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From: Paul Eggert <eggert@cs.ucla.edu>
To: Dmitry Gutov <raaahh@gmail.com>
Cc: 13149@debbugs.gnu.org
Subject: bug#13149: 24.3.50; Emacs thinks file was changed outside Emacs, but it was not
Date: Mon, 14 Jan 2013 22:45:31 -0800	[thread overview]
Message-ID: <50F4FB0B.5070003@cs.ucla.edu> (raw)
In-Reply-To: <50F484CB.6010905@gmail.com>

On 01/14/2013 02:20 PM, Dmitry Gutov wrote:

> stat_mtime=1358201692.000000000
> stat_mtime=1358201692.912737000

That looks like a file system bug, I'm afraid.
Does the following work around the bug, if you
set the variable sloppy-file-time-stamps?

=== modified file 'src/ChangeLog'
--- src/ChangeLog	2013-01-14 17:46:14 +0000
+++ src/ChangeLog	2013-01-15 05:38:42 +0000
@@ -1,3 +1,10 @@
+2013-01-15  Paul Eggert  <eggert@penguin.cs.ucla.edu>
+
+	Add workaround for file system time stamp bug (Bug#13149).
+	Reported by Dmitry Gutov for Ubuntu vboxsf mounting MS Windows 7.
+	* fileio.c (syms_of_fileio) <sloppy-file-time-stamps>: New variable.
+	(Fverify_visited_file_modtime): Use it.
+
 2013-01-14  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Avoid needless casts with XSAVE_POINTER.

=== modified file 'src/fileio.c'
--- src/fileio.c	2013-01-14 17:46:14 +0000
+++ src/fileio.c	2013-01-15 05:38:42 +0000
@@ -5358,7 +5358,17 @@
   mtime = (stat (SSDATA (filename), &st) == 0
 	   ? get_stat_mtime (&st)
 	   : time_error_value (errno));
-  if (EMACS_TIME_EQ (mtime, b->modtime)
+
+  /* On a few buggy file systems, the fractional part of the time stamp,
+     or perhaps even the low order bit of the seconds part, can
+     spontaneously change even though the file has not changed.  If
+     SLOPPY_FILE_TIME_STAMPS, work around these bugs at the cost of
+     possibly missing some changes.  */
+  if ((EMACS_TIME_EQ (mtime, b->modtime)
+       || (sloppy_file_time_stamps
+	   && EMACS_TIME_VALID_P (mtime)
+	   && EMACS_TIME_VALID_P (b->modtime)
+	   && EMACS_SECS (mtime) >> 1 == EMACS_SECS (b->modtime) >> 1))
       && (b->modtime_size < 0
 	  || st.st_size == b->modtime_size))
     return Qt;
@@ -6036,6 +6046,13 @@
   write_region_inhibit_fsync = 0;
 #endif
 
+  DEFVAR_BOOL ("sloppy-file-time-stamps", sloppy_file_time_stamps,
+	       doc: /* Non-nil means file time stamps are sloppy.
+When non-nil, ignore low-order part of time stamp when inferring whether
+a file may have changed.  Although this suppresses bogus diagnostics
+on buggy file systems, it can also lose changes to files.  */);
+  sloppy_file_time_stamps = 0;
+
   DEFVAR_BOOL ("delete-by-moving-to-trash", delete_by_moving_to_trash,
                doc: /* Specifies whether to use the system's trash can.
 When non-nil, certain file deletion commands use the function







  reply	other threads:[~2013-01-15  6:45 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-11 21:51 bug#13149: 24.3.50; Emacs thinks file was changed outside Emacs, but it was not Drew Adams
2012-12-11 22:48 ` Dmitry Gutov
2012-12-11 22:54   ` Drew Adams
2013-01-14  5:10     ` Dmitry Gutov
2013-01-14 14:57       ` Dmitry Gutov
2013-01-14 17:02         ` Eli Zaretskii
2013-01-14 22:22           ` Dmitry Gutov
2013-01-14 18:28         ` Paul Eggert
2013-01-14 22:20           ` Dmitry Gutov
2013-01-15  6:45             ` Paul Eggert [this message]
2013-01-15  8:54               ` Dmitry Gutov
2013-01-15 17:31                 ` Paul Eggert
2013-01-15 21:38                   ` Dmitry Gutov
2013-01-15 21:47                     ` Paul Eggert
2013-01-15 22:11                       ` Dmitry Gutov
2013-01-15 22:38                         ` Paul Eggert
2013-01-15 23:09                           ` Dmitry Gutov
2013-01-15 23:44                             ` Dmitry Gutov
2013-01-16  5:57                               ` Paul Eggert
2013-01-17 10:32                                 ` Dmitry Gutov
2013-01-17 17:05                                   ` Eli Zaretskii
2013-01-18  4:15                                     ` Dmitry Gutov
2013-01-18  7:49                                       ` Eli Zaretskii
2013-01-17 21:14                                   ` Paul Eggert
2013-01-18  4:55                                     ` Dmitry Gutov
2013-01-18  5:26                                       ` Paul Eggert
2013-01-17 21:33                                   ` Paul Eggert
2013-01-18  4:36                                     ` Dmitry Gutov
2013-01-18  5:01                                       ` Paul Eggert
2013-01-18  5:10                                         ` Dmitry Gutov
2013-01-18  5:25                                           ` Paul Eggert
2013-01-18  5:54                                             ` Dmitry Gutov
2013-01-18  6:22                                               ` Dmitry Gutov
2013-01-18  7:56                                             ` Eli Zaretskii
2013-01-18 14:45                                               ` Dmitry Gutov
2013-01-18 21:35                                               ` Paul Eggert
2013-01-18 22:52                                                 ` Dmitry Gutov
2013-01-19  0:55                                                   ` Paul Eggert
2013-01-19  1:09                                                     ` Dmitry Gutov
2013-01-19  2:37                                                       ` Paul Eggert
2013-01-19  4:02                                                         ` Dmitry Gutov
2013-01-19  4:51                                                           ` Paul Eggert
     [not found]                                                             ` <DEB91990BBBB4255BFB466956EB54214@us.oracl!e.com>
     [not found]                                                             ` <DEB91990BBBB4255BFB466956EB54214@us.oracl! e.com>
     [not found]                                                             ` <DEB91990BBBB4255BFB466956EB54214@us.oracl!>
     [not found]                                                               ` <e.com@[87.69.4.28]>
     [not found]                                                                 ` <83wq! urc1u3.fsf@gnu.org>
     [not found]                                                             ` <DEB91990BBBB4255BFB466956! EB54214@us.oracl!>
2013-01-19  5:02                                                             ` Drew Adams
2013-02-01 16:32                                                               ` Drew Adams
2013-02-01 16:43                                                                 ` Drew Adams
2013-02-01 16:49                                                                   ` Drew Adams
2013-02-01 18:43                                                                 ` Eli Zaretskii
2013-02-01 19:19                                                                   ` Drew Adams
2013-02-01 19:36                                                                     ` Eli Zaretskii
2013-02-01 22:15                                                                       ` Drew Adams
2013-02-02  9:41                                                                         ` Eli Zaretskii
2013-02-02 16:06                                                                           ` Drew Adams
2013-02-01 19:38                                                                     ` Eli Zaretskii
2013-02-01 22:13                                                                       ` Drew Adams
2013-02-01 21:05                                                                 ` Paul Eggert
2013-02-01 22:14                                                                   ` Drew Adams
2013-02-01 22:22                                                                     ` Paul Eggert
2013-02-02  9:43                                                                       ` Eli Zaretskii
2013-03-19  8:39                                                                         ` Uwe Siart
2013-03-19 16:55                                                                           ` Eli Zaretskii
2013-03-19 17:50                                                                             ` Uwe Siart
2014-02-06  1:40                                                                             ` Lars Ingebrigtsen
2014-02-06  6:12                                                                               ` Drew Adams
2014-02-06  6:19                                                                               ` Eli Zaretskii
2013-02-02  9:38                                                                   ` Eli Zaretskii
2013-02-02 19:31                                                                     ` Paul Eggert
2013-01-18  7:57                                       ` Eli Zaretskii
2013-01-17 17:16                                 ` David Engster

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