From c401b6958af7e12c1c2c46f870691bfb0a998fd3 Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Mon, 26 Jul 2010 16:24:17 -0400
Subject: [PATCH] Add new disable hook, allowing plugins to perform cleanup
 after they have been disabled.

---
 IkiWiki.pm                         | 17 ++++++++++-------
 IkiWiki/Plugin/skeleton.pm.example |  5 +++++
 IkiWiki/Setup.pm                   | 24 ++++++++++++++++++++++++
 debian/changelog                   |  2 ++
 doc/plugins/write.mdwn             |  7 +++++++
 5 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/IkiWiki.pm b/IkiWiki.pm
index cfa4f5f03..e08d02922 100644
--- a/IkiWiki.pm
+++ b/IkiWiki.pm
@@ -1596,6 +1596,12 @@ sub loadindex () {
 	if (exists $index->{version} && ! ref $index->{version}) {
 		$pages=$index->{page};
 		%wikistate=%{$index->{state}};
+		# Handle plugins that got disabled by loading a new setup.
+		if (exists $config{setupfile}) {
+			require IkiWiki::Setup;
+			IkiWiki::Setup::disabled_plugins(
+				grep { ! $loaded_plugins{$_} } keys %wikistate);
+		}
 	}
 	else {
 		$pages=$index;
@@ -1663,11 +1669,7 @@ sub loadindex () {
 sub saveindex () {
 	run_hooks(savestate => sub { shift->() });
 
-	my %hookids;
-	foreach my $type (keys %hooks) {
-		$hookids{$_}=1 foreach keys %{$hooks{$type}};
-	}
-	my @hookids=keys %hookids;
+	my @plugins=keys %loaded_plugins;
 
 	if (! -d $config{wikistatedir}) {
 		mkdir($config{wikistatedir});
@@ -1701,7 +1703,7 @@ sub saveindex () {
 		}
 
 		if (exists $pagestate{$page}) {
-			foreach my $id (@hookids) {
+			foreach my $id (@plugins) {
 				foreach my $key (keys %{$pagestate{$page}{$id}}) {
 					$index{page}{$src}{state}{$id}{$key}=$pagestate{$page}{$id}{$key};
 				}
@@ -1710,7 +1712,8 @@ sub saveindex () {
 	}
 
 	$index{state}={};
-	foreach my $id (@hookids) {
+	foreach my $id (@plugins) {
+		$index{state}{$id}={}; # used to detect disabled plugins
 		foreach my $key (keys %{$wikistate{$id}}) {
 			$index{state}{$id}{$key}=$wikistate{$id}{$key};
 		}
diff --git a/IkiWiki/Plugin/skeleton.pm.example b/IkiWiki/Plugin/skeleton.pm.example
index c3a3b0c01..a57a2c8fe 100644
--- a/IkiWiki/Plugin/skeleton.pm.example
+++ b/IkiWiki/Plugin/skeleton.pm.example
@@ -41,6 +41,7 @@ sub import {
 	hook(type => "rename", id => "skeleton", call => \&rename);
 	hook(type => "savestate", id => "skeleton", call => \&savestate);
 	hook(type => "genwrapper", id => "skeleton", call => \&genwrapper);
+	hook(type => "disable", id => "skeleton", call => \&disable);
 }
 
 sub getopt () {
@@ -254,4 +255,8 @@ sub genwrapper () {
 	debug("skeleton plugin running in genwrapper");
 }
 
+sub savestate () {
+	debug("skeleton plugin running in disable");
+}
+
 1
diff --git a/IkiWiki/Setup.pm b/IkiWiki/Setup.pm
index 7af744f6a..f34571bcf 100644
--- a/IkiWiki/Setup.pm
+++ b/IkiWiki/Setup.pm
@@ -124,6 +124,28 @@ sub merge ($) {
 	}
 }
 
+sub disabled_plugins (@) {
+	# Handles running disable hooks of plugins that were enabled
+	# previously, but got disabled when a new setup file was loaded.
+	if (exists $config{setupfile} && @_) {
+		# Fork a child to load the disabled plugins.
+		my $pid=fork();
+		if ($pid == 0) {
+			foreach my $plugin (@_) {
+				print STDERR "** plugin $plugin disabled\n";
+				eval { IkiWiki::loadplugin($plugin, 1) };
+				if (exists $IkiWiki::hooks{disable}{$plugin}{call}) {
+					eval { $IkiWiki::hooks{disable}{$plugin}{call}->() };
+				}
+			}
+			exit(0);
+		}
+		else {
+			waitpid $pid, 0;
+		}
+	}
+}
+
 sub getsetup () {
 	# Gets all available setup data from all plugins. Returns an
 	# ordered list of [plugin, setup] pairs.
@@ -134,6 +156,7 @@ sub getsetup () {
         $config{syslog}=undef;
 
 	# Load all plugins, so that all setup options are available.
+	my %original_loaded_plugins=%IkiWiki::loaded_plugins;
 	my @plugins=IkiWiki::listplugins();
 	foreach my $plugin (@plugins) {
 		eval { IkiWiki::loadplugin($plugin, 1) };
@@ -141,6 +164,7 @@ sub getsetup () {
 			my @s=eval { $IkiWiki::hooks{checkconfig}{$plugin}{call}->() };
 		}
 	}
+	%IkiWiki::loaded_plugins=%original_loaded_plugins;
 	
 	my %sections;
 	foreach my $plugin (@plugins) {
diff --git a/debian/changelog b/debian/changelog
index 167d02c6f..5645b34d4 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -6,6 +6,8 @@ ikiwiki (3.20100723) UNRELEASED; urgency=low
   * git: Fix gitweb historyurl examples so "diff to current" links work.
     (Thanks jrayhawk)
   * meta: Allow syntax closer to html meta to be used.
+  * Add new disable hook, allowing plugins to perform cleanup after they
+    have been disabled.
 
  -- Joey Hess <joeyh@debian.org>  Fri, 23 Jul 2010 14:00:32 -0400
 
diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 2e3902388..10b4df835 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -600,6 +600,13 @@ function of the ikiwiki wrapper when it is being generated.
 The code runs before anything else -- in particular it runs before
 the suid wrapper has sanitized its environment.
 
+### disable
+
+	hook(type => "disable", id => "foo", call => \&disable);
+
+This hook is only run when a previously enabled plugin gets disabled
+during ikiwiki setup. Plugins can use this to perform cleanups.
+
 ## Exported variables
 
 Several variables are exported to your plugin when you `use IkiWiki;`