malloc/tst-mallocfork2: Kill lingering process for unexpected failures

If the test fails due some unexpected failure after the children
creation, either in the signal handler by calling abort or in the main
loop; the created children might not be killed properly.

This patches fixes it by:

  * Avoid aborting in the signal handler by setting a flag that
    an error has occured and add a check in the main loop.

  * Add a atexit handler to handle kill child processes.

Checked on x86_64-linux-gnu.

malloc/tst-mallocfork2.c

@@ -62,6 +62,9 @@ static volatile sig_atomic_t sigusr1_received;
    progress.  Checked by liveness_signal_handler.  */
 static volatile sig_atomic_t progress_indicator = 1;
 
+/* Set to 1 if an error occurs in the signal handler.  */
+static volatile sig_atomic_t error_indicator = 0;
+
 static void
 sigusr1_handler (int signo)
 {
@@ -72,7 +75,8 @@ sigusr1_handler (int signo)
   if (pid == -1)
     {
       write_message ("error: fork\n");
-      abort ();
+      error_indicator = 1;
+      return;
     }
   if (pid == 0)
     _exit (0);
@@ -81,12 +85,14 @@ sigusr1_handler (int signo)
   if (ret < 0)
     {
       write_message ("error: waitpid\n");
-      abort ();
+      error_indicator = 1;
+      return;
     }
   if (status != 0)
     {
       write_message ("error: unexpected exit status from subprocess\n");
-      abort ();
+      error_indicator = 1;
+      return;
     }
 }
 
@@ -122,9 +128,25 @@ signal_sender (int signo, bool sleep)
     }
 }
 
+/* Children processes.  */
+static pid_t sigusr1_sender_pids[5] = { 0 };
+static pid_t sigusr2_sender_pid = 0;
+
+static void
+kill_children (void)
+{
+  for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
+    if (sigusr1_sender_pids[i] > 0)
+      kill (sigusr1_sender_pids[i], SIGKILL);
+  if (sigusr2_sender_pid > 0)
+    kill (sigusr2_sender_pid, SIGKILL);
+}
+
 static int
 do_test (void)
 {
+  atexit (kill_children);
+
   /* shared->barrier is intialized along with sigusr1_sender_pids
      below.  */
   shared = support_shared_allocate (sizeof (*shared));
@@ -148,14 +170,13 @@ do_test (void)
       return 1;
     }
 
-  pid_t sigusr2_sender_pid = xfork ();
+  sigusr2_sender_pid = xfork ();
   if (sigusr2_sender_pid == 0)
     signal_sender (SIGUSR2, true);
 
   /* Send SIGUSR1 signals from several processes.  Hopefully, one
      signal will hit one of the ciritical functions.  Use a barrier to
      avoid sending signals while not running fork/free/malloc.  */
-  pid_t sigusr1_sender_pids[5];
   {
     pthread_barrierattr_t attr;
     xpthread_barrierattr_init (&attr);
@@ -166,7 +187,7 @@ do_test (void)
   }
   for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
     {
-      sigusr1_sender_pids[i] = fork ();
+      sigusr1_sender_pids[i] = xfork ();
       if (sigusr1_sender_pids[i] == 0)
         signal_sender (SIGUSR1, false);
     }
@@ -211,7 +232,7 @@ do_test (void)
         ++malloc_signals;
       xpthread_barrier_wait (&shared->barrier);
 
-      if (objects[slot] == NULL)
+      if (objects[slot] == NULL || error_indicator != 0)
         {
           printf ("error: malloc: %m\n");
           for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
@@ -225,10 +246,6 @@ do_test (void)
   for (int slot = 0; slot < malloc_objects; ++slot)
     free (objects[slot]);
 
-  for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
-    kill (sigusr1_sender_pids[i], SIGKILL);
-  kill (sigusr2_sender_pid, SIGKILL);
-
   printf ("info: signals received during fork: %u\n", fork_signals);
   printf ("info: signals received during free: %u\n", free_signals);
   printf ("info: signals received during malloc: %u\n", malloc_signals);