Bug #41102 for MediaWiki-API: MediaWiki::API crashing

Thu Nov 20 14:17:43 2008 DCOLLINS [...] cpan.org - Ticket created

Subject:

MediaWiki::API crashing

A user reported the following bug: I see it's more than just tests: my bot dies after a timeout producing: Use of uninitialized value in length at /usr/local/share/perl/5.8.8/MediaWiki/API.pm line 271. Can't use an undefined value as a HASH reference at /usr/local/share/perl/5.8.8/ Perlwikipedia.pm line 364. ---- That's what I get when I try to execute code from "synopsis" in http://search.cpan.org/~exobuzz/MediaWiki-API-0.21/lib/ MediaWiki/API.pm (my version is 0.21, so the latest): Use of uninitialized value in length at /usr/local/share/perl/5.8.8/MediaWiki/API.pm line 282. 2: http://en.wikipedia.org/w/api.php returned a zero length string at ./testmwapi.pl line 8. ---- The bug was filed at http://code.google.com/p/perlwikipedia/issues/detail?id=13 and appears to be upstream.

Thu Nov 20 14:37:02 2008 buzz [...] exotica.org.uk - Correspondence added

Show quoted text

> That's what I get when I try to execute > code from "synopsis" in > http://search.cpan.org/~exobuzz/MediaWiki-API-0.21/lib/ > MediaWiki/API.pm (my version is 0.21, so the latest): > Use of uninitialized value in length at > /usr/local/share/perl/5.8.8/MediaWiki/API.pm > line 282. > 2: http://en.wikipedia.org/w/api.php returned a zero length string at > ./testmwapi.pl > line 8.

I am unable to reproduce this. Do you have some code which reproduces this error?. The line in question with (Use of uninitialized value in length at) means that $response->decoded_content is undefined. I don't actually check for this, because I assume that if $response->is_success is ok then there will be some decoded content (even if it is an empty string). I've done a search on the web and I found decoded_content: Returns the content with any Content-Encoding undone and the raw content encoded to perl's Unicode strings. If the Content-Encoding or charset of the message is unknown this method will fail by returning undef. so maybe I need to force this, but the charset/encoding shouldn't be unknown really if the web server is correctly configured. I should check this though and return a different error perhaps. might help to debug the problem. would be easier with some code which reproduces the problem though.

Thu Nov 20 14:37:04 2008 The RT System itself - Status changed from 'new' to 'open'

Thu Nov 20 14:57:42 2008 DCOLLINS [...] cpan.org - Correspondence added

The user reports that the code under synopsis in the POD causes the error. I'm guessing that it's a LWP::UserAgent or HTTP::Response error, feel free to send it to them.

Thu Nov 20 15:15:49 2008 buzz [...] exotica.org.uk - Correspondence added

On Thu Nov 20 14:57:42 2008, DCOLLINS wrote: Show quoted text

> The user reports that the code under synopsis in the POD causes the > error. I'm guessing that it's a LWP::UserAgent or HTTP::Response error, > feel free to send it to them.

Actually, the error they are having may be a different one. My code is somewhat broken in some cases I think. I'll fix it up.

Thu Nov 20 16:31:39 2008 buzz [...] exotica.org.uk - Severity Critical changed to Normal

Thu Nov 20 16:36:31 2008 buzz [...] exotica.org.uk - Correspondence added

I have uploaded a new version which should appear shortly. (or you can get it from http://malus.exotica.org.uk/~buzz/cpan/MediaWiki-API-0.22.tar.gz) The http error handling is much improved, as I had cut some corners a bit, but I believe the problem the user is having is down to a connectivity issue, or LWP problem. However, I have made some changes which might improve it for him, or at least give more information to the cause. This includes telling HTTP::Message to ignore character encoding when decoding content (since the JSON module will handle this and assume UTF-8) and also catching problems HTTP::Message might have when decoding. Please can you ask the user to try this version out and let me know how he gets on.

Fri Nov 21 10:29:47 2008 buzz [...] exotica.org.uk - Correspondence added

Well, this problem seems to have been fixed by the user in question. Setting to resolved

Fri Nov 21 10:29:50 2008 buzz [...] exotica.org.uk - Status changed from 'open' to 'resolved'