cpython/Objects/stringlib/codecs.h

354 lines
11 KiB
C

/* 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 */