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cpython/Objects/stringlib/codecs.h

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/* stringlib: codec implementations */
#if STRINGLIB_IS_UNICODE
/* Mask to quickly check whether a C 'long' contains a
non-ASCII, UTF8-encoded char. */
#if (SIZEOF_LONG == 8)
# define ASCII_CHAR_MASK 0x8080808080808080UL
#elif (SIZEOF_LONG == 4)
# define ASCII_CHAR_MASK 0x80808080UL
#else
# error C 'long' size should be either 4 or 8!
#endif
/* 10xxxxxx */
#define IS_CONTINUATION_BYTE(ch) ((ch) >= 0x80 && (ch) < 0xC0)
Py_LOCAL_INLINE(Py_UCS4)
STRINGLIB(utf8_decode)(const char **inptr, const char *end,
STRINGLIB_CHAR *dest,
Py_ssize_t *outpos)
{
Py_UCS4 ch;
const char *s = *inptr;
const char *aligned_end = (const char *) _Py_ALIGN_DOWN(end, SIZEOF_LONG);
STRINGLIB_CHAR *p = dest + *outpos;
while (s < end) {
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 (_Py_IS_ALIGNED(s, SIZEOF_LONG)) {
/* 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;
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
_p[0] = (STRINGLIB_CHAR)(value & 0xFFu);
_p[1] = (STRINGLIB_CHAR)((value >> 8) & 0xFFu);
_p[2] = (STRINGLIB_CHAR)((value >> 16) & 0xFFu);
_p[3] = (STRINGLIB_CHAR)((value >> 24) & 0xFFu);
# if SIZEOF_LONG == 8
_p[4] = (STRINGLIB_CHAR)((value >> 32) & 0xFFu);
_p[5] = (STRINGLIB_CHAR)((value >> 40) & 0xFFu);
_p[6] = (STRINGLIB_CHAR)((value >> 48) & 0xFFu);
_p[7] = (STRINGLIB_CHAR)((value >> 56) & 0xFFu);
# endif
#else
# if SIZEOF_LONG == 8
_p[0] = (STRINGLIB_CHAR)((value >> 56) & 0xFFu);
_p[1] = (STRINGLIB_CHAR)((value >> 48) & 0xFFu);
_p[2] = (STRINGLIB_CHAR)((value >> 40) & 0xFFu);
_p[3] = (STRINGLIB_CHAR)((value >> 32) & 0xFFu);
_p[4] = (STRINGLIB_CHAR)((value >> 24) & 0xFFu);
_p[5] = (STRINGLIB_CHAR)((value >> 16) & 0xFFu);
_p[6] = (STRINGLIB_CHAR)((value >> 8) & 0xFFu);
_p[7] = (STRINGLIB_CHAR)(value & 0xFFu);
# else
_p[0] = (STRINGLIB_CHAR)((value >> 24) & 0xFFu);
_p[1] = (STRINGLIB_CHAR)((value >> 16) & 0xFFu);
_p[2] = (STRINGLIB_CHAR)((value >> 8) & 0xFFu);
_p[3] = (STRINGLIB_CHAR)(value & 0xFFu);
# endif
#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;
}
}
if (ch < 0xE0) {
/* \xC2\x80-\xDF\xBF -- 0080-07FF */
Py_UCS4 ch2;
if (ch < 0xC2) {
/* invalid sequence
\x80-\xBF -- continuation byte
\xC0-\xC1 -- fake 0000-007F */
goto InvalidStart;
}
if (end - s < 2) {
/* unexpected end of data: the caller will decide whether
it's an error or not */
break;
}
ch2 = (unsigned char)s[1];
if (!IS_CONTINUATION_BYTE(ch2))
/* invalid continuation byte */
goto InvalidContinuation1;
ch = (ch << 6) + ch2 -
((0xC0 << 6) + 0x80);
assert ((ch > 0x007F) && (ch <= 0x07FF));
s += 2;
if (STRINGLIB_MAX_CHAR <= 0x007F ||
(STRINGLIB_MAX_CHAR < 0x07FF && ch > STRINGLIB_MAX_CHAR))
/* Out-of-range */
goto Return;
*p++ = ch;
continue;
}
if (ch < 0xF0) {
/* \xE0\xA0\x80-\xEF\xBF\xBF -- 0800-FFFF */
Py_UCS4 ch2, ch3;
if (end - s < 3) {
/* unexpected end of data: the caller will decide whether
it's an error or not */
if (end - s < 2)
break;
ch2 = (unsigned char)s[1];
if (!IS_CONTINUATION_BYTE(ch2) ||
(ch2 < 0xA0 ? ch == 0xE0 : ch == 0xED))
/* for clarification see comments below */
goto InvalidContinuation1;
break;
}
ch2 = (unsigned char)s[1];
ch3 = (unsigned char)s[2];
if (!IS_CONTINUATION_BYTE(ch2)) {
/* invalid continuation byte */
goto InvalidContinuation1;
}
if (ch == 0xE0) {
if (ch2 < 0xA0)
/* invalid sequence
\xE0\x80\x80-\xE0\x9F\xBF -- fake 0000-0800 */
goto InvalidContinuation1;
} else if (ch == 0xED && ch2 >= 0xA0) {
/* 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 */
goto InvalidContinuation1;
}
if (!IS_CONTINUATION_BYTE(ch3)) {
/* invalid continuation byte */
goto InvalidContinuation2;
}
ch = (ch << 12) + (ch2 << 6) + ch3 -
((0xE0 << 12) + (0x80 << 6) + 0x80);
assert ((ch > 0x07FF) && (ch <= 0xFFFF));
s += 3;
if (STRINGLIB_MAX_CHAR <= 0x07FF ||
(STRINGLIB_MAX_CHAR < 0xFFFF && ch > STRINGLIB_MAX_CHAR))
/* Out-of-range */
goto Return;
*p++ = ch;
continue;
}
if (ch < 0xF5) {
/* \xF0\x90\x80\x80-\xF4\x8F\xBF\xBF -- 10000-10FFFF */
Py_UCS4 ch2, ch3, ch4;
if (end - s < 4) {
/* unexpected end of data: the caller will decide whether
it's an error or not */
if (end - s < 2)
break;
ch2 = (unsigned char)s[1];
if (!IS_CONTINUATION_BYTE(ch2) ||
(ch2 < 0x90 ? ch == 0xF0 : ch == 0xF4))
/* for clarification see comments below */
goto InvalidContinuation1;
if (end - s < 3)
break;
ch3 = (unsigned char)s[2];
if (!IS_CONTINUATION_BYTE(ch3))
goto InvalidContinuation2;
break;
}
ch2 = (unsigned char)s[1];
ch3 = (unsigned char)s[2];
ch4 = (unsigned char)s[3];
if (!IS_CONTINUATION_BYTE(ch2)) {
/* invalid continuation byte */
goto InvalidContinuation1;
}
if (ch == 0xF0) {
if (ch2 < 0x90)
/* invalid sequence
\xF0\x80\x80\x80-\xF0\x8F\xBF\xBF -- fake 0000-FFFF */
goto InvalidContinuation1;
} else if (ch == 0xF4 && ch2 >= 0x90) {
/* invalid sequence
\xF4\x90\x80\80- -- 110000- overflow */
goto InvalidContinuation1;
}
if (!IS_CONTINUATION_BYTE(ch3)) {
/* invalid continuation byte */
goto InvalidContinuation2;
}
if (!IS_CONTINUATION_BYTE(ch4)) {
/* invalid continuation byte */
goto InvalidContinuation3;
}
ch = (ch << 18) + (ch2 << 12) + (ch3 << 6) + ch4 -
((0xF0 << 18) + (0x80 << 12) + (0x80 << 6) + 0x80);
assert ((ch > 0xFFFF) && (ch <= 0x10FFFF));
s += 4;
if (STRINGLIB_MAX_CHAR <= 0xFFFF ||
(STRINGLIB_MAX_CHAR < 0x10FFFF && ch > STRINGLIB_MAX_CHAR))
/* Out-of-range */
goto Return;
*p++ = ch;
continue;
}
goto InvalidStart;
}
ch = 0;
Return:
*inptr = s;
*outpos = p - dest;
return ch;
InvalidStart:
ch = 1;
goto Return;
InvalidContinuation1:
ch = 2;
goto Return;
InvalidContinuation2:
ch = 3;
goto Return;
InvalidContinuation3:
ch = 4;
goto Return;
}
#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
}
/* The pattern for constructing UCS2-repeated masks. */
#if SIZEOF_LONG == 8
# define UCS2_REPEAT_MASK 0x0001000100010001ul
#elif SIZEOF_LONG == 4
# define UCS2_REPEAT_MASK 0x00010001ul
#else
# error C 'long' size should be either 4 or 8!
#endif
/* The mask for fast checking. */
#if STRINGLIB_SIZEOF_CHAR == 1
/* The mask for fast checking of whether a C 'long' contains a
non-ASCII or non-Latin1 UTF16-encoded characters. */
# define FAST_CHAR_MASK (UCS2_REPEAT_MASK * (0xFFFFu & ~STRINGLIB_MAX_CHAR))
#else
/* The mask for fast checking of whether a C 'long' may contain
UTF16-encoded surrogate characters. This is an efficient heuristic,
assuming that non-surrogate characters with a code point >= 0x8000 are
rare in most input.
*/
# define FAST_CHAR_MASK (UCS2_REPEAT_MASK * 0x8000u)
#endif
/* The mask for fast byte-swapping. */
#define STRIPPED_MASK (UCS2_REPEAT_MASK * 0x00FFu)
/* Swap bytes. */
#define SWAB(value) ((((value) >> 8) & STRIPPED_MASK) | \
(((value) & STRIPPED_MASK) << 8))
Py_LOCAL_INLINE(Py_UCS4)
STRINGLIB(utf16_decode)(const unsigned char **inptr, const unsigned char *e,
STRINGLIB_CHAR *dest, Py_ssize_t *outpos,
int native_ordering)
{
Py_UCS4 ch;
const unsigned char *aligned_end =
(const unsigned char *) _Py_ALIGN_DOWN(e, SIZEOF_LONG);
const unsigned char *q = *inptr;
STRINGLIB_CHAR *p = dest + *outpos;
/* Offsets from q for retrieving byte pairs in the right order. */
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
int ihi = !!native_ordering, ilo = !native_ordering;
#else
int ihi = !native_ordering, ilo = !!native_ordering;
#endif
--e;
while (q < e) {
Py_UCS4 ch2;
/* First check for possible aligned read of a C 'long'. Unaligned
reads are more expensive, better to defer to another iteration. */
if (_Py_IS_ALIGNED(q, SIZEOF_LONG)) {
/* Fast path for runs of in-range non-surrogate chars. */
register const unsigned char *_q = q;
while (_q < aligned_end) {
unsigned long block = * (unsigned long *) _q;
if (native_ordering) {
/* Can use buffer directly */
if (block & FAST_CHAR_MASK)
break;
}
else {
/* Need to byte-swap */
if (block & SWAB(FAST_CHAR_MASK))
break;
#if STRINGLIB_SIZEOF_CHAR == 1
block >>= 8;
#else
block = SWAB(block);
#endif
}
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
# if SIZEOF_LONG == 4
p[0] = (STRINGLIB_CHAR)(block & 0xFFFFu);
p[1] = (STRINGLIB_CHAR)(block >> 16);
# elif SIZEOF_LONG == 8
p[0] = (STRINGLIB_CHAR)(block & 0xFFFFu);
p[1] = (STRINGLIB_CHAR)((block >> 16) & 0xFFFFu);
p[2] = (STRINGLIB_CHAR)((block >> 32) & 0xFFFFu);
p[3] = (STRINGLIB_CHAR)(block >> 48);
# endif
#else
# if SIZEOF_LONG == 4
p[0] = (STRINGLIB_CHAR)(block >> 16);
p[1] = (STRINGLIB_CHAR)(block & 0xFFFFu);
# elif SIZEOF_LONG == 8
p[0] = (STRINGLIB_CHAR)(block >> 48);
p[1] = (STRINGLIB_CHAR)((block >> 32) & 0xFFFFu);
p[2] = (STRINGLIB_CHAR)((block >> 16) & 0xFFFFu);
p[3] = (STRINGLIB_CHAR)(block & 0xFFFFu);
# endif
#endif
_q += SIZEOF_LONG;
p += SIZEOF_LONG / 2;
}
q = _q;
if (q >= e)
break;
}
ch = (q[ihi] << 8) | q[ilo];
q += 2;
if (!Py_UNICODE_IS_SURROGATE(ch)) {
#if STRINGLIB_SIZEOF_CHAR < 2
if (ch > STRINGLIB_MAX_CHAR)
/* Out-of-range */
goto Return;
#endif
*p++ = (STRINGLIB_CHAR)ch;
continue;
}
/* UTF-16 code pair: */
if (q >= e)
goto UnexpectedEnd;
if (!Py_UNICODE_IS_HIGH_SURROGATE(ch))
goto IllegalEncoding;
ch2 = (q[ihi] << 8) | q[ilo];
q += 2;
if (!Py_UNICODE_IS_LOW_SURROGATE(ch2))
goto IllegalSurrogate;
ch = Py_UNICODE_JOIN_SURROGATES(ch, ch2);
#if STRINGLIB_SIZEOF_CHAR < 4
/* Out-of-range */
goto Return;
#else
*p++ = (STRINGLIB_CHAR)ch;
#endif
}
ch = 0;
Return:
*inptr = q;
*outpos = p - dest;
return ch;
UnexpectedEnd:
ch = 1;
goto Return;
IllegalEncoding:
ch = 2;
goto Return;
IllegalSurrogate:
ch = 3;
goto Return;
}
#undef UCS2_REPEAT_MASK
#undef FAST_CHAR_MASK
#undef STRIPPED_MASK
#undef SWAB
Py_LOCAL_INLINE(void)
STRINGLIB(utf16_encode)(unsigned short *out,
const STRINGLIB_CHAR *in,
Py_ssize_t len,
int native_ordering)
{
const STRINGLIB_CHAR *end = in + len;
#if STRINGLIB_SIZEOF_CHAR == 1
# define SWAB2(CH) ((CH) << 8)
#else
# define SWAB2(CH) (((CH) << 8) | ((CH) >> 8))
#endif
#if STRINGLIB_MAX_CHAR < 0x10000
if (native_ordering) {
# if STRINGLIB_SIZEOF_CHAR == 2
Py_MEMCPY(out, in, 2 * len);
# else
_PyUnicode_CONVERT_BYTES(STRINGLIB_CHAR, unsigned short, in, end, out);
# endif
} else {
const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
while (in < unrolled_end) {
out[0] = SWAB2(in[0]);
out[1] = SWAB2(in[1]);
out[2] = SWAB2(in[2]);
out[3] = SWAB2(in[3]);
in += 4; out += 4;
}
while (in < end) {
*out++ = SWAB2(*in);
++in;
}
}
#else
if (native_ordering) {
while (in < end) {
Py_UCS4 ch = *in++;
if (ch < 0x10000)
*out++ = ch;
else {
out[0] = Py_UNICODE_HIGH_SURROGATE(ch);
out[1] = Py_UNICODE_LOW_SURROGATE(ch);
out += 2;
}
}
} else {
while (in < end) {
Py_UCS4 ch = *in++;
if (ch < 0x10000)
*out++ = SWAB2((Py_UCS2)ch);
else {
Py_UCS2 ch1 = Py_UNICODE_HIGH_SURROGATE(ch);
Py_UCS2 ch2 = Py_UNICODE_LOW_SURROGATE(ch);
out[0] = SWAB2(ch1);
out[1] = SWAB2(ch2);
out += 2;
}
}
}
#endif
#undef SWAB2
}
#endif /* STRINGLIB_IS_UNICODE */
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