From 1a8a3f64cedeb943062b9b2ae3412e9d66545ef1 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 18 Jul 2013 21:22:58 -0400 Subject: [PATCH] Fix regex match failures for backrefs combined with non-greedy quantifiers. An ancient logic error in cfindloop() could cause the regex engine to fail to find matches that begin later than the start of the string. This function is only used when the regex pattern contains a back reference, and so far as we can tell the error is only reachable if the pattern is non-greedy (i.e. its first quantifier uses the ? modifier). Furthermore, the actual match must begin after some potential match that satisfies the DFA but then fails the back-reference's match test. Reported and fixed by Jeevan Chalke, with cosmetic adjustments by me. --- src/backend/regex/regexec.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c index 8b462756e3..16cdd89757 100644 --- a/src/backend/regex/regexec.c +++ b/src/backend/regex/regexec.c @@ -464,19 +464,21 @@ cfindloop(struct vars * v, *coldp = cold; return er; } - if ((shorter) ? end == estop : end == begin) - { - /* no point in trying again */ - *coldp = cold; - return REG_NOMATCH; - } - /* go around and try again */ + /* try next shorter/longer match with same begin point */ if (shorter) + { + if (end == estop) + break; /* NOTE BREAK OUT */ estart = end + 1; + } else + { + if (end == begin) + break; /* NOTE BREAK OUT */ estop = end - 1; - } - } + } + } /* end loop over endpoint positions */ + } /* end loop over beginning positions */ } while (close < v->stop); *coldp = cold; -- 2.50.1