diff options
Diffstat (limited to 'src/backend/regex/regcomp.c')
| -rw-r--r-- | src/backend/regex/regcomp.c | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c index 3f0504789e6..6ae804034d4 100644 --- a/src/backend/regex/regcomp.c +++ b/src/backend/regex/regcomp.c @@ -1646,8 +1646,9 @@ freesrnode(struct vars * v, /* might be NULL */ freecnfa(&sr->cnfa); sr->flags = 0; - if (v != NULL) + if (v != NULL && v->treechain != NULL) { + /* we're still parsing, maybe we can reuse the subre */ sr->left = v->treefree; v->treefree = sr; } @@ -1693,6 +1694,20 @@ numst(struct subre * t, /* * markst - mark tree nodes as INUSE + * + * Note: this is a great deal more subtle than it looks. During initial + * parsing of a regex, all subres are linked into the treechain list; + * discarded ones are also linked into the treefree list for possible reuse. + * After we are done creating all subres required for a regex, we run markst() + * then cleanst(), which results in discarding all subres not reachable from + * v->tree. We then clear v->treechain, indicating that subres must be found + * by descending from v->tree. This changes the behavior of freesubre(): it + * will henceforth FREE() unwanted subres rather than sticking them into the + * treefree list. (Doing that any earlier would result in dangling links in + * the treechain list.) This all means that freev() will clean up correctly + * if invoked before or after markst()+cleanst(); but it would not work if + * called partway through this state conversion, so we mustn't error out + * in or between these two functions. */ static void markst(struct subre * t) @@ -1790,25 +1805,27 @@ newlacon(struct vars * v, int pos) { int n; + struct subre *newlacons; struct subre *sub; if (v->nlacons == 0) { - v->lacons = (struct subre *) MALLOC(2 * sizeof(struct subre)); n = 1; /* skip 0th */ - v->nlacons = 2; + newlacons = (struct subre *) MALLOC(2 * sizeof(struct subre)); } else { - v->lacons = (struct subre *) REALLOC(v->lacons, - (v->nlacons + 1) * sizeof(struct subre)); - n = v->nlacons++; + n = v->nlacons; + newlacons = (struct subre *) REALLOC(v->lacons, + (n + 1) * sizeof(struct subre)); } - if (v->lacons == NULL) + if (newlacons == NULL) { ERR(REG_ESPACE); return 0; } + v->lacons = newlacons; + v->nlacons = n + 1; sub = &v->lacons[n]; sub->begin = begin; sub->end = end; |