test-skeleton: don't force -d on noMMU

There's a few tests whose do_test() is supposed to time out or terminate
with a signal. Tests communicate it to the test skeleton by defining
EXPECTED_SIGNAL or EXPECTED_STATUS and the skeleton completes with
success code when that happens. Running test suite in direct mode by
default changes that, as a result test running script reports failures
for the tests that actually pass or hangs.

Instead of switching to direct test running when building for noMMU use
vfork() and exec() the test in the child process in direct mode.
This makes the default test process behavior the same on MMU and noMMU
targets.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

test/test-skeleton.c

@@ -222,18 +222,15 @@ handler_killpid(int sig)
 
 /* We provide the entry point here.  */
 int
-main (int argc, char *argv[])
+main (int argc, char *argv[], char *envp[])
 {
-#ifdef __ARCH_USE_MMU__
   int direct = 0;	/* Directly call the test function?  */
-#else
-  int direct = 1;
-#endif
   int status;
   int opt;
   unsigned int timeoutfactor = 1;
   pid_t termpid;
   char *envstr_timeoutfactor;
+  char **argv1;
 
   /* Make uses of freed and uninitialized memory known.  */
 #ifdef __MALLOC_STANDARD__
@@ -303,19 +300,21 @@ main (int argc, char *argv[])
   /* make sure temporary files are deleted.  */
   atexit (delete_temp_files);
 
-  /* Correct for the possible parameters.  */
-  argv[optind - 1] = argv[0];
-  argv += optind - 1;
-  argc -= optind - 1;
+  /* If we are not expected to fork run the function immediately.  */
+  if (direct)
+    {
+      /* Correct for the possible parameters.  */
+      argv[optind - 1] = argv[0];
+      argv += optind - 1;
+      argc -= optind - 1;
 
-  /* Call the initializing function, if one is available.  */
+      /* Call the initializing function, if one is available.  */
 #ifdef PREPARE
-  PREPARE (argc, argv);
+      PREPARE (argc, argv);
 #endif
 
-  /* If we are not expected to fork run the function immediately.  */
-  if (direct)
-    return TEST_FUNCTION;
+      return TEST_FUNCTION;
+    }
 
   /* Set up the test environment:
      - prevent core dumps
@@ -340,15 +339,51 @@ main (int argc, char *argv[])
       if (setpgid (0, 0) != 0)
 	printf ("Failed to set the process group ID: %m\n");
 
+      /* Correct for the possible parameters.  */
+      argv[optind - 1] = argv[0];
+      argv += optind - 1;
+      argc -= optind - 1;
+
+      /* Call the initializing function, if one is available.  */
+#ifdef PREPARE
+      PREPARE (argc, argv);
+#endif
+
       /* Execute the test function and exit with the return value.   */
       exit (TEST_FUNCTION);
     }
   else if (pid < 0)
-#endif
     {
       perror ("Cannot fork test program");
       exit (1);
     }
+#else
+  argv1 = malloc ((argc + 2) * sizeof(void *));
+  argv1[0] = argv[0];
+  argv1[1] = "-d";
+  memcpy(argv1 + 2, argv + 1, argc * sizeof(void *));
+
+  pid = vfork ();
+  if (pid == 0)
+    {
+      /* This is the child.  */
+      /* We put the test process in its own pgrp so that if it bogusly
+	 generates any job control signals, they won't hit the whole build.  */
+      if (setpgid (0, 0) != 0)
+	printf ("Failed to set the process group ID: %m\n");
+
+      if (execve (argv1[0], argv1, envp) < 0)
+	{
+	  perror ("Cannot exec test program");
+	  _exit (1);
+	}
+    }
+  else if (pid < 0)
+    {
+      perror ("Cannot vfork test program");
+      exit (1);
+    }
+#endif
 
 #ifdef __XXX_HANDLE_CTRL_C
   signal (SIGTERM, handler_killpid);