core: fs: verify call to fs_ops->readdir

Check if fs_ops->readdir is available before calling it.
At least PXELINUX doesn't implement it.

Signed-off-by: Sebastian Herbszt <herbszt@gmx.de>
LKML-Reference: <1267974170$3058@local>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/core/fs/readdir.c b/core/fs/readdir.c
index d2b112b..d20fc33 100644 (file)
--- a/core/fs/readdir.c
+++ b/core/fs/readdir.c
@@ -28,8 +28,11 @@ struct dirent *readdir(DIR *dir)
     struct file *dd_dir = (struct file *)dir;
     int rv = -1;
     
-    if (dd_dir)
-       rv = dd_dir->fs->fs_ops->readdir(dd_dir, &buf);
+    if (dd_dir) {
+        if (dd_dir->fs->fs_ops->readdir) {
+           rv = dd_dir->fs->fs_ops->readdir(dd_dir, &buf);
+        }
+    }
 
     return rv < 0 ? NULL : &buf;
 }