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 · 67255d8 · 67255d8
1 parent 3703677
commit 67255d8
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
@@ -165,7 +165,9 @@ int 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;