SID-02039: Problem with regex

Status:	Answered	TWiki version:		Perl version:
Category:		Server OS:		Last update:	10 years ago

Each time I try to view the SandBox web page: UniandesVBFPhenomenologyProject, the following error appears:

TWiki detected an internal error - please check your TWiki logs and webserver logs for more information.

Nested quantifiers in regex; marked by <-- HERE in m/\bTwistyContrib_1_2_C++ <-- HERE Program=(.+?)\b/

How can I check my Twiki logs or modify again the twiki?

-- Andres Florez - 2015-03-20

Discussion and Answer

Hello Andres,

I "fixed" it in TWiki:Sandbox.UniandesVBFPhenomenologyProject, but I'd rather call this a workaround. From the error message I guessed that the '++' is a problem, and by simply removing it the page shows ok. A '+' is a quantifier in Perl regexes, and two of them confuse Perl. Your web server's error log might show the module and line where the error occurs.

Old:

%TWISTY{id="1_2_C++Program"; ...

New:

%;TWISTY{id="1_2_CProgram" ...

So, if you can get rid of the '++' easily, that could be good enough.

However, I am far from understanding the problem fully. Most likely it is a bug. A very interesting symptom (do you experience this, too?): If I log in, the error disappears - if I log out again, the error reappears. Unfortunately I could not reproduce the error in the current development version (SVN TWiki), and I am not familiar with Twisty code. So, without a hint where this happens I seem to be lost.

-- Harald Jörg - 2015-03-20

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-- Peter Thoeny - 2015-12-03

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