Lighttpd

there is a weired thing i've encountered and while trying to see the problem in the code it fixed itself in a very weired way.

I started tracking the issue with the following debug values:

debug.log-condition-handling = "enable" 
debug.log-file-not-found = "enable" 
debug.log-request-handling = "enable" 

with only 1 worker process

here is the output that concerned me:

2008-07-21 17:22:48: (response.c.382) -- before doc_root
2008-07-21 17:22:48: (response.c.383) Doc-Root     : /home/site_images/some_name/public_html/
2008-07-21 17:22:48: (response.c.384) Rel-Path     : /engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.385) Path         :
2008-07-21 17:22:48: (configfile-glue.c.524) === start of condition block ===
2008-07-21 17:22:48: (configfile-glue.c.482) 1 (cached) result: false
2008-07-21 17:22:48: (configfile-glue.c.524) === start of condition block ===
2008-07-21 17:22:48: (configfile-glue.c.482) 2 (cached) result: false
.........
.........
.........
2008-07-21 17:22:48: (configfile-glue.c.524) === start of condition block ===
2008-07-21 17:22:48: (configfile-glue.c.482) 266 (cached) result: false
2008-07-21 17:22:48: (response.c.433) -- after doc_root
2008-07-21 17:22:48: (response.c.434) Doc-Root     : /home/site_images/
2008-07-21 17:22:48: (response.c.435) Rel-Path     : /engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.436) Path         : /home/site_images/engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.453) -- logical -> physical
2008-07-21 17:22:48: (response.c.454) Doc-Root     : /home/site_images/
2008-07-21 17:22:48: (response.c.455) Rel-Path     : /engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.456) Path         : /home/site_images/engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.473) -- handling physical path
2008-07-21 17:22:48: (response.c.474) Path         : /home/site_images/engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.530) -- file not found
2008-07-21 17:22:48: (response.c.531) Path         : /home/site_images/engine_images/logo.jpg
2008-07-21 17:22:48: (response.c.158) run condition

if you noticed

-- before doc_root
Doc-Root     : /home/site_images/some_name/public_html/

and

-- after doc_root
Doc-Root     : /home/site_images/

i had lighty 1.4.18 so i upgraded to the latest one on the site 1.4.19. same thing

so, my question was, why on earth does the doc_root change. to make things even more strange for me, the behavior that actually bothered me was random 404s. i mean, that i was pointing my browser to a certain resource and while refreshing, from time to time i was getting a 404. i figured, since the config file is pretty complex, maybe the thing processes another condition in some weired way ... i spent 2 days on that but didn't spot any issues.

so another debug idea comes to me... hey, let's check response.c see if i can miraculously spot the issue ... of course, that didn't happen :) ... but another miracle fixed it, apparently ... here is what i did:
- opened response.c and went to line 382 coressponding to the "-- before doc_root" output.
- after those logging lines and before the "-- after doc_root" ones i noticed the switch block:

switch(r = plugins_call_handle_docroot(srv, con)) {
...
}

- looking at the other lines in between the "-- before" and "--after", i figured that only plugins_call_handle_docroot could change that doc_root value
- the easiest way at that moment for me was to add logging lines and recompile see what happens.
- so i added those lines and the code looks as follows:

                if (con->conf.log_request_handling) {
                        log_error_write(srv, __FILE__, __LINE__,  "s",  "-- before doc_root");
                        log_error_write(srv, __FILE__, __LINE__,  "sb", "Doc-Root     :", con->physical.doc_root);
                        log_error_write(srv, __FILE__, __LINE__,  "sb", "Rel-Path     :", con->physical.rel_path);
                        log_error_write(srv, __FILE__, __LINE__,  "sb", "Path         :", con->physical.path);
                }
                /* the docroot plugin should set the doc_root and might also set the physical.path
                 * for us (all vhost-plugins are supposed to set the doc_root)
                 * */
                switch(r = plugins_call_handle_docroot(srv, con)) {
                case HANDLER_GO_ON:
                        break;
                case HANDLER_FINISHED:
                case HANDLER_COMEBACK:
                case HANDLER_WAIT_FOR_EVENT:
                case HANDLER_ERROR:
                        return r;
                default:
                        log_error_write(srv, __FILE__, __LINE__, "");
                        break;
                }

                if (con->conf.log_request_handling) {
                        log_error_write(srv, __FILE__, __LINE__,  "s",  "-- before -- after doc_root");
                        log_error_write(srv, __FILE__, __LINE__,  "sb", "Doc-Root     :", con->physical.doc_root);
                        log_error_write(srv, __FILE__, __LINE__,  "sb", "Rel-Path     :", con->physical.rel_path);
                        log_error_write(srv, __FILE__, __LINE__,  "sb", "Path         :", con->physical.path);
                }

                /* MacOS X and Windows can't distiguish between upper and lower-case
                 *

- i simply added the "-- before -- after doc_root" section
- configure&make&make install
- running the tests again
- pointed the browser to a resource and kept refreshing
- guess what? it never happened again ... i've refreshed for 30 minutes with multiple resources, tried everything i knew was failing... it never happened again ! it normally gave like 3-4 404s in every 10 refreshes.

doesn't make any sense but i swear this is the pure truth. so i'm thinking there is some kind of memory leak maybe threads overlapping some byte code. i have no idea.

if this makes any sense for you and you need my help with more info, i'll gladly try to provide it.

here are the important config values:

server.document-root = "/home/site_images/" 

$HTTP["host"] == "www.some_name.com" {
  server.document-root = "/home/site_images/some_name/public_html/" 
...

  $HTTP["url"] =~ "engine_javascripts" {
    server.document-root = "/home/site_images/some_name/public_html/" 
        #################
        # this is the only condition that was matching the request giving random 404s
        # a few other locations did the same thing but exactly the same pattern
        # just different engine_xxx locations
        #################
  }

...

}

-- ionut.dumitru