22 files changed, 2069 insertions, 37 deletions

diff --git a/IkiWiki.pm b/IkiWiki.pm
index 0cb3bf143..a11b330f2 100644
--- a/IkiWiki.pm
+++ b/IkiWiki.pm
@@ -1381,7 +1381,7 @@ sub check_content (@) {
 		foreach my $line (split("\n", $params{content})) {
 			push @diff, $line if ! exists $old{$_};
 		}
-		$params{content}=join("\n", @diff);
+		$params{diff}=join("\n", @diff);
 	}
 
 	my $ok;
diff --git a/IkiWiki/Plugin/blogspam.pm b/IkiWiki/Plugin/blogspam.pm
index da63d3edb..626c8ec42 100644
--- a/IkiWiki/Plugin/blogspam.pm
+++ b/IkiWiki/Plugin/blogspam.pm
@@ -88,7 +88,7 @@ sub checkcontent (@) {
 
 	my %req=(
 		ip => $ENV{REMOTE_ADDR},
-		comment => $params{content},
+		comment => defined $params{diff} ? $params{diff} : $params{content},
 		subject => defined $params{subject} ? $params{subject} : "",
 		name => defined $params{author} ? $params{author} : "",
 		link => exists $params{url} ? $params{url} : "",
diff --git a/IkiWiki/Plugin/google.pm b/IkiWiki/Plugin/google.pm
index 4bba5775c..1683220e7 100644
--- a/IkiWiki/Plugin/google.pm
+++ b/IkiWiki/Plugin/google.pm
@@ -24,7 +24,7 @@ sub getsetup () {
 
 sub checkconfig () {
 	if (! length $config{url}) {
-		error(sprintf(gettext("Must specify %s when using the google search plugin"), "url"));
+		error(sprintf(gettext("Must specify %s when using the %s plugin"), "url", 'google'));
 	}
 	my $uri=URI->new($config{url});
 	if (! $uri || ! defined $uri->host) {
diff --git a/IkiWiki/Plugin/parentlinks.pm b/IkiWiki/Plugin/parentlinks.pm
index ebf1d449a..1ee69cbff 100644
--- a/IkiWiki/Plugin/parentlinks.pm
+++ b/IkiWiki/Plugin/parentlinks.pm
@@ -36,7 +36,7 @@ sub parentlinks ($) {
 		$depth=$i;
 		$height=($pagedepth - $depth);
 		push @ret, {
-			url => urlto($path, $page),
+			url => urlto(bestlink($page, $path), $page),
 			page => $title,
 			depth => $depth,
 			height => $height,
diff --git a/IkiWiki/Plugin/po.pm b/IkiWiki/Plugin/po.pm
new file mode 100644
index 000000000..cdb9271e4
--- /dev/null
+++ b/IkiWiki/Plugin/po.pm
@@ -0,0 +1,1135 @@
+#!/usr/bin/perl
+# .po as a wiki page type
+# Licensed under GPL v2 or greater
+# Copyright (C) 2008-2009 intrigeri <intrigeri@boum.org>
+# inspired by the GPL'd po4a-translate,
+# which is Copyright 2002, 2003, 2004 by Martin Quinson (mquinson#debian.org)
+package IkiWiki::Plugin::po;
+
+use warnings;
+use strict;
+use IkiWiki 3.00;
+use Encode;
+use Locale::Po4a::Common qw(nowrapi18n);
+use Locale::Po4a::Chooser;
+use Locale::Po4a::Po;
+use File::Basename;
+use File::Copy;
+use File::Spec;
+use File::Temp;
+use Memoize;
+use UNIVERSAL;
+
+my %translations;
+my @origneedsbuild;
+my %origsubs;
+
+memoize("istranslatable");
+memoize("_istranslation");
+memoize("percenttranslated");
+
+sub import {
+	hook(type => "getsetup", id => "po", call => \&getsetup);
+	hook(type => "checkconfig", id => "po", call => \&checkconfig);
+	hook(type => "needsbuild", id => "po", call => \&needsbuild);
+	hook(type => "scan", id => "po", call => \&scan, last => 1);
+	hook(type => "filter", id => "po", call => \&filter);
+	hook(type => "htmlize", id => "po", call => \&htmlize);
+	hook(type => "pagetemplate", id => "po", call => \&pagetemplate, last => 1);
+	hook(type => "rename", id => "po", call => \&renamepages, first => 1);
+	hook(type => "delete", id => "po", call => \&mydelete);
+	hook(type => "change", id => "po", call => \&change);
+	hook(type => "checkcontent", id => "po", call => \&checkcontent);
+	hook(type => "canremove", id => "po", call => \&canremove);
+	hook(type => "canrename", id => "po", call => \&canrename);
+	hook(type => "editcontent", id => "po", call => \&editcontent);
+	hook(type => "formbuilder_setup", id => "po", call => \&formbuilder_setup, last => 1);
+	hook(type => "formbuilder", id => "po", call => \&formbuilder);
+
+	$origsubs{'bestlink'}=\&IkiWiki::bestlink;
+	inject(name => "IkiWiki::bestlink", call => \&mybestlink);
+	$origsubs{'beautify_urlpath'}=\&IkiWiki::beautify_urlpath;
+	inject(name => "IkiWiki::beautify_urlpath", call => \&mybeautify_urlpath);
+	$origsubs{'targetpage'}=\&IkiWiki::targetpage;
+	inject(name => "IkiWiki::targetpage", call => \&mytargetpage);
+	$origsubs{'urlto'}=\&IkiWiki::urlto;
+	inject(name => "IkiWiki::urlto", call => \&myurlto);
+	$origsubs{'cgiurl'}=\&IkiWiki::cgiurl;
+	inject(name => "IkiWiki::cgiurl", call => \&mycgiurl);
+}
+
+
+# ,----
+# | Table of contents
+# `----
+
+# 1. Hooks
+# 2. Injected functions
+# 3. Blackboxes for private data
+# 4. Helper functions
+# 5. PageSpecs
+
+
+# ,----
+# | Hooks
+# `----
+
+sub getsetup () {
+	return
+		plugin => {
+			safe => 0,
+			rebuild => 1,
+		},
+		po_master_language => {
+			type => "string",
+			example => {
+				'code' => 'en',
+				'name' => 'English'
+			},
+			description => "master language (non-PO files)",
+			safe => 1,
+			rebuild => 1,
+		},
+		po_slave_languages => {
+			type => "string",
+			example => {
+				'fr' => 'Français',
+				'es' => 'Castellano',
+				'de' => 'Deutsch'
+			},
+			description => "slave languages (PO files)",
+			safe => 1,
+			rebuild => 1,
+		},
+		po_translatable_pages => {
+			type => "pagespec",
+			example => "!*/Discussion",
+			description => "PageSpec controlling which pages are translatable",
+			link => "ikiwiki/PageSpec",
+			safe => 1,
+			rebuild => 1,
+		},
+		po_link_to => {
+			type => "string",
+			example => "current",
+			description => "internal linking behavior (default/current/negotiated)",
+			safe => 1,
+			rebuild => 1,
+		},
+}
+
+sub checkconfig () {
+	foreach my $field (qw{po_master_language po_slave_languages}) {
+		if (! exists $config{$field} || ! defined $config{$field}) {
+			error(sprintf(gettext("Must specify %s when using the %s plugin"),
+				      $field, 'po'));
+		}
+	}
+	if (! (keys %{$config{po_slave_languages}})) {
+		error(gettext("At least one slave language must be defined ".
+			      "in po_slave_languages when using the po plugin"));
+	}
+	map {
+		islanguagecode($_)
+			or error(sprintf(gettext("%s is not a valid language code"), $_));
+	} ($config{po_master_language}{code}, keys %{$config{po_slave_languages}});
+	if (! exists $config{po_translatable_pages} ||
+	    ! defined $config{po_translatable_pages}) {
+		$config{po_translatable_pages}="";
+	}
+	if (! exists $config{po_link_to} ||
+	    ! defined $config{po_link_to}) {
+		$config{po_link_to}='default';
+	}
+	elsif ($config{po_link_to} !~ /^(default|current|negotiated)$/) {
+		warn(sprintf(gettext('%s is not a valid value for po_link_to, falling back to po_link_to=default'),
+			     $config{po_link_to}));
+		$config{po_link_to}='default';
+	}
+	elsif ($config{po_link_to} eq "negotiated" && ! $config{usedirs}) {
+		warn(gettext('po_link_to=negotiated requires usedirs to be enabled, falling back to po_link_to=default'));
+		$config{po_link_to}='default';
+	}
+	push @{$config{wiki_file_prune_regexps}}, qr/\.pot$/;
+}
+
+sub needsbuild () {
+	my $needsbuild=shift;
+
+	# backup @needsbuild content so that change() can know whether
+	# a given master page was rendered because its source file was changed
+	@origneedsbuild=(@$needsbuild);
+
+	flushmemoizecache();
+	buildtranslationscache();
+
+	# make existing translations depend on the corresponding master page
+	foreach my $master (keys %translations) {
+		map add_depends($_, $master), values %{otherlanguages($master)};
+	}
+}
+
+# Massage the recorded state of internal links so that:
+# - it matches the actually generated links, rather than the links as written
+#   in the pages' source
+# - backlinks are consistent in all cases
+sub scan (@) {
+	my %params=@_;
+	my $page=$params{page};
+	my $content=$params{content};
+
+	if (istranslation($page)) {
+		foreach my $destpage (@{$links{$page}}) {
+			if (istranslatable($destpage)) {
+				# replace one occurence of $destpage in $links{$page}
+				# (we only want to replace the one that was added by
+				# IkiWiki::Plugin::link::scan, other occurences may be
+				# there for other reasons)
+				for (my $i=0; $i<@{$links{$page}}; $i++) {
+					if (@{$links{$page}}[$i] eq $destpage) {
+						@{$links{$page}}[$i] = $destpage . '.' . lang($page);
+						last;
+					}
+				}
+			}
+		}
+	}
+	elsif (! istranslatable($page) && ! istranslation($page)) {
+		foreach my $destpage (@{$links{$page}}) {
+			if (istranslatable($destpage)) {
+				# make sure any destpage's translations has
+				# $page in its backlinks
+				push @{$links{$page}},
+					values %{otherlanguages($destpage)};
+			}
+		}
+	}
+}
+
+# We use filter to convert PO to the master page's format,
+# since the rest of ikiwiki should not work on PO files.
+sub filter (@) {
+	my %params = @_;
+
+	my $page = $params{page};
+	my $destpage = $params{destpage};
+	my $content = $params{content};
+	if (istranslation($page) && ! alreadyfiltered($page, $destpage)) {
+		$content = po_to_markup($page, $content);
+		setalreadyfiltered($page, $destpage);
+	}
+	return $content;
+}
+
+sub htmlize (@) {
+	my %params=@_;
+
+	my $page = $params{page};
+	my $content = $params{content};
+
+	# ignore PO files this plugin did not create
+	return $content unless istranslation($page);
+
+	# force content to be htmlize'd as if it was the same type as the master page
+	return IkiWiki::htmlize($page, $page,
+		pagetype(srcfile($pagesources{masterpage($page)})),
+		$content);
+}
+
+sub pagetemplate (@) {
+	my %params=@_;
+	my $page=$params{page};
+	my $destpage=$params{destpage};
+	my $template=$params{template};
+
+	my ($masterpage, $lang) = istranslation($page);
+
+	if (istranslation($page) && $template->query(name => "percenttranslated")) {
+		$template->param(percenttranslated => percenttranslated($page));
+	}
+	if ($template->query(name => "istranslation")) {
+		$template->param(istranslation => scalar istranslation($page));
+	}
+	if ($template->query(name => "istranslatable")) {
+		$template->param(istranslatable => istranslatable($page));
+	}
+	if ($template->query(name => "HOMEPAGEURL")) {
+		$template->param(homepageurl => homepageurl($page));
+	}
+	if ($template->query(name => "otherlanguages")) {
+		$template->param(otherlanguages => [otherlanguagesloop($page)]);
+		map add_depends($page, $_), (values %{otherlanguages($page)});
+	}
+	if ($config{discussion} && istranslation($page)) {
+		my $discussionlink=gettext("discussion");
+		if ($page !~ /.*\/\Q$discussionlink\E$/i &&
+		   (length $config{cgiurl} ||
+		    exists $links{$masterpage."/".$discussionlink})) {
+			$template->param('discussionlink' => htmllink(
+				$page,
+				$destpage,
+				$masterpage . '/' . gettext("Discussion"),
+				noimageinline => 1,
+				forcesubpage => 0,
+				linktext => gettext("Discussion"),
+		));
+		}
+	}
+	# Remove broken parentlink to ./index.html on home page's translations.
+	# It works because this hook has the "last" parameter set, to ensure it
+	# runs after parentlinks' own pagetemplate hook.
+	if ($template->param('parentlinks')
+	    && istranslation($page)
+	    && $masterpage eq "index") {
+		$template->param('parentlinks' => []);
+	}
+} # }}}
+
+# Add the renamed page translations to the list of to-be-renamed pages.
+sub renamepages (@) {
+	my %params = @_;
+
+	my %torename = %{$params{torename}};
+	my $session = $params{session};
+
+	# Save the page(s) the user asked to rename, so that our
+	# canrename hook can tell the difference between:
+	#  - a translation being renamed as a consequence of its master page
+	#    being renamed
+	#  - a user trying to directly rename a translation
+	# This is why this hook has to be run first, before the list of pages
+	# to rename is modified by other plugins.
+	my @orig_torename;
+	@orig_torename=@{$session->param("po_orig_torename")}
+		if defined $session->param("po_orig_torename");
+	push @orig_torename, $torename{src};
+	$session->param(po_orig_torename => \@orig_torename);
+	IkiWiki::cgi_savesession($session);
+
+	return () unless istranslatable($torename{src});
+
+	my @ret;
+	my %otherpages=%{otherlanguages($torename{src})};
+	while (my ($lang, $otherpage) = each %otherpages) {
+		push @ret, {
+			src => $otherpage,
+			srcfile => $pagesources{$otherpage},
+			dest => otherlanguage($torename{dest}, $lang),
+			destfile => $torename{dest}.".".$lang.".po",
+			required => 0,
+		};
+	}
+	return @ret;
+}
+
+sub mydelete (@) {
+	my @deleted=@_;
+
+	map { deletetranslations($_) } grep istranslatablefile($_), @deleted;
+}
+
+sub change (@) {
+	my @rendered=@_;
+
+	# All meta titles are first extracted at scan time, i.e. before we turn
+	# PO files back into translated markdown; escaping of double-quotes in
+	# PO files breaks the meta plugin's parsing enough to save ugly titles
+	# to %pagestate at this time.
+	#
+	# Then, at render time, every page passes in turn through the Great
+	# Rendering Chain (filter->preprocess->linkify->htmlize), and the meta
+	# plugin's preprocess hook is this time in a position to correctly
+	# extract the titles from slave pages.
+	#
+	# This is, unfortunately, too late: if the page A, linking to the page
+	# B, is rendered before B, it will display the wrongly-extracted meta
+	# title as the link text to B.
+	#
+	# On the one hand, such a corner case only happens on rebuild: on
+	# refresh, every rendered page is fixed to contain correct meta titles.
+	# On the other hand, it can take some time to get every page fixed.
+	# We therefore re-render every rendered page after a rebuild to fix them
+	# at once. As this more or less doubles the time needed to rebuild the
+	# wiki, we do so only when really needed.
+
+	if (@rendered
+	    && exists $config{rebuild} && defined $config{rebuild} && $config{rebuild}
+	    && UNIVERSAL::can("IkiWiki::Plugin::meta", "getsetup")
+	    && exists $config{meta_overrides_page_title}
+	    && defined $config{meta_overrides_page_title}
+	    && $config{meta_overrides_page_title}) {
+		debug(sprintf(gettext("re-rendering all pages to fix meta titles")));
+		resetalreadyfiltered();
+		require IkiWiki::Render;
+		foreach my $file (@rendered) {
+			debug(sprintf(gettext("rendering %s"), $file));
+			IkiWiki::render($file);
+		}
+	}
+
+	my $updated_po_files=0;
+
+	# Refresh/create POT and PO files as needed.
+	foreach my $file (grep {istranslatablefile($_)} @rendered) {
+		my $page=pagename($file);
+		my $masterfile=srcfile($file);
+		my $updated_pot_file=0;
+		# Only refresh Pot file if it does not exist, or if
+		# $pagesources{$page} was changed: don't if only the HTML was
+		# refreshed, e.g. because of a dependency.
+		if ((grep { $_ eq $pagesources{$page} } @origneedsbuild)
+		    || ! -e potfile($masterfile)) {
+			refreshpot($masterfile);
+			$updated_pot_file=1;
+		}
+		my @pofiles;
+		map {
+			push @pofiles, $_ if ($updated_pot_file || ! -e $_);
+		} (pofiles($masterfile));
+		if (@pofiles) {
+			refreshpofiles($masterfile, @pofiles);
+			map { IkiWiki::rcs_add($_) } @pofiles if $config{rcs};
+			$updated_po_files=1;
+		}
+	}
+
+	if ($updated_po_files) {
+		commit_and_refresh(
+			gettext("updated PO files"),
+			"IkiWiki::Plugin::po::change");
+	}
+}
+
+sub checkcontent (@) {
+	my %params=@_;
+
+	if (istranslation($params{page})) {
+		my $res = isvalidpo($params{content});
+		if ($res) {
+			return undef;
+		}
+		else {
+			return "$res";
+		}
+	}
+	return undef;
+}
+
+sub canremove (@) {
+	my %params = @_;
+
+	if (istranslation($params{page})) {
+		return gettext("Can not remove a translation. Removing the master page, ".
+			       "though, removes its translations as well.");
+	}
+	return undef;
+}
+
+sub canrename (@) {
+	my %params = @_;
+	my $session = $params{session};
+
+	if (istranslation($params{src})) {
+		my $masterpage = masterpage($params{src});
+		# Tell the difference between:
+		#  - a translation being renamed as a consequence of its master page
+		#    being renamed, which is allowed
+		#  - a user trying to directly rename a translation, which is forbidden
+		# by looking for the master page in the list of to-be-renamed pages we
+		# saved early in the renaming process.
+		my $orig_torename = $session->param("po_orig_torename");
+		unless (grep { $_ eq $masterpage } @{$orig_torename}) {
+			return gettext("Can not rename a translation. Renaming the master page, ".
+				       "though, renames its translations as well.");
+		}
+	}
+	return undef;
+}
+
+# As we're previewing or saving a page, the content may have
+# changed, so tell the next filter() invocation it must not be lazy.
+sub editcontent () {
+	my %params=@_;
+
+	unsetalreadyfiltered($params{page}, $params{page});
+	return $params{content};
+}
+
+sub formbuilder_setup (@) {
+	my %params=@_;
+	my $form=$params{form};
+	my $q=$params{cgi};
+
+	return unless defined $form->field("do");
+
+	if ($form->field("do") eq "create") {
+		# Warn the user: new pages must be written in master language.
+		my $template=template("pocreatepage.tmpl");
+		$template->param(LANG => $config{po_master_language}{name});
+		$form->tmpl_param(message => $template->output);
+	}
+	elsif ($form->field("do") eq "edit") {
+		# Remove the rename/remove buttons on slave pages.
+		# This has to be done after the rename/remove plugins have added
+		# their buttons, which is why this hook must be run last.
+		# The canrename/canremove hooks already ensure this is forbidden
+		# at the backend level, so this is only UI sugar.
+		if (istranslation($form->field("page"))) {
+			map {
+				for (my $i = 0; $i < @{$params{buttons}}; $i++) {
+					if (@{$params{buttons}}[$i] eq $_) {
+						delete  @{$params{buttons}}[$i];
+						last;
+					}
+				}
+			} qw(Rename Remove);
+		}
+	}
+}
+
+sub formbuilder (@) {
+	my %params=@_;
+	my $form=$params{form};
+	my $q=$params{cgi};
+
+	return unless defined $form->field("do");
+
+	# Do not allow to create pages of type po: they are automatically created.
+	# The main reason to do so is to bypass the "favor the type of linking page
+	# on page creation" logic, which is unsuitable when a broken link is clicked
+	# on a slave (PO) page.
+	# This cannot be done in the formbuilder_setup hook as the list of types is
+	# computed later.
+	if ($form->field("do") eq "create") {
+	        foreach my $field ($form->field) {
+			next unless "$field" eq "type";
+			if ($field->type eq 'select') {
+				# remove po from the list of types
+				my @types = grep { $_ ne 'po' } $field->options;
+				$field->options(\@types) if @types;
+			}
+		}
+	}
+}
+
+# ,----
+# | Injected functions
+# `----
+
+# Implement po_link_to 'current' and 'negotiated' settings.
+sub mybestlink ($$) {
+	my $page=shift;
+	my $link=shift;
+
+	my $res=$origsubs{'bestlink'}->(masterpage($page), $link);
+	if (length $res
+	    && ($config{po_link_to} eq "current" || $config{po_link_to} eq "negotiated")
+	    && istranslatable($res)
+	    && istranslation($page)) {
+		return $res . "." . lang($page);
+	}
+	return $res;
+}
+
+sub mybeautify_urlpath ($) {
+	my $url=shift;
+
+	my $res=$origsubs{'beautify_urlpath'}->($url);
+	if ($config{po_link_to} eq "negotiated") {
+		$res =~ s!/\Qindex.$config{po_master_language}{code}.$config{htmlext}\E$!/!;
+		$res =~ s!/\Qindex.$config{htmlext}\E$!/!;
+		map {
+			$res =~ s!/\Qindex.$_.$config{htmlext}\E$!/!;
+		} (keys %{$config{po_slave_languages}});
+	}
+	return $res;
+}
+
+sub mytargetpage ($$) {
+	my $page=shift;
+	my $ext=shift;
+
+	if (istranslation($page) || istranslatable($page)) {
+		my ($masterpage, $lang) = (masterpage($page), lang($page));
+		if (! $config{usedirs} || $masterpage eq 'index') {
+			return $masterpage . "." . $lang . "." . $ext;
+		}
+		else {
+			return $masterpage . "/index." . $lang . "." . $ext;
+		}
+	}
+	return $origsubs{'targetpage'}->($page, $ext);
+}
+
+sub myurlto ($$;$) {
+	my $to=shift;
+	my $from=shift;
+	my $absolute=shift;
+
+	# workaround hard-coded /index.$config{htmlext} in IkiWiki::urlto()
+	if (! length $to
+	    && $config{po_link_to} eq "current"
+	    && istranslatable('index')) {
+		return IkiWiki::beautify_urlpath(IkiWiki::baseurl($from) . "index." . lang($from) . ".$config{htmlext}");
+	}
+	# avoid using our injected beautify_urlpath if run by cgi_editpage,
+	# so that one is redirected to the just-edited page rather than to the
+	# negociated translation; to prevent unnecessary fiddling with caller/inject,
+	# we only do so when our beautify_urlpath would actually do what we want to
+	# avoid, i.e. when po_link_to = negotiated
+	if ($config{po_link_to} eq "negotiated") {
+		my @caller = caller(1);
+		my $run_by_editpage = 0;
+		$run_by_editpage = 1 if (exists $caller[3] && defined $caller[3]
+					 && $caller[3] eq "IkiWiki::cgi_editpage");
+		inject(name => "IkiWiki::beautify_urlpath", call => $origsubs{'beautify_urlpath'})
+			if $run_by_editpage;
+		my $res = $origsubs{'urlto'}->($to,$from,$absolute);
+		inject(name => "IkiWiki::beautify_urlpath", call => \&mybeautify_urlpath)
+			if $run_by_editpage;
+		return $res;
+	}
+	else {
+		return $origsubs{'urlto'}->($to,$from,$absolute)
+	}
+}
+
+sub mycgiurl (@) {
+	my %params=@_;
+
+	# slave pages have no subpages
+	if (istranslation($params{'from'})) {
+		$params{'from'} = masterpage($params{'from'});
+	}
+	return $origsubs{'cgiurl'}->(%params);
+}
+
+# ,----
+# | Blackboxes for private data
+# `----
+
+{
+	my %filtered;
+
+	sub alreadyfiltered($$) {
+		my $page=shift;
+		my $destpage=shift;
+
+		return exists $filtered{$page}{$destpage}
+			 && $filtered{$page}{$destpage} eq 1;
+	}
+
+	sub setalreadyfiltered($$) {
+		my $page=shift;
+		my $destpage=shift;
+
+		$filtered{$page}{$destpage}=1;
+	}
+
+	sub unsetalreadyfiltered($$) {
+		my $page=shift;
+		my $destpage=shift;
+
+		if (exists $filtered{$page}{$destpage}) {
+			delete $filtered{$page}{$destpage};
+		}
+	}
+
+	sub resetalreadyfiltered() {
+		undef %filtered;
+	}
+}
+
+# ,----
+# | Helper functions
+# `----
+
+sub maybe_add_leading_slash ($;$) {
+	my $str=shift;
+	my $add=shift;
+	$add=1 unless defined $add;
+	return '/' . $str if $add;
+	return $str;
+}
+
+sub istranslatablefile ($) {
+	my $file=shift;
+
+	return 0 unless defined $file;
+	return 0 if defined pagetype($file) && pagetype($file) eq 'po';
+	return 0 if $file =~ /\.pot$/;
+	return 0 unless -e "$config{srcdir}/$file"; # underlay dirs may be read-only
+	return 1 if pagespec_match(pagename($file), $config{po_translatable_pages});
+	return;
+}
+
+sub istranslatable ($) {
+	my $page=shift;
+
+	$page=~s#^/##;
+	return 1 if istranslatablefile($pagesources{$page});
+	return;
+}
+
+sub _istranslation ($) {
+	my $page=shift;
+
+	$page='' unless defined $page && length $page;
+	my $hasleadingslash = ($page=~s#^/##);
+	my $file=$pagesources{$page};
+	return 0 unless defined $file
+			 && defined pagetype($file)
+			 && pagetype($file) eq 'po';
+	return 0 if $file =~ /\.pot$/;
+
+	my ($masterpage, $lang) = ($page =~ /(.*)[.]([a-z]{2})$/);
+	return 0 unless defined $masterpage && defined $lang
+			 && length $masterpage && length $lang
+			 && defined $pagesources{$masterpage}
+			 && defined $config{po_slave_languages}{$lang};
+
+	return (maybe_add_leading_slash($masterpage, $hasleadingslash), $lang)
+		if istranslatable($masterpage);
+}
+
+sub istranslation ($) {
+	my $page=shift;
+
+	if (1 < (my ($masterpage, $lang) = _istranslation($page))) {
+		my $hasleadingslash = ($masterpage=~s#^/##);
+		$translations{$masterpage}{$lang}=$page unless exists $translations{$masterpage}{$lang};
+		return (maybe_add_leading_slash($masterpage, $hasleadingslash), $lang);
+	}
+	return "";
+}
+
+sub masterpage ($) {
+	my $page=shift;
+
+	if ( 1 < (my ($masterpage, $lang) = _istranslation($page))) {
+		return $masterpage;
+	}
+	return $page;
+}
+
+sub lang ($) {
+	my $page=shift;
+
+	if (1 < (my ($masterpage, $lang) = _istranslation($page))) {
+		return $lang;
+	}
+	return $config{po_master_language}{code};
+}
+
+sub islanguagecode ($) {
+	my $code=shift;
+
+	return $code =~ /^[a-z]{2}$/;
+}
+
+sub otherlanguage ($$) {
+	my $page=shift;
+	my $code=shift;
+
+	return masterpage($page) if $code eq $config{po_master_language}{code};
+	return masterpage($page) . '.' . $code;
+}
+
+sub otherlanguages ($) {
+	my $page=shift;
+
+	my %ret;
+	return \%ret unless istranslation($page) || istranslatable($page);
+	my $curlang=lang($page);
+	foreach my $lang
+		($config{po_master_language}{code}, keys %{$config{po_slave_languages}}) {
+		next if $lang eq $curlang;
+		$ret{$lang}=otherlanguage($page, $lang);
+	}
+	return \%ret;
+}
+
+sub potfile ($) {
+	my $masterfile=shift;
+
+	(my $name, my $dir, my $suffix) = fileparse($masterfile, qr/\.[^.]*/);
+	$dir='' if $dir eq './';
+	return File::Spec->catpath('', $dir, $name . ".pot");
+}
+
+sub pofile ($$) {
+	my $masterfile=shift;
+	my $lang=shift;
+
+	(my $name, my $dir, my $suffix) = fileparse($masterfile, qr/\.[^.]*/);
+	$dir='' if $dir eq './';
+	return File::Spec->catpath('', $dir, $name . "." . $lang . ".po");
+}
+
+sub pofiles ($) {
+	my $masterfile=shift;
+
+	return map pofile($masterfile, $_), (keys %{$config{po_slave_languages}});
+}
+
+sub refreshpot ($) {
+	my $masterfile=shift;
+
+	my $potfile=potfile($masterfile);
+	my %options = ("markdown" => (pagetype($masterfile) eq 'mdwn') ? 1 : 0);
+	my $doc=Locale::Po4a::Chooser::new('text',%options);
+	$doc->{TT}{utf_mode} = 1;
+	$doc->{TT}{file_in_charset} = 'utf-8';
+	$doc->{TT}{file_out_charset} = 'utf-8';
+	$doc->read($masterfile);
+	# let's cheat a bit to force porefs option to be passed to
+	# Locale::Po4a::Po; this is undocument use of internal
+	# Locale::Po4a::TransTractor's data, compulsory since this module
+	# prevents us from using the porefs option.
+	$doc->{TT}{po_out}=Locale::Po4a::Po->new({ 'porefs' => 'none' });
+	$doc->{TT}{po_out}->set_charset('utf-8');
+	# do the actual work
+	$doc->parse;
+	IkiWiki::prep_writefile(basename($potfile),dirname($potfile));
+	$doc->writepo($potfile);
+}
+
+sub refreshpofiles ($@) {
+	my $masterfile=shift;
+	my @pofiles=@_;
+
+	my $potfile=potfile($masterfile);
+	if (! -e $potfile) {
+		error("po(refreshpofiles) ".sprintf(gettext("POT file (%s) does not exist"), $potfile));
+	}
+
+	foreach my $pofile (@pofiles) {
+		IkiWiki::prep_writefile(basename($pofile),dirname($pofile));
+		if (-e $pofile) {
+			system("msgmerge", "-U", "--backup=none", $pofile, $potfile) == 0
+				or error("po(refreshpofiles) ".
+					 sprintf(gettext("failed to update %s"),
+						 $pofile));
+		}
+		else {
+			File::Copy::syscopy($potfile,$pofile)
+				or error("po(refreshpofiles) ".
+					 sprintf(gettext("failed to copy the POT file to %s"),
+						 $pofile));
+		}
+	}
+}
+
+sub buildtranslationscache() {
+	# use istranslation's side-effect
+	map istranslation($_), (keys %pagesources);
+}
+
+sub resettranslationscache() {
+	undef %translations;
+}
+
+sub flushmemoizecache() {
+	Memoize::flush_cache("istranslatable");
+	Memoize::flush_cache("_istranslation");
+	Memoize::flush_cache("percenttranslated");
+}
+
+sub urlto_with_orig_beautiful_urlpath($$) {
+	my $to=shift;
+	my $from=shift;
+
+	inject(name => "IkiWiki::beautify_urlpath", call => $origsubs{'beautify_urlpath'});
+	my $res=urlto($to, $from);
+	inject(name => "IkiWiki::beautify_urlpath", call => \&mybeautify_urlpath);
+
+	return $res;
+}
+
+sub percenttranslated ($) {
+	my $page=shift;
+
+	$page=~s/^\///;
+	return gettext("N/A") unless istranslation($page);
+	my $file=srcfile($pagesources{$page});
+	my $masterfile = srcfile($pagesources{masterpage($page)});
+	my %options = (
+		"markdown" => (pagetype($masterfile) eq 'mdwn') ? 1 : 0,
+	);
+	my $doc=Locale::Po4a::Chooser::new('text',%options);
+	$doc->process(
+		'po_in_name'	=> [ $file ],
+		'file_in_name'	=> [ $masterfile ],
+		'file_in_charset'  => 'utf-8',
+		'file_out_charset' => 'utf-8',
+	) or error("po(percenttranslated) ".
+		   sprintf(gettext("failed to translate %s"), $page));
+	my ($percent,$hit,$queries) = $doc->stats();
+	$percent =~ s/\.[0-9]+$//;
+	return $percent;
+}
+
+sub languagename ($) {
+	my $code=shift;
+
+	return $config{po_master_language}{name}
+		if $code eq $config{po_master_language}{code};
+	return $config{po_slave_languages}{$code}
+		if defined $config{po_slave_languages}{$code};
+	return;
+}
+
+sub otherlanguagesloop ($) {
+	my $page=shift;
+
+	my @ret;
+	my %otherpages=%{otherlanguages($page)};
+	while (my ($lang, $otherpage) = each %otherpages) {
+		if (istranslation($page) && masterpage($page) eq $otherpage) {
+			push @ret, {
+				url => urlto_with_orig_beautiful_urlpath($otherpage, $page),
+				code => $lang,
+				language => languagename($lang),
+				master => 1,
+			};
+		}
+		else {
+			push @ret, {
+				url => urlto_with_orig_beautiful_urlpath($otherpage, $page),
+				code => $lang,
+				language => languagename($lang),
+				percent => percenttranslated($otherpage),
+			}
+		}
+	}
+	return sort {
+			return -1 if $a->{code} eq $config{po_master_language}{code};
+			return 1 if $b->{code} eq $config{po_master_language}{code};
+			return $a->{language} cmp $b->{language};
+		} @ret;
+}
+
+sub homepageurl (;$) {
+	my $page=shift;
+
+	return urlto('', $page);
+}
+
+sub deletetranslations ($) {
+	my $deletedmasterfile=shift;
+
+	my $deletedmasterpage=pagename($deletedmasterfile);
+	my @todelete;
+	map {
+		my $file = newpagefile($deletedmasterpage.'.'.$_, 'po');
+		my $absfile = "$config{srcdir}/$file";
+		if (-e $absfile && ! -l $absfile && ! -d $absfile) {
+			push @todelete, $file;
+		}
+	} keys %{$config{po_slave_languages}};
+
+	map {
+		if ($config{rcs}) {
+			IkiWiki::rcs_remove($_);
+		}
+		else {
+			IkiWiki::prune("$config{srcdir}/$_");
+		}
+	} @todelete;
+
+	if (@todelete) {
+		commit_and_refresh(
+			gettext("removed obsolete PO files"),
+			"IkiWiki::Plugin::po::deletetranslations");
+	}
+}
+
+sub commit_and_refresh ($$) {
+	my ($msg, $author) = (shift, shift);
+
+	if ($config{rcs}) {
+		IkiWiki::disable_commit_hook();
+		IkiWiki::rcs_commit_staged($msg, $author, "127.0.0.1");
+		IkiWiki::enable_commit_hook();
+		IkiWiki::rcs_update();
+	}
+	# Reinitialize module's private variables.
+	resetalreadyfiltered();
+	resettranslationscache();
+	flushmemoizecache();
+	# Trigger a wiki refresh.
+	require IkiWiki::Render;
+	# without preliminary saveindex/loadindex, refresh()
+	# complains about a lot of uninitialized variables
+	IkiWiki::saveindex();
+	IkiWiki::loadindex();
+	IkiWiki::refresh();
+	IkiWiki::saveindex();
+}
+
+# on success, returns the filtered content.
+# on error, if $nonfatal, warn and return undef; else, error out.
+sub po_to_markup ($$;$) {
+	my ($page, $content) = (shift, shift);
+	my $nonfatal = shift;
+
+	$content = '' unless defined $content;
+	$content = decode_utf8(encode_utf8($content));
+	# CRLF line terminators make poor Locale::Po4a feel bad
+	$content=~s/\r\n/\n/g;
+
+	# There are incompatibilities between some File::Temp versions
+	# (including 0.18, bundled with Lenny's perl-modules package)
+	# and others (e.g. 0.20, previously present in the archive as
+	# a standalone package): under certain circumstances, some
+	# return a relative filename, whereas others return an absolute one;
+	# we here use this module in a way that is at least compatible
+	# with 0.18 and 0.20. Beware, hit'n'run refactorers!
+	my $infile = new File::Temp(TEMPLATE => "ikiwiki-po-filter-in.XXXXXXXXXX",
+				    DIR => File::Spec->tmpdir,
+				    UNLINK => 1)->filename;
+	my $outfile = new File::Temp(TEMPLATE => "ikiwiki-po-filter-out.XXXXXXXXXX",
+				     DIR => File::Spec->tmpdir,
+				     UNLINK => 1)->filename;
+
+	my $fail = sub ($) {
+		my $msg = "po(po_to_markup) - $page : " . shift;
+		if ($nonfatal) {
+			warn $msg;
+			return undef;
+		}
+		error($msg, sub { unlink $infile, $outfile});
+	};
+
+	writefile(basename($infile), File::Spec->tmpdir, $content)
+		or return $fail->(sprintf(gettext("failed to write %s"), $infile));
+
+	my $masterfile = srcfile($pagesources{masterpage($page)});
+	my %options = (
+		"markdown" => (pagetype($masterfile) eq 'mdwn') ? 1 : 0,
+	);
+	my $doc=Locale::Po4a::Chooser::new('text',%options);
+	$doc->process(
+		'po_in_name'	=> [ $infile ],
+		'file_in_name'	=> [ $masterfile ],
+		'file_in_charset'  => 'utf-8',
+		'file_out_charset' => 'utf-8',
+	) or return $fail->(gettext("failed to translate"));
+	$doc->write($outfile)
+		or return $fail->(sprintf(gettext("failed to write %s"), $outfile));
+
+	$content = readfile($outfile)
+		or return $fail->(sprintf(gettext("failed to read %s"), $outfile));
+
+	# Unlinking should happen automatically, thanks to File::Temp,
+	# but it does not work here, probably because of the way writefile()
+	# and Locale::Po4a::write() work.
+	unlink $infile, $outfile;
+
+	return $content;
+}
+
+# returns a SuccessReason or FailReason object
+sub isvalidpo ($) {
+	my $content = shift;
+
+	# NB: we don't use po_to_markup here, since Po4a parser does
+	# not mind invalid PO content
+	$content = '' unless defined $content;
+	$content = decode_utf8(encode_utf8($content));
+
+	# There are incompatibilities between some File::Temp versions
+	# (including 0.18, bundled with Lenny's perl-modules package)
+	# and others (e.g. 0.20, previously present in the archive as
+	# a standalone package): under certain circumstances, some
+	# return a relative filename, whereas others return an absolute one;
+	# we here use this module in a way that is at least compatible
+	# with 0.18 and 0.20. Beware, hit'n'run refactorers!
+	my $infile = new File::Temp(TEMPLATE => "ikiwiki-po-isvalidpo.XXXXXXXXXX",
+				    DIR => File::Spec->tmpdir,
+				    UNLINK => 1)->filename;
+
+	my $fail = sub ($) {
+		my $msg = '[po/isvalidpo] ' . shift;
+		unlink $infile;
+		return IkiWiki::FailReason->new("$msg");
+	};
+
+	writefile(basename($infile), File::Spec->tmpdir, $content)
+		or return $fail->(sprintf(gettext("failed to write %s"), $infile));
+
+	my $res = (system("msgfmt", "--check", $infile, "-o", "/dev/null") == 0);
+
+	# Unlinking should happen automatically, thanks to File::Temp,
+	# but it does not work here, probably because of the way writefile()
+	# and Locale::Po4a::write() work.
+	unlink $infile;
+
+	if ($res) {
+	    return IkiWiki::SuccessReason->new("valid gettext data");
+	}
+	return IkiWiki::FailReason->new("invalid gettext data, go back ".
+					"to previous page to go on with edit");
+}
+
+# ,----
+# | PageSpecs
+# `----
+
+package IkiWiki::PageSpec;
+
+sub match_istranslation ($;@) {
+	my $page=shift;
+
+	if (IkiWiki::Plugin::po::istranslation($page)) {
+		return IkiWiki::SuccessReason->new("is a translation page");
+	}
+	else {
+		return IkiWiki::FailReason->new("is not a translation page");
+	}
+}
+
+sub match_istranslatable ($;@) {
+	my $page=shift;
+
+	if (IkiWiki::Plugin::po::istranslatable($page)) {
+		return IkiWiki::SuccessReason->new("is set as translatable in po_translatable_pages");
+	}
+	else {
+		return IkiWiki::FailReason->new("is not set as translatable in po_translatable_pages");
+	}
+}
+
+sub match_lang ($$;@) {
+	my $page=shift;
+	my $wanted=shift;
+
+	my $regexp=IkiWiki::glob2re($wanted);
+	my $lang=IkiWiki::Plugin::po::lang($page);
+	if ($lang !~ /^$regexp$/i) {
+		return IkiWiki::FailReason->new("file language is $lang, not $wanted");
+	}
+	else {
+		return IkiWiki::SuccessReason->new("file language is $wanted");
+	}
+}
+
+sub match_currentlang ($$;@) {
+	my $page=shift;
+	shift;
+	my %params=@_;
+
+	return IkiWiki::FailReason->new("no location provided") unless exists $params{location};
+
+	my $currentlang=IkiWiki::Plugin::po::lang($params{location});
+	my $lang=IkiWiki::Plugin::po::lang($page);
+
+	if ($lang eq $currentlang) {
+		return IkiWiki::SuccessReason->new("file language is the same as current one, i.e. $currentlang");
+	}
+	else {
+		return IkiWiki::FailReason->new("file language is $lang, whereas current language is $currentlang");
+	}
+}
+
+1
diff --git a/IkiWiki/Plugin/remove.pm b/IkiWiki/Plugin/remove.pm
index ee5784f20..cbc8a0f2c 100644
--- a/IkiWiki/Plugin/remove.pm
+++ b/IkiWiki/Plugin/remove.pm
@@ -54,6 +54,25 @@ sub check_canremove ($$$) {
 			error("renaming of attachments is not allowed");
 		}
 	}
+
+	my $canremove;
+	IkiWiki::run_hooks(canremove => sub {
+		return if defined $canremove;
+		my $ret=shift->(page => $page, cgi => $q, session => $session);
+		if (defined $ret) {
+			if ($ret eq "") {
+				$canremove=1;
+			}
+			elsif (ref $ret eq 'CODE') {
+				$ret->();
+				$canremove=0;
+			}
+			elsif (defined $ret) {
+				error($ret);
+				$canremove=0;
+			}
+		}
+	});
 }
 
 sub formbuilder_setup (@) {
diff --git a/IkiWiki/Plugin/rename.pm b/IkiWiki/Plugin/rename.pm
index 0b6e74705..d0e5894dc 100644
--- a/IkiWiki/Plugin/rename.pm
+++ b/IkiWiki/Plugin/rename.pm
@@ -10,7 +10,7 @@ sub import {
 	hook(type => "formbuilder_setup", id => "rename", call => \&formbuilder_setup);
 	hook(type => "formbuilder", id => "rename", call => \&formbuilder);
 	hook(type => "sessioncgi", id => "rename", call => \&sessioncgi);
-
+	hook(type => "rename", id => "rename", call => \&rename_subpages);
 }
 
 sub getsetup () {
@@ -87,6 +87,27 @@ sub check_canrename ($$$$$$) {
 			IkiWiki::Plugin::attachment::check_canattach($session, $dest, $srcfile);
 		}
 	}
+
+	my $canrename;
+	IkiWiki::run_hooks(canrename => sub {
+		return if defined $canrename;
+		my $ret=shift->(cgi => $q, session => $session,
+			src => $src, srcfile => $srcfile,
+			dest => $dest, destfile => $destfile);
+		if (defined $ret) {
+			if ($ret eq "") {
+				$canrename=1;
+			}
+			elsif (ref $ret eq 'CODE') {
+				$ret->();
+				$canrename=0;
+			}
+			elsif (defined $ret) {
+				error($ret);
+				$canrename=0;
+			}
+		}
+	});
 }
 
 sub rename_form ($$$) {
@@ -293,27 +314,13 @@ sub sessioncgi ($$) {
 				required => 1,
 			};
 
-			# See if any subpages need to be renamed.
-			if ($q->param("subpages") && $src ne $dest) {
-				foreach my $p (keys %pagesources) {
-					next unless $pagesources{$p}=~m/^\Q$src\E\//;
-					# If indexpages is enabled, the
-					# srcfile should not be confused
-					# with a subpage.
-					next if $pagesources{$p} eq $srcfile;
-
-					my $d=$pagesources{$p};
-					$d=~s/^\Q$src\E\//$dest\//;
-					push @torename, {
-						src => $p,
-						srcfile => $pagesources{$p},
-						dest => pagename($d),
-						destfile => $d,
-						required => 0,
-					};
-				}
-			}
-			
+			@torename=rename_hook(
+				torename => \@torename,
+				done => {},
+				cgi => $q,
+				session => $session,
+			);
+
 			require IkiWiki::Render;
 			IkiWiki::disable_commit_hook() if $config{rcs};
 			my %origpagesources=%pagesources;
@@ -407,7 +414,40 @@ sub sessioncgi ($$) {
 		exit 0;
 	}
 }
-						
+
+# Add subpages to the list of pages to be renamed, if needed.
+sub rename_subpages (@) {
+	my %params = @_;
+
+	my %torename = %{$params{torename}};
+	my $q = $params{cgi};
+	my $src = $torename{src};
+	my $srcfile = $torename{src};
+	my $dest = $torename{dest};
+	my $destfile = $torename{dest};
+
+	return () unless ($q->param("subpages") && $src ne $dest);
+
+	my @ret;
+	foreach my $p (keys %pagesources) {
+		next unless $pagesources{$p}=~m/^\Q$src\E\//;
+		# If indexpages is enabled, the srcfile should not be confused
+		# with a subpage.
+		next if $pagesources{$p} eq $srcfile;
+
+		my $d=$pagesources{$p};
+		$d=~s/^\Q$src\E\//$dest\//;
+		push @ret, {
+			src => $p,
+			srcfile => $pagesources{$p},
+			dest => pagename($d),
+			destfile => $d,
+			required => 0,
+		};
+	}
+	return @ret;
+}
+
 sub linklist {
 	# generates a list of links in a form suitable for FormBuilder
 	my $dest=shift;
@@ -439,7 +479,43 @@ sub renamepage_hook ($$$$) {
 
 	return $content;
 }
-			
+
+sub rename_hook (@) {
+	my %params = @_;
+
+	my @torename=@{$params{torename}};
+	my %done=%{$params{done}};
+	my $q=$params{cgi};
+	my $session=$params{session};
+
+	return () unless @torename;
+
+	my @nextset;
+	foreach my $torename (@torename) {
+		unless (exists $done{$torename->{src}} && $done{$torename->{src}}) {
+			IkiWiki::run_hooks(rename => sub {
+				push @nextset, shift->(
+					torename => $torename,
+					cgi => $q,
+					session => $session,
+				);
+			});
+			$done{$torename->{src}}=1;
+		}
+	}
+
+	push @torename, rename_hook(
+		torename => \@nextset,
+		done => \%done,
+		cgi => $q,
+		session => $session,
+	);
+
+	# dedup
+	my %seen;
+	return grep { ! $seen{$_->{src}}++ } @torename;
+}
+
 sub do_rename ($$$) {
 	my $rename=shift;
 	my $q=shift;
diff --git a/IkiWiki/Plugin/search.pm b/IkiWiki/Plugin/search.pm
index d79e3170e..393c17e0f 100644
--- a/IkiWiki/Plugin/search.pm
+++ b/IkiWiki/Plugin/search.pm
@@ -33,7 +33,7 @@ sub getsetup () {
 sub checkconfig () {
 	foreach my $required (qw(url cgiurl)) {
 		if (! length $config{$required}) {
-			error(sprintf(gettext("Must specify %s when using the search plugin"), $required));
+			error(sprintf(gettext("Must specify %s when using the %s plugin"), $required, 'search'));
 		}
 	}
 	
diff --git a/IkiWiki/Plugin/skeleton.pm.example b/IkiWiki/Plugin/skeleton.pm.example
index ea7d6e47f..573510191 100644
--- a/IkiWiki/Plugin/skeleton.pm.example
+++ b/IkiWiki/Plugin/skeleton.pm.example
@@ -30,10 +30,14 @@ sub import {
 	hook(type => "auth", id => "skeleton", call => \&auth);
 	hook(type => "sessioncgi", id => "skeleton", call => \&sessioncgi);
 	hook(type => "canedit", id => "skeleton", call => \&canedit);
+	hook(type => "canremove", id => "skeleton", call => \&canremove);
+	hook(type => "canrename", id => "skeleton", call => \&canrename);
 	hook(type => "checkcontent", id => "skeleton", call => \&checkcontent);
 	hook(type => "editcontent", id => "skeleton", call => \&editcontent);
 	hook(type => "formbuilder_setup", id => "skeleton", call => \&formbuilder_setup);
 	hook(type => "formbuilder", id => "skeleton", call => \&formbuilder);
+	hook(type => "renamepage", id => "skeleton", call => \&renamepage);
+	hook(type => "rename", id => "skeleton", call => \&rename);
 	hook(type => "savestate", id => "skeleton", call => \&savestate);
 }
 
@@ -181,6 +185,18 @@ sub canedit ($$$) {
 	debug("skeleton plugin running in canedit");
 }
 
+sub canremove (@) {
+	my %params=@_;
+
+	debug("skeleton plugin running in canremove");
+}
+
+sub canrename (@) {
+	my %params=@_;
+
+	debug("skeleton plugin running in canrename");
+}
+
 sub checkcontent (@) {
 	my %params=@_;
 
@@ -207,6 +223,18 @@ sub formbuilder (@) {
 	debug("skeleton plugin running in formbuilder");
 }
 
+sub renamepage (@) {
+	my %params=@_;
+	
+	debug("skeleton plugin running in renamepage");
+}
+
+sub rename (@) {
+	my %params=@_;
+	
+	debug("skeleton plugin running in rename");
+}
+
 sub savestate () {
 	debug("skeleton plugin running in savestate");
 }
diff --git a/debian/changelog b/debian/changelog
index 05b7be70f..dffab5349 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+ikiwiki (3.15) unstable; urgency=low
+
+  * Add new hooks: canremove, canrename, rename. (intrigeri)
+  * rename: Refactor subpage rename handling code into rename hook. (intrigeri)
+  * po: New plugin, suporting translation of wiki pages using po files.
+    (intrigeri)
+
+ -- Joey Hess <joeyh@debian.org>  Tue, 02 Jun 2009 17:03:41 -0400
+
 ikiwiki (3.14159) unstable; urgency=low
 
   * svn: Fix rcs_rename to properly scope call to dirname.
diff --git a/debian/control b/debian/control
index 233de8f7c..5205ed749 100644
--- a/debian/control
+++ b/debian/control
@@ -35,7 +35,8 @@ Suggests: viewvc | gitweb | viewcvs, libsearch-xapian-perl,
   liblocale-gettext-perl (>= 1.05-1), libtext-typography-perl,
   libtext-csv-perl, libdigest-sha1-perl, graphviz, libnet-amazon-s3-perl,
   sparkline-php, texlive, dvipng, libtext-wikicreole-perl,
-  libsort-naturally-perl, libtext-textile-perl, libhighlight-perl
+  libsort-naturally-perl, libtext-textile-perl, libhighlight-perl,
+  po4a (>= 0.35-1), gettext
 Conflicts: ikiwiki-plugin-table
 Replaces: ikiwiki-plugin-table
 Provides: ikiwiki-plugin-table
diff --git a/debian/copyright b/debian/copyright
index 5fc55f5c5..bcd2c1a47 100644
--- a/debian/copyright
+++ b/debian/copyright
@@ -128,6 +128,10 @@ Copyright:
  © 2008 Simon McVittie <http://smcv.pseudorandom.co.uk/>
 License: GPL-2+
 
+Files: po.pm
+Copyright: © 2008-2009 intrigeri <intrigeri@boum.org>
+License: GPL-2+
+
 Files: 404.pm
 Copyright: © 2009 Simon McVittie <http://smcv.pseudorandom.co.uk/>
 License: GPL-2+
diff --git a/doc/ikiwiki/pagespec/po.mdwn b/doc/ikiwiki/pagespec/po.mdwn
new file mode 100644
index 000000000..a5f88cf66
--- /dev/null
+++ b/doc/ikiwiki/pagespec/po.mdwn
@@ -0,0 +1,16 @@
+[[!if test="enabled(po)"
+     then="This wiki has po support **enabled**."
+     else="This wiki has po support **disabled**."]]
+
+If the [po](plugins/po) plugin is enabled, the regular
+[[ikiwiki/PageSpec]] syntax is expanded with the following additional
+tests that can be used to improve user navigation in a multi-lingual
+wiki:
+
+* "`lang(LL)`" - Tests whether a page is written in the language
+  specified as a ISO639-1 (two-letter) language code.
+* "`currentlang()`" - Tests whether a page is written in the same
+  language as the current page.
+
+Note: every non-po page is considered to be written in
+`po_master_language`, as specified in `ikiwiki.setup`.
diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn
new file mode 100644
index 000000000..235674f31
--- /dev/null
+++ b/doc/plugins/po.mdwn
@@ -0,0 +1,294 @@
+[[!template id=plugin name=po core=0 author="[[intrigeri]]"]]
+[[!tag type/format]]
+
+This plugin adds support for multi-lingual wikis, translated with
+gettext, using [po4a](http://po4a.alioth.debian.org/).
+
+It depends on the Perl `Locale::Po4a::Po` library (`apt-get install po4a`).
+As detailed bellow in the security section, `po4a` is subject to
+denial-of-service attacks before version 0.35.
+
+[[!toc levels=2]]
+
+Introduction
+============
+
+A language is chosen as the "master" one, and any other supported
+language is a "slave" one.
+
+A page written in the "master" language is a "master" page. It can be
+of any page type supported by ikiwiki, except `po`. It does not have to be
+named a special way: migration to this plugin does not imply any page
+renaming work.
+
+Example: `bla/page.mdwn` is a "master" Markdown page written in
+English; if `usedirs` is enabled, it is rendered as
+`bla/page/index.en.html`, else as `bla/page.en.html`.
+
+Any translation of a "master" page into a "slave" language is called
+a "slave" page; it is written in the gettext PO format. `po` is now
+a page type supported by ikiwiki.
+
+Example: `bla/page.fr.po` is the PO "message catalog" used to
+translate `bla/page.mdwn` into French; if `usedirs` is enabled, it is
+rendered as `bla/page/index.fr.html`, else as `bla/page.fr.html`
+
+(In)Compatibility
+=================
+
+This plugin does not support the `indexpages` mode. If you don't know
+what it is, you probably don't care.
+
+
+Configuration
+=============
+
+Supported languages
+-------------------
+
+`po_master_language` is used to set the "master" language in
+`ikiwiki.setup`, such as:
+
+        po_master_language => { 'code' => 'en', 'name' => 'English' }
+
+`po_slave_languages` is used to set the list of supported "slave"
+languages, such as:
+
+        po_slave_languages => { 'fr' => 'Français',
+                                'es' => 'Castellano',
+                                'de' => 'Deutsch',
+        }
+
+Decide which pages are translatable
+-----------------------------------
+
+The `po_translatable_pages` setting configures what pages are
+translatable. It is a [[ikiwiki/PageSpec]], so you have lots of
+control over what kind of pages are translatable.
+
+The `.po` files are not considered as being translatable, so you don't need to
+worry about excluding them explicitly from this [[ikiwiki/PageSpec]].
+
+Internal links
+--------------
+
+### Links targets
+
+The `po_link_to` option in `ikiwiki.setup` is used to decide how
+internal links should be generated, depending on web server features
+and site-specific preferences.
+
+#### Default linking behavior
+
+If `po_link_to` is unset, or set to `default`, ikiwiki's default
+linking behavior is preserved: `\[[destpage]]` links to the master
+language's page.
+
+#### Link to current language
+
+If `po_link_to` is set to `current`, `\[[destpage]]` links to the
+`destpage`'s version written in the current page's language, if
+available, *i.e.*:
+
+* `foo/destpage/index.LL.html` if `usedirs` is enabled
+* `foo/destpage.LL.html` if `usedirs` is disabled
+
+#### Link to negotiated language
+
+If `po_link_to` is set to `negotiated`, `\[[page]]` links to the
+negotiated preferred language, *i.e.* `foo/page/`.
+
+(In)compatibility notes:
+
+* if `usedirs` is disabled, it does not make sense to set `po_link_to`
+  to `negotiated`; this option combination is neither implemented
+  nor allowed.
+* if the web server does not support Content Negotiation, setting
+  `po_link_to` to `negotiated` will produce a unusable website.
+
+Server support
+==============
+
+Apache
+------
+
+Using Apache `mod_negotiation` makes it really easy to have Apache
+serve any page in the client's preferred language, if available.
+This is the default Debian Apache configuration.
+
+When `usedirs` is enabled, one has to set `DirectoryIndex index` for
+the wiki context.
+
+Setting `DefaultLanguage LL` (replace `LL` with your default MIME
+language code) for the wiki context can help to ensure
+`bla/page/index.en.html` is served as `Content-Language: LL`.
+
+lighttpd
+--------
+
+lighttpd unfortunately does not support content negotiation.
+
+**FIXME**: does `mod_magnet` provide the functionality needed to
+ emulate this?
+
+
+Usage
+=====
+
+Templates
+---------
+
+When `po_link_to` is not set to `negotiated`, one should replace some
+occurrences of `BASEURL` with `HOMEPAGEURL` to get correct links to
+the wiki homepage.
+
+The `ISTRANSLATION` and `ISTRANSLATABLE` variables can be used to
+display things only on translatable or translation pages.
+
+### Display page's versions in other languages
+
+The `OTHERLANGUAGES` loop provides ways to display other languages'
+versions of the same page, and the translations' status.
+
+An example of its use can be found in the default
+`templates/page.tmpl`. In case you want to customize it, the following
+variables are available inside the loop (for every page in):
+
+* `URL` - url to the page
+* `CODE` - two-letters language code
+* `LANGUAGE` - language name (as defined in `po_slave_languages`)
+* `MASTER` - is true (1) if, and only if the page is a "master" page
+* `PERCENT` - for "slave" pages, is set to the translation completeness, in percents
+
+### Display the current translation status
+
+The `PERCENTTRANSLATED` variable is set to the translation
+completeness, expressed in percent, on "slave" pages. It is used by
+the default `templates/page.tmpl`.
+
+Additional PageSpec tests
+-------------------------
+
+This plugin enhances the regular [[ikiwiki/PageSpec]] syntax with some
+additional tests that are documented [[here|ikiwiki/pagespec/po]].
+
+Automatic PO file update
+------------------------
+
+Committing changes to a "master" page:
+
+1. updates the POT file and the PO files for the "slave" languages;
+   the updated PO files are then put under version control;
+2. triggers a refresh of the corresponding HTML slave pages.
+
+Also, when the plugin has just been enabled, or when a page has just
+been declared as being translatable, the needed POT and PO files are
+created, and the PO files are checked into version control.
+
+Discussion pages and other sub-pages
+------------------------------------
+
+Discussion should happen in the language in which the pages are
+written for real, *i.e.* the "master" one. If discussion pages are
+enabled, "slave" pages therefore link to the "master" page's
+discussion page.
+
+Likewise, "slave" pages are not supposed to have sub-pages;
+[[WikiLinks|wikilink]] that appear on a "slave" page therefore link to
+the master page's sub-pages.
+
+Translating
+-----------
+
+One can edit the PO files using ikiwiki's CGI (a message-by-message
+interface could also be implemented at some point).
+
+If [[tips/untrusted_git_push]] is setup, one can edit the PO files in one's
+preferred `$EDITOR`, without needing to be online.
+
+Markup languages support
+------------------------
+
+[[Markdown|mdwn]] is well supported. Some other markup languages supported
+by ikiwiki mostly work, but some pieces of syntax are not rendered
+correctly on the slave pages:
+
+* [[reStructuredText|rst]]: anonymous hyperlinks and internal
+  cross-references
+* [[wikitext]]: conversion of newlines to paragraphs
+* [[creole]]: verbatim text is wrapped, tables are broken
+* [[html]] and LaTeX: not supported yet; the dedicated po4a modules
+  could be used to support them, but they would need a security audit
+* other markup languages have not been tested.
+
+Security
+========
+
+[[po/security]] contains a detailed security analysis of this plugin
+and its dependencies.
+
+When using po4a older than 0.35, it is recommended to uninstall
+`Text::WrapI18N` (Debian package `libtext-wrapi18n-perl`), in order to
+avoid a potential denial of service.
+
+TODO
+====
+
+Better links
+------------
+
+Once the fix to
+[[bugs/pagetitle_function_does_not_respect_meta_titles]] from
+[[intrigeri]]'s `meta` branch is merged into ikiwiki upstream, the
+generated links' text will be optionally based on the page titles set
+with the [[meta|plugins/meta]] plugin, and will thus be translatable.
+It will also allow displaying the translation status in links to slave
+pages. Both were implemented, and reverted in commit
+ea753782b222bf4ba2fb4683b6363afdd9055b64, which should be reverted
+once [[intrigeri]]'s `meta` branch is merged.
+
+An integration branch, called `meta-po`, merges [[intrigeri]]'s `po`
+and `meta` branches, and thus has thise additional features.
+
+Robustness tests
+----------------
+
+### Enabling/disabling the plugin
+
+* enabling the plugin with `po_translatable_pages` set to blacklist: **OK**
+* enabling the plugin with `po_translatable_pages` set to whitelist: **OK**
+* enabling the plugin without `po_translatable_pages` set: **OK**
+* disabling the plugin: **OK**
+
+### Changing the plugin config
+
+* adding existing pages to `po_translatable_pages`: **OK**
+* removing existing pages from `po_translatable_pages`: **OK**
+* adding a language to `po_slave_languages`: **OK**
+* removing a language from `po_slave_languages`: **OK**
+* changing `po_master_language`: **OK**
+* replacing `po_master_language` with a language previously part of
+  `po_slave_languages`: needs two rebuilds, but **OK** (this is quite
+  a perverse test actually)
+
+### Creating/deleting/renaming pages
+
+All cases of master/slave page creation/deletion/rename, both via RCS
+and via CGI, have been tested.
+
+### Misc
+
+* general test with `usedirs` disabled: **OK**
+* general test with `indexpages` enabled: **not OK**
+* general test with `po_link_to=default` with `userdirs` enabled: **OK**
+* general test with `po_link_to=default` with `userdirs` disabled: **OK**
+
+Misc. bugs
+----------
+
+Documentation
+-------------
+
+Maybe write separate documentation depending on the people it targets:
+translators, wiki administrators, hackers. This plugin may be complex
+enough to deserve this.
diff --git a/doc/plugins/po/discussion.mdwn b/doc/plugins/po/discussion.mdwn
new file mode 100644
index 000000000..570b2a6ef
--- /dev/null
+++ b/doc/plugins/po/discussion.mdwn
@@ -0,0 +1,208 @@
+[[!toc ]]
+
+----
+
+# Security review
+
+## Probable holes
+
+_(The list of things to fix.)_
+
+### po4a-gettextize
+
+* po4a CVS 2009-01-16
+* Perl 5.10.0
+
+`po4a-gettextize` uses more or less the same po4a features as our
+`refreshpot` function.
+
+Without specifying an input charset, zzuf'ed `po4a-gettextize` quickly
+errors out, complaining it was not able to detect the input charset;
+it leaves no incomplete file on disk. I therefore had to pretend the
+input was in UTF-8, as does the po plugin.
+
+        zzuf -c -s 13 -r 0.1 \
+            po4a-gettextize -f text -o markdown -M utf-8 -L utf-8 \
+             -m GPL-3 -p GPL-3.pot
+
+Crashes with:
+
+        Malformed UTF-8 character (UTF-16 surrogate 0xdfa4) in substitution
+        iterator at /usr/share/perl5/Locale/Po4a/Po.pm line 1449.
+        Malformed UTF-8 character (fatal) at /usr/share/perl5/Locale/Po4a/Po.pm
+        line 1449.
+
+An incomplete pot file is left on disk. Unfortunately Po.pm tells us
+nothing about the place where the crash happens.
+
+> It's fairly standard perl behavior when fed malformed utf-8. As long
+> as it doesn't crash ikiwiki, it's probably acceptable. Ikiwiki can
+> do some similar things itself when fed malformed utf-8 (doesn't
+> crash tho) --[[Joey]]
+
+----
+
+## Potential gotchas
+
+_(Things not to do.)_
+
+
+### Blindly activating more po4a format modules
+
+The format modules we want to use have to be checked, as not all are
+safe (e.g. the LaTeX module's behaviour is changed by commands
+included in the content); they may use regexps generated from
+the content.
+
+----
+
+## Hopefully non-holes
+
+_(AKA, the assumptions that will be the root of most security holes...)_
+
+### PO file features
+
+No [documented](http://www.gnu.org/software/gettext/manual/gettext.html#PO-Files)
+directive that can be put in po files is supposed to cause mischief
+(ie, include other files, run commands, crash gettext, whatever).
+
+### gettext
+
+#### Security history
+
+The only past security issue I could find in GNU gettext is
+[CVE-2004-0966](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-0966),
+*i.e.* [Debian bug #278283](http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=278283):
+the autopoint and gettextize scripts in the GNU gettext package (1.14
+and later versions) may allow local users to overwrite files via
+a symlink attack on temporary files.
+
+This plugin would not have allowed to exploit this bug, as it does not
+use, either directly or indirectly, the faulty scripts.
+
+Note: the lack of found security issues can either indicate that there
+are none, or reveal that no-one ever bothered to find or publish them.
+
+#### msgmerge
+
+`refreshpofiles()` runs this external program.
+
+* I was not able to crash it with `zzuf`.
+* I could not find any past security hole.
+
+#### msgfmt
+
+`isvalidpo()` runs this external program.
+
+* I was not able to make it behave badly using zzuf: it exits cleanly
+  when too many errors are detected.
+* I could not find any past security hole.
+
+### po4a
+
+#### Security history
+
+The only past security issue I could find in po4a is
+[CVE-2007-4462](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-4462):
+`lib/Locale/Po4a/Po.pm` in po4a before 0.32 allowed local users to
+overwrite arbitrary files via a symlink attack on the
+gettextization.failed.po temporary file.
+
+This plugin would not have allowed to exploit this bug, as it does not
+use, either directly or indirectly, the faulty `gettextize` function.
+
+Note: the lack of found security issues can either indicate that there
+are none, or reveal that no-one ever bothered to find or publish them.
+
+#### General feeling
+
+Are there any security issues on running po4a on untrusted content?
+
+To say the least, this issue is not well covered, at least publicly:
+
+* the documentation does not talk about it;
+* grep'ing the source code for `security` or `trust` gives no answer.
+
+On the other hand, a po4a developer answered my questions in
+a convincing manner, stating that processing untrusted content was not
+an initial goal, and analysing in detail the possible issues.
+The following analysis was done with his help.
+
+#### Details
+
+* the core (`Po.pm`, `Transtractor.pm`) should be safe
+* po4a source code was fully checked for other potential symlink
+  attacks, after discovery of one such issue
+* the only external program run by the core is `diff`, in `Po.pm` (in
+  parts of its code we don't use)
+* `Locale::gettext` is only used to display translated error messages
+* Nicolas François "hopes" `DynaLoader` is safe, and has "no reason to
+  think that `Encode` is not safe"
+* Nicolas François has "no reason to think that `Encode::Guess` is not
+  safe". The po plugin nevertheless avoids using it by defining the
+  input charset (`file_in_charset`) before asking `TransTractor` to
+  read any file. NB: this hack depends on po4a internals.
+
+##### Locale::Po4a::Text
+
+* does not run any external program
+* only `do_paragraph()` builds regexp's that expand untrusted
+  variables; according to [[Joey]], this is "Freaky code, but seems ok
+  due to use of `quotementa`".
+
+##### Text::WrapI18N
+
+`Text::WrapI18N` can cause DoS
+([Debian bug #470250](http://bugs.debian.org/470250)).
+It is optional, and we do not need the features it provides.
+
+If a recent enough po4a (>=0.35) is installed, this module's use is
+fully disabled. Else, the wiki administrator is warned about this
+at runtime.
+
+##### Term::ReadKey
+
+`Term::ReadKey` is not a hard dependency in our case, *i.e.* po4a
+works nicely without it. But the po4a Debian package recommends
+`libterm-readkey-perl`, so it will probably be installed on most
+systems using the po plugin.
+
+`Term::ReadKey` has too far reaching implications for us to
+be able to guarantee anything wrt. security.
+
+If a recent enough po4a (>=2009-01-15 CVS, which will probably be
+released as 0.35) is installed, this module's use is fully disabled.
+
+##### Fuzzing input
+
+###### po4a-translate
+
+* po4a CVS 2009-01-16
+* Perl 5.10.0
+
+`po4a-translate` uses more or less the same po4a features as our
+`filter` function.
+
+Without specifying an input charset, same behaviour as
+`po4a-gettextize`, so let's specify UTF-8 as input charset as of now.
+
+`LICENSES` is a 21M file containing 100 concatenated copies of all the
+files in `/usr/share/common-licenses/`; I had no existing PO file or
+translated versions at hand, which renders these tests
+quite incomplete.
+
+        zzuf -cv -s 0:10 -r 0.001:0.3 \
+          po4a-translate -d -f text -o markdown -M utf-8 -L utf-8 \
+            -k 0 -m LICENSES -p LICENSES.fr.po -l test.fr
+
+... seems to lose the fight, at the `readpo(LICENSES.fr.po)` step,
+against some kind of infinite loop, deadlock, or any similar beast.
+
+The root of this bug lies in `Text::WrapI18N`, see the corresponding
+section.
+
+
+----
+
+## Fixed holes
+
diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index d0f6a09e1..ac0935773 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -330,6 +330,26 @@ This hook should avoid directly redirecting the user to a signin page,
 since it's sometimes used to test to see which pages in a set of pages a
 user can edit.
 
+### canremove
+
+	hook(type => "canremove", id => "foo", call => \&canremove);
+
+This hook can be used to implement arbitrary access methods to control
+when a page can be removed using the web interface (commits from
+revision control bypass it). It works exactly like the `canedit` hook,
+but is passed the named parameters `cgi` (a CGI object), `session`
+(a session object) and `page` (the page subject to deletion).
+
+### canrename
+
+	hook(type => "canrename", id => "foo", call => \&canrename);
+
+This hook can be used to implement arbitrary access methods to control when
+a page can be renamed using the web interface (commits from revision control
+bypass it). It works exactly like the `canedit` hook,
+but is passed the named parameters `cgi` (a CGI object), `session` (a
+session object), `src`, `srcfile`, `dest` and `destfile`.
+
 ### checkcontent
 	
 	hook(type => "checkcontent", id => "foo", call => \&checkcontent);
@@ -342,8 +362,9 @@ the content the user has entered is a comment, it may also be passed some
 additional parameters: `author`, `url`, and `subject`. The `subject`
 parameter may also be filled with the user's comment about the change.
 
-Note: When the user edits an existing wiki page, the passed `content` will
-include only the lines that they added to the page, or modified.
+Note: When the user edits an existing wiki page, this hook is also
+passed a `diff` named parameter, which will include only the lines
+that they added to the page, or modified.
 
 The hook should return `undef` on success. If the content is disallowed, it
 should return a message stating what the problem is, or a function
@@ -394,9 +415,28 @@ they're saved, etc.
 	hook(type => "renamepage", id => "foo", call => \&renamepage);
 
 This hook is called by the [[plugins/rename]] plugin when it renames
-something. The hook is passed named parameters: `page`, `oldpage`,
-`newpage`, and `content`, and should try to modify the content to reflect
-the name change. For example, by converting links to point to the new page.
+something, once per page linking to the renamed page's old location.
+The hook is passed named parameters: `page`, `oldpage`, `newpage`, and
+`content`, and should try to modify the content of `page` to reflect
+the name change. For example, by converting links to point to the
+new page.
+
+### rename
+
+	hook(type => "rename", id => "foo", call => \&rename);
+
+When a page or set of pages is renamed, the referenced function is
+called for every page, and is passed named parameters:
+
+* `torename`: a reference to a hash with keys: `src`, `srcfile`,
+  `dest`, `destfile`, `required`.
+* `cgi`: a CGI object
+* `session`: a session object.
+
+Such a hook function returns any additional rename hashes it wants to
+add. This hook is applied recursively to returned additional rename
+hashes, so that it handles the case where two plugins use the hook:
+plugin A would see when plugin B adds a new file to be renamed.
 
 ### getsetup
 
diff --git a/doc/todo/need_global_renamepage_hook.mdwn b/doc/todo/need_global_renamepage_hook.mdwn
index b123340af..e3cec4a9b 100644
--- a/doc/todo/need_global_renamepage_hook.mdwn
+++ b/doc/todo/need_global_renamepage_hook.mdwn
@@ -61,7 +61,7 @@ would solve my problem. Hmmm? --[[intrigeri]]
 >>> not be broken. I will thus keep the existing `renamepage` as it
 >>> is, and call `rename` the global hook I need. --[[intrigeri]]
 
->>>> Done in my `po` branch. --[[intrigeri]]
+>>>> [[Done]] in my `po` branch. --[[intrigeri]]
 
 I think I see a problem in the rename hook. The hook is called
 before the plugin adds any subpages to the set of pages to rename.
diff --git a/t/po.t b/t/po.t
new file mode 100755
index 000000000..b6885a37e
--- /dev/null
+++ b/t/po.t
@@ -0,0 +1,177 @@
+#!/usr/bin/perl
+# -*- cperl-indent-level: 8; -*-
+use warnings;
+use strict;
+use File::Temp qw{tempdir};
+
+BEGIN {
+	unless (eval { require Locale::Po4a::Chooser }) {
+		eval q{
+			use Test::More skip_all => "Locale::Po4a::Chooser::new is not available"
+		}
+	}
+	unless (eval { require Locale::Po4a::Po }) {
+		eval q{
+			use Test::More skip_all => "Locale::Po4a::Po::new is not available"
+		}
+	}
+}
+
+use Test::More tests => 65;
+
+BEGIN { use_ok("IkiWiki"); }
+
+my $msgprefix;
+
+my $dir = tempdir("ikiwiki-test-po.XXXXXXXXXX",
+		  DIR => File::Spec->tmpdir,
+		  CLEANUP => 1);
+
+### Init
+%config=IkiWiki::defaultconfig();
+$config{srcdir} = "$dir/src";
+$config{destdir} = "$dir/dst";
+$config{discussion} = 0;
+$config{po_master_language} = { code => 'en',
+				name => 'English'
+			      };
+$config{po_slave_languages} = {
+			       es => 'Castellano',
+			       fr => "Français"
+			      };
+$config{po_translatable_pages}='index or test1 or test2 or translatable';
+$config{po_link_to}='negotiated';
+IkiWiki::loadplugins();
+IkiWiki::checkconfig();
+ok(IkiWiki::loadplugin('po'), "po plugin loaded");
+
+### seed %pagesources and %pagecase
+$pagesources{'index'}='index.mdwn';
+$pagesources{'index.fr'}='index.fr.po';
+$pagesources{'index.es'}='index.es.po';
+$pagesources{'test1'}='test1.mdwn';
+$pagesources{'test1.fr'}='test1.fr.po';
+$pagesources{'test2'}='test2.mdwn';
+$pagesources{'test2.es'}='test2.es.po';
+$pagesources{'test2.fr'}='test2.fr.po';
+$pagesources{'test3'}='test3.mdwn';
+$pagesources{'test3.es'}='test3.es.mdwn';
+$pagesources{'translatable'}='translatable.mdwn';
+$pagesources{'translatable.fr'}='translatable.fr.po';
+$pagesources{'translatable.es'}='translatable.es.po';
+$pagesources{'nontranslatable'}='nontranslatable.mdwn';
+foreach my $page (keys %pagesources) {
+    $IkiWiki::pagecase{lc $page}=$page;
+}
+
+### populate srcdir
+writefile('index.mdwn', $config{srcdir}, '[[translatable]] [[nontranslatable]]');
+writefile('test1.mdwn', $config{srcdir}, 'test1 content');
+writefile('test2.mdwn', $config{srcdir}, 'test2 content');
+writefile('test3.mdwn', $config{srcdir}, 'test3 content');
+writefile('translatable.mdwn', $config{srcdir}, '[[nontranslatable]]');
+writefile('nontranslatable.mdwn', $config{srcdir}, '[[/]] [[translatable]]');
+
+### istranslatable/istranslation
+# we run these tests twice because memoization attempts made them
+# succeed once every two tries...
+foreach (1, 2) {
+ok(IkiWiki::Plugin::po::istranslatable('index'), "index is translatable");
+ok(IkiWiki::Plugin::po::istranslatable('/index'), "/index is translatable");
+ok(! IkiWiki::Plugin::po::istranslatable('index.fr'), "index.fr is not translatable");
+ok(! IkiWiki::Plugin::po::istranslatable('index.es'), "index.es is not translatable");
+ok(! IkiWiki::Plugin::po::istranslatable('/index.fr'), "/index.fr is not translatable");
+ok(! IkiWiki::Plugin::po::istranslation('index'), "index is not a translation");
+ok(IkiWiki::Plugin::po::istranslation('index.fr'), "index.fr is a translation");
+ok(IkiWiki::Plugin::po::istranslation('index.es'), "index.es is a translation");
+ok(IkiWiki::Plugin::po::istranslation('/index.fr'), "/index.fr is a translation");
+ok(IkiWiki::Plugin::po::istranslatable('test2'), "test2 is translatable");
+ok(! IkiWiki::Plugin::po::istranslation('test2'), "test2 is not a translation");
+ok(! IkiWiki::Plugin::po::istranslatable('test3'), "test3 is not translatable");
+ok(! IkiWiki::Plugin::po::istranslation('test3'), "test3 is not a translation");
+}
+
+### links
+require IkiWiki::Render;
+
+sub refresh_n_scan(@) {
+	my @masterfiles_rel=@_;
+	foreach my $masterfile_rel (@masterfiles_rel) {
+		my $masterfile=srcfile($masterfile_rel);
+		IkiWiki::scan($masterfile_rel);
+		next unless IkiWiki::Plugin::po::istranslatable(pagename($masterfile_rel));
+		my @pofiles=IkiWiki::Plugin::po::pofiles($masterfile);
+		IkiWiki::Plugin::po::refreshpot($masterfile);
+		IkiWiki::Plugin::po::refreshpofiles($masterfile, @pofiles);
+		map IkiWiki::scan(IkiWiki::abs2rel($_, $config{srcdir})), @pofiles;
+	}
+}
+
+$config{po_link_to}='negotiated';
+$msgprefix="links (po_link_to=negotiated)";
+refresh_n_scan('index.mdwn', 'translatable.mdwn', 'nontranslatable.mdwn');
+is_deeply(\@{$links{'index'}}, ['translatable', 'nontranslatable'], "$msgprefix index");
+is_deeply(\@{$links{'index.es'}}, ['translatable.es', 'nontranslatable'], "$msgprefix index.es");
+is_deeply(\@{$links{'index.fr'}}, ['translatable.fr', 'nontranslatable'], "$msgprefix index.fr");
+is_deeply(\@{$links{'translatable'}}, ['nontranslatable'], "$msgprefix translatable");
+is_deeply(\@{$links{'translatable.es'}}, ['nontranslatable'], "$msgprefix translatable.es");
+is_deeply(\@{$links{'translatable.fr'}}, ['nontranslatable'], "$msgprefix translatable.fr");
+is_deeply(\@{$links{'nontranslatable'}}, ['/', 'translatable', 'translatable.fr', 'translatable.es'], "$msgprefix nontranslatable");
+
+$config{po_link_to}='current';
+$msgprefix="links (po_link_to=current)";
+refresh_n_scan('index.mdwn', 'translatable.mdwn', 'nontranslatable.mdwn');
+is_deeply(\@{$links{'index'}}, ['translatable', 'nontranslatable'], "$msgprefix index");
+is_deeply(\@{$links{'index.es'}}, [ map bestlink('index.es', $_), ('translatable.es', 'nontranslatable')], "$msgprefix index.es");
+is_deeply(\@{$links{'index.fr'}}, [ map bestlink('index.fr', $_), ('translatable.fr', 'nontranslatable')], "$msgprefix index.fr");
+is_deeply(\@{$links{'translatable'}}, [bestlink('translatable', 'nontranslatable')], "$msgprefix translatable");
+is_deeply(\@{$links{'translatable.es'}}, ['nontranslatable'], "$msgprefix translatable.es");
+is_deeply(\@{$links{'translatable.fr'}}, ['nontranslatable'], "$msgprefix translatable.fr");
+is_deeply(\@{$links{'nontranslatable'}}, ['/', 'translatable', 'translatable.fr', 'translatable.es'], "$msgprefix nontranslatable");
+
+### targetpage
+$config{usedirs}=0;
+$msgprefix="targetpage (usedirs=0)";
+is(targetpage('test1', 'html'), 'test1.en.html', "$msgprefix test1");
+is(targetpage('test1.fr', 'html'), 'test1.fr.html', "$msgprefix test1.fr");
+$config{usedirs}=1;
+$msgprefix="targetpage (usedirs=1)";
+is(targetpage('index', 'html'), 'index.en.html', "$msgprefix index");
+is(targetpage('index.fr', 'html'), 'index.fr.html', "$msgprefix index.fr");
+is(targetpage('test1', 'html'), 'test1/index.en.html', "$msgprefix test1");
+is(targetpage('test1.fr', 'html'), 'test1/index.fr.html', "$msgprefix test1.fr");
+is(targetpage('test3', 'html'), 'test3/index.html', "$msgprefix test3 (non-translatable page)");
+is(targetpage('test3.es', 'html'), 'test3.es/index.html', "$msgprefix test3.es (non-translatable page)");
+
+### urlto -> index
+$config{po_link_to}='current';
+$msgprefix="urlto (po_link_to=current)";
+is(urlto('', 'index'), './index.en.html', "$msgprefix index -> ''");
+is(urlto('', 'nontranslatable'), '../index.en.html', "$msgprefix nontranslatable -> ''");
+is(urlto('', 'translatable.fr'), '../index.fr.html', "$msgprefix translatable.fr -> ''");
+$config{po_link_to}='negotiated';
+$msgprefix="urlto (po_link_to=negotiated)";
+is(urlto('', 'index'), './', "$msgprefix index -> ''");
+is(urlto('', 'nontranslatable'), '../', "$msgprefix nontranslatable -> ''");
+is(urlto('', 'translatable.fr'), '../', "$msgprefix translatable.fr -> ''");
+
+### bestlink
+$config{po_link_to}='current';
+$msgprefix="bestlink (po_link_to=current)";
+is(bestlink('test1.fr', 'test2'), 'test2.fr', "$msgprefix test1.fr -> test2");
+is(bestlink('test1.fr', 'test2.es'), 'test2.es', "$msgprefix test1.fr -> test2.es");
+$config{po_link_to}='negotiated';
+$msgprefix="bestlink (po_link_to=negotiated)";
+is(bestlink('test1.fr', 'test2'), 'test2.fr', "$msgprefix test1.fr -> test2");
+is(bestlink('test1.fr', 'test2.es'), 'test2.es', "$msgprefix test1.fr -> test2.es");
+
+### beautify_urlpath
+$config{po_link_to}='default';
+$msgprefix="beautify_urlpath (po_link_to=default)";
+is(IkiWiki::beautify_urlpath('test1/index.en.html'), './test1/index.en.html', "$msgprefix test1/index.en.html");
+is(IkiWiki::beautify_urlpath('test1/index.fr.html'), './test1/index.fr.html', "$msgprefix test1/index.fr.html");
+$config{po_link_to}='negotiated';
+$msgprefix="beautify_urlpath (po_link_to=negotiated)";
+is(IkiWiki::beautify_urlpath('test1/index.html'), './test1/', "$msgprefix test1/index.html");
+is(IkiWiki::beautify_urlpath('test1/index.en.html'), './test1/', "$msgprefix test1/index.en.html");
+is(IkiWiki::beautify_urlpath('test1/index.fr.html'), './test1/', "$msgprefix test1/index.fr.html");
diff --git a/t/syntax.t b/t/syntax.t
index 05d955f33..a3760a2b2 100755
--- a/t/syntax.t
+++ b/t/syntax.t
@@ -6,7 +6,7 @@ use Test::More;
 my @progs="ikiwiki.in";
 my @libs="IkiWiki.pm";
 # monotone, external, amazon_s3 skipped since they need perl modules
-push @libs, map { chomp; $_ } `find IkiWiki -type f -name \\*.pm | grep -v monotone.pm | grep -v external.pm | grep -v amazon_s3.pm`;
+push @libs, map { chomp; $_ } `find IkiWiki -type f -name \\*.pm | grep -v monotone.pm | grep -v external.pm | grep -v amazon_s3.pm | grep -v po.pm`;
 push @libs, 'IkiWiki/Plugin/skeleton.pm.example';
 
 plan(tests => (@progs + @libs));
diff --git a/templates/page.tmpl b/templates/page.tmpl
index 29ba688c7..8622d1a01 100644
--- a/templates/page.tmpl
+++ b/templates/page.tmpl
@@ -28,6 +28,9 @@
 </span>
 <span class="title">
 <TMPL_VAR TITLE>
+<TMPL_IF NAME="ISTRANSLATION">
+(<TMPL_VAR NAME="PERCENTTRANSLATED">&nbsp;%)
+</TMPL_IF>
 </span>
 </span><!--.header-->
 <TMPL_IF NAME="SEARCHFORM">
@@ -60,6 +63,24 @@
 </ul>
 </div>
 </TMPL_IF>
+
+<TMPL_IF NAME="OTHERLANGUAGES">
+<div id="otherlanguages">
+<ul>
+<TMPL_LOOP NAME="OTHERLANGUAGES">
+<li>
+<a href="<TMPL_VAR NAME="URL">"><TMPL_VAR NAME="LANGUAGE"></a>
+<TMPL_IF NAME="MASTER">
+(master)
+<TMPL_ELSE>
+(<TMPL_VAR NAME="PERCENT">&nbsp;%)
+</TMPL_IF>
+</li>
+</TMPL_LOOP>
+</ul>
+</div> <!-- #otherlanguages -->
+</TMPL_IF>
+
 </div> <!-- .pageheader -->
 
 <TMPL_IF SIDEBAR>
diff --git a/templates/pocreatepage.tmpl b/templates/pocreatepage.tmpl
new file mode 100644
index 000000000..96c8fdd78
--- /dev/null
+++ b/templates/pocreatepage.tmpl
@@ -0,0 +1,3 @@
+<p>
+<b>WARNING</b> this page must be written in <TMPL_VAR NAME="LANG">.
+</p>
\ No newline at end of file
diff --git a/underlays/basewiki/ikiwiki/pagespec/po.mdwn b/underlays/basewiki/ikiwiki/pagespec/po.mdwn
new file mode 120000
index 000000000..255c3de9a
--- /dev/null
+++ b/underlays/basewiki/ikiwiki/pagespec/po.mdwn
@@ -0,0 +1 @@
+../../../../doc/ikiwiki/pagespec/po.mdwn
\ No newline at end of file