Fixed bug #570

SDL_SemWaitTimeout in src/thread/generic/SDL_syssem.c line 179 (SVN trunk): --sem->count; should be if (retval == 0) { --sem->count; } Without this, sem->count will underflow on timeout effectively breaking the semaphore. It appears that the implementation has been wrong since the initial revision.
libsdl-org · Sep 21, 2009 · e95881b · e95881b
1 parent 24ba42b
commit e95881b
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/src/thread/generic/SDL_syssem.c b/src/thread/generic/SDL_syssem.c
@@ -176,7 +176,9 @@ SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
                                      sem->count_lock, timeout);
     }
     --sem->waiters_count;
-    --sem->count;
+    if (retval == 0) {
+        --sem->count;
+    }
     SDL_UnlockMutex(sem->count_lock);
 
     return retval;