Removes trailing spaces. Removes tabs.

[vlc] / src / vlc.c

diff --git a/src/vlc.c b/src/vlc.c
index a30ca34dd1fdc915ae7d10b5c5809d218809e754..c884610acb7e4070184e6767f06b29af4b4dab16 100644 (file)
--- a/src/vlc.c
+++ b/src/vlc.c
@@ -98,11 +98,30 @@ int main( int i_argc, char *ppsz_argv[] )
     }
 
 #if !defined(WIN32) && !defined(UNDER_CE)
-    /* Synchronously intercepted signals. Thy request a clean shutdown,
-     * and force an unclean shutdown if they are triggered again 2+ seconds
-     * later. We have to handle SIGTERM cleanly because of daemon mode.
+    /* Synchronously intercepted POSIX signals.
+     *
+     * In a threaded program such as VLC, the only sane way to handle signals
+     * is to block them in all thread but one - this is the only way to
+     * predict which thread will receive them. If any piece of code depends
+     * on delivery of one of this signal it is intrinsically not thread-safe
+     * and MUST NOT be used in VLC, whether we like it or not.
+     * There is only one exception: if the signal is raised with
+     * pthread_kill() - we do not use this in LibVLC but some pthread
+     * implementations use them internally. You should really use conditions
+     * for thread synchronization anyway.
+     *
+     * Signal that request a clean shutdown, and force an unclean shutdown
+     * if they are triggered again 2+ seconds later.
+     * We have to handle SIGTERM cleanly because of daemon mode.
      * Note that we set the signals after the vlc_create call. */
     static const int exitsigs[] = { SIGINT, SIGHUP, SIGQUIT, SIGTERM };
+    /* Signals that cause a no-op:
+     * - SIGALRM should not happen, but lets stay on the safe side.
+     * - SIGPIPE might happen with sockets and would crash VLC. It MUST be
+     *   blocked by any LibVLC-dependant application, in addition to VLC.
+     * - SIGCHLD is comes after exec*() (such as httpd CGI support) and must
+     *   be dequeued to cleanup zombie processes.
+     */
     static const int dummysigs[] = { SIGALRM, SIGPIPE, SIGCHLD };
 
     sigset_t set;
@@ -214,13 +233,16 @@ int main( int i_argc, char *ppsz_argv[] )
  *****************************************************************************/
 static void *SigHandler (void *data)
 {
-    const sigset_t *set = (sigset_t *)data;
+    const sigset_t *exitset = (sigset_t *)data;
+    sigset_t fullset;
     time_t abort_time = 0;
 
+    pthread_sigmask (SIG_BLOCK, exitset, &fullset);
+
     for (;;)
     {
         int i_signal, state;
-        (void)sigwait (set, &i_signal);
+        (void)sigwait (&fullset, &i_signal);
 
 #ifdef __APPLE__
         /* In Mac OS X up to 10.4.8 sigwait (among others) is not a pthread
@@ -228,6 +250,9 @@ static void *SigHandler (void *data)
         pthread_testcancel();
 #endif
 
+        if (!sigismember (exitset, i_signal))
+            continue; /* Ignore "dummy" signals */
+
         /* Once a signal has been trapped, the termination sequence will be
          * armed and subsequent signals will be ignored to avoid sending
          * signals to a libvlc structure having been destroyed */
@@ -248,7 +273,7 @@ static void *SigHandler (void *data)
         if (time (NULL) <= abort_time)
         {
             /* If user asks again more than 2 seconds later, die badly */
-            pthread_sigmask (SIG_UNBLOCK, set, NULL);
+            pthread_sigmask (SIG_UNBLOCK, exitset, NULL);
             fprintf (stderr, "user insisted too much, dying badly\n");
             abort ();
         }