From 03ee6591dd305613a22902fb777a192fe1970adc Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 7 Nov 2015 12:43:24 -0500 Subject: [PATCH] Fix enforcement of restrictions inside regexp lookaround constraints. Lookahead and lookbehind constraints aren't allowed to contain backrefs, and parentheses within them are always considered non-capturing. Or so says the manual. But the regexp parser forgot about these rules once inside a parenthesized subexpression, so that constructs like (\w)(?=(\1)) were accepted (but then not correctly executed --- a case like this acted like (\w)(?=\w), without any enforcement that the two \w's match the same text). And in (?=((foo))) the innermost parentheses would be counted as capturing parentheses, though no text would ever be captured for them. To fix, properly pass down the "type" argument to the recursive invocation of parse(). Back-patch to all supported branches; it was agreed that silent misexecution of such patterns is worse than throwing an error, even though new errors in minor releases are generally not desirable. --- src/backend/regex/regcomp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c index f4eebf84d7b..c7d43a766c2 100644 --- a/src/backend/regex/regcomp.c +++ b/src/backend/regex/regcomp.c @@ -943,7 +943,7 @@ parseqatom(struct vars * v, EMPTYARC(lp, s); EMPTYARC(s2, rp); NOERR(); - atom = parse(v, ')', PLAIN, s, s2); + atom = parse(v, ')', type, s, s2); assert(SEE(')') || ISERR()); NEXT(); NOERR();