/* bytes object implementation */

#define PY_SSIZE_T_CLEAN

#include "Python.h"

#include "bytes_methods.h"
#include "pystrhex.h"
#include <stddef.h>

/*[clinic input]
class bytes "PyBytesObject*" "&PyBytes_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=1a1d9102afc1b00c]*/

#include "clinic/bytesobject.c.h"

#ifdef COUNT_ALLOCS
Py_ssize_t null_strings, one_strings;
#endif

static PyBytesObject *characters[UCHAR_MAX + 1];
static PyBytesObject *nullstring;

/* PyBytesObject_SIZE gives the basic size of a string; any memory allocation
   for a string of length n should request PyBytesObject_SIZE + n bytes.

   Using PyBytesObject_SIZE instead of sizeof(PyBytesObject) saves
   3 bytes per string allocation on a typical system.
*/
#define PyBytesObject_SIZE (offsetof(PyBytesObject, ob_sval) + 1)

/*
   For PyBytes_FromString(), the parameter `str' points to a null-terminated
   string containing exactly `size' bytes.

   For PyBytes_FromStringAndSize(), the parameter the parameter `str' is
   either NULL or else points to a string containing at least `size' bytes.
   For PyBytes_FromStringAndSize(), the string in the `str' parameter does
   not have to be null-terminated.  (Therefore it is safe to construct a
   substring by calling `PyBytes_FromStringAndSize(origstring, substrlen)'.)
   If `str' is NULL then PyBytes_FromStringAndSize() will allocate `size+1'
   bytes (setting the last byte to the null terminating character) and you can
   fill in the data yourself.  If `str' is non-NULL then the resulting
   PyBytes object must be treated as immutable and you must not fill in nor
   alter the data yourself, since the strings may be shared.

   The PyObject member `op->ob_size', which denotes the number of "extra
   items" in a variable-size object, will contain the number of bytes
   allocated for string data, not counting the null terminating character.
   It is therefore equal to the `size' parameter (for
   PyBytes_FromStringAndSize()) or the length of the string in the `str'
   parameter (for PyBytes_FromString()).
*/
static PyObject *
_PyBytes_FromSize(Py_ssize_t size, int use_calloc)
{
    PyBytesObject *op;
    assert(size >= 0);

    if (size == 0 && (op = nullstring) != NULL) {
#ifdef COUNT_ALLOCS
        null_strings++;
#endif
        Py_INCREF(op);
        return (PyObject *)op;
    }

    if ((size_t)size > (size_t)PY_SSIZE_T_MAX - PyBytesObject_SIZE) {
        PyErr_SetString(PyExc_OverflowError,
                        "byte string is too large");
        return NULL;
    }

    /* Inline PyObject_NewVar */
    if (use_calloc)
        op = (PyBytesObject *)PyObject_Calloc(1, PyBytesObject_SIZE + size);
    else
        op = (PyBytesObject *)PyObject_Malloc(PyBytesObject_SIZE + size);
    if (op == NULL)
        return PyErr_NoMemory();
    (void)PyObject_INIT_VAR(op, &PyBytes_Type, size);
    op->ob_shash = -1;
    if (!use_calloc)
        op->ob_sval[size] = '\0';
    /* empty byte string singleton */
    if (size == 0) {
        nullstring = op;
        Py_INCREF(op);
    }
    return (PyObject *) op;
}

PyObject *
PyBytes_FromStringAndSize(const char *str, Py_ssize_t size)
{
    PyBytesObject *op;
    if (size < 0) {
        PyErr_SetString(PyExc_SystemError,
            "Negative size passed to PyBytes_FromStringAndSize");
        return NULL;
    }
    if (size == 1 && str != NULL &&
        (op = characters[*str & UCHAR_MAX]) != NULL)
    {
#ifdef COUNT_ALLOCS
        one_strings++;
#endif
        Py_INCREF(op);
        return (PyObject *)op;
    }

    op = (PyBytesObject *)_PyBytes_FromSize(size, 0);
    if (op == NULL)
        return NULL;
    if (str == NULL)
        return (PyObject *) op;

    Py_MEMCPY(op->ob_sval, str, size);
    /* share short strings */
    if (size == 1) {
        characters[*str & UCHAR_MAX] = op;
        Py_INCREF(op);
    }
    return (PyObject *) op;
}

PyObject *
PyBytes_FromString(const char *str)
{
    size_t size;
    PyBytesObject *op;

    assert(str != NULL);
    size = strlen(str);
    if (size > PY_SSIZE_T_MAX - PyBytesObject_SIZE) {
        PyErr_SetString(PyExc_OverflowError,
            "byte string is too long");
        return NULL;
    }
    if (size == 0 && (op = nullstring) != NULL) {
#ifdef COUNT_ALLOCS
        null_strings++;
#endif
        Py_INCREF(op);
        return (PyObject *)op;
    }
    if (size == 1 && (op = characters[*str & UCHAR_MAX]) != NULL) {
#ifdef COUNT_ALLOCS
        one_strings++;
#endif
        Py_INCREF(op);
        return (PyObject *)op;
    }

    /* Inline PyObject_NewVar */
    op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + size);
    if (op == NULL)
        return PyErr_NoMemory();
    (void)PyObject_INIT_VAR(op, &PyBytes_Type, size);
    op->ob_shash = -1;
    Py_MEMCPY(op->ob_sval, str, size+1);
    /* share short strings */
    if (size == 0) {
        nullstring = op;
        Py_INCREF(op);
    } else if (size == 1) {
        characters[*str & UCHAR_MAX] = op;
        Py_INCREF(op);
    }
    return (PyObject *) op;
}

PyObject *
PyBytes_FromFormatV(const char *format, va_list vargs)
{
    va_list count;
    Py_ssize_t n = 0;
    const char* f;
    char *s;
    PyObject* string;

    Py_VA_COPY(count, vargs);
    /* step 1: figure out how large a buffer we need */
    for (f = format; *f; f++) {
        if (*f == '%') {
            const char* p = f;
            while (*++f && *f != '%' && !Py_ISALPHA(*f))
                ;

            /* skip the 'l' or 'z' in {%ld, %zd, %lu, %zu} since
             * they don't affect the amount of space we reserve.
             */
            if ((*f == 'l' || *f == 'z') &&
                            (f[1] == 'd' || f[1] == 'u'))
                ++f;

            switch (*f) {
            case 'c':
            {
                int c = va_arg(count, int);
                if (c < 0 || c > 255) {
                    PyErr_SetString(PyExc_OverflowError,
                                    "PyBytes_FromFormatV(): %c format "
                                    "expects an integer in range [0; 255]");
                    return NULL;
                }
                n++;
                break;
            }
            case '%':
                n++;
                break;
            case 'd': case 'u': case 'i': case 'x':
                (void) va_arg(count, int);
                /* 20 bytes is enough to hold a 64-bit
                   integer.  Decimal takes the most space.
                   This isn't enough for octal. */
                n += 20;
                break;
            case 's':
                s = va_arg(count, char*);
                n += strlen(s);
                break;
            case 'p':
                (void) va_arg(count, int);
                /* maximum 64-bit pointer representation:
                 * 0xffffffffffffffff
                 * so 19 characters is enough.
                 * XXX I count 18 -- what's the extra for?
                 */
                n += 19;
                break;
            default:
                /* if we stumble upon an unknown
                   formatting code, copy the rest of
                   the format string to the output
                   string. (we cannot just skip the
                   code, since there's no way to know
                   what's in the argument list) */
                n += strlen(p);
                goto expand;
            }
        } else
            n++;
    }
 expand:
    /* step 2: fill the buffer */
    /* Since we've analyzed how much space we need for the worst case,
       use sprintf directly instead of the slower PyOS_snprintf. */
    string = PyBytes_FromStringAndSize(NULL, n);
    if (!string)
        return NULL;

    s = PyBytes_AsString(string);

    for (f = format; *f; f++) {
        if (*f == '%') {
            const char* p = f++;
            Py_ssize_t i;
            int longflag = 0;
            int size_tflag = 0;
            /* parse the width.precision part (we're only
               interested in the precision value, if any) */
            n = 0;
            while (Py_ISDIGIT(*f))
                n = (n*10) + *f++ - '0';
            if (*f == '.') {
                f++;
                n = 0;
                while (Py_ISDIGIT(*f))
                    n = (n*10) + *f++ - '0';
            }
            while (*f && *f != '%' && !Py_ISALPHA(*f))
                f++;
            /* handle the long flag, but only for %ld and %lu.
               others can be added when necessary. */
            if (*f == 'l' && (f[1] == 'd' || f[1] == 'u')) {
                longflag = 1;
                ++f;
            }
            /* handle the size_t flag. */
            if (*f == 'z' && (f[1] == 'd' || f[1] == 'u')) {
                size_tflag = 1;
                ++f;
            }

            switch (*f) {
            case 'c':
            {
                int c = va_arg(vargs, int);
                /* c has been checked for overflow in the first step */
                *s++ = (unsigned char)c;
                break;
            }
            case 'd':
                if (longflag)
                    sprintf(s, "%ld", va_arg(vargs, long));
                else if (size_tflag)
                    sprintf(s, "%" PY_FORMAT_SIZE_T "d",
                        va_arg(vargs, Py_ssize_t));
                else
                    sprintf(s, "%d", va_arg(vargs, int));
                s += strlen(s);
                break;
            case 'u':
                if (longflag)
                    sprintf(s, "%lu",
                        va_arg(vargs, unsigned long));
                else if (size_tflag)
                    sprintf(s, "%" PY_FORMAT_SIZE_T "u",
                        va_arg(vargs, size_t));
                else
                    sprintf(s, "%u",
                        va_arg(vargs, unsigned int));
                s += strlen(s);
                break;
            case 'i':
                sprintf(s, "%i", va_arg(vargs, int));
                s += strlen(s);
                break;
            case 'x':
                sprintf(s, "%x", va_arg(vargs, int));
                s += strlen(s);
                break;
            case 's':
                p = va_arg(vargs, char*);
                i = strlen(p);
                if (n > 0 && i > n)
                    i = n;
                Py_MEMCPY(s, p, i);
                s += i;
                break;
            case 'p':
                sprintf(s, "%p", va_arg(vargs, void*));
                /* %p is ill-defined:  ensure leading 0x. */
                if (s[1] == 'X')
                    s[1] = 'x';
                else if (s[1] != 'x') {
                    memmove(s+2, s, strlen(s)+1);
                    s[0] = '0';
                    s[1] = 'x';
                }
                s += strlen(s);
                break;
            case '%':
                *s++ = '%';
                break;
            default:
                strcpy(s, p);
                s += strlen(s);
                goto end;
            }
        } else
            *s++ = *f;
    }

 end:
    _PyBytes_Resize(&string, s - PyBytes_AS_STRING(string));
    return string;
}

PyObject *
PyBytes_FromFormat(const char *format, ...)
{
    PyObject* ret;
    va_list vargs;

#ifdef HAVE_STDARG_PROTOTYPES
    va_start(vargs, format);
#else
    va_start(vargs);
#endif
    ret = PyBytes_FromFormatV(format, vargs);
    va_end(vargs);
    return ret;
}

/* Helpers for formatstring */

Py_LOCAL_INLINE(PyObject *)
getnextarg(PyObject *args, Py_ssize_t arglen, Py_ssize_t *p_argidx)
{
    Py_ssize_t argidx = *p_argidx;
    if (argidx < arglen) {
        (*p_argidx)++;
        if (arglen < 0)
            return args;
        else
            return PyTuple_GetItem(args, argidx);
    }
    PyErr_SetString(PyExc_TypeError,
                    "not enough arguments for format string");
    return NULL;
}

/* Format codes
 * F_LJUST      '-'
 * F_SIGN       '+'
 * F_BLANK      ' '
 * F_ALT        '#'
 * F_ZERO       '0'
 */
#define F_LJUST (1<<0)
#define F_SIGN  (1<<1)
#define F_BLANK (1<<2)
#define F_ALT   (1<<3)
#define F_ZERO  (1<<4)

/* Returns a new reference to a PyBytes object, or NULL on failure. */

static PyObject *
formatfloat(PyObject *v, int flags, int prec, int type)
{
    char *p;
    PyObject *result;
    double x;

    x = PyFloat_AsDouble(v);
    if (x == -1.0 && PyErr_Occurred()) {
        PyErr_Format(PyExc_TypeError, "float argument required, "
                     "not %.200s", Py_TYPE(v)->tp_name);
        return NULL;
    }

    if (prec < 0)
        prec = 6;

    p = PyOS_double_to_string(x, type, prec,
                              (flags & F_ALT) ? Py_DTSF_ALT : 0, NULL);

    if (p == NULL)
        return NULL;
    result = PyBytes_FromStringAndSize(p, strlen(p));
    PyMem_Free(p);
    return result;
}

static PyObject *
formatlong(PyObject *v, int flags, int prec, int type)
{
    PyObject *result, *iobj;
    if (type == 'i')
        type = 'd';
    if (PyLong_Check(v))
        return _PyUnicode_FormatLong(v, flags & F_ALT, prec, type);
    if (PyNumber_Check(v)) {
        /* make sure number is a type of integer for o, x, and X */
        if (type == 'o' || type == 'x' || type == 'X')
            iobj = PyNumber_Index(v);
        else
            iobj = PyNumber_Long(v);
        if (iobj == NULL) {
            if (!PyErr_ExceptionMatches(PyExc_TypeError))
                return NULL;
        }
        else if (!PyLong_Check(iobj))
            Py_CLEAR(iobj);
        if (iobj != NULL) {
            result = _PyUnicode_FormatLong(iobj, flags & F_ALT, prec, type);
            Py_DECREF(iobj);
            return result;
        }
    }
    PyErr_Format(PyExc_TypeError,
        "%%%c format: %s is required, not %.200s", type,
        (type == 'o' || type == 'x' || type == 'X') ? "an integer"
                                                    : "a number",
        Py_TYPE(v)->tp_name);
    return NULL;
}

static int
byte_converter(PyObject *arg, char *p)
{
    if (PyBytes_Check(arg) && PyBytes_Size(arg) == 1) {
        *p = PyBytes_AS_STRING(arg)[0];
        return 1;
    }
    else if (PyByteArray_Check(arg) && PyByteArray_Size(arg) == 1) {
        *p = PyByteArray_AS_STRING(arg)[0];
        return 1;
    }
    else {
        PyObject *iobj;
        long ival;
        int overflow;
        /* make sure number is a type of integer */
        if (PyLong_Check(arg)) {
            ival = PyLong_AsLongAndOverflow(arg, &overflow);
        }
        else {
            iobj = PyNumber_Index(arg);
            if (iobj == NULL) {
                if (!PyErr_ExceptionMatches(PyExc_TypeError))
                    return 0;
                goto onError;
            }
            ival = PyLong_AsLongAndOverflow(iobj, &overflow);
            Py_DECREF(iobj);
        }
        if (!overflow && ival == -1 && PyErr_Occurred())
            goto onError;
        if (overflow || !(0 <= ival && ival <= 255)) {
            PyErr_SetString(PyExc_OverflowError,
                            "%c arg not in range(256)");
            return 0;
        }
        *p = (char)ival;
        return 1;
    }
  onError:
    PyErr_SetString(PyExc_TypeError,
        "%c requires an integer in range(256) or a single byte");
    return 0;
}

static PyObject *
format_obj(PyObject *v, const char **pbuf, Py_ssize_t *plen)
{
    PyObject *func, *result;
    _Py_IDENTIFIER(__bytes__);
    /* is it a bytes object? */
    if (PyBytes_Check(v)) {
        *pbuf = PyBytes_AS_STRING(v);
        *plen = PyBytes_GET_SIZE(v);
        Py_INCREF(v);
        return v;
    }
    if (PyByteArray_Check(v)) {
        *pbuf = PyByteArray_AS_STRING(v);
        *plen = PyByteArray_GET_SIZE(v);
        Py_INCREF(v);
        return v;
    }
    /* does it support __bytes__? */
    func = _PyObject_LookupSpecial(v, &PyId___bytes__);
    if (func != NULL) {
        result = PyObject_CallFunctionObjArgs(func, NULL);
        Py_DECREF(func);
        if (result == NULL)
            return NULL;
        if (!PyBytes_Check(result)) {
            PyErr_Format(PyExc_TypeError,
                         "__bytes__ returned non-bytes (type %.200s)",
                         Py_TYPE(result)->tp_name);
            Py_DECREF(result);
            return NULL;
        }
        *pbuf = PyBytes_AS_STRING(result);
        *plen = PyBytes_GET_SIZE(result);
        return result;
    }
    PyErr_Format(PyExc_TypeError,
                 "%%b requires bytes, or an object that implements __bytes__, not '%.100s'",
                 Py_TYPE(v)->tp_name);
    return NULL;
}

/* fmt%(v1,v2,...) is roughly equivalent to sprintf(fmt, v1, v2, ...)

   FORMATBUFLEN is the length of the buffer in which the ints &
   chars are formatted. XXX This is a magic number. Each formatting
   routine does bounds checking to ensure no overflow, but a better
   solution may be to malloc a buffer of appropriate size for each
   format. For now, the current solution is sufficient.
*/
#define FORMATBUFLEN (size_t)120

PyObject *
_PyBytes_Format(PyObject *format, PyObject *args)
{
    char *fmt, *res;
    Py_ssize_t arglen, argidx;
    Py_ssize_t reslen, rescnt, fmtcnt;
    int args_owned = 0;
    PyObject *result;
    PyObject *dict = NULL;
    if (format == NULL || !PyBytes_Check(format) || args == NULL) {
        PyErr_BadInternalCall();
        return NULL;
    }
    fmt = PyBytes_AS_STRING(format);
    fmtcnt = PyBytes_GET_SIZE(format);
    reslen = rescnt = fmtcnt + 100;
    result = PyBytes_FromStringAndSize((char *)NULL, reslen);
    if (result == NULL)
        return NULL;
    res = PyBytes_AsString(result);
    if (PyTuple_Check(args)) {
        arglen = PyTuple_GET_SIZE(args);
        argidx = 0;
    }
    else {
        arglen = -1;
        argidx = -2;
    }
    if (Py_TYPE(args)->tp_as_mapping && Py_TYPE(args)->tp_as_mapping->mp_subscript &&
        !PyTuple_Check(args) && !PyBytes_Check(args) && !PyUnicode_Check(args) &&
        !PyByteArray_Check(args)) {
            dict = args;
    }
    while (--fmtcnt >= 0) {
        if (*fmt != '%') {
            if (--rescnt < 0) {
                rescnt = fmtcnt + 100;
                reslen += rescnt;
                if (_PyBytes_Resize(&result, reslen))
                    return NULL;
                res = PyBytes_AS_STRING(result)
                    + reslen - rescnt;
                --rescnt;
            }
            *res++ = *fmt++;
        }
        else {
            /* Got a format specifier */
            int flags = 0;
            Py_ssize_t width = -1;
            int prec = -1;
            int c = '\0';
            int fill;
            PyObject *v = NULL;
            PyObject *temp = NULL;
            const char *pbuf = NULL;
            int sign;
            Py_ssize_t len = 0;
            char onechar; /* For byte_converter() */

            fmt++;
            if (*fmt == '(') {
                char *keystart;
                Py_ssize_t keylen;
                PyObject *key;
                int pcount = 1;

                if (dict == NULL) {
                    PyErr_SetString(PyExc_TypeError,
                             "format requires a mapping");
                    goto error;
                }
                ++fmt;
                --fmtcnt;
                keystart = fmt;
                /* Skip over balanced parentheses */
                while (pcount > 0 && --fmtcnt >= 0) {
                    if (*fmt == ')')
                        --pcount;
                    else if (*fmt == '(')
                        ++pcount;
                    fmt++;
                }
                keylen = fmt - keystart - 1;
                if (fmtcnt < 0 || pcount > 0) {
                    PyErr_SetString(PyExc_ValueError,
                               "incomplete format key");
                    goto error;
                }
                key = PyBytes_FromStringAndSize(keystart,
                                                 keylen);
                if (key == NULL)
                    goto error;
                if (args_owned) {
                    Py_DECREF(args);
                    args_owned = 0;
                }
                args = PyObject_GetItem(dict, key);
                Py_DECREF(key);
                if (args == NULL) {
                    goto error;
                }
                args_owned = 1;
                arglen = -1;
                argidx = -2;
            }
            while (--fmtcnt >= 0) {
                switch (c = *fmt++) {
                case '-': flags |= F_LJUST; continue;
                case '+': flags |= F_SIGN; continue;
                case ' ': flags |= F_BLANK; continue;
                case '#': flags |= F_ALT; continue;
                case '0': flags |= F_ZERO; continue;
                }
                break;
            }
            if (c == '*') {
                v = getnextarg(args, arglen, &argidx);
                if (v == NULL)
                    goto error;
                if (!PyLong_Check(v)) {
                    PyErr_SetString(PyExc_TypeError,
                                    "* wants int");
                    goto error;
                }
                width = PyLong_AsSsize_t(v);
                if (width == -1 && PyErr_Occurred())
                    goto error;
                if (width < 0) {
                    flags |= F_LJUST;
                    width = -width;
                }
                if (--fmtcnt >= 0)
                    c = *fmt++;
            }
            else if (c >= 0 && isdigit(c)) {
                width = c - '0';
                while (--fmtcnt >= 0) {
                    c = Py_CHARMASK(*fmt++);
                    if (!isdigit(c))
                        break;
                    if (width > (PY_SSIZE_T_MAX - ((int)c - '0')) / 10) {
                        PyErr_SetString(
                            PyExc_ValueError,
                            "width too big");
                        goto error;
                    }
                    width = width*10 + (c - '0');
                }
            }
            if (c == '.') {
                prec = 0;
                if (--fmtcnt >= 0)
                    c = *fmt++;
                if (c == '*') {
                    v = getnextarg(args, arglen, &argidx);
                    if (v == NULL)
                        goto error;
                    if (!PyLong_Check(v)) {
                        PyErr_SetString(
                            PyExc_TypeError,
                            "* wants int");
                        goto error;
                    }
                    prec = _PyLong_AsInt(v);
                    if (prec == -1 && PyErr_Occurred())
                        goto error;
                    if (prec < 0)
                        prec = 0;
                    if (--fmtcnt >= 0)
                        c = *fmt++;
                }
                else if (c >= 0 && isdigit(c)) {
                    prec = c - '0';
                    while (--fmtcnt >= 0) {
                        c = Py_CHARMASK(*fmt++);
                        if (!isdigit(c))
                            break;
                        if (prec > (INT_MAX - ((int)c - '0')) / 10) {
                            PyErr_SetString(
                                PyExc_ValueError,
                                "prec too big");
                            goto error;
                        }
                        prec = prec*10 + (c - '0');
                    }
                }
            } /* prec */
            if (fmtcnt >= 0) {
                if (c == 'h' || c == 'l' || c == 'L') {
                    if (--fmtcnt >= 0)
                        c = *fmt++;
                }
            }
            if (fmtcnt < 0) {
                PyErr_SetString(PyExc_ValueError,
                                "incomplete format");
                goto error;
            }
            if (c != '%') {
                v = getnextarg(args, arglen, &argidx);
                if (v == NULL)
                    goto error;
            }
            sign = 0;
            fill = ' ';
            switch (c) {
            case '%':
                pbuf = "%";
                len = 1;
                break;
            case 'r':
                // %r is only for 2/3 code; 3 only code should use %a
            case 'a':
                temp = PyObject_ASCII(v);
                if (temp == NULL)
                    goto error;
                assert(PyUnicode_IS_ASCII(temp));
                pbuf = (const char *)PyUnicode_1BYTE_DATA(temp);
                len = PyUnicode_GET_LENGTH(temp);
                if (prec >= 0 && len > prec)
                    len = prec;
                break;
            case 's':
                // %s is only for 2/3 code; 3 only code should use %b
            case 'b':
                temp = format_obj(v, &pbuf, &len);
                if (temp == NULL)
                    goto error;
                if (prec >= 0 && len > prec)
                    len = prec;
                break;
            case 'i':
            case 'd':
            case 'u':
            case 'o':
            case 'x':
            case 'X':
                temp = formatlong(v, flags, prec, c);
                if (!temp)
                    goto error;
                assert(PyUnicode_IS_ASCII(temp));
                pbuf = (const char *)PyUnicode_1BYTE_DATA(temp);
                len = PyUnicode_GET_LENGTH(temp);
                sign = 1;
                if (flags & F_ZERO)
                    fill = '0';
                break;
            case 'e':
            case 'E':
            case 'f':
            case 'F':
            case 'g':
            case 'G':
                temp = formatfloat(v, flags, prec, c);
                if (temp == NULL)
                    goto error;
                pbuf = PyBytes_AS_STRING(temp);
                len = PyBytes_GET_SIZE(temp);
                sign = 1;
                if (flags & F_ZERO)
                    fill = '0';
                break;
            case 'c':
                pbuf = &onechar;
                len = byte_converter(v, &onechar);
                if (!len)
                    goto error;
                break;
            default:
                PyErr_Format(PyExc_ValueError,
                  "unsupported format character '%c' (0x%x) "
                  "at index %zd",
                  c, c,
                  (Py_ssize_t)(fmt - 1 -
                               PyBytes_AsString(format)));
                goto error;
            }
            if (sign) {
                if (*pbuf == '-' || *pbuf == '+') {
                    sign = *pbuf++;
                    len--;
                }
                else if (flags & F_SIGN)
                    sign = '+';
                else if (flags & F_BLANK)
                    sign = ' ';
                else
                    sign = 0;
            }
            if (width < len)
                width = len;
            if (rescnt - (sign != 0) < width) {
                reslen -= rescnt;
                rescnt = width + fmtcnt + 100;
                reslen += rescnt;
                if (reslen < 0) {
                    Py_DECREF(result);
                    Py_XDECREF(temp);
                    return PyErr_NoMemory();
                }
                if (_PyBytes_Resize(&result, reslen)) {
                    Py_XDECREF(temp);
                    return NULL;
                }
                res = PyBytes_AS_STRING(result)
                    + reslen - rescnt;
            }
            if (sign) {
                if (fill != ' ')
                    *res++ = sign;
                rescnt--;
                if (width > len)
                    width--;
            }
            if ((flags & F_ALT) && (c == 'x' || c == 'X')) {
                assert(pbuf[0] == '0');
                assert(pbuf[1] == c);
                if (fill != ' ') {
                    *res++ = *pbuf++;
                    *res++ = *pbuf++;
                }
                rescnt -= 2;
                width -= 2;
                if (width < 0)
                    width = 0;
                len -= 2;
            }
            if (width > len && !(flags & F_LJUST)) {
                do {
                    --rescnt;
                    *res++ = fill;
                } while (--width > len);
            }
            if (fill == ' ') {
                if (sign)
                    *res++ = sign;
                if ((flags & F_ALT) &&
                    (c == 'x' || c == 'X')) {
                    assert(pbuf[0] == '0');
                    assert(pbuf[1] == c);
                    *res++ = *pbuf++;
                    *res++ = *pbuf++;
                }
            }
            Py_MEMCPY(res, pbuf, len);
            res += len;
            rescnt -= len;
            while (--width >= len) {
                --rescnt;
                *res++ = ' ';
            }
            if (dict && (argidx < arglen) && c != '%') {
                PyErr_SetString(PyExc_TypeError,
                           "not all arguments converted during bytes formatting");
                Py_XDECREF(temp);
                goto error;
            }
            Py_XDECREF(temp);
        } /* '%' */
    } /* until end */
    if (argidx < arglen && !dict) {
        PyErr_SetString(PyExc_TypeError,
                        "not all arguments converted during bytes formatting");
        goto error;
    }
    if (args_owned) {
        Py_DECREF(args);
    }
    if (_PyBytes_Resize(&result, reslen - rescnt))
        return NULL;
    return result;

 error:
    Py_DECREF(result);
    if (args_owned) {
        Py_DECREF(args);
    }
    return NULL;
}

/* =-= */

static void
bytes_dealloc(PyObject *op)
{
    Py_TYPE(op)->tp_free(op);
}

/* Unescape a backslash-escaped string. If unicode is non-zero,
   the string is a u-literal. If recode_encoding is non-zero,
   the string is UTF-8 encoded and should be re-encoded in the
   specified encoding.  */

PyObject *PyBytes_DecodeEscape(const char *s,
                                Py_ssize_t len,
                                const char *errors,
                                Py_ssize_t unicode,
                                const char *recode_encoding)
{
    int c;
    char *p, *buf;
    const char *end;
    PyObject *v;
    Py_ssize_t newlen = recode_encoding ? 4*len:len;
    v = PyBytes_FromStringAndSize((char *)NULL, newlen);
    if (v == NULL)
        return NULL;
    p = buf = PyBytes_AsString(v);
    end = s + len;
    while (s < end) {
        if (*s != '\\') {
          non_esc:
            if (recode_encoding && (*s & 0x80)) {
                PyObject *u, *w;
                char *r;
                const char* t;
                Py_ssize_t rn;
                t = s;
                /* Decode non-ASCII bytes as UTF-8. */
                while (t < end && (*t & 0x80)) t++;
                u = PyUnicode_DecodeUTF8(s, t - s, errors);
                if(!u) goto failed;

                /* Recode them in target encoding. */
                w = PyUnicode_AsEncodedString(
                    u, recode_encoding, errors);
                Py_DECREF(u);
                if (!w)                 goto failed;

                /* Append bytes to output buffer. */
                assert(PyBytes_Check(w));
                r = PyBytes_AS_STRING(w);
                rn = PyBytes_GET_SIZE(w);
                Py_MEMCPY(p, r, rn);
                p += rn;
                Py_DECREF(w);
                s = t;
            } else {
                *p++ = *s++;
            }
            continue;
        }
        s++;
        if (s==end) {
            PyErr_SetString(PyExc_ValueError,
                            "Trailing \\ in string");
            goto failed;
        }
        switch (*s++) {
        /* XXX This assumes ASCII! */
        case '\n': break;
        case '\\': *p++ = '\\'; break;
        case '\'': *p++ = '\''; break;
        case '\"': *p++ = '\"'; break;
        case 'b': *p++ = '\b'; break;
        case 'f': *p++ = '\014'; break; /* FF */
        case 't': *p++ = '\t'; break;
        case 'n': *p++ = '\n'; break;
        case 'r': *p++ = '\r'; break;
        case 'v': *p++ = '\013'; break; /* VT */
        case 'a': *p++ = '\007'; break; /* BEL, not classic C */
        case '0': case '1': case '2': case '3':
        case '4': case '5': case '6': case '7':
            c = s[-1] - '0';
            if (s < end && '0' <= *s && *s <= '7') {
                c = (c<<3) + *s++ - '0';
                if (s < end && '0' <= *s && *s <= '7')
                    c = (c<<3) + *s++ - '0';
            }
            *p++ = c;
            break;
        case 'x':
            if (s+1 < end && Py_ISXDIGIT(s[0]) && Py_ISXDIGIT(s[1])) {
                unsigned int x = 0;
                c = Py_CHARMASK(*s);
                s++;
                if (Py_ISDIGIT(c))
                    x = c - '0';
                else if (Py_ISLOWER(c))
                    x = 10 + c - 'a';
                else
                    x = 10 + c - 'A';
                x = x << 4;
                c = Py_CHARMASK(*s);
                s++;
                if (Py_ISDIGIT(c))
                    x += c - '0';
                else if (Py_ISLOWER(c))
                    x += 10 + c - 'a';
                else
                    x += 10 + c - 'A';
                *p++ = x;
                break;
            }
            if (!errors || strcmp(errors, "strict") == 0) {
                PyErr_Format(PyExc_ValueError,
                             "invalid \\x escape at position %d",
                             s - 2 - (end - len));
                goto failed;
            }
            if (strcmp(errors, "replace") == 0) {
                *p++ = '?';
            } else if (strcmp(errors, "ignore") == 0)
                /* do nothing */;
            else {
                PyErr_Format(PyExc_ValueError,
                             "decoding error; unknown "
                             "error handling code: %.400s",
                             errors);
                goto failed;
            }
            /* skip \x */
            if (s < end && Py_ISXDIGIT(s[0]))
                s++; /* and a hexdigit */
            break;
        default:
            *p++ = '\\';
            s--;
            goto non_esc; /* an arbitrary number of unescaped
                             UTF-8 bytes may follow. */
        }
    }
    if (p-buf < newlen)
        _PyBytes_Resize(&v, p - buf);
    return v;
  failed:
    Py_DECREF(v);
    return NULL;
}

/* -------------------------------------------------------------------- */
/* object api */

Py_ssize_t
PyBytes_Size(PyObject *op)
{
    if (!PyBytes_Check(op)) {
        PyErr_Format(PyExc_TypeError,
             "expected bytes, %.200s found", Py_TYPE(op)->tp_name);
        return -1;
    }
    return Py_SIZE(op);
}

char *
PyBytes_AsString(PyObject *op)
{
    if (!PyBytes_Check(op)) {
        PyErr_Format(PyExc_TypeError,
             "expected bytes, %.200s found", Py_TYPE(op)->tp_name);
        return NULL;
    }
    return ((PyBytesObject *)op)->ob_sval;
}

int
PyBytes_AsStringAndSize(PyObject *obj,
                         char **s,
                         Py_ssize_t *len)
{
    if (s == NULL) {
        PyErr_BadInternalCall();
        return -1;
    }

    if (!PyBytes_Check(obj)) {
        PyErr_Format(PyExc_TypeError,
             "expected bytes, %.200s found", Py_TYPE(obj)->tp_name);
        return -1;
    }

    *s = PyBytes_AS_STRING(obj);
    if (len != NULL)
        *len = PyBytes_GET_SIZE(obj);
    else if (strlen(*s) != (size_t)PyBytes_GET_SIZE(obj)) {
        PyErr_SetString(PyExc_ValueError,
                        "embedded null byte");
        return -1;
    }
    return 0;
}

/* -------------------------------------------------------------------- */
/* Methods */

#include "stringlib/stringdefs.h"

#include "stringlib/fastsearch.h"
#include "stringlib/count.h"
#include "stringlib/find.h"
#include "stringlib/join.h"
#include "stringlib/partition.h"
#include "stringlib/split.h"
#include "stringlib/ctype.h"

#include "stringlib/transmogrify.h"

PyObject *
PyBytes_Repr(PyObject *obj, int smartquotes)
{
    PyBytesObject* op = (PyBytesObject*) obj;
    Py_ssize_t i, length = Py_SIZE(op);
    Py_ssize_t newsize, squotes, dquotes;
    PyObject *v;
    unsigned char quote, *s, *p;

    /* Compute size of output string */
    squotes = dquotes = 0;
    newsize = 3; /* b'' */
    s = (unsigned char*)op->ob_sval;
    for (i = 0; i < length; i++) {
        Py_ssize_t incr = 1;
        switch(s[i]) {
        case '\'': squotes++; break;
        case '"':  dquotes++; break;
        case '\\': case '\t': case '\n': case '\r':
            incr = 2; break; /* \C */
        default:
            if (s[i] < ' ' || s[i] >= 0x7f)
                incr = 4; /* \xHH */
        }
        if (newsize > PY_SSIZE_T_MAX - incr)
            goto overflow;
        newsize += incr;
    }
    quote = '\'';
    if (smartquotes && squotes && !dquotes)
        quote = '"';
    if (squotes && quote == '\'') {
        if (newsize > PY_SSIZE_T_MAX - squotes)
            goto overflow;
        newsize += squotes;
    }

    v = PyUnicode_New(newsize, 127);
    if (v == NULL) {
        return NULL;
    }
    p = PyUnicode_1BYTE_DATA(v);

    *p++ = 'b', *p++ = quote;
    for (i = 0; i < length; i++) {
        unsigned char c = op->ob_sval[i];
        if (c == quote || c == '\\')
            *p++ = '\\', *p++ = c;
        else if (c == '\t')
            *p++ = '\\', *p++ = 't';
        else if (c == '\n')
            *p++ = '\\', *p++ = 'n';
        else if (c == '\r')
            *p++ = '\\', *p++ = 'r';
        else if (c < ' ' || c >= 0x7f) {
            *p++ = '\\';
            *p++ = 'x';
            *p++ = Py_hexdigits[(c & 0xf0) >> 4];
            *p++ = Py_hexdigits[c & 0xf];
        }
        else
            *p++ = c;
    }
    *p++ = quote;
    assert(_PyUnicode_CheckConsistency(v, 1));
    return v;

  overflow:
    PyErr_SetString(PyExc_OverflowError,
                    "bytes object is too large to make repr");
    return NULL;
}

static PyObject *
bytes_repr(PyObject *op)
{
    return PyBytes_Repr(op, 1);
}

static PyObject *
bytes_str(PyObject *op)
{
    if (Py_BytesWarningFlag) {
        if (PyErr_WarnEx(PyExc_BytesWarning,
                         "str() on a bytes instance", 1))
            return NULL;
    }
    return bytes_repr(op);
}

static Py_ssize_t
bytes_length(PyBytesObject *a)
{
    return Py_SIZE(a);
}

/* This is also used by PyBytes_Concat() */
static PyObject *
bytes_concat(PyObject *a, PyObject *b)
{
    Py_ssize_t size;
    Py_buffer va, vb;
    PyObject *result = NULL;

    va.len = -1;
    vb.len = -1;
    if (PyObject_GetBuffer(a, &va, PyBUF_SIMPLE) != 0 ||
        PyObject_GetBuffer(b, &vb, PyBUF_SIMPLE) != 0) {
        PyErr_Format(PyExc_TypeError, "can't concat %.100s to %.100s",
                     Py_TYPE(a)->tp_name, Py_TYPE(b)->tp_name);
        goto done;
    }

    /* Optimize end cases */
    if (va.len == 0 && PyBytes_CheckExact(b)) {
        result = b;
        Py_INCREF(result);
        goto done;
    }
    if (vb.len == 0 && PyBytes_CheckExact(a)) {
        result = a;
        Py_INCREF(result);
        goto done;
    }

    size = va.len + vb.len;
    if (size < 0) {
        PyErr_NoMemory();
        goto done;
    }

    result = PyBytes_FromStringAndSize(NULL, size);
    if (result != NULL) {
        memcpy(PyBytes_AS_STRING(result), va.buf, va.len);
        memcpy(PyBytes_AS_STRING(result) + va.len, vb.buf, vb.len);
    }

  done:
    if (va.len != -1)
        PyBuffer_Release(&va);
    if (vb.len != -1)
        PyBuffer_Release(&vb);
    return result;
}

static PyObject *
bytes_repeat(PyBytesObject *a, Py_ssize_t n)
{
    Py_ssize_t i;
    Py_ssize_t j;
    Py_ssize_t size;
    PyBytesObject *op;
    size_t nbytes;
    if (n < 0)
        n = 0;
    /* watch out for overflows:  the size can overflow int,
     * and the # of bytes needed can overflow size_t
     */
    if (n > 0 && Py_SIZE(a) > PY_SSIZE_T_MAX / n) {
        PyErr_SetString(PyExc_OverflowError,
            "repeated bytes are too long");
        return NULL;
    }
    size = Py_SIZE(a) * n;
    if (size == Py_SIZE(a) && PyBytes_CheckExact(a)) {
        Py_INCREF(a);
        return (PyObject *)a;
    }
    nbytes = (size_t)size;
    if (nbytes + PyBytesObject_SIZE <= nbytes) {
        PyErr_SetString(PyExc_OverflowError,
            "repeated bytes are too long");
        return NULL;
    }
    op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + nbytes);
    if (op == NULL)
        return PyErr_NoMemory();
    (void)PyObject_INIT_VAR(op, &PyBytes_Type, size);
    op->ob_shash = -1;
    op->ob_sval[size] = '\0';
    if (Py_SIZE(a) == 1 && n > 0) {
        memset(op->ob_sval, a->ob_sval[0] , n);
        return (PyObject *) op;
    }
    i = 0;
    if (i < size) {
        Py_MEMCPY(op->ob_sval, a->ob_sval, Py_SIZE(a));
        i = Py_SIZE(a);
    }
    while (i < size) {
        j = (i <= size-i)  ?  i  :  size-i;
        Py_MEMCPY(op->ob_sval+i, op->ob_sval, j);
        i += j;
    }
    return (PyObject *) op;
}

static int
bytes_contains(PyObject *self, PyObject *arg)
{
    Py_ssize_t ival = PyNumber_AsSsize_t(arg, PyExc_ValueError);
    if (ival == -1 && PyErr_Occurred()) {
        Py_buffer varg;
        Py_ssize_t pos;
        PyErr_Clear();
        if (PyObject_GetBuffer(arg, &varg, PyBUF_SIMPLE) != 0)
            return -1;
        pos = stringlib_find(PyBytes_AS_STRING(self), Py_SIZE(self),
                             varg.buf, varg.len, 0);
        PyBuffer_Release(&varg);
        return pos >= 0;
    }
    if (ival < 0 || ival >= 256) {
        PyErr_SetString(PyExc_ValueError, "byte must be in range(0, 256)");
        return -1;
    }

    return memchr(PyBytes_AS_STRING(self), (int) ival, Py_SIZE(self)) != NULL;
}

static PyObject *
bytes_item(PyBytesObject *a, Py_ssize_t i)
{
    if (i < 0 || i >= Py_SIZE(a)) {
        PyErr_SetString(PyExc_IndexError, "index out of range");
        return NULL;
    }
    return PyLong_FromLong((unsigned char)a->ob_sval[i]);
}

Py_LOCAL(int)
bytes_compare_eq(PyBytesObject *a, PyBytesObject *b)
{
    int cmp;
    Py_ssize_t len;

    len = Py_SIZE(a);
    if (Py_SIZE(b) != len)
        return 0;

    if (a->ob_sval[0] != b->ob_sval[0])
        return 0;

    cmp = memcmp(a->ob_sval, b->ob_sval, len);
    return (cmp == 0);
}

static PyObject*
bytes_richcompare(PyBytesObject *a, PyBytesObject *b, int op)
{
    int c;
    Py_ssize_t len_a, len_b;
    Py_ssize_t min_len;
    PyObject *result;

    /* Make sure both arguments are strings. */
    if (!(PyBytes_Check(a) && PyBytes_Check(b))) {
        if (Py_BytesWarningFlag && (op == Py_EQ || op == Py_NE)) {
            if (PyObject_IsInstance((PyObject*)a,
                                    (PyObject*)&PyUnicode_Type) ||
                PyObject_IsInstance((PyObject*)b,
                                    (PyObject*)&PyUnicode_Type)) {
                if (PyErr_WarnEx(PyExc_BytesWarning,
                            "Comparison between bytes and string", 1))
                    return NULL;
            }
            else if (PyObject_IsInstance((PyObject*)a,
                                    (PyObject*)&PyLong_Type) ||
                PyObject_IsInstance((PyObject*)b,
                                    (PyObject*)&PyLong_Type)) {
                if (PyErr_WarnEx(PyExc_BytesWarning,
                            "Comparison between bytes and int", 1))
                    return NULL;
            }
        }
        result = Py_NotImplemented;
    }
    else if (a == b) {
        switch (op) {
        case Py_EQ:
        case Py_LE:
        case Py_GE:
            /* a string is equal to itself */
            result = Py_True;
            break;
        case Py_NE:
        case Py_LT:
        case Py_GT:
            result = Py_False;
            break;
        default:
            PyErr_BadArgument();
            return NULL;
        }
    }
    else if (op == Py_EQ || op == Py_NE) {
        int eq = bytes_compare_eq(a, b);
        eq ^= (op == Py_NE);
        result = eq ? Py_True : Py_False;
    }
    else {
        len_a = Py_SIZE(a);
        len_b = Py_SIZE(b);
        min_len = Py_MIN(len_a, len_b);
        if (min_len > 0) {
            c = Py_CHARMASK(*a->ob_sval) - Py_CHARMASK(*b->ob_sval);
            if (c == 0)
                c = memcmp(a->ob_sval, b->ob_sval, min_len);
        }
        else
            c = 0;
        if (c == 0)
            c = (len_a < len_b) ? -1 : (len_a > len_b) ? 1 : 0;
        switch (op) {
        case Py_LT: c = c <  0; break;
        case Py_LE: c = c <= 0; break;
        case Py_GT: c = c >  0; break;
        case Py_GE: c = c >= 0; break;
        default:
            PyErr_BadArgument();
            return NULL;
        }
        result = c ? Py_True : Py_False;
    }

    Py_INCREF(result);
    return result;
}

static Py_hash_t
bytes_hash(PyBytesObject *a)
{
    if (a->ob_shash == -1) {
        /* Can't fail */
        a->ob_shash = _Py_HashBytes(a->ob_sval, Py_SIZE(a));
    }
    return a->ob_shash;
}

static PyObject*
bytes_subscript(PyBytesObject* self, PyObject* item)
{
    if (PyIndex_Check(item)) {
        Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
        if (i == -1 && PyErr_Occurred())
            return NULL;
        if (i < 0)
            i += PyBytes_GET_SIZE(self);
        if (i < 0 || i >= PyBytes_GET_SIZE(self)) {
            PyErr_SetString(PyExc_IndexError,
                            "index out of range");
            return NULL;
        }
        return PyLong_FromLong((unsigned char)self->ob_sval[i]);
    }
    else if (PySlice_Check(item)) {
        Py_ssize_t start, stop, step, slicelength, cur, i;
        char* source_buf;
        char* result_buf;
        PyObject* result;

        if (PySlice_GetIndicesEx(item,
                         PyBytes_GET_SIZE(self),
                         &start, &stop, &step, &slicelength) < 0) {
            return NULL;
        }

        if (slicelength <= 0) {
            return PyBytes_FromStringAndSize("", 0);
        }
        else if (start == 0 && step == 1 &&
                 slicelength == PyBytes_GET_SIZE(self) &&
                 PyBytes_CheckExact(self)) {
            Py_INCREF(self);
            return (PyObject *)self;
        }
        else if (step == 1) {
            return PyBytes_FromStringAndSize(
                PyBytes_AS_STRING(self) + start,
                slicelength);
        }
        else {
            source_buf = PyBytes_AS_STRING(self);
            result = PyBytes_FromStringAndSize(NULL, slicelength);
            if (result == NULL)
                return NULL;

            result_buf = PyBytes_AS_STRING(result);
            for (cur = start, i = 0; i < slicelength;
                 cur += step, i++) {
                result_buf[i] = source_buf[cur];
            }

            return result;
        }
    }
    else {
        PyErr_Format(PyExc_TypeError,
                     "byte indices must be integers or slices, not %.200s",
                     Py_TYPE(item)->tp_name);
        return NULL;
    }
}

static int
bytes_buffer_getbuffer(PyBytesObject *self, Py_buffer *view, int flags)
{
    return PyBuffer_FillInfo(view, (PyObject*)self, (void *)self->ob_sval, Py_SIZE(self),
                             1, flags);
}

static PySequenceMethods bytes_as_sequence = {
    (lenfunc)bytes_length, /*sq_length*/
    (binaryfunc)bytes_concat, /*sq_concat*/
    (ssizeargfunc)bytes_repeat, /*sq_repeat*/
    (ssizeargfunc)bytes_item, /*sq_item*/
    0,                  /*sq_slice*/
    0,                  /*sq_ass_item*/
    0,                  /*sq_ass_slice*/
    (objobjproc)bytes_contains /*sq_contains*/
};

static PyMappingMethods bytes_as_mapping = {
    (lenfunc)bytes_length,
    (binaryfunc)bytes_subscript,
    0,
};

static PyBufferProcs bytes_as_buffer = {
    (getbufferproc)bytes_buffer_getbuffer,
    NULL,
};


#define LEFTSTRIP 0
#define RIGHTSTRIP 1
#define BOTHSTRIP 2

/*[clinic input]
bytes.split

    sep: object = None
        The delimiter according which to split the bytes.
        None (the default value) means split on ASCII whitespace characters
        (space, tab, return, newline, formfeed, vertical tab).
    maxsplit: Py_ssize_t = -1
        Maximum number of splits to do.
        -1 (the default value) means no limit.

Return a list of the sections in the bytes, using sep as the delimiter.
[clinic start generated code]*/

static PyObject *
bytes_split_impl(PyBytesObject*self, PyObject *sep, Py_ssize_t maxsplit)
/*[clinic end generated code: output=8bde44dacb36ef2e input=8b809b39074abbfa]*/
{
    Py_ssize_t len = PyBytes_GET_SIZE(self), n;
    const char *s = PyBytes_AS_STRING(self), *sub;
    Py_buffer vsub;
    PyObject *list;

    if (maxsplit < 0)
        maxsplit = PY_SSIZE_T_MAX;
    if (sep == Py_None)
        return stringlib_split_whitespace((PyObject*) self, s, len, maxsplit);
    if (PyObject_GetBuffer(sep, &vsub, PyBUF_SIMPLE) != 0)
        return NULL;
    sub = vsub.buf;
    n = vsub.len;

    list = stringlib_split((PyObject*) self, s, len, sub, n, maxsplit);
    PyBuffer_Release(&vsub);
    return list;
}

/*[clinic input]
bytes.partition

    self: self(type="PyBytesObject *")
    sep: Py_buffer
    /

Partition the bytes into three parts using the given separator.

This will search for the separator sep in the bytes. If the separator is found,
returns a 3-tuple containing the part before the separator, the separator
itself, and the part after it.

If the separator is not found, returns a 3-tuple containing the original bytes
object and two empty bytes objects.
[clinic start generated code]*/

static PyObject *
bytes_partition_impl(PyBytesObject *self, Py_buffer *sep)
/*[clinic end generated code: output=f532b392a17ff695 input=bc855dc63ca949de]*/
{
    return stringlib_partition(
        (PyObject*) self,
        PyBytes_AS_STRING(self), PyBytes_GET_SIZE(self),
        sep->obj, (const char *)sep->buf, sep->len
        );
}

/*[clinic input]
bytes.rpartition

    self: self(type="PyBytesObject *")
    sep: Py_buffer
    /

Partition the bytes into three parts using the given separator.

This will search for the separator sep in the bytes, starting and the end. If
the separator is found, returns a 3-tuple containing the part before the
separator, the separator itself, and the part after it.

If the separator is not found, returns a 3-tuple containing two empty bytes
objects and the original bytes object.
[clinic start generated code]*/

static PyObject *
bytes_rpartition_impl(PyBytesObject *self, Py_buffer *sep)
/*[clinic end generated code: output=191b114cbb028e50 input=6588fff262a9170e]*/
{
    return stringlib_rpartition(
        (PyObject*) self,
        PyBytes_AS_STRING(self), PyBytes_GET_SIZE(self),
        sep->obj, (const char *)sep->buf, sep->len
        );
}

/*[clinic input]
bytes.rsplit = bytes.split

Return a list of the sections in the bytes, using sep as the delimiter.

Splitting is done starting at the end of the bytes and working to the front.
[clinic start generated code]*/

static PyObject *
bytes_rsplit_impl(PyBytesObject*self, PyObject *sep, Py_ssize_t maxsplit)
/*[clinic end generated code: output=0b6570b977911d88 input=0f86c9f28f7d7b7b]*/
{
    Py_ssize_t len = PyBytes_GET_SIZE(self), n;
    const char *s = PyBytes_AS_STRING(self), *sub;
    Py_buffer vsub;
    PyObject *list;

    if (maxsplit < 0)
        maxsplit = PY_SSIZE_T_MAX;
    if (sep == Py_None)
        return stringlib_rsplit_whitespace((PyObject*) self, s, len, maxsplit);
    if (PyObject_GetBuffer(sep, &vsub, PyBUF_SIMPLE) != 0)
        return NULL;
    sub = vsub.buf;
    n = vsub.len;

    list = stringlib_rsplit((PyObject*) self, s, len, sub, n, maxsplit);
    PyBuffer_Release(&vsub);
    return list;
}


/*[clinic input]
bytes.join

    iterable_of_bytes: object
    /

Concatenate any number of bytes objects.

The bytes whose method is called is inserted in between each pair.

The result is returned as a new bytes object.

Example: b'.'.join([b'ab', b'pq', b'rs']) -> b'ab.pq.rs'.
[clinic start generated code]*/

static PyObject *
bytes_join(PyBytesObject*self, PyObject *iterable_of_bytes)
/*[clinic end generated code: output=634aff14764ff997 input=7fe377b95bd549d2]*/
{
    return stringlib_bytes_join((PyObject*)self, iterable_of_bytes);
}

PyObject *
_PyBytes_Join(PyObject *sep, PyObject *x)
{
    assert(sep != NULL && PyBytes_Check(sep));
    assert(x != NULL);
    return bytes_join((PyBytesObject*)sep, x);
}

/* helper macro to fixup start/end slice values */
#define ADJUST_INDICES(start, end, len)         \
    if (end > len)                          \
        end = len;                          \
    else if (end < 0) {                     \
        end += len;                         \
        if (end < 0)                        \
        end = 0;                        \
    }                                       \
    if (start < 0) {                        \
        start += len;                       \
        if (start < 0)                      \
        start = 0;                      \
    }

Py_LOCAL_INLINE(Py_ssize_t)
bytes_find_internal(PyBytesObject *self, PyObject *args, int dir)
{
    PyObject *subobj;
    char byte;
    Py_buffer subbuf;
    const char *sub;
    Py_ssize_t len, sub_len;
    Py_ssize_t start=0, end=PY_SSIZE_T_MAX;
    Py_ssize_t res;

    if (!stringlib_parse_args_finds_byte("find/rfind/index/rindex",
                                         args, &subobj, &byte, &start, &end))
        return -2;

    if (subobj) {
        if (PyObject_GetBuffer(subobj, &subbuf, PyBUF_SIMPLE) != 0)
            return -2;

        sub = subbuf.buf;
        sub_len = subbuf.len;
    }
    else {
        sub = &byte;
        sub_len = 1;
    }
    len = PyBytes_GET_SIZE(self);

    ADJUST_INDICES(start, end, len);
    if (end - start < sub_len)
        res = -1;
    /* Issue #23573: FIXME, windows has no memrchr() */
    else if (sub_len == 1 && dir > 0) {
        unsigned char needle = *sub;
        res = stringlib_fastsearch_memchr_1char(
            PyBytes_AS_STRING(self) + start, end - start,
            needle, needle, FAST_SEARCH);
        if (res >= 0)
            res += start;
    }
    else {
        if (dir > 0)
            res = stringlib_find_slice(
                PyBytes_AS_STRING(self), len,
                sub, sub_len, start, end);
        else
            res = stringlib_rfind_slice(
                PyBytes_AS_STRING(self), len,
                sub, sub_len, start, end);
    }

    if (subobj)
        PyBuffer_Release(&subbuf);

    return res;
}


PyDoc_STRVAR(find__doc__,
"B.find(sub[, start[, end]]) -> int\n\
\n\
Return the lowest index in B where substring sub is found,\n\
such that sub is contained within B[start:end].  Optional\n\
arguments start and end are interpreted as in slice notation.\n\
\n\
Return -1 on failure.");

static PyObject *
bytes_find(PyBytesObject *self, PyObject *args)
{
    Py_ssize_t result = bytes_find_internal(self, args, +1);
    if (result == -2)
        return NULL;
    return PyLong_FromSsize_t(result);
}


PyDoc_STRVAR(index__doc__,
"B.index(sub[, start[, end]]) -> int\n\
\n\
Like B.find() but raise ValueError when the substring is not found.");

static PyObject *
bytes_index(PyBytesObject *self, PyObject *args)
{
    Py_ssize_t result = bytes_find_internal(self, args, +1);
    if (result == -2)
        return NULL;
    if (result == -1) {
        PyErr_SetString(PyExc_ValueError,
                        "substring not found");
        return NULL;
    }
    return PyLong_FromSsize_t(result);
}


PyDoc_STRVAR(rfind__doc__,
"B.rfind(sub[, start[, end]]) -> int\n\
\n\
Return the highest index in B where substring sub is found,\n\
such that sub is contained within B[start:end].  Optional\n\
arguments start and end are interpreted as in slice notation.\n\
\n\
Return -1 on failure.");

static PyObject *
bytes_rfind(PyBytesObject *self, PyObject *args)
{
    Py_ssize_t result = bytes_find_internal(self, args, -1);
    if (result == -2)
        return NULL;
    return PyLong_FromSsize_t(result);
}


PyDoc_STRVAR(rindex__doc__,
"B.rindex(sub[, start[, end]]) -> int\n\
\n\
Like B.rfind() but raise ValueError when the substring is not found.");

static PyObject *
bytes_rindex(PyBytesObject *self, PyObject *args)
{
    Py_ssize_t result = bytes_find_internal(self, args, -1);
    if (result == -2)
        return NULL;
    if (result == -1) {
        PyErr_SetString(PyExc_ValueError,
                        "substring not found");
        return NULL;
    }
    return PyLong_FromSsize_t(result);
}


Py_LOCAL_INLINE(PyObject *)
do_xstrip(PyBytesObject *self, int striptype, PyObject *sepobj)
{
    Py_buffer vsep;
    char *s = PyBytes_AS_STRING(self);
    Py_ssize_t len = PyBytes_GET_SIZE(self);
    char *sep;
    Py_ssize_t seplen;
    Py_ssize_t i, j;

    if (PyObject_GetBuffer(sepobj, &vsep, PyBUF_SIMPLE) != 0)
        return NULL;
    sep = vsep.buf;
    seplen = vsep.len;

    i = 0;
    if (striptype != RIGHTSTRIP) {
        while (i < len && memchr(sep, Py_CHARMASK(s[i]), seplen)) {
            i++;
        }
    }

    j = len;
    if (striptype != LEFTSTRIP) {
        do {
            j--;
        } while (j >= i && memchr(sep, Py_CHARMASK(s[j]), seplen));
        j++;
    }

    PyBuffer_Release(&vsep);

    if (i == 0 && j == len && PyBytes_CheckExact(self)) {
        Py_INCREF(self);
        return (PyObject*)self;
    }
    else
        return PyBytes_FromStringAndSize(s+i, j-i);
}


Py_LOCAL_INLINE(PyObject *)
do_strip(PyBytesObject *self, int striptype)
{
    char *s = PyBytes_AS_STRING(self);
    Py_ssize_t len = PyBytes_GET_SIZE(self), i, j;

    i = 0;
    if (striptype != RIGHTSTRIP) {
        while (i < len && Py_ISSPACE(s[i])) {
            i++;
        }
    }

    j = len;
    if (striptype != LEFTSTRIP) {
        do {
            j--;
        } while (j >= i && Py_ISSPACE(s[j]));
        j++;
    }

    if (i == 0 && j == len && PyBytes_CheckExact(self)) {
        Py_INCREF(self);
        return (PyObject*)self;
    }
    else
        return PyBytes_FromStringAndSize(s+i, j-i);
}


Py_LOCAL_INLINE(PyObject *)
do_argstrip(PyBytesObject *self, int striptype, PyObject *bytes)
{
    if (bytes != NULL && bytes != Py_None) {
        return do_xstrip(self, striptype, bytes);
    }
    return do_strip(self, striptype);
}

/*[clinic input]
bytes.strip

    self: self(type="PyBytesObject *")
    bytes: object = None
    /

Strip leading and trailing bytes contained in the argument.

If the argument is omitted or None, strip leading and trailing ASCII whitespace.
[clinic start generated code]*/

static PyObject *
bytes_strip_impl(PyBytesObject *self, PyObject *bytes)
/*[clinic end generated code: output=c7c228d3bd104a1b input=37daa5fad1395d95]*/
{
    return do_argstrip(self, BOTHSTRIP, bytes);
}

/*[clinic input]
bytes.lstrip

    self: self(type="PyBytesObject *")
    bytes: object = None
    /

Strip leading bytes contained in the argument.

If the argument is omitted or None, strip leading  ASCII whitespace.
[clinic start generated code]*/

static PyObject *
bytes_lstrip_impl(PyBytesObject *self, PyObject *bytes)
/*[clinic end generated code: output=28602e586f524e82 input=88811b09dfbc2988]*/
{
    return do_argstrip(self, LEFTSTRIP, bytes);
}

/*[clinic input]
bytes.rstrip

    self: self(type="PyBytesObject *")
    bytes: object = None
    /

Strip trailing bytes contained in the argument.

If the argument is omitted or None, strip trailing ASCII whitespace.
[clinic start generated code]*/

static PyObject *
bytes_rstrip_impl(PyBytesObject *self, PyObject *bytes)
/*[clinic end generated code: output=547e3815c95447da input=8f93c9cd361f0140]*/
{
    return do_argstrip(self, RIGHTSTRIP, bytes);
}


PyDoc_STRVAR(count__doc__,
"B.count(sub[, start[, end]]) -> int\n\
\n\
Return the number of non-overlapping occurrences of substring sub in\n\
string B[start:end].  Optional arguments start and end are interpreted\n\
as in slice notation.");

static PyObject *
bytes_count(PyBytesObject *self, PyObject *args)
{
    PyObject *sub_obj;
    const char *str = PyBytes_AS_STRING(self), *sub;
    Py_ssize_t sub_len;
    char byte;
    Py_ssize_t start = 0, end = PY_SSIZE_T_MAX;

    Py_buffer vsub;
    PyObject *count_obj;

    if (!stringlib_parse_args_finds_byte("count", args, &sub_obj, &byte,
                                         &start, &end))
        return NULL;

    if (sub_obj) {
        if (PyObject_GetBuffer(sub_obj, &vsub, PyBUF_SIMPLE) != 0)
            return NULL;

        sub = vsub.buf;
        sub_len = vsub.len;
    }
    else {
        sub = &byte;
        sub_len = 1;
    }

    ADJUST_INDICES(start, end, PyBytes_GET_SIZE(self));

    count_obj = PyLong_FromSsize_t(
        stringlib_count(str + start, end - start, sub, sub_len, PY_SSIZE_T_MAX)
        );

    if (sub_obj)
        PyBuffer_Release(&vsub);

    return count_obj;
}


/*[clinic input]
bytes.translate

    self: self(type="PyBytesObject *")
    table: object
        Translation table, which must be a bytes object of length 256.
    [
    deletechars: object
    ]
    /

Return a copy with each character mapped by the given translation table.

All characters occurring in the optional argument deletechars are removed.
The remaining characters are mapped through the given translation table.
[clinic start generated code]*/

static PyObject *
bytes_translate_impl(PyBytesObject *self, PyObject *table, int group_right_1,
                     PyObject *deletechars)
/*[clinic end generated code: output=233df850eb50bf8d input=d8fa5519d7cc4be7]*/
{
    char *input, *output;
    Py_buffer table_view = {NULL, NULL};
    Py_buffer del_table_view = {NULL, NULL};
    const char *table_chars;
    Py_ssize_t i, c, changed = 0;
    PyObject *input_obj = (PyObject*)self;
    const char *output_start, *del_table_chars=NULL;
    Py_ssize_t inlen, tablen, dellen = 0;
    PyObject *result;
    int trans_table[256];

    if (PyBytes_Check(table)) {
        table_chars = PyBytes_AS_STRING(table);
        tablen = PyBytes_GET_SIZE(table);
    }
    else if (table == Py_None) {
        table_chars = NULL;
        tablen = 256;
    }
    else {
        if (PyObject_GetBuffer(table, &table_view, PyBUF_SIMPLE) != 0)
            return NULL;
        table_chars = table_view.buf;
        tablen = table_view.len;
    }

    if (tablen != 256) {
        PyErr_SetString(PyExc_ValueError,
          "translation table must be 256 characters long");
        PyBuffer_Release(&table_view);
        return NULL;
    }

    if (deletechars != NULL) {
        if (PyBytes_Check(deletechars)) {
            del_table_chars = PyBytes_AS_STRING(deletechars);
            dellen = PyBytes_GET_SIZE(deletechars);
        }
        else {
            if (PyObject_GetBuffer(deletechars, &del_table_view, PyBUF_SIMPLE) != 0) {
                PyBuffer_Release(&table_view);
                return NULL;
            }
            del_table_chars = del_table_view.buf;
            dellen = del_table_view.len;
        }
    }
    else {
        del_table_chars = NULL;
        dellen = 0;
    }

    inlen = PyBytes_GET_SIZE(input_obj);
    result = PyBytes_FromStringAndSize((char *)NULL, inlen);
    if (result == NULL) {
        PyBuffer_Release(&del_table_view);
        PyBuffer_Release(&table_view);
        return NULL;
    }
    output_start = output = PyBytes_AsString(result);
    input = PyBytes_AS_STRING(input_obj);

    if (dellen == 0 && table_chars != NULL) {
        /* If no deletions are required, use faster code */
        for (i = inlen; --i >= 0; ) {
            c = Py_CHARMASK(*input++);
            if (Py_CHARMASK((*output++ = table_chars[c])) != c)
                changed = 1;
        }
        if (!changed && PyBytes_CheckExact(input_obj)) {
            Py_INCREF(input_obj);
            Py_DECREF(result);
            result = input_obj;
        }
        PyBuffer_Release(&del_table_view);
        PyBuffer_Release(&table_view);
        return result;
    }

    if (table_chars == NULL) {
        for (i = 0; i < 256; i++)
            trans_table[i] = Py_CHARMASK(i);
    } else {
        for (i = 0; i < 256; i++)
            trans_table[i] = Py_CHARMASK(table_chars[i]);
    }
    PyBuffer_Release(&table_view);

    for (i = 0; i < dellen; i++)
        trans_table[(int) Py_CHARMASK(del_table_chars[i])] = -1;
    PyBuffer_Release(&del_table_view);

    for (i = inlen; --i >= 0; ) {
        c = Py_CHARMASK(*input++);
        if (trans_table[c] != -1)
            if (Py_CHARMASK(*output++ = (char)trans_table[c]) == c)
                continue;
        changed = 1;
    }
    if (!changed && PyBytes_CheckExact(input_obj)) {
        Py_DECREF(result);
        Py_INCREF(input_obj);
        return input_obj;
    }
    /* Fix the size of the resulting string */
    if (inlen > 0)
        _PyBytes_Resize(&result, output - output_start);
    return result;
}


/*[clinic input]

@staticmethod
bytes.maketrans

    frm: Py_buffer
    to: Py_buffer
    /

Return a translation table useable for the bytes or bytearray translate method.

The returned table will be one where each byte in frm is mapped to the byte at
the same position in to.

The bytes objects frm and to must be of the same length.
[clinic start generated code]*/

static PyObject *
bytes_maketrans_impl(Py_buffer *frm, Py_buffer *to)
/*[clinic end generated code: output=a36f6399d4b77f6f input=de7a8fc5632bb8f1]*/
{
    return _Py_bytes_maketrans(frm, to);
}

/* find and count characters and substrings */

#define findchar(target, target_len, c)                         \
  ((char *)memchr((const void *)(target), c, target_len))

/* String ops must return a string.  */
/* If the object is subclass of string, create a copy */
Py_LOCAL(PyBytesObject *)
return_self(PyBytesObject *self)
{
    if (PyBytes_CheckExact(self)) {
        Py_INCREF(self);
        return self;
    }
    return (PyBytesObject *)PyBytes_FromStringAndSize(
        PyBytes_AS_STRING(self),
        PyBytes_GET_SIZE(self));
}

Py_LOCAL_INLINE(Py_ssize_t)
countchar(const char *target, Py_ssize_t target_len, char c, Py_ssize_t maxcount)
{
    Py_ssize_t count=0;
    const char *start=target;
    const char *end=target+target_len;

    while ( (start=findchar(start, end-start, c)) != NULL ) {
        count++;
        if (count >= maxcount)
            break;
        start += 1;
    }
    return count;
}


/* Algorithms for different cases of string replacement */

/* len(self)>=1, from="", len(to)>=1, maxcount>=1 */
Py_LOCAL(PyBytesObject *)
replace_interleave(PyBytesObject *self,
                   const char *to_s, Py_ssize_t to_len,
                   Py_ssize_t maxcount)
{
    char *self_s, *result_s;
    Py_ssize_t self_len, result_len;
    Py_ssize_t count, i;
    PyBytesObject *result;

    self_len = PyBytes_GET_SIZE(self);

    /* 1 at the end plus 1 after every character;
       count = min(maxcount, self_len + 1) */
    if (maxcount <= self_len)
        count = maxcount;
    else
        /* Can't overflow: self_len + 1 <= maxcount <= PY_SSIZE_T_MAX. */
        count = self_len + 1;

    /* Check for overflow */
    /*   result_len = count * to_len + self_len; */
    assert(count > 0);
    if (to_len > (PY_SSIZE_T_MAX - self_len) / count) {
        PyErr_SetString(PyExc_OverflowError,
                        "replacement bytes are too long");
        return NULL;
    }
    result_len = count * to_len + self_len;

    if (! (result = (PyBytesObject *)
                     PyBytes_FromStringAndSize(NULL, result_len)) )
        return NULL;

    self_s = PyBytes_AS_STRING(self);
    result_s = PyBytes_AS_STRING(result);

    /* TODO: special case single character, which doesn't need memcpy */

    /* Lay the first one down (guaranteed this will occur) */
    Py_MEMCPY(result_s, to_s, to_len);
    result_s += to_len;
    count -= 1;

    for (i=0; i<count; i++) {
        *result_s++ = *self_s++;
        Py_MEMCPY(result_s, to_s, to_len);
        result_s += to_len;
    }

    /* Copy the rest of the original string */
    Py_MEMCPY(result_s, self_s, self_len-i);

    return result;
}

/* Special case for deleting a single character */
/* len(self)>=1, len(from)==1, to="", maxcount>=1 */
Py_LOCAL(PyBytesObject *)
replace_delete_single_character(PyBytesObject *self,
                                char from_c, Py_ssize_t maxcount)
{
    char *self_s, *result_s;
    char *start, *next, *end;
    Py_ssize_t self_len, result_len;
    Py_ssize_t count;
    PyBytesObject *result;

    self_len = PyBytes_GET_SIZE(self);
    self_s = PyBytes_AS_STRING(self);

    count = countchar(self_s, self_len, from_c, maxcount);
    if (count == 0) {
        return return_self(self);
    }

    result_len = self_len - count;  /* from_len == 1 */
    assert(result_len>=0);

    if ( (result = (PyBytesObject *)
                    PyBytes_FromStringAndSize(NULL, result_len)) == NULL)
        return NULL;
    result_s = PyBytes_AS_STRING(result);

    start = self_s;
    end = self_s + self_len;
    while (count-- > 0) {
        next = findchar(start, end-start, from_c);
        if (next == NULL)
            break;
        Py_MEMCPY(result_s, start, next-start);
        result_s += (next-start);
        start = next+1;
    }
    Py_MEMCPY(result_s, start, end-start);

    return result;
}

/* len(self)>=1, len(from)>=2, to="", maxcount>=1 */

Py_LOCAL(PyBytesObject *)
replace_delete_substring(PyBytesObject *self,
                         const char *from_s, Py_ssize_t from_len,
                         Py_ssize_t maxcount) {
    char *self_s, *result_s;
    char *start, *next, *end;
    Py_ssize_t self_len, result_len;
    Py_ssize_t count, offset;
    PyBytesObject *result;

    self_len = PyBytes_GET_SIZE(self);
    self_s = PyBytes_AS_STRING(self);

    count = stringlib_count(self_s, self_len,
                            from_s, from_len,
                            maxcount);

    if (count == 0) {
        /* no matches */
        return return_self(self);
    }

    result_len = self_len - (count * from_len);
    assert (result_len>=0);

    if ( (result = (PyBytesObject *)
          PyBytes_FromStringAndSize(NULL, result_len)) == NULL )
        return NULL;

    result_s = PyBytes_AS_STRING(result);

    start = self_s;
    end = self_s + self_len;
    while (count-- > 0) {
        offset = stringlib_find(start, end-start,
                                from_s, from_len,
                                0);
        if (offset == -1)
            break;
        next = start + offset;

        Py_MEMCPY(result_s, start, next-start);

        result_s += (next-start);
        start = next+from_len;
    }
    Py_MEMCPY(result_s, start, end-start);
    return result;
}

/* len(self)>=1, len(from)==len(to)==1, maxcount>=1 */
Py_LOCAL(PyBytesObject *)
replace_single_character_in_place(PyBytesObject *self,
                                  char from_c, char to_c,
                                  Py_ssize_t maxcount)
{
    char *self_s, *result_s, *start, *end, *next;
    Py_ssize_t self_len;
    PyBytesObject *result;

    /* The result string will be the same size */
    self_s = PyBytes_AS_STRING(self);
    self_len = PyBytes_GET_SIZE(self);

    next = findchar(self_s, self_len, from_c);

    if (next == NULL) {
        /* No matches; return the original string */
        return return_self(self);
    }

    /* Need to make a new string */
    result = (PyBytesObject *) PyBytes_FromStringAndSize(NULL, self_len);
    if (result == NULL)
        return NULL;
    result_s = PyBytes_AS_STRING(result);
    Py_MEMCPY(result_s, self_s, self_len);

    /* change everything in-place, starting with this one */
    start =  result_s + (next-self_s);
    *start = to_c;
    start++;
    end = result_s + self_len;

    while (--maxcount > 0) {
        next = findchar(start, end-start, from_c);
        if (next == NULL)
            break;
        *next = to_c;
        start = next+1;
    }

    return result;
}

/* len(self)>=1, len(from)==len(to)>=2, maxcount>=1 */
Py_LOCAL(PyBytesObject *)
replace_substring_in_place(PyBytesObject *self,
                           const char *from_s, Py_ssize_t from_len,
                           const char *to_s, Py_ssize_t to_len,
                           Py_ssize_t maxcount)
{
    char *result_s, *start, *end;
    char *self_s;
    Py_ssize_t self_len, offset;
    PyBytesObject *result;

    /* The result string will be the same size */

    self_s = PyBytes_AS_STRING(self);
    self_len = PyBytes_GET_SIZE(self);

    offset = stringlib_find(self_s, self_len,
                            from_s, from_len,
                            0);
    if (offset == -1) {
        /* No matches; return the original string */
        return return_self(self);
    }

    /* Need to make a new string */
    result = (PyBytesObject *) PyBytes_FromStringAndSize(NULL, self_len);
    if (result == NULL)
        return NULL;
    result_s = PyBytes_AS_STRING(result);
    Py_MEMCPY(result_s, self_s, self_len);

    /* change everything in-place, starting with this one */
    start =  result_s + offset;
    Py_MEMCPY(start, to_s, from_len);
    start += from_len;
    end = result_s + self_len;

    while ( --maxcount > 0) {
        offset = stringlib_find(start, end-start,
                                from_s, from_len,
                                0);
        if (offset==-1)
            break;
        Py_MEMCPY(start+offset, to_s, from_len);
        start += offset+from_len;
    }

    return result;
}

/* len(self)>=1, len(from)==1, len(to)>=2, maxcount>=1 */
Py_LOCAL(PyBytesObject *)
replace_single_character(PyBytesObject *self,
                         char from_c,
                         const char *to_s, Py_ssize_t to_len,
                         Py_ssize_t maxcount)
{
    char *self_s, *result_s;
    char *start, *next, *end;
    Py_ssize_t self_len, result_len;
    Py_ssize_t count;
    PyBytesObject *result;

    self_s = PyBytes_AS_STRING(self);
    self_len = PyBytes_GET_SIZE(self);

    count = countchar(self_s, self_len, from_c, maxcount);
    if (count == 0) {
        /* no matches, return unchanged */
        return return_self(self);
    }

    /* use the difference between current and new, hence the "-1" */
    /*   result_len = self_len + count * (to_len-1)  */
    assert(count > 0);
    if (to_len - 1 > (PY_SSIZE_T_MAX - self_len) / count) {
        PyErr_SetString(PyExc_OverflowError,
                        "replacement bytes are too long");
        return NULL;
    }
    result_len = self_len + count * (to_len - 1);

    if ( (result = (PyBytesObject *)
          PyBytes_FromStringAndSize(NULL, result_len)) == NULL)
        return NULL;
    result_s = PyBytes_AS_STRING(result);

    start = self_s;
    end = self_s + self_len;
    while (count-- > 0) {
        next = findchar(start, end-start, from_c);
        if (next == NULL)
            break;

        if (next == start) {
            /* replace with the 'to' */
            Py_MEMCPY(result_s, to_s, to_len);
            result_s += to_len;
            start += 1;
        } else {
            /* copy the unchanged old then the 'to' */
            Py_MEMCPY(result_s, start, next-start);
            result_s += (next-start);
            Py_MEMCPY(result_s, to_s, to_len);
            result_s += to_len;
            start = next+1;
        }
    }
    /* Copy the remainder of the remaining string */
    Py_MEMCPY(result_s, start, end-start);

    return result;
}

/* len(self)>=1, len(from)>=2, len(to)>=2, maxcount>=1 */
Py_LOCAL(PyBytesObject *)
replace_substring(PyBytesObject *self,
                  const char *from_s, Py_ssize_t from_len,
                  const char *to_s, Py_ssize_t to_len,
                  Py_ssize_t maxcount) {
    char *self_s, *result_s;
    char *start, *next, *end;
    Py_ssize_t self_len, result_len;
    Py_ssize_t count, offset;
    PyBytesObject *result;

    self_s = PyBytes_AS_STRING(self);
    self_len = PyBytes_GET_SIZE(self);

    count = stringlib_count(self_s, self_len,
                            from_s, from_len,
                            maxcount);

    if (count == 0) {
        /* no matches, return unchanged */
        return return_self(self);
    }

    /* Check for overflow */
    /*    result_len = self_len + count * (to_len-from_len) */
    assert(count > 0);
    if (to_len - from_len > (PY_SSIZE_T_MAX - self_len) / count) {
        PyErr_SetString(PyExc_OverflowError,
                        "replacement bytes are too long");
        return NULL;
    }
    result_len = self_len + count * (to_len-from_len);

    if ( (result = (PyBytesObject *)
          PyBytes_FromStringAndSize(NULL, result_len)) == NULL)
        return NULL;
    result_s = PyBytes_AS_STRING(result);

    start = self_s;
    end = self_s + self_len;
    while (count-- > 0) {
        offset = stringlib_find(start, end-start,
                                from_s, from_len,
                                0);
        if (offset == -1)
            break;
        next = start+offset;
        if (next == start) {
            /* replace with the 'to' */
            Py_MEMCPY(result_s, to_s, to_len);
            result_s += to_len;
            start += from_len;
        } else {
            /* copy the unchanged old then the 'to' */
            Py_MEMCPY(result_s, start, next-start);
            result_s += (next-start);
            Py_MEMCPY(result_s, to_s, to_len);
            result_s += to_len;
            start = next+from_len;
        }
    }
    /* Copy the remainder of the remaining string */
    Py_MEMCPY(result_s, start, end-start);

    return result;
}


Py_LOCAL(PyBytesObject *)
replace(PyBytesObject *self,
    const char *from_s, Py_ssize_t from_len,
    const char *to_s, Py_ssize_t to_len,
    Py_ssize_t maxcount)
{
    if (maxcount < 0) {
        maxcount = PY_SSIZE_T_MAX;
    } else if (maxcount == 0 || PyBytes_GET_SIZE(self) == 0) {
        /* nothing to do; return the original string */
        return return_self(self);
    }

    if (maxcount == 0 ||
        (from_len == 0 && to_len == 0)) {
        /* nothing to do; return the original string */
        return return_self(self);
    }

    /* Handle zero-length special cases */

    if (from_len == 0) {
        /* insert the 'to' string everywhere.   */
        /*    >>> "Python".replace("", ".")     */
        /*    '.P.y.t.h.o.n.'                   */
        return replace_interleave(self, to_s, to_len, maxcount);
    }

    /* Except for "".replace("", "A") == "A" there is no way beyond this */
    /* point for an empty self string to generate a non-empty string */
    /* Special case so the remaining code always gets a non-empty string */
    if (PyBytes_GET_SIZE(self) == 0) {
        return return_self(self);
    }

    if (to_len == 0) {
        /* delete all occurrences of 'from' string */
        if (from_len == 1) {
            return replace_delete_single_character(
                self, from_s[0], maxcount);
        } else {
            return replace_delete_substring(self, from_s,
                                            from_len, maxcount);
        }
    }

    /* Handle special case where both strings have the same length */

    if (from_len == to_len) {
        if (from_len == 1) {
            return replace_single_character_in_place(
                self,
                from_s[0],
                to_s[0],
                maxcount);
        } else {
            return replace_substring_in_place(
                self, from_s, from_len, to_s, to_len,
                maxcount);
        }
    }

    /* Otherwise use the more generic algorithms */
    if (from_len == 1) {
        return replace_single_character(self, from_s[0],
                                        to_s, to_len, maxcount);
    } else {
        /* len('from')>=2, len('to')>=1 */
        return replace_substring(self, from_s, from_len, to_s, to_len,
                                 maxcount);
    }
}


/*[clinic input]
bytes.replace

    old: Py_buffer
    new: Py_buffer
    count: Py_ssize_t = -1
        Maximum number of occurrences to replace.
        -1 (the default value) means replace all occurrences.
    /

Return a copy with all occurrences of substring old replaced by new.

If the optional argument count is given, only the first count occurrences are
replaced.
[clinic start generated code]*/

static PyObject *
bytes_replace_impl(PyBytesObject*self, Py_buffer *old, Py_buffer *new,
                   Py_ssize_t count)
/*[clinic end generated code: output=403dc9d7a83c5a1d input=b2fbbf0bf04de8e5]*/
{
    return (PyObject *)replace((PyBytesObject *) self,
                               (const char *)old->buf, old->len,
                               (const char *)new->buf, new->len, count);
}

/** End DALKE **/

/* Matches the end (direction >= 0) or start (direction < 0) of self
 * against substr, using the start and end arguments. Returns
 * -1 on error, 0 if not found and 1 if found.
 */
Py_LOCAL(int)
_bytes_tailmatch(PyBytesObject *self, PyObject *substr, Py_ssize_t start,
                  Py_ssize_t end, int direction)
{
    Py_ssize_t len = PyBytes_GET_SIZE(self);
    Py_ssize_t slen;
    Py_buffer sub_view = {NULL, NULL};
    const char* sub;
    const char* str;

    if (PyBytes_Check(substr)) {
        sub = PyBytes_AS_STRING(substr);
        slen = PyBytes_GET_SIZE(substr);
    }
    else {
        if (PyObject_GetBuffer(substr, &sub_view, PyBUF_SIMPLE) != 0)
            return -1;
        sub = sub_view.buf;
        slen = sub_view.len;
    }
    str = PyBytes_AS_STRING(self);

    ADJUST_INDICES(start, end, len);

    if (direction < 0) {
        /* startswith */
        if (start+slen > len)
            goto notfound;
    } else {
        /* endswith */
        if (end-start < slen || start > len)
            goto notfound;

        if (end-slen > start)
            start = end - slen;
    }
    if (end-start < slen)
        goto notfound;
    if (memcmp(str+start, sub, slen) != 0)
        goto notfound;

    PyBuffer_Release(&sub_view);
    return 1;

notfound:
    PyBuffer_Release(&sub_view);
    return 0;
}


PyDoc_STRVAR(startswith__doc__,
"B.startswith(prefix[, start[, end]]) -> bool\n\
\n\
Return True if B starts with the specified prefix, False otherwise.\n\
With optional start, test B beginning at that position.\n\
With optional end, stop comparing B at that position.\n\
prefix can also be a tuple of bytes to try.");

static PyObject *
bytes_startswith(PyBytesObject *self, PyObject *args)
{
    Py_ssize_t start = 0;
    Py_ssize_t end = PY_SSIZE_T_MAX;
    PyObject *subobj;
    int result;

    if (!stringlib_parse_args_finds("startswith", args, &subobj, &start, &end))
        return NULL;
    if (PyTuple_Check(subobj)) {
        Py_ssize_t i;
        for (i = 0; i < PyTuple_GET_SIZE(subobj); i++) {
            result = _bytes_tailmatch(self,
                            PyTuple_GET_ITEM(subobj, i),
                            start, end, -1);
            if (result == -1)
                return NULL;
            else if (result) {
                Py_RETURN_TRUE;
            }
        }
        Py_RETURN_FALSE;
    }
    result = _bytes_tailmatch(self, subobj, start, end, -1);
    if (result == -1) {
        if (PyErr_ExceptionMatches(PyExc_TypeError))
            PyErr_Format(PyExc_TypeError, "startswith first arg must be bytes "
                         "or a tuple of bytes, not %s", Py_TYPE(subobj)->tp_name);
        return NULL;
    }
    else
        return PyBool_FromLong(result);
}


PyDoc_STRVAR(endswith__doc__,
"B.endswith(suffix[, start[, end]]) -> bool\n\
\n\
Return True if B ends with the specified suffix, False otherwise.\n\
With optional start, test B beginning at that position.\n\
With optional end, stop comparing B at that position.\n\
suffix can also be a tuple of bytes to try.");

static PyObject *
bytes_endswith(PyBytesObject *self, PyObject *args)
{
    Py_ssize_t start = 0;
    Py_ssize_t end = PY_SSIZE_T_MAX;
    PyObject *subobj;
    int result;

    if (!stringlib_parse_args_finds("endswith", args, &subobj, &start, &end))
        return NULL;
    if (PyTuple_Check(subobj)) {
        Py_ssize_t i;
        for (i = 0; i < PyTuple_GET_SIZE(subobj); i++) {
            result = _bytes_tailmatch(self,
                            PyTuple_GET_ITEM(subobj, i),
                            start, end, +1);
            if (result == -1)
                return NULL;
            else if (result) {
                Py_RETURN_TRUE;
            }
        }
        Py_RETURN_FALSE;
    }
    result = _bytes_tailmatch(self, subobj, start, end, +1);
    if (result == -1) {
        if (PyErr_ExceptionMatches(PyExc_TypeError))
            PyErr_Format(PyExc_TypeError, "endswith first arg must be bytes or "
                         "a tuple of bytes, not %s", Py_TYPE(subobj)->tp_name);
        return NULL;
    }
    else
        return PyBool_FromLong(result);
}


/*[clinic input]
bytes.decode

    encoding: str(c_default="NULL") = 'utf-8'
        The encoding with which to decode the bytes.
    errors: str(c_default="NULL") = 'strict'
        The error handling scheme to use for the handling of decoding errors.
        The default is 'strict' meaning that decoding errors raise a
        UnicodeDecodeError. Other possible values are 'ignore' and 'replace'
        as well as any other name registered with codecs.register_error that
        can handle UnicodeDecodeErrors.

Decode the bytes using the codec registered for encoding.
[clinic start generated code]*/

static PyObject *
bytes_decode_impl(PyBytesObject*self, const char *encoding,
                  const char *errors)
/*[clinic end generated code: output=2d2016ff8e0bb176 input=958174769d2a40ca]*/
{
    return PyUnicode_FromEncodedObject((PyObject*)self, encoding, errors);
}


/*[clinic input]
bytes.splitlines

    keepends: int(py_default="False") = 0

Return a list of the lines in the bytes, breaking at line boundaries.

Line breaks are not included in the resulting list unless keepends is given and
true.
[clinic start generated code]*/

static PyObject *
bytes_splitlines_impl(PyBytesObject*self, int keepends)
/*[clinic end generated code: output=995c3598f7833cad input=ddb93e3351080c8c]*/
{
    return stringlib_splitlines(
        (PyObject*) self, PyBytes_AS_STRING(self),
        PyBytes_GET_SIZE(self), keepends
        );
}

static int
hex_digit_to_int(Py_UCS4 c)
{
    if (c >= 128)
        return -1;
    if (Py_ISDIGIT(c))
        return c - '0';
    else {
        if (Py_ISUPPER(c))
            c = Py_TOLOWER(c);
        if (c >= 'a' && c <= 'f')
            return c - 'a' + 10;
    }
    return -1;
}

/*[clinic input]
@classmethod
bytes.fromhex

    string: unicode
    /

Create a bytes object from a string of hexadecimal numbers.

Spaces between two numbers are accepted.
Example: bytes.fromhex('B9 01EF') -> b'\\xb9\\x01\\xef'.
[clinic start generated code]*/

static PyObject *
bytes_fromhex_impl(PyTypeObject *type, PyObject *string)
/*[clinic end generated code: output=0973acc63661bb2e input=bf4d1c361670acd3]*/
{
    PyObject *newstring;
    char *buf;
    Py_ssize_t hexlen, byteslen, i, j;
    int top, bot;
    void *data;
    unsigned int kind;

    assert(PyUnicode_Check(string));
    if (PyUnicode_READY(string))
        return NULL;
    kind = PyUnicode_KIND(string);
    data = PyUnicode_DATA(string);
    hexlen = PyUnicode_GET_LENGTH(string);

    byteslen = hexlen/2; /* This overestimates if there are spaces */
    newstring = PyBytes_FromStringAndSize(NULL, byteslen);
    if (!newstring)
        return NULL;
    buf = PyBytes_AS_STRING(newstring);
    for (i = j = 0; i < hexlen; i += 2) {
        /* skip over spaces in the input */
        while (PyUnicode_READ(kind, data, i) == ' ')
            i++;
        if (i >= hexlen)
            break;
        top = hex_digit_to_int(PyUnicode_READ(kind, data, i));
        bot = hex_digit_to_int(PyUnicode_READ(kind, data, i+1));
        if (top == -1 || bot == -1) {
            PyErr_Format(PyExc_ValueError,
                         "non-hexadecimal number found in "
                         "fromhex() arg at position %zd", i);
            goto error;
        }
        buf[j++] = (top << 4) + bot;
    }
    if (j != byteslen && _PyBytes_Resize(&newstring, j) < 0)
        goto error;
    return newstring;

  error:
    Py_XDECREF(newstring);
    return NULL;
}

PyDoc_STRVAR(hex__doc__,
"B.hex() -> string\n\
\n\
Create a string of hexadecimal numbers from a bytes object.\n\
Example: b'\\xb9\\x01\\xef'.hex() -> 'b901ef'.");

static PyObject *
bytes_hex(PyBytesObject *self)
{
    char* argbuf = PyBytes_AS_STRING(self);
    Py_ssize_t arglen = PyBytes_GET_SIZE(self);
    return _Py_strhex(argbuf, arglen);
}

static PyObject *
bytes_getnewargs(PyBytesObject *v)
{
    return Py_BuildValue("(y#)", v->ob_sval, Py_SIZE(v));
}


static PyMethodDef
bytes_methods[] = {
    {"__getnewargs__",          (PyCFunction)bytes_getnewargs,  METH_NOARGS},
    {"capitalize", (PyCFunction)stringlib_capitalize, METH_NOARGS,
     _Py_capitalize__doc__},
    {"center", (PyCFunction)stringlib_center, METH_VARARGS, center__doc__},
    {"count", (PyCFunction)bytes_count, METH_VARARGS, count__doc__},
    BYTES_DECODE_METHODDEF
    {"endswith", (PyCFunction)bytes_endswith, METH_VARARGS,
     endswith__doc__},
    {"expandtabs", (PyCFunction)stringlib_expandtabs, METH_VARARGS | METH_KEYWORDS,
     expandtabs__doc__},
    {"find", (PyCFunction)bytes_find, METH_VARARGS, find__doc__},
    BYTES_FROMHEX_METHODDEF
    {"hex", (PyCFunction)bytes_hex, METH_NOARGS, hex__doc__},
    {"index", (PyCFunction)bytes_index, METH_VARARGS, index__doc__},
    {"isalnum", (PyCFunction)stringlib_isalnum, METH_NOARGS,
     _Py_isalnum__doc__},
    {"isalpha", (PyCFunction)stringlib_isalpha, METH_NOARGS,
     _Py_isalpha__doc__},
    {"isdigit", (PyCFunction)stringlib_isdigit, METH_NOARGS,
     _Py_isdigit__doc__},
    {"islower", (PyCFunction)stringlib_islower, METH_NOARGS,
     _Py_islower__doc__},
    {"isspace", (PyCFunction)stringlib_isspace, METH_NOARGS,
     _Py_isspace__doc__},
    {"istitle", (PyCFunction)stringlib_istitle, METH_NOARGS,
     _Py_istitle__doc__},
    {"isupper", (PyCFunction)stringlib_isupper, METH_NOARGS,
     _Py_isupper__doc__},
    BYTES_JOIN_METHODDEF
    {"ljust", (PyCFunction)stringlib_ljust, METH_VARARGS, ljust__doc__},
    {"lower", (PyCFunction)stringlib_lower, METH_NOARGS, _Py_lower__doc__},
    BYTES_LSTRIP_METHODDEF
    BYTES_MAKETRANS_METHODDEF
    BYTES_PARTITION_METHODDEF
    BYTES_REPLACE_METHODDEF
    {"rfind", (PyCFunction)bytes_rfind, METH_VARARGS, rfind__doc__},
    {"rindex", (PyCFunction)bytes_rindex, METH_VARARGS, rindex__doc__},
    {"rjust", (PyCFunction)stringlib_rjust, METH_VARARGS, rjust__doc__},
    BYTES_RPARTITION_METHODDEF
    BYTES_RSPLIT_METHODDEF
    BYTES_RSTRIP_METHODDEF
    BYTES_SPLIT_METHODDEF
    BYTES_SPLITLINES_METHODDEF
    {"startswith", (PyCFunction)bytes_startswith, METH_VARARGS,
     startswith__doc__},
    BYTES_STRIP_METHODDEF
    {"swapcase", (PyCFunction)stringlib_swapcase, METH_NOARGS,
     _Py_swapcase__doc__},
    {"title", (PyCFunction)stringlib_title, METH_NOARGS, _Py_title__doc__},
    BYTES_TRANSLATE_METHODDEF
    {"upper", (PyCFunction)stringlib_upper, METH_NOARGS, _Py_upper__doc__},
    {"zfill", (PyCFunction)stringlib_zfill, METH_VARARGS, zfill__doc__},
    {NULL,     NULL}                         /* sentinel */
};

static PyObject *
bytes_mod(PyObject *v, PyObject *w)
{
    if (!PyBytes_Check(v))
        Py_RETURN_NOTIMPLEMENTED;
    return _PyBytes_Format(v, w);
}

static PyNumberMethods bytes_as_number = {
    0,              /*nb_add*/
    0,              /*nb_subtract*/
    0,              /*nb_multiply*/
    bytes_mod,      /*nb_remainder*/
};

static PyObject *
str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);

static PyObject *
bytes_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    PyObject *x = NULL;
    const char *encoding = NULL;
    const char *errors = NULL;
    PyObject *new = NULL;
    PyObject *func;
    Py_ssize_t size;
    static char *kwlist[] = {"source", "encoding", "errors", 0};
    _Py_IDENTIFIER(__bytes__);

    if (type != &PyBytes_Type)
        return str_subtype_new(type, args, kwds);
    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|Oss:bytes", kwlist, &x,
                                     &encoding, &errors))
        return NULL;
    if (x == NULL) {
        if (encoding != NULL || errors != NULL) {
            PyErr_SetString(PyExc_TypeError,
                            "encoding or errors without sequence "
                            "argument");
            return NULL;
        }
        return PyBytes_FromStringAndSize(NULL, 0);
    }

    if (PyUnicode_Check(x)) {
        /* Encode via the codec registry */
        if (encoding == NULL) {
            PyErr_SetString(PyExc_TypeError,
                            "string argument without an encoding");
            return NULL;
        }
        new = PyUnicode_AsEncodedString(x, encoding, errors);
        if (new == NULL)
            return NULL;
        assert(PyBytes_Check(new));
        return new;
    }

    /* If it's not unicode, there can't be encoding or errors */
    if (encoding != NULL || errors != NULL) {
        PyErr_SetString(PyExc_TypeError,
            "encoding or errors without a string argument");
        return NULL;
    }

    /* We'd like to call PyObject_Bytes here, but we need to check for an
       integer argument before deferring to PyBytes_FromObject, something
       PyObject_Bytes doesn't do. */
    func = _PyObject_LookupSpecial(x, &PyId___bytes__);
    if (func != NULL) {
        new = PyObject_CallFunctionObjArgs(func, NULL);
        Py_DECREF(func);
        if (new == NULL)
            return NULL;
        if (!PyBytes_Check(new)) {
            PyErr_Format(PyExc_TypeError,
                         "__bytes__ returned non-bytes (type %.200s)",
                         Py_TYPE(new)->tp_name);
            Py_DECREF(new);
            return NULL;
        }
        return new;
    }
    else if (PyErr_Occurred())
        return NULL;

    /* Is it an integer? */
    size = PyNumber_AsSsize_t(x, PyExc_OverflowError);
    if (size == -1 && PyErr_Occurred()) {
        if (PyErr_ExceptionMatches(PyExc_OverflowError))
            return NULL;
        PyErr_Clear();
    }
    else if (size < 0) {
        PyErr_SetString(PyExc_ValueError, "negative count");
        return NULL;
    }
    else {
        new = _PyBytes_FromSize(size, 1);
        if (new == NULL)
            return NULL;
        return new;
    }

    return PyBytes_FromObject(x);
}

PyObject *
PyBytes_FromObject(PyObject *x)
{
    PyObject *new, *it;
    Py_ssize_t i, size;

    if (x == NULL) {
        PyErr_BadInternalCall();
        return NULL;
    }

    if (PyBytes_CheckExact(x)) {
        Py_INCREF(x);
        return x;
    }

    /* Use the modern buffer interface */
    if (PyObject_CheckBuffer(x)) {
        Py_buffer view;
        if (PyObject_GetBuffer(x, &view, PyBUF_FULL_RO) < 0)
            return NULL;
        new = PyBytes_FromStringAndSize(NULL, view.len);
        if (!new)
            goto fail;
        if (PyBuffer_ToContiguous(((PyBytesObject *)new)->ob_sval,
                                  &view, view.len, 'C') < 0)
            goto fail;
        PyBuffer_Release(&view);
        return new;
      fail:
        Py_XDECREF(new);
        PyBuffer_Release(&view);
        return NULL;
    }
    if (PyUnicode_Check(x)) {
        PyErr_SetString(PyExc_TypeError,
                        "cannot convert unicode object to bytes");
        return NULL;
    }

    if (PyList_CheckExact(x)) {
        new = PyBytes_FromStringAndSize(NULL, Py_SIZE(x));
        if (new == NULL)
            return NULL;
        for (i = 0; i < Py_SIZE(x); i++) {
            Py_ssize_t value = PyNumber_AsSsize_t(
                PyList_GET_ITEM(x, i), PyExc_ValueError);
            if (value == -1 && PyErr_Occurred()) {
                Py_DECREF(new);
                return NULL;
            }
            if (value < 0 || value >= 256) {
                PyErr_SetString(PyExc_ValueError,
                                "bytes must be in range(0, 256)");
                Py_DECREF(new);
                return NULL;
            }
            ((PyBytesObject *)new)->ob_sval[i] = (char) value;
        }
        return new;
    }
    if (PyTuple_CheckExact(x)) {
        new = PyBytes_FromStringAndSize(NULL, Py_SIZE(x));
        if (new == NULL)
            return NULL;
        for (i = 0; i < Py_SIZE(x); i++) {
            Py_ssize_t value = PyNumber_AsSsize_t(
                PyTuple_GET_ITEM(x, i), PyExc_ValueError);
            if (value == -1 && PyErr_Occurred()) {
                Py_DECREF(new);
                return NULL;
            }
            if (value < 0 || value >= 256) {
                PyErr_SetString(PyExc_ValueError,
                                "bytes must be in range(0, 256)");
                Py_DECREF(new);
                return NULL;
            }
            ((PyBytesObject *)new)->ob_sval[i] = (char) value;
        }
        return new;
    }

    /* For iterator version, create a string object and resize as needed */
    size = PyObject_LengthHint(x, 64);
    if (size == -1 && PyErr_Occurred())
        return NULL;
    /* Allocate an extra byte to prevent PyBytes_FromStringAndSize() from
       returning a shared empty bytes string. This required because we
       want to call _PyBytes_Resize() the returned object, which we can
       only do on bytes objects with refcount == 1. */
    if (size == 0)
        size = 1;
    new = PyBytes_FromStringAndSize(NULL, size);
    if (new == NULL)
        return NULL;
    assert(Py_REFCNT(new) == 1);

    /* Get the iterator */
    it = PyObject_GetIter(x);
    if (it == NULL)
        goto error;

    /* Run the iterator to exhaustion */
    for (i = 0; ; i++) {
        PyObject *item;
        Py_ssize_t value;

        /* Get the next item */
        item = PyIter_Next(it);
        if (item == NULL) {
            if (PyErr_Occurred())
                goto error;
            break;
        }

        /* Interpret it as an int (__index__) */
        value = PyNumber_AsSsize_t(item, PyExc_ValueError);
        Py_DECREF(item);
        if (value == -1 && PyErr_Occurred())
            goto error;

        /* Range check */
        if (value < 0 || value >= 256) {
            PyErr_SetString(PyExc_ValueError,
                            "bytes must be in range(0, 256)");
            goto error;
        }

        /* Append the byte */
        if (i >= size) {
            size = 2 * size + 1;
            if (_PyBytes_Resize(&new, size) < 0)
                goto error;
        }
        ((PyBytesObject *)new)->ob_sval[i] = (char) value;
    }
    _PyBytes_Resize(&new, i);

    /* Clean up and return success */
    Py_DECREF(it);
    return new;

  error:
    Py_XDECREF(it);
    Py_XDECREF(new);
    return NULL;
}

static PyObject *
str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    PyObject *tmp, *pnew;
    Py_ssize_t n;

    assert(PyType_IsSubtype(type, &PyBytes_Type));
    tmp = bytes_new(&PyBytes_Type, args, kwds);
    if (tmp == NULL)
        return NULL;
    assert(PyBytes_CheckExact(tmp));
    n = PyBytes_GET_SIZE(tmp);
    pnew = type->tp_alloc(type, n);
    if (pnew != NULL) {
        Py_MEMCPY(PyBytes_AS_STRING(pnew),
                  PyBytes_AS_STRING(tmp), n+1);
        ((PyBytesObject *)pnew)->ob_shash =
            ((PyBytesObject *)tmp)->ob_shash;
    }
    Py_DECREF(tmp);
    return pnew;
}

PyDoc_STRVAR(bytes_doc,
"bytes(iterable_of_ints) -> bytes\n\
bytes(string, encoding[, errors]) -> bytes\n\
bytes(bytes_or_buffer) -> immutable copy of bytes_or_buffer\n\
bytes(int) -> bytes object of size given by the parameter initialized with null bytes\n\
bytes() -> empty bytes object\n\
\n\
Construct an immutable array of bytes from:\n\
  - an iterable yielding integers in range(256)\n\
  - a text string encoded using the specified encoding\n\
  - any object implementing the buffer API.\n\
  - an integer");

static PyObject *bytes_iter(PyObject *seq);

PyTypeObject PyBytes_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "bytes",
    PyBytesObject_SIZE,
    sizeof(char),
    bytes_dealloc,                      /* tp_dealloc */
    0,                                          /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    0,                                          /* tp_reserved */
    (reprfunc)bytes_repr,                       /* tp_repr */
    &bytes_as_number,                           /* tp_as_number */
    &bytes_as_sequence,                         /* tp_as_sequence */
    &bytes_as_mapping,                          /* tp_as_mapping */
    (hashfunc)bytes_hash,                       /* tp_hash */
    0,                                          /* tp_call */
    bytes_str,                                  /* tp_str */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    0,                                          /* tp_setattro */
    &bytes_as_buffer,                           /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
        Py_TPFLAGS_BYTES_SUBCLASS,              /* tp_flags */
    bytes_doc,                                  /* tp_doc */
    0,                                          /* tp_traverse */
    0,                                          /* tp_clear */
    (richcmpfunc)bytes_richcompare,             /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    bytes_iter,                                 /* tp_iter */
    0,                                          /* tp_iternext */
    bytes_methods,                              /* tp_methods */
    0,                                          /* tp_members */
    0,                                          /* tp_getset */
    &PyBaseObject_Type,                         /* tp_base */
    0,                                          /* tp_dict */
    0,                                          /* tp_descr_get */
    0,                                          /* tp_descr_set */
    0,                                          /* tp_dictoffset */
    0,                                          /* tp_init */
    0,                                          /* tp_alloc */
    bytes_new,                                  /* tp_new */
    PyObject_Del,                               /* tp_free */
};

void
PyBytes_Concat(PyObject **pv, PyObject *w)
{
    assert(pv != NULL);
    if (*pv == NULL)
        return;
    if (w == NULL) {
        Py_CLEAR(*pv);
        return;
    }

    if (Py_REFCNT(*pv) == 1 && PyBytes_CheckExact(*pv)) {
        /* Only one reference, so we can resize in place */
        Py_ssize_t oldsize;
        Py_buffer wb;

        wb.len = -1;
        if (PyObject_GetBuffer(w, &wb, PyBUF_SIMPLE) != 0) {
            PyErr_Format(PyExc_TypeError, "can't concat %.100s to %.100s",
                         Py_TYPE(w)->tp_name, Py_TYPE(*pv)->tp_name);
            Py_CLEAR(*pv);
            return;
        }

        oldsize = PyBytes_GET_SIZE(*pv);
        if (oldsize > PY_SSIZE_T_MAX - wb.len) {
            PyErr_NoMemory();
            goto error;
        }
        if (_PyBytes_Resize(pv, oldsize + wb.len) < 0)
            goto error;

        memcpy(PyBytes_AS_STRING(*pv) + oldsize, wb.buf, wb.len);
        PyBuffer_Release(&wb);
        return;

      error:
        PyBuffer_Release(&wb);
        Py_CLEAR(*pv);
        return;
    }

    else {
        /* Multiple references, need to create new object */
        PyObject *v;
        v = bytes_concat(*pv, w);
        Py_DECREF(*pv);
        *pv = v;
    }
}

void
PyBytes_ConcatAndDel(PyObject **pv, PyObject *w)
{
    PyBytes_Concat(pv, w);
    Py_XDECREF(w);
}


/* The following function breaks the notion that bytes are immutable:
   it changes the size of a bytes object.  We get away with this only if there
   is only one module referencing the object.  You can also think of it
   as creating a new bytes object and destroying the old one, only
   more efficiently.  In any case, don't use this if the bytes object may
   already be known to some other part of the code...
   Note that if there's not enough memory to resize the bytes object, the
   original bytes object at *pv is deallocated, *pv is set to NULL, an "out of
   memory" exception is set, and -1 is returned.  Else (on success) 0 is
   returned, and the value in *pv may or may not be the same as on input.
   As always, an extra byte is allocated for a trailing \0 byte (newsize
   does *not* include that), and a trailing \0 byte is stored.
*/

int
_PyBytes_Resize(PyObject **pv, Py_ssize_t newsize)
{
    PyObject *v;
    PyBytesObject *sv;
    v = *pv;
    if (!PyBytes_Check(v) || Py_REFCNT(v) != 1 || newsize < 0) {
        *pv = 0;
        Py_DECREF(v);
        PyErr_BadInternalCall();
        return -1;
    }
    /* XXX UNREF/NEWREF interface should be more symmetrical */
    _Py_DEC_REFTOTAL;
    _Py_ForgetReference(v);
    *pv = (PyObject *)
        PyObject_REALLOC(v, PyBytesObject_SIZE + newsize);
    if (*pv == NULL) {
        PyObject_Del(v);
        PyErr_NoMemory();
        return -1;
    }
    _Py_NewReference(*pv);
    sv = (PyBytesObject *) *pv;
    Py_SIZE(sv) = newsize;
    sv->ob_sval[newsize] = '\0';
    sv->ob_shash = -1;          /* invalidate cached hash value */
    return 0;
}

void
PyBytes_Fini(void)
{
    int i;
    for (i = 0; i < UCHAR_MAX + 1; i++)
        Py_CLEAR(characters[i]);
    Py_CLEAR(nullstring);
}

/*********************** Bytes Iterator ****************************/

typedef struct {
    PyObject_HEAD
    Py_ssize_t it_index;
    PyBytesObject *it_seq; /* Set to NULL when iterator is exhausted */
} striterobject;

static void
striter_dealloc(striterobject *it)
{
    _PyObject_GC_UNTRACK(it);
    Py_XDECREF(it->it_seq);
    PyObject_GC_Del(it);
}

static int
striter_traverse(striterobject *it, visitproc visit, void *arg)
{
    Py_VISIT(it->it_seq);
    return 0;
}

static PyObject *
striter_next(striterobject *it)
{
    PyBytesObject *seq;
    PyObject *item;

    assert(it != NULL);
    seq = it->it_seq;
    if (seq == NULL)
        return NULL;
    assert(PyBytes_Check(seq));

    if (it->it_index < PyBytes_GET_SIZE(seq)) {
        item = PyLong_FromLong(
            (unsigned char)seq->ob_sval[it->it_index]);
        if (item != NULL)
            ++it->it_index;
        return item;
    }

    Py_DECREF(seq);
    it->it_seq = NULL;
    return NULL;
}

static PyObject *
striter_len(striterobject *it)
{
    Py_ssize_t len = 0;
    if (it->it_seq)
        len = PyBytes_GET_SIZE(it->it_seq) - it->it_index;
    return PyLong_FromSsize_t(len);
}

PyDoc_STRVAR(length_hint_doc,
             "Private method returning an estimate of len(list(it)).");

static PyObject *
striter_reduce(striterobject *it)
{
    if (it->it_seq != NULL) {
        return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
                             it->it_seq, it->it_index);
    } else {
        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
        if (u == NULL)
            return NULL;
        return Py_BuildValue("N(N)", _PyObject_GetBuiltin("iter"), u);
    }
}

PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");

static PyObject *
striter_setstate(striterobject *it, PyObject *state)
{
    Py_ssize_t index = PyLong_AsSsize_t(state);
    if (index == -1 && PyErr_Occurred())
        return NULL;
    if (it->it_seq != NULL) {
        if (index < 0)
            index = 0;
        else if (index > PyBytes_GET_SIZE(it->it_seq))
            index = PyBytes_GET_SIZE(it->it_seq); /* iterator exhausted */
        it->it_index = index;
    }
    Py_RETURN_NONE;
}

PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");

static PyMethodDef striter_methods[] = {
    {"__length_hint__", (PyCFunction)striter_len, METH_NOARGS,
     length_hint_doc},
    {"__reduce__",      (PyCFunction)striter_reduce, METH_NOARGS,
     reduce_doc},
    {"__setstate__",    (PyCFunction)striter_setstate, METH_O,
     setstate_doc},
    {NULL,              NULL}           /* sentinel */
};

PyTypeObject PyBytesIter_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "bytes_iterator",                           /* tp_name */
    sizeof(striterobject),                      /* tp_basicsize */
    0,                                          /* tp_itemsize */
    /* methods */
    (destructor)striter_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 */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    0,                                          /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
    0,                                          /* tp_doc */
    (traverseproc)striter_traverse,     /* tp_traverse */
    0,                                          /* tp_clear */
    0,                                          /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    PyObject_SelfIter,                          /* tp_iter */
    (iternextfunc)striter_next,                 /* tp_iternext */
    striter_methods,                            /* tp_methods */
    0,
};

static PyObject *
bytes_iter(PyObject *seq)
{
    striterobject *it;

    if (!PyBytes_Check(seq)) {
        PyErr_BadInternalCall();
        return NULL;
    }
    it = PyObject_GC_New(striterobject, &PyBytesIter_Type);
    if (it == NULL)
        return NULL;
    it->it_index = 0;
    Py_INCREF(seq);
    it->it_seq = (PyBytesObject *)seq;
    _PyObject_GC_TRACK(it);
    return (PyObject *)it;
}