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Simplify memory management for regex DFAs a little.

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Coverity complained that functions in regexec.c might leak DFA
storage.  It's wrong, but this logic is confusing enough that it's
not so surprising Coverity couldn't make sense of it.  Rewrite
in hopes of making it more legible to humans as well as machines.
This commit is contained in:
Tom Lane
2021-02-21 20:29:11 -05:00
parent 6ee479abfc
commit 190c79884a
2 changed files with 13 additions and 11 deletions
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18
src/backend/regex/rege_dfa.c
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@@ -499,7 +499,7 @@ newdfa(struct vars *v,
struct dfa *d;
size_t nss = cnfa->nstates * 2;
int wordsper = (cnfa->nstates + UBITS - 1) / UBITS;
struct smalldfa *smallwas = sml;
bool ismalloced = false;
assert(cnfa != NULL && cnfa->nstates != 0);
@@ -514,6 +514,7 @@ newdfa(struct vars *v,
ERR(REG_ESPACE);
return NULL;
}
ismalloced = true;
}
d = &sml->dfa;
d->ssets = sml->ssets;
@@ -521,8 +522,8 @@ newdfa(struct vars *v,
d->work = &d->statesarea[nss];
d->outsarea = sml->outsarea;
d->incarea = sml->incarea;
d->cptsmalloced = 0;
d->mallocarea = (smallwas == NULL) ? (char *) sml : NULL;
d->ismalloced = ismalloced;
d->arraysmalloced = false; /* not separately allocated, anyway */
}
else
{
@@ -540,8 +541,9 @@ newdfa(struct vars *v,
sizeof(struct sset *));
d->incarea = (struct arcp *) MALLOC(nss * cnfa->ncolors *
sizeof(struct arcp));
d->cptsmalloced = 1;
d->mallocarea = (char *) d;
d->ismalloced = true;
d->arraysmalloced = true;
/* now freedfa() will behave sanely */
if (d->ssets == NULL || d->statesarea == NULL ||
d->outsarea == NULL || d->incarea == NULL)
{
@@ -573,7 +575,7 @@ newdfa(struct vars *v,
static void
freedfa(struct dfa *d)
{
if (d->cptsmalloced)
if (d->arraysmalloced)
{
if (d->ssets != NULL)
FREE(d->ssets);
@@ -585,8 +587,8 @@ freedfa(struct dfa *d)
FREE(d->incarea);
}
if (d->mallocarea != NULL)
FREE(d->mallocarea);
if (d->ismalloced)
FREE(d);
}
/*