diff -r 20aa57f413df README-show_thread.txt
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/README-show_thread.txt	Thu Oct 22 18:28:53 2009 -0400
@@ -0,0 +1,25 @@
+This patch adds support to redirect to a thread given a file posted in it.
+For example, if "1256239265762.jpg" is thread 38372, post 38411, requesting
+<http://host/foo/wakaba.pl?task=thread&filename=src/1256239265762.jpg> will
+redirect to <http://host/foo/res/38372.html#38411> (thus highlighting the
+pertinent post).
+
+
+The example.htaccess contains a RewriteRule to enable requests such as
+<http://host/foo/src/1256239265762.jpg/thread> to redirect internally to
+wakaba.pl, so those interested only need to add "/thread" to an existing
+image URL in order to jump to the thread where it was posted.
+
+If you prefer, you can also set up a single RewriteRule in a parent directory,
+or even within httpd.conf. This works for any subdirectory nested to arbitrary
+depth, so long as no other .htaccess files declare their own RewriteRules.
+(This rule won't work if defined in the same directory as wakaba.pl.)
+
+RewriteRule ^(.*)/+(src/+[^/]+)/+thread/*$ $1/wakaba.pl?task=thread&filename=$2 [L]
+
+
+For Lighttpd, make sure mod_rewrite is enabled in lighttpd.conf, and add the
+following rule to your url.rewrite (or url.rewrite_once) list:
+
+"^(.*)/+(src/+[^/]+)/+thread/*$" => "$1/wakaba.pl?task=thread&filename=$2"
+
diff -r 20aa57f413df example.htaccess
--- a/example.htaccess	Thu Oct 22 17:28:57 2009 -0400
+++ b/example.htaccess	Thu Oct 22 18:28:53 2009 -0400
@@ -22,4 +22,5 @@
 RewriteEngine On
 RewriteCond %{HTTP_ACCEPT} application/xhtml\+xml
 RewriteRule \.html$ - [T=application/xhtml+xml;charset=utf-8]
+RewriteRule ^(src/+[^/]+)/+thread/*$ wakaba.pl?task=thread&filename=$1 [L]
 </IfModule>
diff -r 20aa57f413df wakaba.pl
--- a/wakaba.pl	Thu Oct 22 17:28:57 2009 -0400
+++ b/wakaba.pl	Thu Oct 22 18:28:53 2009 -0400
@@ -95,6 +95,11 @@
 
 	delete_stuff($password,$fileonly,$archive,$admin,@posts);
 }
+elsif($task eq "thread")
+{
+	my $filename=$query->param("filename");
+	show_thread($filename);
+}
 elsif($task eq "admin")
 {
 	my $password=$query->param("berra"); # lol obfuscation
@@ -1231,6 +1236,27 @@
 
 
 #
+# Jump to thread from filename
+#
+sub show_thread($)
+{
+	my ($filename) = @_;
+	my ($sth, $num, $parent);
+
+	$filename =~ s-/+-/-g;
+	$sth=$dbh->prepare("SELECT num,parent FROM ".SQL_TABLE." WHERE image=?;") or make_error(S_SQLFAIL);
+	$sth->execute($filename) or make_error(S_SQLFAIL);
+	($num, $parent) = $sth->fetchrow_array();
+	if ($num) {
+		make_http_forward(get_reply_link($num, $parent),ALTERNATE_REDIRECT);
+	} else {
+		make_error(S_NOTHREADERR);
+	}
+}
+
+
+
+#
 # Admin interface
 #