hi list, please find attached a patch to implement a simple mechanism, via the new evhttp_is_cbset() function, to check is a given http callback is already known to the libevent.
The patch applies to latest stable release libevent-1.4.9-stable. Motivation ========== Almost all is dynamic in our code, so the libevent-http callbacks register/unregister procedures are made by plug-ins during their startup/shutdown phases. Due to a cut && paste error in a plug-in code I registered the same http callback 2 times at plug-in startup and unregistered it just once at plug-in shutdown. Unfortunately the libevent http register procedure does not check if the callback has been already declared. In the event of unbalanced register/unregister callbacks the libevent still had a hook to a function that was really out of available address space becuase the plug-in which defined the callback was itself unloaded by the plug-in manager. A http browser attempted to access to the plug-in embedded web server while it was unloaded, and because the libevent had registered the hook to the callback the program generated a segmentation violation. The attached simple program will attempt to show what happened and how I tried to solve the problem (edit EVENTDIR in Makefile to meet your libevent installation). Another way to solve the problem is to allow the evhttp_set_cb() function to check for already registered callbacks, but this is out of the scope of the current patch. tnks for your attention /rocco
webcallback.diff
Description: patch for unbalanced register/unregister http callbacks
unbalanced-cb.tar.gz
Description: test program for the unbalanced cb patch
-- Rocco Carbone mail-to: <rocco /at/ ntop /dot/ org> Pisa Italy Life is in the details In other words, you are welcome to use, share and improve me. You are forbidden to forbid anyone else to use, share and improve what I gave you.
_______________________________________________ Libevent-users mailing list Libevent-users@monkey.org http://monkeymail.org/mailman/listinfo/libevent-users
