posix: Ignore non opened files on tst-spawn5

The make program  might open a pipe for its job server, which triggers
an invalid check on the spawned process.  This patch now passes the
lowest file descriptor as ithe first argument, so only the range
that was actually opened is checked.

Checked on x86_64-linux-gnu and i686-linux-gnu and centos7 (which
triggers the issue).

posix/tst-spawn5.c

@@ -58,11 +58,24 @@ open_multiple_temp_files (void)
   return lowfd;
 }
 
+static int
+parse_fd (const char *str)
+{
+  char *endptr;
+  long unsigned int fd = strtoul (str, &endptr, 10);
+  if (*endptr != '\0' || fd > INT_MAX)
+    FAIL_EXIT1 ("invalid file descriptor value: %s", str);
+  return fd;
+}
+
 /* Called on process re-execution.  The arguments are the expected opened
    file descriptors.  */
 _Noreturn static void
 handle_restart (int argc, char *argv[])
 {
+  TEST_VERIFY (argc > 0);
+  int lowfd = parse_fd (argv[0]);
+
   size_t nfds = argc > 1 ? argc - 1 : 0;
   struct fd_t
   {
@@ -71,12 +84,7 @@ handle_restart (int argc, char *argv[])
   } *fds = xmalloc (sizeof (struct fd_t) * nfds);
   for (int i = 0; i < nfds; i++)
     {
-      char *endptr;
-      long unsigned int fd = strtoul (argv[i+1], &endptr, 10);
-      if (*endptr != '\0' || fd > INT_MAX)
-	FAIL_EXIT1 ("argv[%d]: invalid file descriptor value: %s", i, argv[i]);
-
-      fds[i].fd = fd;
+      fds[i].fd = parse_fd (argv[i + 1]);
       fds[i].found = false;
     }
 
@@ -104,12 +112,9 @@ handle_restart (int argc, char *argv[])
         FAIL_EXIT1 ("readdir: invalid file descriptor name: /proc/self/fd/%s",
                     e->d_name);
 
-      /* Skip the descriptor which is used to enumerate the descriptors.  */
-      if (fd == dirfd (dirp)
-          || fd == STDIN_FILENO
-	  || fd == STDOUT_FILENO
-	  || fd == STDERR_FILENO)
-        continue;
+      /* Ignore the descriptors not in the range of the opened files.  */
+      if (fd < lowfd || fd == dirfd (dirp))
+	continue;
 
       bool found = false;
       for (int i = 0; i < nfds; i++)
@@ -117,7 +122,11 @@ handle_restart (int argc, char *argv[])
 	  fds[i].found = found = true;
 
       if (!found)
-        FAIL_EXIT1 ("unexpected open file descriptor: %ld", fd);
+	{
+	  char *path = xasprintf ("/proc/self/fd/%s", e->d_name);
+	  char *resolved = xreadlink (path);
+	  FAIL_EXIT1 ("unexpected open file descriptor %ld: %s", fd, resolved);
+	}
     }
   closedir (dirp);
 
@@ -134,15 +143,17 @@ static void
 spawn_closefrom_test (posix_spawn_file_actions_t *fa, int lowfd, int highfd,
 		      int *extrafds, size_t nextrafds)
 {
-  /* 3 or 6 elements from initial_argv:
+  /* 3 or 7 elements from initial_argv:
        + path to ld.so          optional
        + --library-path         optional
        + the library path       optional
        + application name
        + --direct
        + --restart
-     up to 2 * maximum_fd arguments (the expected open file descriptors),
-     plus NULL.  */
+       + lowest opened file descriptor
+       + up to 2 * maximum_fd arguments (the expected open file descriptors),
+	 plus NULL.  */
+
   int argv_size = initial_argv_count + 2 * NFDS + 1;
   char *args[argv_size];
   int argc = 0;
@@ -150,6 +161,8 @@ spawn_closefrom_test (posix_spawn_file_actions_t *fa, int lowfd, int highfd,
   for (char **arg = initial_argv; *arg != NULL; arg++)
     args[argc++] = *arg;
 
+  args[argc++] = xasprintf ("%d", lowfd);
+
   for (int i = lowfd; i < highfd; i++)
     args[argc++] = xasprintf ("%d", i);
 
@@ -265,14 +278,16 @@ do_test (int argc, char *argv[])
 
      - six parameters left if called through re-execution:
        + argv[1]: the application name
-       + argv[2]: first expected open file descriptor
-       + argv[n]: last expected open file descritptor
+       + argv[2]: the lowest file descriptor expected
+       + argv[3]: first expected open file descriptor   optional
+       + argv[n]: last expected open file descritptor   optional
 
      * When built with --enable-hardcoded-path-in-tests or issued without
        using the loader directly.  */
 
   if (restart)
-    handle_restart (argc, argv);
+    /* Ignore the application name. */
+    handle_restart (argc - 1, &argv[1]);
 
   TEST_VERIFY_EXIT (argc == 2 || argc == 5);