Work around bug in CIFS and vboxsf file systems.

The bug was observed on Ubuntu operating inside a virtual machine,
editing files mounted via CIFS or vboxsf from the MS Windows 7 host.
The workaround introduces a race condition on non-buggy hosts,
but it's an unlikely race and anyway there's a nearly identical
nearby race that can't be fixed.
* fileio.c (valid_timestamp_file_system, timestamp_file_system):
New static vars.
(Fwrite_region): Test for file system time stamp bug.
(init_fileio): New function.
* lisp.h (init_fileio): Declare it.
* emacs.c (main): Call it.

Fixes: debbugs:13149

1 files changed, 13 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 4cd417868a1..2954df9d6b8 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,18 @@
 2013-01-19  Paul Eggert  <eggert@cs.ucla.edu>
 
+        Work around bug in CIFS and vboxsf file systems (Bug#13149).
+        The bug was observed on Ubuntu operating inside a virtual machine,
+        editing files mounted via CIFS or vboxsf from the MS Windows 7 host.
+        The workaround introduces a race condition on non-buggy hosts,
+        but it's an unlikely race and anyway there's a nearly identical
+        nearby race that can't be fixed.
+        * fileio.c (valid_timestamp_file_system, timestamp_file_system):
+        New static vars.
+        (Fwrite_region): Test for file system time stamp bug.
+        (init_fileio): New function.
+        * lisp.h (init_fileio): Declare it.
+        * emacs.c (main): Call it.
+
         * fileio.c (Finsert_file_contents): Simplify new diagnostic
         and make it more consistent with other stat-failure diagnostics.