[rtems commit] dosfs: Fix file length update

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    78a50d924c8c0a540e0d3ab60579de516e560c95
Changeset: http://git.rtems.org/rtems/commit/?id=78a50d924c8c0a540e0d3ab60579de516e560c95

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Mon Feb 18 08:36:55 2013 +0100

dosfs: Fix file length update

---

 cpukit/libfs/src/dosfs/fat_file.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/cpukit/libfs/src/dosfs/fat_file.c b/cpukit/libfs/src/dosfs/fat_file.c
index b71745f..4425b85 100644
--- a/cpukit/libfs/src/dosfs/fat_file.c
+++ b/cpukit/libfs/src/dosfs/fat_file.c
@@ -633,8 +633,9 @@ fat_file_extend(
     /*  check wether we satisfied request for 'cls2add' clusters */
     if (cls2add != cls_added)
     {
-        new_length -= bytes2add & (fs_info->vol.bpc - 1);
-        new_length -= (cls2add - cls_added) << fs_info->vol.bpc_log2;
+        uint32_t missing = (cls2add - cls_added) << fs_info->vol.bpc_log2;
+
+        new_length -= bytes2add < missing ? bytes2add : missing;
     }
 
     if (cls_added > 0)