Merge remote branch 'smcv/ready/localurl'

21 files changed, 153 insertions, 61 deletions

diff --git a/IkiWiki.pm b/IkiWiki.pm
index c06751dd3..a893edb3b 100644
--- a/IkiWiki.pm
+++ b/IkiWiki.pm
@@ -501,6 +501,12 @@ sub defaultconfig () {
 	return @ret;
 }
 
+# URL to top of wiki as a path starting with /, valid from any wiki page or
+# the CGI; if that's not possible, an absolute URL. Either way, it ends with /
+my $local_url;
+# URL to CGI script, similar to $local_url
+my $local_cgiurl;
+
 sub checkconfig () {
 	# locale stuff; avoid LC_ALL since it overrides everything
 	if (defined $ENV{LC_ALL}) {
@@ -537,7 +543,33 @@ sub checkconfig () {
 	if ($config{cgi} && ! length $config{url}) {
 		error(gettext("Must specify url to wiki with --url when using --cgi"));
 	}
-	
+
+	if (length $config{url}) {
+		eval q{use URI};
+		my $baseurl = URI->new($config{url});
+
+		$local_url = $baseurl->path . "/";
+		$local_cgiurl = undef;
+
+		if (length $config{cgiurl}) {
+			my $cgiurl = URI->new($config{cgiurl});
+
+			$local_cgiurl = $cgiurl->path;
+
+			if ($cgiurl->scheme ne $baseurl->scheme or
+				$cgiurl->authority ne $baseurl->authority) {
+				# too far apart, fall back to absolute URLs
+				$local_url = "$config{url}/";
+				$local_cgiurl = $config{cgiurl};
+			}
+		}
+
+		$local_url =~ s{//$}{/};
+	}
+	else {
+		$local_cgiurl = $config{cgiurl};
+	}
+
 	$config{wikistatedir}="$config{srcdir}/.ikiwiki"
 		unless exists $config{wikistatedir} && defined $config{wikistatedir};
 
@@ -1010,11 +1042,17 @@ sub linkpage ($) {
 sub cgiurl (@) {
 	my %params=@_;
 
-	my $cgiurl=$config{cgiurl};
+	my $cgiurl=$local_cgiurl;
+
 	if (exists $params{cgiurl}) {
 		$cgiurl=$params{cgiurl};
 		delete $params{cgiurl};
 	}
+
+	unless (%params) {
+		return $cgiurl;
+	}
+
 	return $cgiurl."?".
 		join("&", map $_."=".uri_escape_utf8($params{$_}), keys %params);
 }
@@ -1022,7 +1060,7 @@ sub cgiurl (@) {
 sub baseurl (;$) {
 	my $page=shift;
 
-	return "$config{url}/" if ! defined $page;
+	return $local_url if ! defined $page;
 	
 	$page=htmlpage($page);
 	$page=~s/[^\/]+$//;
@@ -1113,6 +1151,12 @@ sub urlto ($$;$) {
 		return $config{url}.beautify_urlpath("/".$to);
 	}
 
+	if (! defined $from) {
+		my $u = $local_url;
+		$u =~ s{/$}{};
+		return $u.beautify_urlpath("/".$to);
+	}
+
 	my $link = abs2rel($to, dirname(htmlpage($from)));
 
 	return beautify_urlpath($link);
diff --git a/IkiWiki/CGI.pm b/IkiWiki/CGI.pm
index f2a32a958..e0bfda9ae 100644
--- a/IkiWiki/CGI.pm
+++ b/IkiWiki/CGI.pm
@@ -116,7 +116,7 @@ sub cgi_signin ($$;$) {
 		required => 'NONE',
 		javascript => 0,
 		params => $q,
-		action => $config{cgiurl},
+		action => cgiurl(),
 		header => 0,
 		template => {type => 'div'},
 		stylesheet => 1,
@@ -198,7 +198,7 @@ sub cgi_prefs ($$) {
 		required => 'NONE',
 		javascript => 0,
 		params => $q,
-		action => $config{cgiurl},
+		action => cgiurl(),
 		template => {type => 'div'},
 		stylesheet => 1,
 		fieldsets => [
@@ -231,11 +231,11 @@ sub cgi_prefs ($$) {
 	
 	if ($form->submitted eq 'Logout') {
 		$session->delete();
-		redirect($q, $config{url});
+		redirect($q, baseurl(undef));
 		return;
 	}
 	elsif ($form->submitted eq 'Cancel') {
-		redirect($q, $config{url});
+		redirect($q, baseurl(undef));
 		return;
 	}
 	elsif ($form->submitted eq 'Save Preferences' && $form->validate) {
diff --git a/IkiWiki/Plugin/comments.pm b/IkiWiki/Plugin/comments.pm
index a39dab36c..a3cb7c3d5 100644
--- a/IkiWiki/Plugin/comments.pm
+++ b/IkiWiki/Plugin/comments.pm
@@ -237,7 +237,7 @@ sub preprocess {
 	}
 
 	if ($params{page} =~ m/\/\Q$config{comments_pagename}\E\d+_/) {
-		$pagestate{$page}{meta}{permalink} = urlto(IkiWiki::dirname($params{page}), undef, 1).
+		$pagestate{$page}{meta}{permalink} = urlto(IkiWiki::dirname($params{page}), undef).
 			"#".page_to_id($params{page});
 	}
 
@@ -301,7 +301,7 @@ sub editcomment ($$) {
 		required => [qw{editcontent}],
 		javascript => 0,
 		params => $cgi,
-		action => $config{cgiurl},
+		action => IkiWiki::cgiurl(),
 		header => 0,
 		table => 0,
 		template => { template('editcomment.tmpl') },
@@ -372,7 +372,7 @@ sub editcomment ($$) {
 		error(gettext("bad page name"));
 	}
 
-	my $baseurl = urlto($page, undef, 1);
+	my $baseurl = urlto($page, undef);
 
 	$form->title(sprintf(gettext("commenting on %s"),
 			IkiWiki::pagetitle($page)));
@@ -386,7 +386,7 @@ sub editcomment ($$) {
 	if ($form->submitted eq CANCEL) {
 		# bounce back to the page they wanted to comment on, and exit.
 		# CANCEL need not be considered in future
-		IkiWiki::redirect($cgi, urlto($page, undef, 1));
+		IkiWiki::redirect($cgi, urlto($page, undef));
 		exit;
 	}
 
@@ -552,7 +552,7 @@ sub editcomment ($$) {
 		# Jump to the new comment on the page.
 		# The trailing question mark tries to avoid broken
 		# caches and get the most recent version of the page.
-		IkiWiki::redirect($cgi, urlto($page, undef, 1).
+		IkiWiki::redirect($cgi, urlto($page, undef).
 			"?updated#".page_to_id($location));
 
 	}
@@ -656,6 +656,7 @@ sub commentmoderation ($$) {
 	$template->param(
 		sid => $session->id,
 		comments => \@comments,
+		cgiurl => IkiWiki::cgiurl(),
 	);
 	IkiWiki::printheader($session);
 	my $out=$template->output;
@@ -810,14 +811,14 @@ sub pagetemplate (@) {
 	if ($shown) {
 		if ($template->query(name => 'commentsurl')) {
 			$template->param(commentsurl =>
-				urlto($page, undef, 1).'#comments');
+				urlto($page, undef).'#comments');
 		}
 
 		if ($template->query(name => 'atomcommentsurl') && $config{usedirs}) {
 			# This will 404 until there are some comments, but I
 			# think that's probably OK...
 			$template->param(atomcommentsurl =>
-				urlto($page, undef, 1).'comments.atom');
+				urlto($page, undef).'comments.atom');
 		}
 
 		if ($template->query(name => 'commentslink')) {
diff --git a/IkiWiki/Plugin/editpage.pm b/IkiWiki/Plugin/editpage.pm
index 1a04a72b5..b3ae1fded 100644
--- a/IkiWiki/Plugin/editpage.pm
+++ b/IkiWiki/Plugin/editpage.pm
@@ -75,7 +75,7 @@ sub cgi_editpage ($$) {
 		required => [qw{editcontent}],
 		javascript => 0,
 		params => $q,
-		action => $config{cgiurl},
+		action => IkiWiki::cgiurl(),
 		header => 0,
 		table => 0,
 		template => { template("editpage.tmpl") },
@@ -98,7 +98,7 @@ sub cgi_editpage ($$) {
 		error(gettext("bad page name"));
 	}
 
-	my $baseurl = urlto($page, undef, 1);
+	my $baseurl = urlto($page, undef);
 
 	my $from;
 	if (defined $form->field('from')) {
@@ -156,13 +156,13 @@ sub cgi_editpage ($$) {
 	my $previewing=0;
 	if ($form->submitted eq "Cancel") {
 		if ($form->field("do") eq "create" && defined $from) {
-			redirect($q, urlto($from, undef, 1));
+			redirect($q, urlto($from, undef));
 		}
 		elsif ($form->field("do") eq "create") {
-			redirect($q, $config{url});
+			redirect($q, baseurl(undef));
 		}
 		else {
-			redirect($q, urlto($page, undef, 1));
+			redirect($q, urlto($page, undef));
 		}
 		exit;
 	}
@@ -262,7 +262,7 @@ sub cgi_editpage ($$) {
 					@page_locs=$page;
 				}
 				else {
-					redirect($q, urlto($page, undef, 1));
+					redirect($q, urlto($page, undef));
 					exit;
 				}
 			}
@@ -434,7 +434,7 @@ sub cgi_editpage ($$) {
 		else {
 			# The trailing question mark tries to avoid broken
 			# caches and get the most recent version of the page.
-			redirect($q, urlto($page, undef, 1)."?updated");
+			redirect($q, urlto($page, undef)."?updated");
 		}
 	}
 
diff --git a/IkiWiki/Plugin/goto.pm b/IkiWiki/Plugin/goto.pm
index 348a663ef..7f31fa5ca 100644
--- a/IkiWiki/Plugin/goto.pm
+++ b/IkiWiki/Plugin/goto.pm
@@ -64,7 +64,7 @@ sub cgi_goto ($;$) {
 		)
 	}
 	else {
-		IkiWiki::redirect($q, urlto($link, undef, 1));
+		IkiWiki::redirect($q, urlto($link, undef));
 	}
 
 	exit;
diff --git a/IkiWiki/Plugin/img.pm b/IkiWiki/Plugin/img.pm
index bd527c8c8..b554a3dfc 100644
--- a/IkiWiki/Plugin/img.pm
+++ b/IkiWiki/Plugin/img.pm
@@ -152,8 +152,8 @@ sub preprocess (@) {
 		$imgurl=urlto($imglink, $params{destpage});
 	}
 	else {
-		$fileurl="$config{url}/$file";
-		$imgurl="$config{url}/$imglink";
+		$fileurl=urlto($file, undef);
+		$imgurl=urlto($imglink, undef);
 	}
 
 	if (! exists $params{class}) {
diff --git a/IkiWiki/Plugin/inline.pm b/IkiWiki/Plugin/inline.pm
index 1fe40a5ea..765271564 100644
--- a/IkiWiki/Plugin/inline.pm
+++ b/IkiWiki/Plugin/inline.pm
@@ -300,7 +300,7 @@ sub preprocess_inline (@) {
 	    IkiWiki->can("cgi_editpage")) {
 		# Add a blog post form, with feed buttons.
 		my $formtemplate=template_depends("blogpost.tmpl", $params{page}, blind_cache => 1);
-		$formtemplate->param(cgiurl => $config{cgiurl});
+		$formtemplate->param(cgiurl => IkiWiki::cgiurl());
 		$formtemplate->param(rootpage => rootpage(%params));
 		$formtemplate->param(rssurl => $rssurl) if $feeds && $rss;
 		$formtemplate->param(atomurl => $atomurl) if $feeds && $atom;
diff --git a/IkiWiki/Plugin/openid.pm b/IkiWiki/Plugin/openid.pm
index fae9fb77f..0220a3cf6 100644
--- a/IkiWiki/Plugin/openid.pm
+++ b/IkiWiki/Plugin/openid.pm
@@ -77,7 +77,7 @@ sub openid_selector {
 
 	my $template=IkiWiki::template("openid-selector.tmpl");
 	$template->param(
-		cgiurl => $config{cgiurl},
+		cgiurl => IkiWiki::cgiurl(),
 		(defined $openid_error ? (openid_error => $openid_error) : ()),
 		(defined $openid_url ? (openid_url => $openid_url) : ()),
 		($real_cgi_signin ? (nonopenidform => $real_cgi_signin->($q, $session, 1)) : ()),
@@ -148,7 +148,7 @@ sub validate ($$$;$) {
 	}
 
 	my $cgiurl=$config{openid_cgiurl};
-	$cgiurl=$config{cgiurl} if ! defined $cgiurl;
+	$cgiurl=IkiWiki::cgiurl() if ! defined $cgiurl;
 
 	my $trust_root=$config{openid_realm};
 	$trust_root=$cgiurl if ! defined $trust_root;
@@ -175,7 +175,7 @@ sub auth ($$) {
 			IkiWiki::redirect($q, $setup_url);
 		}
 		elsif ($csr->user_cancel) {
-			IkiWiki::redirect($q, $config{url});
+			IkiWiki::redirect($q, IkiWiki::baseurl(undef));
 		}
 		elsif (my $vident = $csr->verified_identity) {
 			$session->param(name => $vident->url);
@@ -249,7 +249,7 @@ sub getobj ($$) {
 	}
 	
 	my $cgiurl=$config{openid_cgiurl};
-	$cgiurl=$config{cgiurl} if ! defined $cgiurl;
+	$cgiurl=IkiWiki::cgiurl() if ! defined $cgiurl;
 
 	return Net::OpenID::Consumer->new(
 		ua => $ua,
diff --git a/IkiWiki/Plugin/parentlinks.pm b/IkiWiki/Plugin/parentlinks.pm
index bbd2c5752..203ea13b6 100644
--- a/IkiWiki/Plugin/parentlinks.pm
+++ b/IkiWiki/Plugin/parentlinks.pm
@@ -27,7 +27,7 @@ sub parentlinks ($) {
 	if (! length $page) {
 		# dynamic page
 		return {
-			url => $config{url},
+			url => IkiWiki::baseurl(undef),
 			page => $config{wikiname},
 		};
 	}
diff --git a/IkiWiki/Plugin/pinger.pm b/IkiWiki/Plugin/pinger.pm
index cc9f52d2b..932619496 100644
--- a/IkiWiki/Plugin/pinger.pm
+++ b/IkiWiki/Plugin/pinger.pm
@@ -106,6 +106,8 @@ sub ping {
 			# only ping when a page was changed, so a ping loop
 			# will still be avoided.
 			next if $url=~/^\Q$config{cgiurl}\E/;
+			my $local_cgiurl = IkiWiki::cgiurl();
+			next if $url=~/^\Q$local_cgiurl\E/;
 			
 			$ua->get($url);
 		}
diff --git a/IkiWiki/Plugin/poll.pm b/IkiWiki/Plugin/poll.pm
index b333e2cdc..27df104ab 100644
--- a/IkiWiki/Plugin/poll.pm
+++ b/IkiWiki/Plugin/poll.pm
@@ -52,7 +52,7 @@ sub preprocess (@) {
 	foreach my $choice (@choices) {
 		if ($open && exists $config{cgiurl}) {
 			# use POST to avoid robots
-			$ret.="<form method=\"POST\" action=\"$config{cgiurl}\">\n";
+			$ret.="<form method=\"POST\" action=\"".IkiWiki::cgiurl()."\">\n";
 		}
 		my $percent=$total > 0 ? int($choices{$choice} / $total * 100) : 0;
 		$ret.="<p>\n";
@@ -103,7 +103,7 @@ sub sessioncgi ($$) {
 		my $oldchoice=$session->param($choice_param);
 		if (defined $oldchoice && $oldchoice eq $choice) {
 			# Same vote; no-op.
-			IkiWiki::redirect($cgi, urlto($page, undef, 1));
+			IkiWiki::redirect($cgi, urlto($page, undef));
 			exit;
 		}
 
@@ -153,7 +153,7 @@ sub sessioncgi ($$) {
 		error($@) if $@;
 		my $cookie = CGI::Cookie->new(-name=> $session->name, -value=> $session->id);
 		print $cgi->redirect(-cookie => $cookie,
-			-url => urlto($page, undef, 1));
+			-url => urlto($page, undef));
 		exit;
 	}
 }
diff --git a/IkiWiki/Plugin/recentchanges.pm b/IkiWiki/Plugin/recentchanges.pm
index 562f61d40..de12bb2c6 100644
--- a/IkiWiki/Plugin/recentchanges.pm
+++ b/IkiWiki/Plugin/recentchanges.pm
@@ -84,7 +84,7 @@ sub sessioncgi ($$) {
 		method => 'POST',
 		javascript => 0,
 		params => $q,
-		action => $config{cgiurl},
+		action => IkiWiki::cgiurl(),
 		stylesheet => 1,
 		template => { template('revert.tmpl') },
 		fields => [qw{revertmessage do sid rev}],
@@ -127,7 +127,7 @@ sub sessioncgi ($$) {
 		exit 0;
 	}
 
-	IkiWiki::redirect($q, urlto($config{recentchangespage}, ''));
+	IkiWiki::redirect($q, urlto($config{recentchangespage}, undef));
 	exit 0;
 }
 
@@ -178,7 +178,7 @@ sub store ($$$) {
 			else {
 				$_->{link} = pagetitle($_->{page});
 			}
-			$_->{baseurl}="$config{url}/" if length $config{url};
+			$_->{baseurl}=IkiWiki::baseurl(undef) if length $config{url};
 
 			$_;
 		} @{$change->{pages}}
@@ -226,7 +226,7 @@ sub store ($$$) {
 		wikiname => $config{wikiname},
 	);
 	
-	$template->param(permalink => "$config{url}/$config{recentchangespage}/#change-".titlepage($change->{rev}))
+	$template->param(permalink => urlto($config{recentchangespage}, undef)."#change-".titlepage($change->{rev}))
 		if exists $config{url};
 	
 	IkiWiki::run_hooks(pagetemplate => sub {
diff --git a/IkiWiki/Plugin/relativedate.pm b/IkiWiki/Plugin/relativedate.pm
index 7296889ab..4ae0be861 100644
--- a/IkiWiki/Plugin/relativedate.pm
+++ b/IkiWiki/Plugin/relativedate.pm
@@ -28,18 +28,17 @@ sub format (@) {
 
 	if (! ($params{content}=~s!^(<body[^>]*>)!$1.include_javascript($params{page})!em)) {
 		# no <body> tag, probably in preview mode
-		$params{content}=include_javascript($params{page}, 1).$params{content};
+		$params{content}=include_javascript(undef).$params{content};
 	}
 	return $params{content};
 }
 
-sub include_javascript ($;$) {
-	my $page=shift;
-	my $absolute=shift;
+sub include_javascript ($) {
+	my $from=shift;
 	
-	return '<script src="'.urlto("ikiwiki/ikiwiki.js", $page, $absolute).
+	return '<script src="'.urlto("ikiwiki/ikiwiki.js", $from).
 		'" type="text/javascript" charset="utf-8"></script>'."\n".
-		'<script src="'.urlto("ikiwiki/relativedate.js", $page, $absolute).
+		'<script src="'.urlto("ikiwiki/relativedate.js", $from).
 		'" type="text/javascript" charset="utf-8"></script>';
 }
 
diff --git a/IkiWiki/Plugin/remove.pm b/IkiWiki/Plugin/remove.pm
index 1717c8cf3..336a781ed 100644
--- a/IkiWiki/Plugin/remove.pm
+++ b/IkiWiki/Plugin/remove.pm
@@ -100,7 +100,7 @@ sub confirmation_form ($$) {
 		method => 'POST',
 		javascript => 0,
 		params => $q,
-		action => $config{cgiurl},
+		action => IkiWiki::cgiurl(),
 		stylesheet => 1,
 		fields => [qw{do page}],
 	);
@@ -240,7 +240,7 @@ sub sessioncgi ($$) {
 				if (! exists $pagesources{$parent}) {
 					$parent="index";
 				}
-				IkiWiki::redirect($q, urlto($parent, '/', 1));
+				IkiWiki::redirect($q, urlto($parent, undef));
 			}
 		}
 		else {
diff --git a/IkiWiki/Plugin/rename.pm b/IkiWiki/Plugin/rename.pm
index a05e85be0..57747d3c9 100644
--- a/IkiWiki/Plugin/rename.pm
+++ b/IkiWiki/Plugin/rename.pm
@@ -126,7 +126,7 @@ sub rename_form ($$$) {
 		method => 'POST',
 		javascript => 0,
 		params => $q,
-		action => $config{cgiurl},
+		action => IkiWiki::cgiurl(),
 		stylesheet => 1,
 		fields => [qw{do page new_name attachment}],
 	);
diff --git a/IkiWiki/Plugin/search.pm b/IkiWiki/Plugin/search.pm
index 8fb9dff0c..78eb750b5 100644
--- a/IkiWiki/Plugin/search.pm
+++ b/IkiWiki/Plugin/search.pm
@@ -58,7 +58,7 @@ sub pagetemplate (@) {
 	if ($template->query(name => "searchform")) {
 		if (! defined $form) {
 			my $searchform = template("searchform.tmpl", blind_cache => 1);
-			$searchform->param(searchaction => $config{cgiurl});
+			$searchform->param(searchaction => IkiWiki::cgiurl());
 			$searchform->param(html5 => $config{html5});
 			$form=$searchform->output;
 		}
@@ -176,7 +176,7 @@ sub cgi ($) {
 		# only works for GET requests
 		chdir("$config{wikistatedir}/xapian") || error("chdir: $!");
 		$ENV{OMEGA_CONFIG_FILE}="./omega.conf";
-		$ENV{CGIURL}=$config{cgiurl},
+		$ENV{CGIURL}=IkiWiki::cgiurl();
 		IkiWiki::loadindex();
 		$ENV{HELPLINK}=htmllink("", "", "ikiwiki/searching",
 			noimageinline => 1, linktext => "Help");
diff --git a/IkiWiki/Plugin/toggle.pm b/IkiWiki/Plugin/toggle.pm
index 1f93f87fe..af4d2ba3a 100644
--- a/IkiWiki/Plugin/toggle.pm
+++ b/IkiWiki/Plugin/toggle.pm
@@ -70,19 +70,18 @@ sub format (@) {
 		$params{content}=~s/<div class="toggleableend">//g;
 		if (! ($params{content}=~s!^(<body[^>]*>)!$1.include_javascript($params{page})!em)) {
 			# no <body> tag, probably in preview mode
-			$params{content}=include_javascript($params{page}, 1).$params{content};
+			$params{content}=include_javascript(undef).$params{content};
 		}
 	}
 	return $params{content};
 }
 
-sub include_javascript ($;$) {
-	my $page=shift;
-	my $absolute=shift;
+sub include_javascript ($) {
+	my $from=shift;
 	
-	return '<script src="'.urlto("ikiwiki/ikiwiki.js", $page, $absolute).
+	return '<script src="'.urlto("ikiwiki/ikiwiki.js", $from).
 		'" type="text/javascript" charset="utf-8"></script>'."\n".
-		'<script src="'.urlto("ikiwiki/toggle.js", $page, $absolute).
+		'<script src="'.urlto("ikiwiki/toggle.js", $from).
 		'" type="text/javascript" charset="utf-8"></script>';
 }
 
diff --git a/IkiWiki/Plugin/websetup.pm b/IkiWiki/Plugin/websetup.pm
index 9c032fdc6..6a5190301 100644
--- a/IkiWiki/Plugin/websetup.pm
+++ b/IkiWiki/Plugin/websetup.pm
@@ -288,7 +288,7 @@ sub showform ($$) {
 		fieldsets => [
 			[main => gettext("main")], 
 		],
-		action => $config{cgiurl},
+		action => IkiWiki::cgiurl(),
 		template => {type => 'div'},
 		stylesheet => 1,
 	);
@@ -344,7 +344,7 @@ sub showform ($$) {
 	IkiWiki::decode_form_utf8($form);
 	
 	if ($form->submitted eq "Cancel") {
-		IkiWiki::redirect($cgi, $config{url});
+		IkiWiki::redirect($cgi, IkiWiki::baseurl(undef));
 		return;
 	}
 	elsif (($form->submitted eq 'Save Setup' || $form->submitted eq 'Rebuild Wiki') && $form->validate) {
diff --git a/IkiWiki/Plugin/wmd.pm b/IkiWiki/Plugin/wmd.pm
index 71d7c9d17..134cfb910 100644
--- a/IkiWiki/Plugin/wmd.pm
+++ b/IkiWiki/Plugin/wmd.pm
@@ -31,14 +31,13 @@ sub formbuilder_setup (@) {
 			$form->field("do") eq "comment";
 
 	$form->tmpl_param("wmd_preview", "<div class=\"wmd-preview\"></div>\n".
-		include_javascript(undef, 1));
+		include_javascript(undef));
 }
 
-sub include_javascript ($;$) {
-	my $page=shift;
-	my $absolute=shift;
+sub include_javascript ($) {
+	my $from=shift;
 
-	my $wmdjs=urlto("wmd/wmd.js", $page, $absolute);
+	my $wmdjs=urlto("wmd/wmd.js", $from);
 	return <<"EOF"
 <script type="text/javascript">
 wmd_options = {
diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 6b751f0cd..33db3e707 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -988,6 +988,10 @@ Construct a relative url to the first parameter from the page named by the
 second. The first parameter can be either a page name, or some other
 destination file, as registered by `will_render`.
 
+If the second parameter is `undef`, the URL will be valid from any page on the
+wiki, or from the CGI; if possible it'll be a path starting with `/`, but an
+absolute URL will be used if the wiki and the CGI are on different servers.
+
 If the third parameter is passed and is true, an absolute url will be
 constructed instead of the default relative url.
 
diff --git a/t/urlto.t b/t/urlto.t
new file mode 100755
index 000000000..a0b3baa45
--- /dev/null
+++ b/t/urlto.t
@@ -0,0 +1,44 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+use Test::More tests => 19;
+
+BEGIN { use_ok("IkiWiki"); }
+
+$IkiWiki::config{srcdir} = '/does/not/exist/';
+$IkiWiki::config{usedirs} = 1;
+$IkiWiki::config{htmlext} = "HTML";
+$IkiWiki::config{wiki_file_chars} = "A-Za-z0-9._";
+
+$IkiWiki::config{url} = "http://smcv.example.co.uk";
+$IkiWiki::config{cgiurl} = "http://smcv.example.co.uk/cgi-bin/ikiwiki.cgi";
+is(IkiWiki::checkconfig(), 1);
+
+# absolute version
+is(IkiWiki::cgiurl(cgiurl => $config{cgiurl}), "http://smcv.example.co.uk/cgi-bin/ikiwiki.cgi");
+is(IkiWiki::cgiurl(cgiurl => $config{cgiurl}, do => 'badger'), "http://smcv.example.co.uk/cgi-bin/ikiwiki.cgi?do=badger");
+is(IkiWiki::urlto('index', undef, 1), "http://smcv.example.co.uk/");
+is(IkiWiki::urlto('stoats', undef, 1), "http://smcv.example.co.uk/stoats/");
+
+# "local" (absolute path within site) version (default for cgiurl)
+is(IkiWiki::cgiurl(), "/cgi-bin/ikiwiki.cgi");
+is(IkiWiki::cgiurl(do => 'badger'), "/cgi-bin/ikiwiki.cgi?do=badger");
+is(IkiWiki::baseurl(undef), "/");
+is(IkiWiki::urlto('index', undef), "/");
+is(IkiWiki::urlto('stoats', undef), "/stoats/");
+
+# fully-relative version (default for urlto and baseurl)
+is(IkiWiki::baseurl('badger/mushroom'), "../../");
+is(IkiWiki::urlto('badger/mushroom', 'snake'), "../badger/mushroom/");
+
+# explicit cgiurl override
+is(IkiWiki::cgiurl(cgiurl => 'https://foo/ikiwiki'), "https://foo/ikiwiki");
+is(IkiWiki::cgiurl(do => 'badger', cgiurl => 'https://foo/ikiwiki'), "https://foo/ikiwiki?do=badger");
+
+# with url and cgiurl on different sites, "local" degrades to absolute
+$IkiWiki::config{url} = "http://example.co.uk/~smcv";
+$IkiWiki::config{cgiurl} = "http://dynamic.example.co.uk/~smcv/ikiwiki.cgi";
+is(IkiWiki::checkconfig(), 1);
+is(IkiWiki::cgiurl(), "http://dynamic.example.co.uk/~smcv/ikiwiki.cgi");
+is(IkiWiki::baseurl(undef), "http://example.co.uk/~smcv/");
+is(IkiWiki::urlto('stoats', undef), "http://example.co.uk/~smcv/stoats/");