Boost C++ Libraries: Ticket #7758: Regex will create stack error after upgrade of boost

attachment set

david.ecker@… — Mon, 03 Dec 2012 14:00:49 GMT

attachment → BoostRegexTest.cpp

cpp file

attachment set

david.ecker@… — Mon, 03 Dec 2012 14:04:04 GMT

attachment → Session.txt

Input File

david.ecker@… — Mon, 03 Dec 2012 14:13:37 GMT

I am testing using Visual Studio 2010, 64bit.

status changed; resolution set

John Maddock — Mon, 03 Dec 2012 16:56:19 GMT

status new → closed
resolution → invalid

The program throws a std::runtime_error because the match was taking too long to find - without a try-catch block around the code there is a stack error (I don't understand that one), but with a try-catch block the exception is caught and everything is behaving as expected.

Is there a reason for the leading .* in the expression? It serves no good purpose other than to make the expression harder to match - you can get the same information from match_results::prefix() and way better performance.

status changed; resolution deleted

david.ecker@… — Mon, 03 Dec 2012 20:59:12 GMT

status closed → reopened
resolution invalid

I haven't posted the whole code. Catching the exception is not really the problem. The user ist able to enter his own regex for a defined job. I just posted one as an example. With this regex he can describe what parts of the text are to be extracted or replaced or used further on.

The main problem is, that a whole bunch of different configured jobs exist, since it did work fast with boost 1.31. I can't really upgrade boost, because it will break existing user defined regex jobs.

anonymous — Tue, 04 Dec 2012 16:46:31 GMT

Investigating some more I believe you are correct - I'm testing a fix now (there's an optimization heuristic that's used almost everywhere else, but not for .* for some strange reason).

In the mean time, try building both Boost and your code with BOOST_REGEX_RECURSIVE defined as the issue doesn't occur in the stack-recursive implementation. Unfortunately, you should be aware that that implementation (with BOOST_REGEX_RECURSIVE defined) isn't really considered safe to use with VC10, as it's harder to safely trap stack overflows (and throw an exception) than it was in earlier Visual Studio releases. Of course nearly every other regex implementation out there is stack recursive and also has this issue...

status changed; resolution set

John Maddock — Tue, 04 Dec 2012 16:51:20 GMT

status reopened → closed
resolution → fixed

(In [81705]) Add missing optimization for leading .* repeats. Fixes #7758.