I’ve been meaning to write a Bugzilla extension to turn mentions of commits in bug messages into a link to view the commit via our web-based SVN viewer for ages – this morning I finally found the time to do it.

I needed to use the bug_format_comment hook to format comments as they’re being displayed, turning mentions of commits (e.g. “Commit 123” or “r123”) into links.

The code was pretty simple:

The following is in /var/lib/bugzilla3/extensions/LinkCommits/Extension.pm:

package Bugzilla::Extension::LinkCommits;
use strict;
use base qw(Bugzilla::Extension);

use constant NAME => 'LinkCommits';

our $VERSION = '0.1';

sub bug_format_comment {
    my ($self, $args) = @_;
   
    my $regexes = $args->{'regexes'};
    
    my $commit_match = qr/\b( (?:Commit|r) \s? (\d+) )/x;
    push(@$regexes, { match => $commit_match, replace => \&_link_commit });
}

sub _link_commit {
    my $args = shift;
    my $text      = $args->{matches}->[0];
    my $commitnum = $args->{matches}->[1];

    my $url = "http://warehouse.uk2.net/repolist/?diff=uk2&rev="
        . join ':', $commitnum - 1, $commitnum;
    return qq{$text};
};

# This must be the last line of your extension.
__PACKAGE__->NAME;

And that is about it. Hopefully this might be of use to someone. Bugzilla comes with a comprehensive Example extension which illustrates this along with various other hooks, but I suspect I’m not the only one looking to create a simple plugin to make tweaks to bug comments when displaying (like auto-linking to commits), so this might help someone.