libringbuffer shm: be resilient to app crash between shm_open and shm_unlink

[lttng-ust.git] / libringbuffer / shm.c

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 873e6e87597311ae9a5cc03c3d1c27a53dae025c..36f7e36b6a573dc2738b4444d92da563ed5830c9 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -67,8 +67,14 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
         * We specifically do _not_ use the / at the beginning of the
         * pathname so that some OS implementations can keep it local to
         * the process (POSIX leaves this implementation-defined).
+        * Ignore the shm_unlink errors, because we handle leaks that
+        * could occur by applications crashing between shm_open and
+        * shm_unlink by unlinking the shm before every open. Therefore,
+        * we can only leak one single shm (and only if the application
+        * crashes between shm_open and the following shm_unlink).
         */
        do {
+               (void) shm_unlink("ust-shm-tmp");
                shmfd = shm_open("ust-shm-tmp",
                                 O_CREAT | O_EXCL | O_RDWR, 0700);
        } while (shmfd < 0 && errno == EEXIST);