2 files changed, 13 insertions, 8 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index e8ac547ff2a..5905c667852 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2012-11-13  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Fix a race with verify-visited-file-modtime (Bug#12863).
+        Since at least 1991 Emacs has ignored an mtime difference of no
+        more than one second, but my guess is that this was to work around
+        file system bugs that were fixed long ago.  Since the race is
+        causing problems now, let's remove that code.
+        * fileio.c (Fverify_visited_file_modtime): Do not accept a file
+        whose time stamp is off by no more than a second.  Insist that the
+        file time stamps match exactly.
+
 2012-11-12  Dmitry Antipov  <dmantipov@yandex.ru>
 
         * frame.h (struct frame): Convert external_tool_bar member to
diff --git a/src/fileio.c b/src/fileio.c
index d47d7dd9e0b..b9541e78838 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5076,7 +5076,7 @@ See Info node `(elisp)Modification Time' for more details.  */)
   struct stat st;
   Lisp_Object handler;
   Lisp_Object filename;
-  EMACS_TIME mtime, diff;
+  EMACS_TIME mtime;
 
   if (NILP (buf))
     b = current_buffer;
@@ -5101,13 +5101,7 @@ See Info node `(elisp)Modification Time' for more details.  */)
   mtime = (stat (SSDATA (filename), &st) == 0
            ? get_stat_mtime (&st)
            : time_error_value (errno));
-  if ((EMACS_TIME_EQ (mtime, b->modtime)
-       /* If both exist, accept them if they are off by one second.  */
-       || (EMACS_TIME_VALID_P (mtime) && EMACS_TIME_VALID_P (b->modtime)
-           && ((diff = (EMACS_TIME_LT (mtime, b->modtime)
-                        ? sub_emacs_time (b->modtime, mtime)
-                        : sub_emacs_time (mtime, b->modtime))),
-               EMACS_TIME_LE (diff, make_emacs_time (1, 0)))))
+  if (EMACS_TIME_EQ (mtime, b->modtime)
       && (st.st_size == b->modtime_size
           || b->modtime_size < 0))
     return Qt;