tdb: rework cleanup logic in tdb_runtime_check_for_robust_mutexes()

The cleanup logic used six goto lables, at least I'm not able to make
sane modifications to such a beast.

By using state flags that track which objects are initialized and need
cleanup, we get rid of the goto labels. It comes at a cost though: you
have to be careful to correctly set the cleanup flags.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Uri Simchoni <uri@samba.org>

diff --git a/lib/tdb/common/mutex.c b/lib/tdb/common/mutex.c
index e57031dc222b5de64c4497f8054d6b34221788fe..d8167bedd276972efd2802f2f6fec7f6580188c4 100644 (file)
--- a/lib/tdb/common/mutex.c
+++ b/lib/tdb/common/mutex.c
@@ -766,8 +766,8 @@ static void tdb_robust_mutex_handler(int sig)
 
 _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
 {
-       void *ptr;
-       pthread_mutex_t *m;
+       void *ptr = NULL;
+       pthread_mutex_t *m = NULL;
        pthread_mutexattr_t ma;
        int ret = 1;
        int pipe_down[2] = { -1, -1 };
@@ -777,6 +777,8 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
        bool ok;
        static bool initialized;
        sigset_t mask, old_mask, suspend_mask;
+       bool cleanup_ma = false;
+       bool cleanup_sigmask = false;
 
        if (initialized) {
                return tdb_mutex_locking_cached;
@@ -796,37 +798,38 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
        if (ptr == MAP_FAILED) {
                return false;
        }
-       m = (pthread_mutex_t *)ptr;
 
        ret = pipe(pipe_down);
        if (ret != 0) {
-               goto cleanup_mmap;
+               goto cleanup;
        }
        ret = pipe(pipe_up);
        if (ret != 0) {
-               goto cleanup_pipe;
+               goto cleanup;
        }
 
        ret = pthread_mutexattr_init(&ma);
        if (ret != 0) {
-               goto cleanup_pipe;
+               goto cleanup;
        }
+       cleanup_ma = true;
        ret = pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_ERRORCHECK);
        if (ret != 0) {
-               goto cleanup_ma;
+               goto cleanup;
        }
        ret = pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED);
        if (ret != 0) {
-               goto cleanup_ma;
+               goto cleanup;
        }
        ret = pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST);
        if (ret != 0) {
-               goto cleanup_ma;
+               goto cleanup;
        }
-       ret = pthread_mutex_init(m, &ma);
+       ret = pthread_mutex_init(ptr, &ma);
        if (ret != 0) {
-               goto cleanup_ma;
+               goto cleanup;
        }
+       m = (pthread_mutex_t *)ptr;
 
        /*
         * Block SIGCHLD so we can atomically wait for it later with
@@ -836,14 +839,15 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
        sigaddset(&mask, SIGCHLD);
        ret = pthread_sigmask(SIG_BLOCK, &mask, &old_mask);
        if (ret != 0) {
-               goto cleanup_m;
+               goto cleanup;
        }
+       cleanup_sigmask = true;
        suspend_mask = old_mask;
        sigdelset(&suspend_mask, SIGCHLD);
 
        if (tdb_robust_mutex_setup_sigchild(tdb_robust_mutex_handler,
                        &tdb_robust_mutext_old_handler) == false) {
-               goto cleanup_sigmask;
+               goto cleanup;
        }
 
        tdb_robust_mutex_pid = fork();
@@ -867,7 +871,7 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
                _exit(0);
        }
        if (tdb_robust_mutex_pid == -1) {
-               goto cleanup_sig_child;
+               goto cleanup;
        }
        close(pipe_down[0]);
        pipe_down[0] = -1;
@@ -876,7 +880,7 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
 
        nread = read(pipe_up[0], &ret, sizeof(ret));
        if (nread != sizeof(ret)) {
-               goto cleanup_child;
+               goto cleanup;
        }
 
        ret = pthread_mutex_trylock(m);
@@ -884,16 +888,16 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
                if (ret == 0) {
                        pthread_mutex_unlock(m);
                }
-               goto cleanup_child;
+               goto cleanup;
        }
 
        if (write(pipe_down[1], &c, 1) != 1) {
-               goto cleanup_child;
+               goto cleanup;
        }
 
        nread = read(pipe_up[0], &c, 1);
        if (nread != 0) {
-               goto cleanup_child;
+               goto cleanup;
        }
 
        while (tdb_robust_mutex_pid > 0) {
@@ -903,35 +907,35 @@ _PUBLIC_ bool tdb_runtime_check_for_robust_mutexes(void)
                }
        }
        tdb_robust_mutex_setup_sigchild(tdb_robust_mutext_old_handler, NULL);
+       tdb_robust_mutext_old_handler = SIG_ERR;
 
        ret = pthread_mutex_trylock(m);
        if (ret != EOWNERDEAD) {
                if (ret == 0) {
                        pthread_mutex_unlock(m);
                }
-               goto cleanup_sigmask;
+               goto cleanup;
        }
 
        ret = pthread_mutex_consistent(m);
        if (ret != 0) {
-               goto cleanup_sigmask;
+               goto cleanup;
        }
 
        ret = pthread_mutex_trylock(m);
        if (ret != EDEADLK) {
                pthread_mutex_unlock(m);
-               goto cleanup_sigmask;
+               goto cleanup;
        }
 
        ret = pthread_mutex_unlock(m);
        if (ret != 0) {
-               goto cleanup_sigmask;
+               goto cleanup;
        }
 
        tdb_mutex_locking_cached = true;
-       goto cleanup_sigmask;
 
-cleanup_child:
+cleanup:
        while (tdb_robust_mutex_pid > 0) {
                kill(tdb_robust_mutex_pid, SIGKILL);
                ret = sigsuspend(&suspend_mask);
@@ -940,18 +944,21 @@ cleanup_child:
                }
        }
 
-cleanup_sig_child:
-       tdb_robust_mutex_setup_sigchild(tdb_robust_mutext_old_handler, NULL);
-cleanup_sigmask:
-       ret = pthread_sigmask(SIG_SETMASK, &old_mask, NULL);
-       if (ret != 0) {
-               abort();
+       if (tdb_robust_mutext_old_handler != SIG_ERR) {
+               tdb_robust_mutex_setup_sigchild(tdb_robust_mutext_old_handler, NULL);
+       }
+       if (cleanup_sigmask) {
+               ret = pthread_sigmask(SIG_SETMASK, &old_mask, NULL);
+               if (ret != 0) {
+                       abort();
+               }
+       }
+       if (m != NULL) {
+               pthread_mutex_destroy(m);
+       }
+       if (cleanup_ma) {
+               pthread_mutexattr_destroy(&ma);
        }
-cleanup_m:
-       pthread_mutex_destroy(m);
-cleanup_ma:
-       pthread_mutexattr_destroy(&ma);
-cleanup_pipe:
        if (pipe_down[0] != -1) {
                close(pipe_down[0]);
        }
@@ -964,8 +971,9 @@ cleanup_pipe:
        if (pipe_up[1] != -1) {
                close(pipe_up[1]);
        }
-cleanup_mmap:
-       munmap(ptr, sizeof(pthread_mutex_t));
+       if (ptr != NULL) {
+               munmap(ptr, sizeof(pthread_mutex_t));
+       }
 
        return tdb_mutex_locking_cached;
 }