From e2bd904955e2221eddf01110b1f25002de2aaa83 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 18 Jul 2013 21:22:37 -0400 Subject: 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(-) (limited to 'src/backend/regex/regexec.c') diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c index 3748a9c1714..78ebdee39e4 100644 --- a/src/backend/regex/regexec.c +++ b/src/backend/regex/regexec.c @@ -487,19 +487,21 @@ 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; -- cgit v1.2.3