Hi Elison. 2009/3/21 Elison Smith <elison.sm...@gmail.com>: > I am using shared memory to share some data between my module instances in > Apache child processes, and apr_global_mutex_t to achieve > mutually-exclusive reads and writes. > > In a post_config_hook, I create the mutex using apr_global_mutex_create() > and then reopen it inside each child process by calling > apr_global_mutex_child_init() inside a child_init hook. > > However, when I try to grab the lock inside a child, the operation fails > with a "permission denied". For the lock file, I am using "/tmp/tmp" which > is a file writeable by all. > > Any clues? >
the platform on which your module runs is unix? There should be such a permission problem if the parent process starts as root while child processes as user/group that you specify in apache configuration file. In that case, use unixd_set_global_mutex_perms in child_init hook, after apr_global_mutex_create just like this below: ** code snippet from mod_rewrite.c ------------------------------------------------------------------------- #ifdef AP_NEED_SET_MUTEX_PERMS #include "unixd.h" #endif ... /* create the lockfile */ rc = apr_global_mutex_create(&rewrite_mapr_lock_acquire, lockname, APR_LOCK_DEFAULT, p); if (rc != APR_SUCCESS) { ap_log_error(APLOG_MARK, APLOG_CRIT, rc, s, "mod_rewrite: Parent could not create RewriteLock " "file %s", lockname); return rc; } #ifdef AP_NEED_SET_MUTEX_PERMS rc = unixd_set_global_mutex_perms(rewrite_mapr_lock_acquire); if (rc != APR_SUCCESS) { ap_log_error(APLOG_MARK, APLOG_CRIT, rc, s, "mod_rewrite: Parent could not set permissions " "on RewriteLock; check User and Group directives"); return rc; } #endif ------------------------------------------------------------------------- you should also see unixd.h (/path-to-apache/include/unixd.h) ------------------------------------------------------------------------- /** * One of the functions to set mutex permissions should be called in * the parent process on platforms that switch identity when the * server is started as root. * If the child init logic is performed before switching identity * (e.g., MPM setup for an accept mutex), it should only be called * for SysV semaphores. Otherwise, it is safe to call it for all * mutex types. */ AP_DECLARE(apr_status_t) unixd_set_proc_mutex_perms(apr_proc_mutex_t *pmutex); AP_DECLARE(apr_status_t) unixd_set_global_mutex_perms(apr_global_mutex_t *gmutex); AP_DECLARE(apr_status_t) unixd_accept(void **accepted, ap_listen_rec *lr, apr_pool_t *ptrans); ------------------------------------------------------------------------- good luck! Yoichi -- -- Yoichi Kawasaki <yokaw...@gmail.com>