Item14374: .changes file corruption on trunk.foswiki.org causes Use of Uninitialized Variable

Not sure of the root cause, but this needs to be a bit more robust.

The .changes file appears to be a hybrid of the old tabular format and the new JSON format.

?       LucasScott      1467981692      1       {"revision":"1","path":"Main.LucasScottLeftBar","topic":null,"verb":"insert","minor":null,"cuid":"LucasScott","time":1467981692}

And the resulting crash:

Use of uninitialized value in hash element at /var/www/trunk.foswiki.org/core/lib/Foswiki/UI/Changes.pm line 67.
 at /var/www/.plenv/versions/5.22.2/lib/perl5/site_perl/5.22.2/CGI/Carp.pm line 362.
   CGI::Carp::realdie("Use of uninitialized value in hash element at /var/www/trunk."...) called at /var/www/.plenv/versions/5.22.2/lib/perl5/site_perl/5.22.2/CGI/Carp.pm line 454
   CGI::Carp::die("Use of uninitialized value in hash element at /var/www/trunk."...) called at /var/www/trunk.foswiki.org/core/lib/AssertOn.pm line 15
   Assert::__ANON__("Use of uninitialized value in hash element at /var/www/trunk."...) called at /var/www/trunk.foswiki.org/core/lib/Foswiki/UI/Changes.pm line 67
   Foswiki::UI::Changes::changes(Foswiki=HASH(0x1ec6350)) called at /var/www/trunk.foswiki.org/core/lib/Foswiki/UI.pm line 378
   Foswiki::UI::__ANON__() called at /var/www/.plenv/versions/5.22.2/lib/perl5/site_perl/5.22.2/Error.pm line 421
   eval {...} called at /var/www/.plenv/versions/5.22.2/lib/perl5/site_perl/5.22.2/Error.pm line 413
   Error::subs::try(CODE(0x8476d0), HASH(0x1ec5d98)) called at /var/www/trunk.foswiki.org/core/lib/Foswiki/UI.pm line 504
   Foswiki::UI::_execute(Foswiki::Request=HASH(0x1e6c958), CODE(0x1ca6978), "changes", 1) called at /var/www/trunk.foswiki.org/core/lib/Foswiki/UI.pm line 330
   Foswiki::UI::handleRequest(Foswiki::Request=HASH(0x1e6c958)) called at /var/www/trunk.foswiki.org/core/lib/Foswiki/Engine/CGI.pm line 100
   Foswiki::Engine::CGI::run(Foswiki::Engine::CGI=HASH(0x16c6c50)) called at /var/www/trunk.foswiki.org/core/bin/changes line 31.

-- GeorgeClark - 09 Apr 2017

Confirming this as an issue in the tabular format of the .changes file. As this is only needed when sharing a store with Foswiki 1.x, I suspect we could just remove this compatibiblity feature in Foswiki 2.2 or 3

The issue is that eachChangeSince is returning some undefined fields when the .changes file is in tabular format:

$VAR1 = \{
            'cuid' => 'BaseUserMapping_333',
            'revision' => 1,
            'path' => 'Sandbox.FooBar',
            'topic' => undef,
            'more' => '{"minor":null,"path":"Sandbox.FooBar","time":1496450922,"cuid":"BaseUserMapping_333","revision":1,"verb":"insert","topic":null}',
            'time' => 1496450922,
            'verb' => 'insert',
            'user' => 'BaseUserMapping_333',
            'minor' => undef
          };

And the code is expecting that the topic => field is present, so that duplicate change records can be skipped.

-- GeorgeClark - 03 Jun 2017

This seems to be the fix.

diff --git a/RCSStoreContrib/lib/Foswiki/Store/Rcs/Handler.pm b/RCSStoreContrib/lib/Foswiki/Store/Rcs/Handler.pm
index 6768f84..fddb838 100644
--- a/RCSStoreContrib/lib/Foswiki/Store/Rcs/Handler.pm
+++ b/RCSStoreContrib/lib/Foswiki/Store/Rcs/Handler.pm
@@ -1639,6 +1639,12 @@ sub readChanges {
                 while ( my ( $k, $v ) = each %$decoded ) {
                     $row{$k} = $v;
                 }
+                if ( $row{path} && $row{path} =~ /^(.*)\.(.*)$/ ) {
+                    $row{topic} = $2;
+                }
+                elsif ( $row{oldpath} && $row{oldpath} =~ /^(.*)\.(.*)$/ ) {
+                    $row{topic} = $2;
+                }
                 $ok = 1;
             };
         }

-- GeorgeClark - 03 Jun 2017

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