#45013 [Opn->Fbk]: Semaphore cannot be released under certain circumstances.

ID: 45013 Updated by: jani@php.net Reported By: andre at koethur dot de -Status: Open +Status: Feedback Bug Type: Semaphore related Operating System: Linux PHP Version: 4.4.8 New Comment: Please try using this CVS snapshot: http://snaps.php.net/php5.2-latest.tar.gz For Windows (zip): http://snaps.php.net/win32/php5.2-win32-latest.zip For Windows (installer): http://snaps.php.net/win32/php5.2-win32-installer-latest.msi If you can reproduce this problem using latest PHP 5.2 snapshot, update the version string to contain: 5.2CVS-2008mmdd Previous Comments: ------------------------------------------------------------------------ [2008-05-15 20:47:33] andre at koethur dot de Description: ------------ If I acqure a semaphore in one script, then it is not possible to release it in another script, even if I set "auto_release" to false. As I have found out, it has something to do with the "count" attribute of the "sysvsem_sem"-structure. This value is really only needed by the "auto_release"-functionality, so it should be safe to ignore it in php_sysvsem_semop()-function. The current cvs-version of sysvsem.c says on line 290: if (!acquire && sem_ptr->count == 0) I suggest to change it to: if (!acquire && sem_ptr->count == 0 && sem_ptr->auto_release) Reproduce code: --------------- First script, acquire semaphore: <?php $sem_id = sem_get(2405, 1, 0666, false); if ($sem_id !== false) if (sem_acquire($sem_id)) echo 'Sem acquired!'; ?> Second script, release semaphore: <?php $sem_id = sem_get(2405, 1, 0666, false); if ($sem_id !== false) if (sem_release($sem_id)) echo 'Sem released!'; ?> Expected result: ---------------- The second script should run without errors/warnings and the semaphore should be released. Actual result: -------------- Warning: sem_release() [function.sem-release]: SysV semaphore 2 (key 0x965) is not currently acquired ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=45013&edit=1