mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-04 08:59:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 11

More work on bug #672491 and patch #712900.

Browse source 
I've applied a modified version of Greg Chapman's patch. I've included
the fixes without introducing the reorganization mentioned, for the sake
of stability. Also, the second fix mentioned in the patch don't fix the
mentioned problem anymore, because of the change introduced by patch
#720991 (by Greg as well). The new fix wasn't complicated though, and is
included as well.

As a note. It seems that there are other places that require the
"protection" of LASTMARK_SAVE()/LASTMARK_RESTORE(), and are just waiting
for someone to find how to break them. Particularly, I belive that every
recursion of SRE_MATCH() should be protected by these macros. I won't
do that right now since I'm not completely sure about this, and we don't
have much time for testing until the next release.
This commit is contained in:
Gustavo Niemeyer 2003-04-20 07:35:44 +00:00
parent 48f3dcc93e
commit be733ee7fb
3 changed files with 45 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

61
Modules/_sre.c
View file

@ -337,19 +337,6 @@ mark_restore(SRE_STATE* state, int lo, int hi)
return 0;
}
static void
lastmark_restore(SRE_STATE *state, int lastmark)
{
if (state->lastmark > lastmark) {
memset(
state->mark + lastmark + 1, 0,
(state->lastmark - lastmark) * sizeof(void*)
);
state->lastmark = lastmark;
state->lastindex = (lastmark == 0) ? -1 : (lastmark-1)/2+1;
}
}
/* generate 8-bit version */
#define SRE_CHAR unsigned char
@ -690,6 +677,22 @@ SRE_INFO(SRE_STATE* state, SRE_CODE* pattern)
}
#endif
/* macros to preserve lastmark in case of backtracking */
#define LASTMARK_SAVE() \
do { \
lastmark = state->lastmark; \
lastindex = state->lastindex; \
} while (0)
#define LASTMARK_RESTORE() \
do { \
if (state->lastmark > lastmark) { \
memset(state->mark + lastmark + 1, 0, \
(state->lastmark - lastmark) * sizeof(void*)); \
state->lastmark = lastmark; \
state->lastindex = lastindex; \
} \
} while (0)
LOCAL(int)
SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
{
@ -700,7 +703,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
SRE_CHAR* ptr = state->ptr;
int i, count;
SRE_REPEAT* rp;
int lastmark;
int lastmark, lastindex;
SRE_CODE chr;
SRE_REPEAT rep; /* FIXME: <fl> allocate in STATE instead */
@ -927,7 +930,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
/* alternation */
/* <BRANCH> <0=skip> code <JUMP> ... <NULL> */
TRACE(("|%p|%p|BRANCH\n", pattern, ptr));
lastmark = state->lastmark;
LASTMARK_SAVE();
for (; pattern[0]; pattern += pattern[0]) {
if (pattern[1] == SRE_OP_LITERAL &&
(ptr >= end || (SRE_CODE) *ptr != pattern[2]))
@ -939,7 +942,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
i = SRE_MATCH(state, pattern + 1, level + 1);
if (i)
return i;
lastmark_restore(state, lastmark);
LASTMARK_RESTORE();
}
return 0;
@ -979,8 +982,11 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
/* tail is empty. we're finished */
state->ptr = ptr;
return 1;
}
} else if (pattern[pattern[0]] == SRE_OP_LITERAL) {
LASTMARK_SAVE();
if (pattern[pattern[0]] == SRE_OP_LITERAL) {
/* tail starts with a literal. skip positions where
the rest of the pattern cannot possibly match */
chr = pattern[pattern[0]+1];
@ -998,11 +1004,11 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
return i;
ptr--;
count--;
LASTMARK_RESTORE();
}
} else {
/* general case */
lastmark = state->lastmark;
while (count >= (int) pattern[1]) {
state->ptr = ptr;
i = SRE_MATCH(state, pattern + pattern[0], level + 1);
@ -1010,7 +1016,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
return i;
ptr--;
count--;
lastmark_restore(state, lastmark);
LASTMARK_RESTORE();
}
}
return 0;
@ -1055,7 +1061,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
/* general case */
int matchmax = ((int)pattern[2] == 65535);
int c;
lastmark = state->lastmark;
LASTMARK_SAVE();
while (matchmax || count <= (int) pattern[2]) {
state->ptr = ptr;
i = SRE_MATCH(state, pattern + pattern[0], level + 1);
@ -1065,13 +1071,13 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
c = SRE_COUNT(state, pattern+3, 1, level+1);
if (c < 0)
return c;
LASTMARK_RESTORE();
if (c == 0)
break;
assert(c == 1);
ptr++;
count++;
}
lastmark_restore(state, lastmark);
}
return 0;
@ -1113,6 +1119,8 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
TRACE(("|%p|%p|MAX_UNTIL %d\n", pattern, ptr, count));
LASTMARK_SAVE();
if (count < rp->pattern[1]) {
/* not enough matches */
rp->count = count;
@ -1122,6 +1130,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
return i;
rp->count = count - 1;
state->ptr = ptr;
LASTMARK_RESTORE();
return 0;
}
@ -1129,7 +1138,6 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
/* we may have enough matches, but if we can
match another item, do so */
rp->count = count;
lastmark = state->lastmark;
i = mark_save(state, 0, lastmark);
if (i < 0)
return i;
@ -1138,7 +1146,7 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
if (i)
return i;
i = mark_restore(state, 0, lastmark);
state->lastmark = lastmark;
LASTMARK_RESTORE();
if (i < 0)
return i;
rp->count = count - 1;
@ -1182,6 +1190,8 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
return 0;
}
LASTMARK_SAVE();
/* see if the tail matches */
state->repeat = rp->prev;
i = SRE_MATCH(state, pattern, level + 1);
@ -1191,6 +1201,8 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
state->ptr = ptr;
state->repeat = rp;
LASTMARK_RESTORE();
if (count >= rp->pattern[2] && rp->pattern[2] != 65535)
return 0;
@ -3084,3 +3096,6 @@ PyMODINIT_FUNC init_sre(void)
}
#endif /* !defined(SRE_RECURSIVE) */
/* vim:ts=4:sw=4:et
*/