+/* Tests whether a file, given by a file name without slashes, exists in
+ the current directory, by scanning the directory entries. */
+static bool
+dentry_exists (const char *filename)
+{
+ bool exists = false;
+ DIR *dir = opendir (".");
+
+ ASSERT (dir != NULL);
+ for (;;)
+ {
+ struct dirent *d = readdir (dir);
+ if (d == NULL)
+ break;
+ if (strcmp (d->d_name, filename) == 0)
+ {
+ exists = true;
+ break;
+ }
+ }
+ ASSERT (closedir (dir) == 0);
+ return exists;
+}
+
+/* Asserts that a specific file, given by a file name without slashes, does
+ not exist in the current directory. */
+static void
+assert_nonexistent (const char *filename)
+{
+ struct stat st;
+
+ /* The usual way to test the presence of a file is via stat() or lstat(). */
+ errno = 0;
+ if (stat (filename, &st) == -1)
+ ASSERT (errno == ENOENT);
+ else
+ {
+ /* But after renaming a directory over an empty directory on an NFS-
+ mounted file system, on Linux 2.6.18, for a period of 30 seconds the
+ old directory name is "present" according to stat() but "nonexistent"
+ according to dentry_exists(). */
+ ASSERT (!dentry_exists (filename));
+ /* Remove the old directory name, so that subsequent mkdir calls
+ succeed. */
+ (void) rmdir (filename);
+ }
+}
+