1 files changed, 77 insertions, 0 deletions
diff --git a/IkiWiki/Plugin/404.pm b/IkiWiki/Plugin/404.pm
new file mode 100644
index 000000000..5550ea7d1
--- /dev/null
+++ b/IkiWiki/Plugin/404.pm
@@ -0,0 +1,77 @@
+#!/usr/bin/perl
+# Copyright © 2009 Simon McVittie <http://smcv.pseudorandom.co.uk/>
+# Licensed under the GNU GPL, version 2, or any later version published by the
+# Free Software Foundation
+package IkiWiki::Plugin::404;
+
+use warnings;
+use strict;
+use IkiWiki 3.00;
+
+sub import {
+	hook(type => "cgi", id => '404',  call => \&cgi);
+	IkiWiki::loadplugin("goto");
+}
+
+sub getsetup () {
+	return
+		plugin => {
+			# not really a matter of safety, but enabling/disabling
+			# through a web interface is useless - it needs web
+			# server admin action too
+			safe => 0,
+			rebuild => 0,
+		}
+}
+
+sub cgi_page_from_404 ($$$) {
+	my $path = shift;
+	my $baseurl = shift;
+	my $usedirs = shift;
+
+	# fail if missing from environment or whatever
+	return undef unless defined $path;
+	return undef unless defined $baseurl;
+
+	# with usedirs on, path is like /~fred/foo/bar/ or /~fred/foo/bar or
+	#    /~fred/foo/bar/index.html
+	# with usedirs off, path is like /~fred/foo/bar.html
+	# baseurl is like 'http://people.example.com/~fred'
+
+	# convert baseurl to ~fred
+	unless ($baseurl =~ s{^https?://[^/]+/?}{}) {
+		return undef;
+	}
+
+	# convert path to /~fred/foo/bar
+	if ($usedirs) {
+		$path =~ s/\/*(?:index\.$config{htmlext})?$//;
+	}
+	else {
+		$path =~ s/\.$config{htmlext}$//;
+	}
+
+	# remove /~fred/
+	unless ($path =~ s{^/*\Q$baseurl\E/*}{}) {
+		return undef;
+	}
+
+	# special case for the index
+	unless ($path) {
+		return 'index';
+	}
+
+	return $path;
+}
+
+sub cgi ($) {
+	my $cgi=shift;
+
+	if ($ENV{REDIRECT_STATUS} eq '404') {
+		my $page = cgi_page_from_404($ENV{REDIRECT_URL},
+			$config{url}, $config{usedirs});
+		IkiWiki::Plugin::goto::cgi_goto($cgi, $page);
+	}
+}
+
+1;