mirror of
https://github.com/python/cpython.git
synced 2025-11-03 19:34:08 +00:00
353 lines
11 KiB
C
353 lines
11 KiB
C
/* stringlib: codec implementations */
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#if STRINGLIB_IS_UNICODE
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/* Mask to check or force alignment of a pointer to C 'long' boundaries */
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#define LONG_PTR_MASK (size_t) (SIZEOF_LONG - 1)
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/* Mask to quickly check whether a C 'long' contains a
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non-ASCII, UTF8-encoded char. */
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#if (SIZEOF_LONG == 8)
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# define ASCII_CHAR_MASK 0x8080808080808080L
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#elif (SIZEOF_LONG == 4)
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# define ASCII_CHAR_MASK 0x80808080L
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#else
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# error C 'long' size should be either 4 or 8!
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#endif
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Py_LOCAL_INLINE(int)
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STRINGLIB(utf8_try_decode)(const char *start, const char *end,
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STRINGLIB_CHAR *dest,
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const char **src_pos, Py_ssize_t *dest_index)
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{
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int ret;
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Py_ssize_t n;
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const char *s = start;
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const char *aligned_end = (const char *) ((size_t) end & ~LONG_PTR_MASK);
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STRINGLIB_CHAR *p = dest;
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while (s < end) {
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Py_UCS4 ch = (unsigned char)*s;
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if (ch < 0x80) {
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/* Fast path for runs of ASCII characters. Given that common UTF-8
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input will consist of an overwhelming majority of ASCII
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characters, we try to optimize for this case by checking
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as many characters as a C 'long' can contain.
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First, check if we can do an aligned read, as most CPUs have
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a penalty for unaligned reads.
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*/
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if (!((size_t) s & LONG_PTR_MASK)) {
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/* Help register allocation */
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register const char *_s = s;
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register STRINGLIB_CHAR *_p = p;
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while (_s < aligned_end) {
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/* Read a whole long at a time (either 4 or 8 bytes),
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and do a fast unrolled copy if it only contains ASCII
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characters. */
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unsigned long value = *(unsigned long *) _s;
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if (value & ASCII_CHAR_MASK)
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break;
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_p[0] = _s[0];
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_p[1] = _s[1];
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_p[2] = _s[2];
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_p[3] = _s[3];
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#if (SIZEOF_LONG == 8)
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_p[4] = _s[4];
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_p[5] = _s[5];
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_p[6] = _s[6];
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_p[7] = _s[7];
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#endif
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_s += SIZEOF_LONG;
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_p += SIZEOF_LONG;
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}
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s = _s;
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p = _p;
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if (s == end)
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break;
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ch = (unsigned char)*s;
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}
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}
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if (ch < 0x80) {
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s++;
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*p++ = ch;
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continue;
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}
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n = utf8_code_length[ch];
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if (s + n > end) {
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/* unexpected end of data: the caller will decide whether
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it's an error or not */
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goto _error;
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}
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switch (n) {
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case 0:
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/* invalid start byte */
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goto _error;
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case 1:
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/* internal error */
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goto _error;
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case 2:
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if ((s[1] & 0xc0) != 0x80)
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/* invalid continuation byte */
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goto _error;
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ch = ((s[0] & 0x1f) << 6) + (s[1] & 0x3f);
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assert ((ch > 0x007F) && (ch <= 0x07FF));
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s += 2;
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*p++ = ch;
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break;
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case 3:
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/* Decoding UTF-8 sequences in range \xed\xa0\x80-\xed\xbf\xbf
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will result in surrogates in range d800-dfff. Surrogates are
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not valid UTF-8 so they are rejected.
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See http://www.unicode.org/versions/Unicode5.2.0/ch03.pdf
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(table 3-7) and http://www.rfc-editor.org/rfc/rfc3629.txt */
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if ((s[1] & 0xc0) != 0x80 ||
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(s[2] & 0xc0) != 0x80 ||
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((unsigned char)s[0] == 0xE0 &&
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(unsigned char)s[1] < 0xA0) ||
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((unsigned char)s[0] == 0xED &&
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(unsigned char)s[1] > 0x9F)) {
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/* invalid continuation byte */
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goto _error;
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}
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ch = ((s[0] & 0x0f) << 12) + ((s[1] & 0x3f) << 6) + (s[2] & 0x3f);
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assert ((ch > 0x07FF) && (ch <= 0xFFFF));
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s += 3;
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*p++ = ch;
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break;
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case 4:
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if ((s[1] & 0xc0) != 0x80 ||
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(s[2] & 0xc0) != 0x80 ||
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(s[3] & 0xc0) != 0x80 ||
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((unsigned char)s[0] == 0xF0 &&
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(unsigned char)s[1] < 0x90) ||
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((unsigned char)s[0] == 0xF4 &&
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(unsigned char)s[1] > 0x8F)) {
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/* invalid continuation byte */
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goto _error;
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}
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ch = ((s[0] & 0x7) << 18) + ((s[1] & 0x3f) << 12) +
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((s[2] & 0x3f) << 6) + (s[3] & 0x3f);
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assert ((ch > 0xFFFF) && (ch <= 0x10ffff));
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s += 4;
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*p++ = ch;
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break;
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}
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}
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ret = 0;
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goto _ok;
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_error:
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ret = -1;
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_ok:
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*src_pos = s;
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*dest_index = p - dest;
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return ret;
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}
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#undef LONG_PTR_MASK
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#undef ASCII_CHAR_MASK
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/* UTF-8 encoder specialized for a Unicode kind to avoid the slow
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PyUnicode_READ() macro. Delete some parts of the code depending on the kind:
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UCS-1 strings don't need to handle surrogates for example. */
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(utf8_encoder)(PyObject *unicode,
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STRINGLIB_CHAR *data,
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Py_ssize_t size,
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const char *errors)
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{
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#define MAX_SHORT_UNICHARS 300 /* largest size we'll do on the stack */
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Py_ssize_t i; /* index into s of next input byte */
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PyObject *result; /* result string object */
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char *p; /* next free byte in output buffer */
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Py_ssize_t nallocated; /* number of result bytes allocated */
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Py_ssize_t nneeded; /* number of result bytes needed */
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#if STRINGLIB_SIZEOF_CHAR > 1
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PyObject *errorHandler = NULL;
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PyObject *exc = NULL;
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PyObject *rep = NULL;
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#endif
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#if STRINGLIB_SIZEOF_CHAR == 1
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const Py_ssize_t max_char_size = 2;
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char stackbuf[MAX_SHORT_UNICHARS * 2];
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#elif STRINGLIB_SIZEOF_CHAR == 2
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const Py_ssize_t max_char_size = 3;
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char stackbuf[MAX_SHORT_UNICHARS * 3];
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#else /* STRINGLIB_SIZEOF_CHAR == 4 */
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const Py_ssize_t max_char_size = 4;
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char stackbuf[MAX_SHORT_UNICHARS * 4];
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#endif
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assert(size >= 0);
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if (size <= MAX_SHORT_UNICHARS) {
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/* Write into the stack buffer; nallocated can't overflow.
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* At the end, we'll allocate exactly as much heap space as it
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* turns out we need.
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*/
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nallocated = Py_SAFE_DOWNCAST(sizeof(stackbuf), size_t, int);
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result = NULL; /* will allocate after we're done */
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p = stackbuf;
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}
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else {
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if (size > PY_SSIZE_T_MAX / max_char_size) {
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/* integer overflow */
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return PyErr_NoMemory();
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}
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/* Overallocate on the heap, and give the excess back at the end. */
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nallocated = size * max_char_size;
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result = PyBytes_FromStringAndSize(NULL, nallocated);
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if (result == NULL)
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return NULL;
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p = PyBytes_AS_STRING(result);
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}
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for (i = 0; i < size;) {
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Py_UCS4 ch = data[i++];
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if (ch < 0x80) {
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/* Encode ASCII */
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*p++ = (char) ch;
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}
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else
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#if STRINGLIB_SIZEOF_CHAR > 1
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if (ch < 0x0800)
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#endif
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{
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/* Encode Latin-1 */
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*p++ = (char)(0xc0 | (ch >> 6));
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*p++ = (char)(0x80 | (ch & 0x3f));
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}
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#if STRINGLIB_SIZEOF_CHAR > 1
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else if (Py_UNICODE_IS_SURROGATE(ch)) {
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Py_ssize_t newpos;
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Py_ssize_t repsize, k, startpos;
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startpos = i-1;
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rep = unicode_encode_call_errorhandler(
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errors, &errorHandler, "utf-8", "surrogates not allowed",
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unicode, &exc, startpos, startpos+1, &newpos);
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if (!rep)
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goto error;
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if (PyBytes_Check(rep))
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repsize = PyBytes_GET_SIZE(rep);
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else
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repsize = PyUnicode_GET_LENGTH(rep);
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if (repsize > max_char_size) {
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Py_ssize_t offset;
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if (result == NULL)
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offset = p - stackbuf;
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else
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offset = p - PyBytes_AS_STRING(result);
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if (nallocated > PY_SSIZE_T_MAX - repsize + max_char_size) {
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/* integer overflow */
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PyErr_NoMemory();
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goto error;
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}
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nallocated += repsize - max_char_size;
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if (result != NULL) {
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if (_PyBytes_Resize(&result, nallocated) < 0)
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goto error;
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} else {
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result = PyBytes_FromStringAndSize(NULL, nallocated);
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if (result == NULL)
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goto error;
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Py_MEMCPY(PyBytes_AS_STRING(result), stackbuf, offset);
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}
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p = PyBytes_AS_STRING(result) + offset;
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}
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if (PyBytes_Check(rep)) {
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char *prep = PyBytes_AS_STRING(rep);
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for(k = repsize; k > 0; k--)
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*p++ = *prep++;
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} else /* rep is unicode */ {
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enum PyUnicode_Kind repkind;
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void *repdata;
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if (PyUnicode_READY(rep) < 0)
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goto error;
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repkind = PyUnicode_KIND(rep);
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repdata = PyUnicode_DATA(rep);
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for(k=0; k<repsize; k++) {
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Py_UCS4 c = PyUnicode_READ(repkind, repdata, k);
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if (0x80 <= c) {
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raise_encode_exception(&exc, "utf-8",
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unicode,
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i-1, i,
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"surrogates not allowed");
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goto error;
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}
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*p++ = (char)c;
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}
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}
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Py_CLEAR(rep);
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}
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else
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#if STRINGLIB_SIZEOF_CHAR > 2
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if (ch < 0x10000)
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#endif
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{
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*p++ = (char)(0xe0 | (ch >> 12));
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*p++ = (char)(0x80 | ((ch >> 6) & 0x3f));
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*p++ = (char)(0x80 | (ch & 0x3f));
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}
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#if STRINGLIB_SIZEOF_CHAR > 2
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else /* ch >= 0x10000 */
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{
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assert(ch <= MAX_UNICODE);
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/* Encode UCS4 Unicode ordinals */
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*p++ = (char)(0xf0 | (ch >> 18));
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*p++ = (char)(0x80 | ((ch >> 12) & 0x3f));
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*p++ = (char)(0x80 | ((ch >> 6) & 0x3f));
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*p++ = (char)(0x80 | (ch & 0x3f));
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}
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#endif /* STRINGLIB_SIZEOF_CHAR > 2 */
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#endif /* STRINGLIB_SIZEOF_CHAR > 1 */
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}
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if (result == NULL) {
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/* This was stack allocated. */
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nneeded = p - stackbuf;
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assert(nneeded <= nallocated);
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result = PyBytes_FromStringAndSize(stackbuf, nneeded);
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}
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else {
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/* Cut back to size actually needed. */
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nneeded = p - PyBytes_AS_STRING(result);
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assert(nneeded <= nallocated);
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_PyBytes_Resize(&result, nneeded);
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}
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#if STRINGLIB_SIZEOF_CHAR > 1
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Py_XDECREF(errorHandler);
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Py_XDECREF(exc);
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#endif
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return result;
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#if STRINGLIB_SIZEOF_CHAR > 1
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error:
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Py_XDECREF(rep);
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Py_XDECREF(errorHandler);
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Py_XDECREF(exc);
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Py_XDECREF(result);
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return NULL;
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#endif
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#undef MAX_SHORT_UNICHARS
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}
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#endif /* STRINGLIB_IS_UNICODE */
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