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Bug fix for UTF-8 encoding bug (buffer overrun) #541828.

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This commit is contained in:
Marc-André Lemburg 2002-04-10 20:36:13 +00:00
parent e3c764b6c2
commit 68e69338ae
1 changed files with 46 additions and 39 deletions
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85
Objects/unicodeobject.c
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@ -1172,85 +1172,92 @@ int utf8_encoding_error(const Py_UNICODE **source,
} }
#endif #endif
/* Allocation strategy: we default to Latin-1, then do one resize
whenever we hit an order boundary. The assumption is that
characters from higher orders usually occur often enough to warrant
this.
*/
PyObject *PyUnicode_EncodeUTF8(const Py_UNICODE *s, PyObject *PyUnicode_EncodeUTF8(const Py_UNICODE *s,
int size, int size,
const char *errors) const char *errors)
{ {
PyObject *v; PyObject *v;
char *p; char *p;
unsigned int cbAllocated = 2 * size;
unsigned int cbWritten = 0;
int i = 0; int i = 0;
int overalloc = 2;
int len;
/* Short-cut for emtpy strings */ /* Short-cut for emtpy strings */
if (size == 0) if (size == 0)
return PyString_FromStringAndSize(NULL, 0); return PyString_FromStringAndSize(NULL, 0);
/* We allocate 4 more bytes to have room for at least one full v = PyString_FromStringAndSize(NULL, overalloc * size);
UTF-8 sequence; saves a few cycles in the loop below */
v = PyString_FromStringAndSize(NULL, cbAllocated + 4);
if (v == NULL) if (v == NULL)
return NULL; return NULL;
p = PyString_AS_STRING(v); p = PyString_AS_STRING(v);
while (i < size) { while (i < size) {
Py_UCS4 ch = s[i++]; Py_UCS4 ch = s[i++];
if (ch < 0x80) { if (ch < 0x80)
/* Encode ASCII */
*p++ = (char) ch; *p++ = (char) ch;
cbWritten++;
}
else if (ch < 0x0800) { else if (ch < 0x0800) {
/* Encode Latin-1 */
*p++ = (char)(0xc0 | (ch >> 6)); *p++ = (char)(0xc0 | (ch >> 6));
*p++ = (char)(0x80 | (ch & 0x3f)); *p++ = (char)(0x80 | (ch & 0x3f));
cbWritten += 2;
} }
else { else {
/* Encode UCS2 Unicode ordinals */
/* Assure that we have enough room for high order Unicode
ordinals */
if (cbWritten >= cbAllocated) {
cbAllocated += 4 * 10;
if (_PyString_Resize(&v, cbAllocated + 4))
goto onError;
p = PyString_AS_STRING(v) + cbWritten;
}
if (ch < 0x10000) { if (ch < 0x10000) {
/* Check for high surrogate */
/* Special case: check for high surrogate */
if (0xD800 <= ch && ch <= 0xDBFF && i != size) { if (0xD800 <= ch && ch <= 0xDBFF && i != size) {
Py_UCS4 ch2 = s[i]; Py_UCS4 ch2 = s[i];
/* Check for low surrogate */ /* Check for low surrogate and combine the two to
form a UCS4 value */
if (0xDC00 <= ch2 && ch2 <= 0xDFFF) { if (0xDC00 <= ch2 && ch2 <= 0xDFFF) {
ch = ((ch - 0xD800) << 10 | (ch2 - 0xDC00)) + 0x00010000; ch = ((ch - 0xD800) << 10 | (ch2 - 0xDC00)) + 0x10000;
*p++ = (char)(0xf0 | (ch >> 18)); i++;
*p++ = (char)(0x80 | ((ch >> 12) & 0x3f)); goto encodeUCS4;
*p++ = (char)(0x80 | ((ch >> 6) & 0x3f));
*p++ = (char)(0x80 | (ch & 0x3f));
i++;
cbWritten += 4;
continue;
} }
/* Fall through: handles isolated high surrogates */ /* Fall through: handles isolated high surrogates */
} }
if (overalloc < 3) {
len = (int)(p - PyString_AS_STRING(v));
overalloc = 3;
if (_PyString_Resize(&v, overalloc * size))
goto onError;
p = PyString_AS_STRING(v) + len;
}
*p++ = (char)(0xe0 | (ch >> 12)); *p++ = (char)(0xe0 | (ch >> 12));
*p++ = (char)(0x80 | ((ch >> 6) & 0x3f)); *p++ = (char)(0x80 | ((ch >> 6) & 0x3f));
*p++ = (char)(0x80 | (ch & 0x3f)); *p++ = (char)(0x80 | (ch & 0x3f));
cbWritten += 3; continue;
} else {
*p++ = (char)(0xf0 | (ch>>18));
*p++ = (char)(0x80 | ((ch>>12) & 0x3f));
*p++ = (char)(0x80 | ((ch>>6) & 0x3f));
*p++ = (char)(0x80 | (ch & 0x3f));
cbWritten += 4;
} }
/* Encode UCS4 Unicode ordinals */
encodeUCS4:
if (overalloc < 4) {
len = (int)(p - PyString_AS_STRING(v));
overalloc = 4;
if (_PyString_Resize(&v, overalloc * size))
goto onError;
p = PyString_AS_STRING(v) + len;
}
*p++ = (char)(0xf0 | (ch >> 18));
*p++ = (char)(0x80 | ((ch >> 12) & 0x3f));
*p++ = (char)(0x80 | ((ch >> 6) & 0x3f));
*p++ = (char)(0x80 | (ch & 0x3f));
} }
} }
*p = '\0'; *p = '\0';
if (_PyString_Resize(&v, cbWritten)) if (_PyString_Resize(&v, (int)(p - PyString_AS_STRING(v))))
goto onError; goto onError;
return v; return v;