bytesobject.c

/* bytes object implementation */

#define PY_SSIZE_T_CLEAN

#include "Python.h"

#include "bytes_methods.h"
#include <stddef.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()).
*/
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 == 0 && (op = nullstring) != NULL) {
#ifdef COUNT_ALLOCS
        null_strings++;
#endif
        Py_INCREF(op);
        return (PyObject *)op;
    }
    if (size == 1 && str != NULL &&
        (op = characters[*str & UCHAR_MAX]) != NULL)
    {
#ifdef COUNT_ALLOCS
        one_strings++;
#endif
        Py_INCREF(op);
        return (PyObject *)op;
    }

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

    /* 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;
    if (str != NULL)
        Py_MEMCPY(op->ob_sval, str, size);
    op->ob_sval[size] = '\0';
    /* share short strings */
    if (size == 0) {
        nullstring = op;
        Py_INCREF(op);
    } else if (size == 1 && str != NULL) {
        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;
}

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;
    /* Check for integer overflow */
    if (recode_encoding && (len > PY_SSIZE_T_MAX / 4)) {
        PyErr_SetString(PyExc_OverflowError, "string is too large");
        return NULL;
    }
    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_TypeError,
                        "expected bytes with no null");
        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;
    int rc;

    /* Make sure both arguments are strings. */
    if (!(PyBytes_Check(a) && PyBytes_Check(b))) {
        if (Py_BytesWarningFlag && (op == Py_EQ || op == Py_NE)) {
            rc = PyObject_IsInstance((PyObject*)a,
                                     (PyObject*)&PyUnicode_Type);
            if (!rc)
                rc = PyObject_IsInstance((PyObject*)b,
                                         (PyObject*)&PyUnicode_Type);
            if (rc < 0)
                return NULL;
            if (rc) {
                if (PyErr_WarnEx(PyExc_BytesWarning,
                                 "Comparison between bytes and string", 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, 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,
};