diff options
Diffstat (limited to 'Objects/stringlib/codecs.h')
| -rw-r--r-- | Objects/stringlib/codecs.h | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/Objects/stringlib/codecs.h b/Objects/stringlib/codecs.h new file mode 100644 index 0000000..e39948b --- /dev/null +++ b/Objects/stringlib/codecs.h @@ -0,0 +1,353 @@ +/* stringlib: codec implementations */ + +#if STRINGLIB_IS_UNICODE + +/* Mask to check or force alignment of a pointer to C 'long' boundaries */ +#define LONG_PTR_MASK (size_t) (SIZEOF_LONG - 1) + +/* Mask to quickly check whether a C 'long' contains a + non-ASCII, UTF8-encoded char. */ +#if (SIZEOF_LONG == 8) +# define ASCII_CHAR_MASK 0x8080808080808080L +#elif (SIZEOF_LONG == 4) +# define ASCII_CHAR_MASK 0x80808080L +#else +# error C 'long' size should be either 4 or 8! +#endif + +Py_LOCAL_INLINE(int) +STRINGLIB(utf8_try_decode)(const char *start, const char *end, + STRINGLIB_CHAR *dest, + const char **src_pos, Py_ssize_t *dest_index) +{ + int ret; + Py_ssize_t n; + const char *s = start; + const char *aligned_end = (const char *) ((size_t) end & ~LONG_PTR_MASK); + STRINGLIB_CHAR *p = dest; + + while (s < end) { + Py_UCS4 ch = (unsigned char)*s; + + if (ch < 0x80) { + /* Fast path for runs of ASCII characters. Given that common UTF-8 + input will consist of an overwhelming majority of ASCII + characters, we try to optimize for this case by checking + as many characters as a C 'long' can contain. + First, check if we can do an aligned read, as most CPUs have + a penalty for unaligned reads. + */ + if (!((size_t) s & LONG_PTR_MASK)) { + /* Help register allocation */ + register const char *_s = s; + register STRINGLIB_CHAR *_p = p; + while (_s < aligned_end) { + /* Read a whole long at a time (either 4 or 8 bytes), + and do a fast unrolled copy if it only contains ASCII + characters. */ + unsigned long value = *(unsigned long *) _s; + if (value & ASCII_CHAR_MASK) + break; + _p[0] = _s[0]; + _p[1] = _s[1]; + _p[2] = _s[2]; + _p[3] = _s[3]; +#if (SIZEOF_LONG == 8) + _p[4] = _s[4]; + _p[5] = _s[5]; + _p[6] = _s[6]; + _p[7] = _s[7]; +#endif + _s += SIZEOF_LONG; + _p += SIZEOF_LONG; + } + s = _s; + p = _p; + if (s == end) + break; + ch = (unsigned char)*s; + } + } + + if (ch < 0x80) { + s++; + *p++ = ch; + continue; + } + + n = utf8_code_length[ch]; + + if (s + n > end) { + /* unexpected end of data: the caller will decide whether + it's an error or not */ + goto _error; + } + + switch (n) { + case 0: + /* invalid start byte */ + goto _error; + case 1: + /* internal error */ + goto _error; + case 2: + if ((s[1] & 0xc0) != 0x80) + /* invalid continuation byte */ + goto _error; + ch = ((s[0] & 0x1f) << 6) + (s[1] & 0x3f); + assert ((ch > 0x007F) && (ch <= 0x07FF)); + s += 2; + *p++ = ch; + break; + + case 3: + /* Decoding UTF-8 sequences in range \xed\xa0\x80-\xed\xbf\xbf + will result in surrogates in range d800-dfff. Surrogates are + not valid UTF-8 so they are rejected. + See http://www.unicode.org/versions/Unicode5.2.0/ch03.pdf + (table 3-7) and http://www.rfc-editor.org/rfc/rfc3629.txt */ + if ((s[1] & 0xc0) != 0x80 || + (s[2] & 0xc0) != 0x80 || + ((unsigned char)s[0] == 0xE0 && + (unsigned char)s[1] < 0xA0) || + ((unsigned char)s[0] == 0xED && + (unsigned char)s[1] > 0x9F)) { + /* invalid continuation byte */ + goto _error; + } + ch = ((s[0] & 0x0f) << 12) + ((s[1] & 0x3f) << 6) + (s[2] & 0x3f); + assert ((ch > 0x07FF) && (ch <= 0xFFFF)); + s += 3; + *p++ = ch; + break; + + case 4: + if ((s[1] & 0xc0) != 0x80 || + (s[2] & 0xc0) != 0x80 || + (s[3] & 0xc0) != 0x80 || + ((unsigned char)s[0] == 0xF0 && + (unsigned char)s[1] < 0x90) || + ((unsigned char)s[0] == 0xF4 && + (unsigned char)s[1] > 0x8F)) { + /* invalid continuation byte */ + goto _error; + } + ch = ((s[0] & 0x7) << 18) + ((s[1] & 0x3f) << 12) + + ((s[2] & 0x3f) << 6) + (s[3] & 0x3f); + assert ((ch > 0xFFFF) && (ch <= 0x10ffff)); + s += 4; + *p++ = ch; + break; + } + } + ret = 0; + goto _ok; +_error: + ret = -1; +_ok: + *src_pos = s; + *dest_index = p - dest; + return ret; +} + +#undef LONG_PTR_MASK +#undef ASCII_CHAR_MASK + + +/* UTF-8 encoder specialized for a Unicode kind to avoid the slow + PyUnicode_READ() macro. Delete some parts of the code depending on the kind: + UCS-1 strings don't need to handle surrogates for example. */ +Py_LOCAL_INLINE(PyObject *) +STRINGLIB(utf8_encoder)(PyObject *unicode, + STRINGLIB_CHAR *data, + Py_ssize_t size, + const char *errors) +{ +#define MAX_SHORT_UNICHARS 300 /* largest size we'll do on the stack */ + + Py_ssize_t i; /* index into s of next input byte */ + PyObject *result; /* result string object */ + char *p; /* next free byte in output buffer */ + Py_ssize_t nallocated; /* number of result bytes allocated */ + Py_ssize_t nneeded; /* number of result bytes needed */ +#if STRINGLIB_SIZEOF_CHAR > 1 + PyObject *errorHandler = NULL; + PyObject *exc = NULL; + PyObject *rep = NULL; +#endif +#if STRINGLIB_SIZEOF_CHAR == 1 + const Py_ssize_t max_char_size = 2; + char stackbuf[MAX_SHORT_UNICHARS * 2]; +#elif STRINGLIB_SIZEOF_CHAR == 2 + const Py_ssize_t max_char_size = 3; + char stackbuf[MAX_SHORT_UNICHARS * 3]; +#else /* STRINGLIB_SIZEOF_CHAR == 4 */ + const Py_ssize_t max_char_size = 4; + char stackbuf[MAX_SHORT_UNICHARS * 4]; +#endif + + assert(size >= 0); + + if (size <= MAX_SHORT_UNICHARS) { + /* Write into the stack buffer; nallocated can't overflow. + * At the end, we'll allocate exactly as much heap space as it + * turns out we need. + */ + nallocated = Py_SAFE_DOWNCAST(sizeof(stackbuf), size_t, int); + result = NULL; /* will allocate after we're done */ + p = stackbuf; + } + else { + if (size > PY_SSIZE_T_MAX / max_char_size) { + /* integer overflow */ + return PyErr_NoMemory(); + } + /* Overallocate on the heap, and give the excess back at the end. */ + nallocated = size * max_char_size; + result = PyBytes_FromStringAndSize(NULL, nallocated); + if (result == NULL) + return NULL; + p = PyBytes_AS_STRING(result); + } + + for (i = 0; i < size;) { + Py_UCS4 ch = data[i++]; + + if (ch < 0x80) { + /* Encode ASCII */ + *p++ = (char) ch; + + } + else +#if STRINGLIB_SIZEOF_CHAR > 1 + if (ch < 0x0800) +#endif + { + /* Encode Latin-1 */ + *p++ = (char)(0xc0 | (ch >> 6)); + *p++ = (char)(0x80 | (ch & 0x3f)); + } +#if STRINGLIB_SIZEOF_CHAR > 1 + else if (Py_UNICODE_IS_SURROGATE(ch)) { + Py_ssize_t newpos; + Py_ssize_t repsize, k, startpos; + startpos = i-1; + rep = unicode_encode_call_errorhandler( + errors, &errorHandler, "utf-8", "surrogates not allowed", + unicode, &exc, startpos, startpos+1, &newpos); + if (!rep) + goto error; + + if (PyBytes_Check(rep)) + repsize = PyBytes_GET_SIZE(rep); + else + repsize = PyUnicode_GET_LENGTH(rep); + + if (repsize > max_char_size) { + Py_ssize_t offset; + + if (result == NULL) + offset = p - stackbuf; + else + offset = p - PyBytes_AS_STRING(result); + + if (nallocated > PY_SSIZE_T_MAX - repsize + max_char_size) { + /* integer overflow */ + PyErr_NoMemory(); + goto error; + } + nallocated += repsize - max_char_size; + if (result != NULL) { + if (_PyBytes_Resize(&result, nallocated) < 0) + goto error; + } else { + result = PyBytes_FromStringAndSize(NULL, nallocated); + if (result == NULL) + goto error; + Py_MEMCPY(PyBytes_AS_STRING(result), stackbuf, offset); + } + p = PyBytes_AS_STRING(result) + offset; + } + + if (PyBytes_Check(rep)) { + char *prep = PyBytes_AS_STRING(rep); + for(k = repsize; k > 0; k--) + *p++ = *prep++; + } else /* rep is unicode */ { + enum PyUnicode_Kind repkind; + void *repdata; + + if (PyUnicode_READY(rep) < 0) + goto error; + repkind = PyUnicode_KIND(rep); + repdata = PyUnicode_DATA(rep); + + for(k=0; k<repsize; k++) { + Py_UCS4 c = PyUnicode_READ(repkind, repdata, k); + if (0x80 <= c) { + raise_encode_exception(&exc, "utf-8", + unicode, + i-1, i, + "surrogates not allowed"); + goto error; + } + *p++ = (char)c; + } + } + Py_CLEAR(rep); + } + else +#if STRINGLIB_SIZEOF_CHAR > 2 + if (ch < 0x10000) +#endif + { + *p++ = (char)(0xe0 | (ch >> 12)); + *p++ = (char)(0x80 | ((ch >> 6) & 0x3f)); + *p++ = (char)(0x80 | (ch & 0x3f)); + } +#if STRINGLIB_SIZEOF_CHAR > 2 + else /* ch >= 0x10000 */ + { + assert(ch <= MAX_UNICODE); + /* Encode UCS4 Unicode ordinals */ + *p++ = (char)(0xf0 | (ch >> 18)); + *p++ = (char)(0x80 | ((ch >> 12) & 0x3f)); + *p++ = (char)(0x80 | ((ch >> 6) & 0x3f)); + *p++ = (char)(0x80 | (ch & 0x3f)); + } +#endif /* STRINGLIB_SIZEOF_CHAR > 2 */ +#endif /* STRINGLIB_SIZEOF_CHAR > 1 */ + } + + if (result == NULL) { + /* This was stack allocated. */ + nneeded = p - stackbuf; + assert(nneeded <= nallocated); + result = PyBytes_FromStringAndSize(stackbuf, nneeded); + } + else { + /* Cut back to size actually needed. */ + nneeded = p - PyBytes_AS_STRING(result); + assert(nneeded <= nallocated); + _PyBytes_Resize(&result, nneeded); + } + +#if STRINGLIB_SIZEOF_CHAR > 1 + Py_XDECREF(errorHandler); + Py_XDECREF(exc); +#endif + return result; + +#if STRINGLIB_SIZEOF_CHAR > 1 + error: + Py_XDECREF(rep); + Py_XDECREF(errorHandler); + Py_XDECREF(exc); + Py_XDECREF(result); + return NULL; +#endif + +#undef MAX_SHORT_UNICHARS +} + +#endif /* STRINGLIB_IS_UNICODE */ |