
+"read([size]) -> read at most size bytes, returned as a string.\n"
+"\n"
+"If the size argument is negative, read until EOF is reached.\n"
+"Return an empty string at EOF.");
+
+static PyObject *
+bytesio_read(BytesIOObject *self, PyObject *args)
+{
+ Py_ssize_t size, n;
+ char *output;
+ PyObject *arg = Py_None;
+
+ CHECK_CLOSED(self);
+
+ if (!PyArg_ParseTuple(args, "|O:read", &arg))
+ return NULL;
+
+ if (PyLong_Check(arg)) {
+ size = PyLong_AsSsize_t(arg);
+ }
+ 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;
+ }
+
+ assert(self->buf != NULL);
+ output = self->buf + self->pos;
+ self->pos += size;
+
+ return PyString_FromStringAndSize(output, size);
+}
+
+
+PyDoc_STRVAR(read1_doc,
+"read1(size) -> read at most size bytes, returned as a string.\n"
+"\n"
+"If the size argument is negative or omitted, read until EOF is reached.\n"
+"Return an empty string at EOF.");
+
+static PyObject *
+bytesio_read1(BytesIOObject *self, PyObject *n)
+{
+ PyObject *arg, *res;
+
+ arg = PyTuple_Pack(1, n);
+ if (arg == NULL)
+ return NULL;
+ res = bytesio_read(self, arg);
+ Py_DECREF(arg);
+ return res;
+}
+
+PyDoc_STRVAR(readline_doc,
+"readline([size]) -> next line from the file, as a string.\n"
+"\n"
+"Retain newline. A non-negative size argument limits the maximum\n"
+"number of bytes to return (an incomplete line may be returned then).\n"
+"Return an empty string at EOF.\n");
+
+static PyObject *
+bytesio_readline(BytesIOObject *self, PyObject *args)
+{
+ Py_ssize_t size, n;
+ char *output;
+ PyObject *arg = Py_None;
+
+ CHECK_CLOSED(self);
+
+ if (!PyArg_ParseTuple(args, "|O:readline", &arg))
+ return NULL;
+
+ if (PyLong_Check(arg)) {
+ size = PyLong_AsSsize_t(arg);
+ }
+ else if (arg == Py_None) {
+ /* No size limit, by default. */
+ size = -1;
+ }
+ else {
+ PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
+ Py_TYPE(arg)->tp_name);
+ return NULL;
+ }
+
+ n = get_line(self, &output);
+
+ if (size >= 0 && size < n) {
+ size = n - size;
+ n -= size;
+ self->pos -= size;
+ }
+
+ return PyString_FromStringAndSize(output, n);
+}
+
+PyDoc_STRVAR(readlines_doc,
+"readlines([size]) -> list of strings, each a line from the file.\n"
+"\n"
+"Call readline() repeatedly and return a list of the lines so read.\n"
+"The optional size argument, if given, is an approximate bound on the\n"
+"total number of bytes in the lines returned.\n");
+
+static PyObject *
+bytesio_readlines(BytesIOObject *self, PyObject *args)
+{
+ Py_ssize_t maxsize, size, n;
+ PyObject *result, *line;
+ char *output;
+ PyObject *arg = Py_None;
+
+ CHECK_CLOSED(self);
+
+ if (!PyArg_ParseTuple(args, "|O:readlines", &arg))
+ return NULL;
+
+ if (PyLong_Check(arg)) {
+ maxsize = PyLong_AsSsize_t(arg);
+ }
+ else if (arg == Py_None) {
+ /* No size limit, by default. */
+ maxsize = -1;
+ }
+ else {
+ PyErr_Format(PyExc_TypeError, "integer argument expected, got '%s'",
+ Py_TYPE(arg)->tp_name);
+ return NULL;
+ }
+
+ size = 0;
+ result = PyList_New(0);
+ if (!result)
+ return NULL;
+
+ while ((n = get_line(self, &output)) != 0) {
+ line = PyString_FromStringAndSize(output, n);
+ if (!line)
+ goto on_error;
+ if (PyList_Append(result, line) == -1) {
+ Py_DECREF(line);
+ goto on_error;
+ }
+ Py_DECREF(line);
+ size += n;
+ if (maxsize > 0 && size >= maxsize)
+ break;
+ }
+ return result;
+
+ on_error:
+ Py_DECREF(result);
+ return NULL;
+}
+
+PyDoc_STRVAR(readinto_doc,
+"readinto(bytes) -> int. Read up to len(b) bytes into b.\n"
+"\n"
+"Returns number of bytes read (0 for EOF), or None if the object\n"
+"is set not to block as has no data to read.");
+
+static PyObject *
+bytesio_readinto(BytesIOObject *self, PyObject *buffer)
+{
+ void *raw_buffer;
+ Py_ssize_t len;
+
+ CHECK_CLOSED(self);
+
+ if (PyObject_AsWriteBuffer(buffer, &raw_buffer, &len) == -1)
+ return NULL;
+
+ if (self->pos + len > self->string_size)
+ len = self->string_size - self->pos;
+
+ memcpy(raw_buffer, self->buf + self->pos, len);
+ assert(self->pos + len < PY_SSIZE_T_MAX);
+ assert(len >= 0);
+ self->pos += len;
+
+ return PyLong_FromSsize_t(len);
+}
+
+PyDoc_STRVAR(truncate_doc,
+"truncate([size]) -> int. Truncate the file to at most size bytes.\n"
+"\n"
+"Size defaults to the current file position, as returned by tell().\n"
+"Returns the new size. Imply an absolute seek to the position size.");
+
+static PyObject *
+bytesio_truncate(BytesIOObject *self, PyObject *args)
+{
+ Py_ssize_t size;
+ PyObject *arg = Py_None;
+
+ CHECK_CLOSED(self);
+
+ if (!PyArg_ParseTuple(args, "|O:truncate", &arg))
+ return NULL;
+
+ if (PyLong_Check(arg)) {
+ size = PyLong_AsSsize_t(arg);
+ }
+ 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) {
+ self->string_size = size;
+ if (resize_buffer(self, size) < 0)
+ return NULL;
+ }
+ self->pos = size;
+
+ return PyLong_FromSsize_t(size);
+}
+
+static PyObject *
+bytesio_iternext(BytesIOObject *self)
+{
+ char *next;
+ Py_ssize_t n;
+
+ CHECK_CLOSED(self);
+
+ n = get_line(self, &next);
+
+ if (!next || n == 0)
+ return NULL;
+
+ return PyString_FromStringAndSize(next, n);
+}
+
+PyDoc_STRVAR(seek_doc,
+"seek(pos, whence=0) -> int. Change stream position.\n"
+"\n"
+"Seek to byte offset pos relative to position indicated by whence:\n"
+" 0 Start of stream (the default). pos should be >= 0;\n"
+" 1 Current position - pos may be negative;\n"
+" 2 End of stream - pos usually negative.\n"
+"Returns the new absolute position.");
+
+static PyObject *
+bytesio_seek(BytesIOObject *self, PyObject *args)
+{
+ Py_ssize_t pos;
+ int mode = 0;
+
+ CHECK_CLOSED(self);
+
+ if (!PyArg_ParseTuple(args, "n|i:seek", &pos, &mode))
+ return NULL;
+
+ if (pos < 0 && mode == 0) {
+ PyErr_Format(PyExc_ValueError,
+ "negative seek value %zd", pos);
+ return NULL;
+ }
+
+ /* mode 0: offset relative to beginning of the string.
+ mode 1: offset relative to current position.
+ mode 2: offset relative the end of the string. */
+ if (mode == 1) {
+ if (pos > PY_SSIZE_T_MAX - self->pos) {
+ PyErr_SetString(PyExc_OverflowError,
+ "new position too large");
+ return NULL;
+ }
+ pos += self->pos;
+ }
+ else if (mode == 2) {
+ if (pos > PY_SSIZE_T_MAX - self->string_size) {
+ PyErr_SetString(PyExc_OverflowError,
+ "new position too large");
+ return NULL;
+ }
+ pos += self->string_size;
+ }
+ else if (mode != 0) {
+ PyErr_Format(PyExc_ValueError,
+ "invalid whence (%i, should be 0, 1 or 2)", mode);
+ return NULL;
+ }
+
+ if (pos < 0)
+ pos = 0;
+ self->pos = pos;
+
+ return PyLong_FromSsize_t(self->pos);
+}
+
+PyDoc_STRVAR(write_doc,
+"write(str) -> int. Write string str to file.\n"
+"\n"
+"Return the number of bytes written.");
+
+static PyObject *
+bytesio_write(BytesIOObject *self, PyObject *obj)
+{
+ const char *bytes;
+ Py_ssize_t size;
+ Py_ssize_t n = 0;
+
+ CHECK_CLOSED(self);
+
+ if (PyObject_AsReadBuffer(obj, (void *)&bytes, &size) < 0)
+ return NULL;
+
+ if (size != 0) {
+ n = write_bytes(self, bytes, size);
+ if (n < 0)
+ return NULL;
+ }
+
+ return PyLong_FromSsize_t(n);
+}
+
+PyDoc_STRVAR(writelines_doc,
+"writelines(sequence_of_strings) -> None. Write the strings to the file.\n"
+"\n"
+"Note that newlines are not added. The sequence can be any iterable object\n"
+"producing strings. This is equivalent to calling write() for each string.");
+
+static PyObject *
+bytesio_writelines(BytesIOObject *self, PyObject *v)
+{
+ PyObject *it, *item;
+ PyObject *ret;
+
+ CHECK_CLOSED(self);
+
+ it = PyObject_GetIter(v);
+ if (it == NULL)
+ return NULL;
+
+ while ((item = PyIter_Next(it)) != NULL) {
+ ret = bytesio_write(self, item);
+ Py_DECREF(item);
+ if (ret == NULL) {
+ Py_DECREF(it);
+ return NULL;
+ }
+ Py_DECREF(ret);
+ }
+ Py_DECREF(it);
+
+ /* See if PyIter_Next failed */
+ if (PyErr_Occurred())
+ return NULL;
+
+ Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(close_doc,
+"close() -> None. Disable all I/O operations.");
+
+static PyObject *
+bytesio_close(BytesIOObject *self)
+{
+ if (self->buf != NULL) {
+ PyMem_Free(self->buf);
+ self->buf = NULL;
+ }
+ Py_RETURN_NONE;
+}
+
+static void
+bytesio_dealloc(BytesIOObject *self)
+{
+ if (self->buf != NULL) {
+ PyMem_Free(self->buf);
+ self->buf = NULL;
+ }
+ Py_TYPE(self)->tp_free(self);
+}
+
+static PyObject *
+bytesio_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+ BytesIOObject *self;
+
+ assert(type != NULL && type->tp_alloc != NULL);
+ self = (BytesIOObject *)type->tp_alloc(type, 0);
+ if (self == NULL)
+ return NULL;
+
+ self->string_size = 0;
+ self->pos = 0;
+ self->buf_size = 0;
+ self->buf = (char *)PyMem_Malloc(0);
+ if (self->buf == NULL) {
+ Py_DECREF(self);
+ return PyErr_NoMemory();
+ }
+
+ return (PyObject *)self;
+}
+
+static int
+bytesio_init(BytesIOObject *self, PyObject *args, PyObject *kwds)
+{
+ PyObject *initvalue = NULL;
+
+ if (!PyArg_ParseTuple(args, "|O:BytesIO", &initvalue))
+ return -1;
+
+ /* In case, __init__ is called multiple times. */
+ self->string_size = 0;
+ self->pos = 0;
+
+ if (initvalue && initvalue != Py_None) {
+ PyObject *res;
+ res = bytesio_write(self, initvalue);
+ if (res == NULL)
+ return -1;
+ Py_DECREF(res);
+ self->pos = 0;
+ }
+
+ return 0;
+}
+
+static PyGetSetDef bytesio_getsetlist[] = {
+ {"closed", (getter)bytesio_get_closed, NULL,
+ "True if the file is closed."},
+ {0}, /* sentinel */
+};
+
+static struct PyMethodDef bytesio_methods[] = {
+ {"readable", (PyCFunction)return_true, METH_NOARGS, NULL},
+ {"seekable", (PyCFunction)return_true, METH_NOARGS, NULL},
+ {"writable", (PyCFunction)return_true, METH_NOARGS, NULL},
+ {"close", (PyCFunction)bytesio_close, METH_NOARGS, close_doc},
+ {"flush", (PyCFunction)bytesio_flush, METH_NOARGS, flush_doc},
+ {"isatty", (PyCFunction)bytesio_isatty, METH_NOARGS, isatty_doc},
+ {"tell", (PyCFunction)bytesio_tell, METH_NOARGS, tell_doc},
+ {"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},
+ {"readline", (PyCFunction)bytesio_readline, METH_VARARGS, readline_doc},
+ {"readlines", (PyCFunction)bytesio_readlines, METH_VARARGS, readlines_doc},
+ {"read", (PyCFunction)bytesio_read, METH_VARARGS, read_doc},
+ {"getvalue", (PyCFunction)bytesio_getvalue, METH_VARARGS, getval_doc},
+ {"seek", (PyCFunction)bytesio_seek, METH_VARARGS, seek_doc},
+ {"truncate", (PyCFunction)bytesio_truncate, METH_VARARGS, truncate_doc},
+ {NULL, NULL} /* sentinel */
+};
+
+PyDoc_STRVAR(bytesio_doc,
+"BytesIO([buffer]) -> object\n"
+"\n"
+"Create a buffered I/O implementation using an in-memory bytes\n"
+"buffer, ready for reading and writing.");
+
+static PyTypeObject BytesIO_Type = {
+ PyVarObject_HEAD_INIT(NULL, 0)
+ "_bytesio._BytesIO", /*tp_name*/
+ sizeof(BytesIOObject), /*tp_basicsize*/
+ 0, /*tp_itemsize*/
+ (destructor)bytesio_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*/
+ bytesio_doc, /*tp_doc*/
+ 0, /*tp_traverse*/
+ 0, /*tp_clear*/
+ 0, /*tp_richcompare*/
+ 0, /*tp_weaklistoffset*/
+ PyObject_SelfIter, /*tp_iter*/
+ (iternextfunc)bytesio_iternext, /*tp_iternext*/
+ bytesio_methods, /*tp_methods*/
+ 0, /*tp_members*/
+ bytesio_getsetlist, /*tp_getset*/
+ 0, /*tp_base*/
+ 0, /*tp_dict*/
+ 0, /*tp_descr_get*/
+ 0, /*tp_descr_set*/
+ 0, /*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);
+}