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Fix low-probability memory leak in regex execution.

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After an internal failure in shortest() or longest() while pinning down the
exact location of a match, find() forgot to free the DFA structure before
returning.  This is pretty unlikely to occur, since we just successfully
ran the "search" variant of the DFA; but it could happen, and it would
result in a session-lifespan memory leak since this code uses malloc()
directly.  Problem seems to have been aboriginal in Spencer's library,
so back-patch all the way.

In passing, correct a thinko in a comment I added awhile back about the
meaning of the "ntree" field.

I happened across these issues while comparing our code to Tcl's version
of the library.
This commit is contained in:
Tom Lane
2015-09-18 13:55:17 -04:00
parent e8e2999470
commit a39331fa57
3 changed files with 7 additions and 3 deletions
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2
src/backend/regex/regcomp.c
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@ -228,7 +228,7 @@ struct vars
struct subre *tree; /* subexpression tree */
struct subre *treechain; /* all tree nodes allocated */
struct subre *treefree; /* any free tree nodes */
int ntree; /* number of tree nodes */
int ntree; /* number of tree nodes, plus one */
struct cvec *cv; /* interface cvec */
struct cvec *cv2; /* utility cvec */
struct subre *lacons; /* lookahead-constraint vector */