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gh-152026: Track mark-saving contexts with a counter #153160

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Merged
serhiy-storchaka merged 1 commit into from
Jul 6, 2026
+41 −38
Merged

gh-152026: Track mark-saving contexts with a counter #153160

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1 change: 1 addition & 0 deletions Modules/_sre/sre.c
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Original file line number Diff line number Diff line change
Expand Up @@ -738,6 +738,7 @@ state_init(SRE_STATE* state, PatternObject* pattern, PyObject* string,
state->charsize = charsize;
state->match_all = 0;
state->must_advance = 0;
state->save_marks = 0;
state->debug = ((pattern->flags & SRE_FLAG_DEBUG) != 0);

state->beginning = ptr;
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4 changes: 4 additions & 0 deletions Modules/_sre/sre.h
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,10 @@ typedef struct {
int lastmark;
int lastindex;
const void** mark;
int save_marks; /* if nonzero, save and restore mark values on
backtracking instead of only rewinding the lastmark
index; counts enclosing repeat contexts and
possessive bodies */
/* dynamically allocated stuff */
char* data_stack;
size_t data_stack_size;
Expand Down
74 changes: 36 additions & 38 deletions Modules/_sre/sre_lib.h
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Original file line number Diff line number Diff line change
Expand Up @@ -863,7 +863,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
/* <BRANCH> <0=skip> code <JUMP> ... <NULL> */
TRACE(("|%p|%p|BRANCH\n", pattern, ptr));
LASTMARK_SAVE();
if (state->repeat)
if (state->save_marks)
MARK_PUSH(ctx->lastmark);
for (; pattern[0]; pattern += pattern[0]) {
if (pattern[1] == SRE_OP_LITERAL &&
Expand All @@ -878,16 +878,16 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
state->ptr = ptr;
DO_JUMP(JUMP_BRANCH, jump_branch, pattern+1);
if (ret) {
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_KEEP(ctx->lastmark);
LASTMARK_RESTORE();
}
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_FAILURE;

Expand Down Expand Up @@ -933,7 +933,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
}

LASTMARK_SAVE();
if (state->repeat)
if (state->save_marks)
MARK_PUSH(ctx->lastmark);

if (pattern[pattern[0]] == SRE_OP_LITERAL) {
Expand All @@ -952,19 +952,19 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
DO_JUMP(JUMP_REPEAT_ONE_1, jump_repeat_one_1,
pattern+pattern[0]);
if (ret) {
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_KEEP(ctx->lastmark);
LASTMARK_RESTORE();

ptr--;
ctx->count--;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
} else {
/* general case */
Expand All @@ -973,19 +973,19 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
DO_JUMP(JUMP_REPEAT_ONE_2, jump_repeat_one_2,
pattern+pattern[0]);
if (ret) {
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_KEEP(ctx->lastmark);
LASTMARK_RESTORE();

ptr--;
ctx->count--;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
}
RETURN_FAILURE;
Expand Down Expand Up @@ -1035,7 +1035,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
} else {
/* general case */
LASTMARK_SAVE();
if (state->repeat)
if (state->save_marks)
MARK_PUSH(ctx->lastmark);

while ((Py_ssize_t)pattern[2] == SRE_MAXREPEAT
Expand All @@ -1044,12 +1044,12 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
DO_JUMP(JUMP_MIN_REPEAT_ONE,jump_min_repeat_one,
pattern+pattern[0]);
if (ret) {
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_KEEP(ctx->lastmark);
LASTMARK_RESTORE();

Expand All @@ -1063,7 +1063,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
ptr++;
ctx->count++;
}
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
}
RETURN_FAILURE;
Expand Down Expand Up @@ -1140,10 +1140,12 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
ctx->u.rep->prev = state->repeat;
ctx->u.rep->last_ptr = NULL;
state->repeat = ctx->u.rep;
state->save_marks++;

state->ptr = ptr;
DO_JUMP(JUMP_REPEAT, jump_repeat, pattern+pattern[0]);
state->repeat = ctx->u.rep->prev;
state->save_marks--;
repeat_pool_free(state, ctx->u.rep);

if (ret) {
Expand Down Expand Up @@ -1212,8 +1214,10 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
/* cannot match more repeated items here. make sure the
tail matches */
state->repeat = ctx->u.rep->prev;
state->save_marks--;
DO_JUMP(JUMP_MAX_UNTIL_3, jump_max_until_3, pattern);
state->repeat = ctx->u.rep; // restore repeat before return
state->save_marks++;

RETURN_ON_SUCCESS(ret);
state->ptr = ptr;
Expand Down Expand Up @@ -1250,22 +1254,26 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)

/* see if the tail matches */
state->repeat = ctx->u.rep->prev;
state->save_marks--;

LASTMARK_SAVE();
if (state->repeat)
if (state->save_marks)
MARK_PUSH(ctx->lastmark);

DO_JUMP(JUMP_MIN_UNTIL_2, jump_min_until_2, pattern);
SRE_REPEAT *repeat_of_tail = state->repeat;
/* save_marks is balanced across the jump, so this equals the
value tested for MARK_PUSH above */
int pushed = state->save_marks != 0;
state->repeat = ctx->u.rep; // restore repeat before return
state->save_marks++;

if (ret) {
if (repeat_of_tail)
if (pushed)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_ON_ERROR(ret);
RETURN_SUCCESS;
}
if (repeat_of_tail)
if (pushed)
MARK_POP(ctx->lastmark);
LASTMARK_RESTORE();

Expand Down Expand Up @@ -1302,16 +1310,10 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
pointer */
state->ptr = ptr;

/* Set state->repeat to non-NULL */
ctx->u.rep = repeat_pool_malloc(state);
if (!ctx->u.rep) {
RETURN_ERROR(SRE_ERROR_MEMORY);
}
ctx->u.rep->count = -1;
ctx->u.rep->pattern = NULL;
ctx->u.rep->prev = state->repeat;
ctx->u.rep->last_ptr = NULL;
state->repeat = ctx->u.rep;
/* Capture groups in the body can be revisited on backtracking
between iterations, so their marks must be saved and restored,
as is done inside a repeat. */
state->save_marks++;

/* Initialize Count to 0 */
ctx->count = 0;
Expand All @@ -1327,9 +1329,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
}
else {
state->ptr = ptr;
/* Restore state->repeat */
state->repeat = ctx->u.rep->prev;
repeat_pool_free(state, ctx->u.rep);
state->save_marks--;
RETURN_FAILURE;
}
}
Expand Down Expand Up @@ -1402,9 +1402,7 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
}
}

/* Restore state->repeat */
state->repeat = ctx->u.rep->prev;
repeat_pool_free(state, ctx->u.rep);
state->save_marks--;

/* Evaluate Tail */
/* Jump to end of pattern indicated by skip, and then skip
Expand Down Expand Up @@ -1586,17 +1584,17 @@ SRE(match)(SRE_STATE* state, const SRE_CODE* pattern, int toplevel)
if ((uintptr_t)(ptr - (SRE_CHAR *)state->beginning) >= pattern[1]) {
state->ptr = ptr - pattern[1];
LASTMARK_SAVE();
if (state->repeat)
if (state->save_marks)
MARK_PUSH(ctx->lastmark);

DO_JUMP0(JUMP_ASSERT_NOT, jump_assert_not, pattern+2);
if (ret) {
if (state->repeat)
if (state->save_marks)
MARK_POP_DISCARD(ctx->lastmark);
RETURN_ON_ERROR(ret);
RETURN_FAILURE;
}
if (state->repeat)
if (state->save_marks)
MARK_POP(ctx->lastmark);
LASTMARK_RESTORE();
}
Expand Down
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