[Emacs-diffs] trunk r113351: Timestamp fixes for undo.

[Paul Eggert]

------------------------------------------------------------
revno: 113351
revision-id: address@hidden
parent: address@hidden
fixes bug: http://debbugs.gnu.org/14824
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Tue 2013-07-09 23:26:23 -0700
message:
  Timestamp fixes for undo.
  
  * doc/lispref/text.texi (Undo):
  Document (t . 0) and (t . -1) in buffer-undo-list.
  * etc/NEWS: Changes to visited-file-modtime, set-visited-file-modtime.
  * lisp/files.el (clear-visited-file-modtime): Move here from fileio.c.
  * src/atimer.c (schedule_atimer):
  * src/fileio.c (Ffile_newer_than_file_p):
  Minor cleanup: use EMACS_TIME_LT so that we can remove EMACS_TIME_GT.
  * src/buffer.c (buffer-undo-list): Document (t . 0) and (t . -1).
  * src/fileio.c (Fclear_visited_file_modtime): Move to lisp/files.el.
  (syms_of_fileio): Remove Sclear_visited_file_name.
  (Fvisited_file_modtime): Return -1, not (-1 ...), when the visited
  file doesn't exist; this avoids an ambiguity with negative timestamps.
  (Fset_visited_file_modtime): Accept -1 and 0 as time-list arg.
  * src/systime.h (make_emacs_time, invalid_emacs_time):
  Don't assume struct timespec layout; POSIX doesn't guarantee it.
  (EMACS_TIME_NE, EMACS_TIME_GT, EMACS_TIME_GE): Remove.
  * src/undo.c (record_first_change): Push (visited-file-modtime) onto
  undo list rather than reimplementing it by hand, incorrectly.
modified:
  doc/lispref/ChangeLog          changelog-20091113204419-o5vbwnq5f7feedwu-6155
  doc/lispref/text.texi          text.texi-20091113204419-o5vbwnq5f7feedwu-6215
  etc/ChangeLog                  changelog-20091113204419-o5vbwnq5f7feedwu-1485
  etc/NEWS                       news-20100311060928-aoit31wvzf25yr1z-1
  lisp/ChangeLog                 changelog-20091113204419-o5vbwnq5f7feedwu-1432
  lisp/files.el                  files.el-20091113204419-o5vbwnq5f7feedwu-265
  src/ChangeLog                  changelog-20091113204419-o5vbwnq5f7feedwu-1438
  src/atimer.c                   atimer.c-20091113204419-o5vbwnq5f7feedwu-1759
  src/buffer.c                   buffer.c-20091113204419-o5vbwnq5f7feedwu-264
  src/fileio.c                   fileio.c-20091113204419-o5vbwnq5f7feedwu-210
  src/systime.h                  systime.h-20091113204419-o5vbwnq5f7feedwu-510
  src/undo.c                     undo.c-20091113204419-o5vbwnq5f7feedwu-206

=== modified file 'doc/lispref/ChangeLog'
--- a/doc/lispref/ChangeLog     2013-07-06 08:05:21 +0000
+++ b/doc/lispref/ChangeLog     2013-07-10 06:26:23 +0000
@@ -1,3 +1,8 @@
+2013-07-10  Paul Eggert  <address@hidden>
+
+       Timestamp fixes for undo (Bug#14824).
+       * text.texi (Undo): Document (t . 0) and (t . -1) in buffer-undo-list.
+
 2013-07-06  Eli Zaretskii  <address@hidden>
 
        * nonascii.texi (Text Representations): Document that

=== modified file 'doc/lispref/text.texi'
--- a/doc/lispref/text.texi     2013-06-17 15:49:43 +0000
+++ b/doc/lispref/text.texi     2013-07-10 06:26:23 +0000
@@ -1250,14 +1250,18 @@
 positive, point was at the beginning of the deleted text, otherwise it
 was at the end.
 
address@hidden (t @var{sec-high} @var{sec-low} @var{microsec} @var{picosec})
address@hidden (t . @var{time-flag})
 This kind of element indicates that an unmodified buffer became
-modified.  The list @code{(@var{sec-high} @var{sec-low} @var{microsec}
+modified.  A @var{time-flag} of the form
address@hidden(@var{sec-high} @var{sec-low} @var{microsec}
 @var{picosec})} represents the visited file's modification time as of
 when it was previously visited or saved, using the same format as
address@hidden; see @ref{Time of Day}.  @code{primitive-undo} uses those
address@hidden; see @ref{Time of Day}.
+A @var{time-flag} of 0 means the buffer does not correspond to any file;
address@hidden means the visited file previously did not exist.
address@hidden uses these
 values to determine whether to mark the buffer as unmodified once again;
-it does so only if the file's modification time matches those numbers.
+it does so only if the file's status matches that of @var{time-flag}.
 
 @item (nil @var{property} @var{value} @var{beg} . @var{end})
 This kind of element records a change in a text property.

=== modified file 'etc/ChangeLog'
--- a/etc/ChangeLog     2013-07-08 17:54:39 +0000
+++ b/etc/ChangeLog     2013-07-10 06:26:23 +0000
@@ -1,3 +1,8 @@
+2013-07-10  Paul Eggert  <address@hidden>
+
+       Timestamp fixes for undo (Bug#14824).
+       * NEWS: Changes to visited-file-modtime, set-visited-file-modtime.
+
 2013-07-08  Jan Djärv  <address@hidden>
 
        * NEWS: NS can be build with ImageMagick.

=== modified file 'etc/NEWS'
--- a/etc/NEWS  2013-07-08 22:26:37 +0000
+++ b/etc/NEWS  2013-07-10 06:26:23 +0000
@@ -537,6 +537,9 @@
 `file-extended-attributes'.  The attributes can be applied to another
 file using `set-file-extended-attributes'.
 
+** `visited-file-modtime' now returns -1 for nonexistent files.
+Formerly it returned a list (-1 LOW USEC PSEC), but this was ambiguous
+in the presence of files with negative time stamps.
 
 * Lisp Changes in Emacs 24.4
 
@@ -613,6 +616,9 @@
 *** New functions `image-current-frame' and `image-show-frame' for getting
 and setting the current frame of a multi-frame image.
 
+** The function `set-visited-file-modtime' now accepts a 0 or -1 argument
+with the same interpretation as the returned value of `visited-file-modtime'.
+
 ** time-to-seconds is not obsolete any more.
 ** New function special-form-p.
 ** Docstrings can be made dynamic by adding a `dynamic-docstring-function'

=== modified file 'lisp/ChangeLog'
--- a/lisp/ChangeLog    2013-07-10 03:10:27 +0000
+++ b/lisp/ChangeLog    2013-07-10 06:26:23 +0000
@@ -1,3 +1,8 @@
+2013-07-10  Paul Eggert  <address@hidden>
+
+       Timestamp fixes for undo (Bug#14824).
+       * files.el (clear-visited-file-modtime): Move here from fileio.c.
+
 2013-07-10  Leo Liu  <address@hidden>
 
        * files.el (require-final-newline): Allow safe local value.

=== modified file 'lisp/files.el'
--- a/lisp/files.el     2013-07-10 03:10:27 +0000
+++ b/lisp/files.el     2013-07-10 06:26:23 +0000
@@ -4918,6 +4918,11 @@
                     (length autosaved-buffers)
                     (mapconcat 'identity autosaved-buffers ", "))))))))
 
+(defun clear-visited-file-modtime ()
+  "Clear out records of last mod time of visited file.
+Next attempt to save will certainly not complain of a discrepancy."
+  (set-visited-file-modtime 0))
+
 (defun not-modified (&optional arg)
   "Mark current buffer as unmodified, not needing to be saved.
 With prefix ARG, mark buffer as modified, so \\[save-buffer] will save.

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2013-07-09 13:56:47 +0000
+++ b/src/ChangeLog     2013-07-10 06:26:23 +0000
@@ -1,3 +1,21 @@
+2013-07-10  Paul Eggert  <address@hidden>
+
+       Timestamp fixes for undo (Bug#14824).
+       * atimer.c (schedule_atimer):
+       * fileio.c (Ffile_newer_than_file_p):
+       Minor cleanup: use EMACS_TIME_LT so that we can remove EMACS_TIME_GT.
+       * buffer.c (buffer-undo-list): Document (t . 0) and (t . -1).
+       * fileio.c (Fclear_visited_file_modtime): Move to lisp/files.el.
+       (syms_of_fileio): Remove Sclear_visited_file_name.
+       (Fvisited_file_modtime): Return -1, not (-1 ...), when the visited
+       file doesn't exist; this avoids an ambiguity with negative timestamps.
+       (Fset_visited_file_modtime): Accept -1 and 0 as time-list arg.
+       * systime.h (make_emacs_time, invalid_emacs_time):
+       Don't assume struct timespec layout; POSIX doesn't guarantee it.
+       (EMACS_TIME_NE, EMACS_TIME_GT, EMACS_TIME_GE): Remove.
+       * undo.c (record_first_change): Push (visited-file-modtime) onto
+       undo list rather than reimplementing it by hand, incorrectly.
+
 2013-07-09  Ken Brown  <address@hidden>
 
        * sheap.c (STATIC_HEAP_SIZE) [__x86_64__]: Increase to 18MB.

=== modified file 'src/atimer.c'
--- a/src/atimer.c      2013-01-01 09:11:05 +0000
+++ b/src/atimer.c      2013-07-10 06:26:23 +0000
@@ -336,7 +336,7 @@
   struct atimer *a = atimers, *prev = NULL;
 
   /* Look for the first atimer that is ripe after T.  */
-  while (a && EMACS_TIME_GT (t->expiration, a->expiration))
+  while (a && EMACS_TIME_LT (a->expiration, t->expiration))
     prev = a, a = a->next;
 
   /* Insert T in front of the atimer found, if any.  */

=== modified file 'src/buffer.c'
--- a/src/buffer.c      2013-07-06 02:40:50 +0000
+++ b/src/buffer.c      2013-07-10 06:26:23 +0000
@@ -6095,6 +6095,11 @@
 modification time of the most recent save is different, this entry is
 obsolete.
 
+An entry (t . 0) means means the buffer was previously unmodified but
+its time stamp was unknown because it was not associated with a file.
+An entry (t . -1) is similar, except that it means the buffer's visited
+file did not exist.
+
 An entry (nil PROPERTY VALUE BEG . END) indicates that a text property
 was modified between BEG and END.  PROPERTY is the property name,
 and VALUE is the old value.

=== modified file 'src/fileio.c'
--- a/src/fileio.c      2013-07-09 07:04:48 +0000
+++ b/src/fileio.c      2013-07-10 06:26:23 +0000
@@ -3345,7 +3345,7 @@
   if (stat (SSDATA (absname2), &st2) < 0)
     return Qt;
 
-  return (EMACS_TIME_GT (get_stat_mtime (&st1), get_stat_mtime (&st2))
+  return (EMACS_TIME_LT (get_stat_mtime (&st2), get_stat_mtime (&st1))
          ? Qt : Qnil);
 }
 
@@ -5375,36 +5375,19 @@
   return Qnil;
 }
 
-DEFUN ("clear-visited-file-modtime", Fclear_visited_file_modtime,
-       Sclear_visited_file_modtime, 0, 0, 0,
-       doc: /* Clear out records of last mod time of visited file.
-Next attempt to save will certainly not complain of a discrepancy.  */)
-  (void)
-{
-  current_buffer->modtime = make_emacs_time (0, UNKNOWN_MODTIME_NSECS);
-  current_buffer->modtime_size = -1;
-  return Qnil;
-}
-
 DEFUN ("visited-file-modtime", Fvisited_file_modtime,
        Svisited_file_modtime, 0, 0, 0,
        doc: /* Return the current buffer's recorded visited file modification 
time.
 The value is a list of the form (HIGH LOW USEC PSEC), like the time values that
 `file-attributes' returns.  If the current buffer has no recorded file
 modification time, this function returns 0.  If the visited file
-doesn't exist, HIGH will be -1.
+doesn't exist, return -1.
 See Info node `(elisp)Modification Time' for more details.  */)
   (void)
 {
-  if (EMACS_NSECS (current_buffer->modtime) < 0)
-    {
-      if (EMACS_NSECS (current_buffer->modtime) == NONEXISTENT_MODTIME_NSECS)
-       {
-         /* make_lisp_time won't work here if time_t is unsigned.  */
-         return list4i (-1, 65535, 0, 0);
-       }
-      return make_number (0);
-    }
+  int ns = EMACS_NSECS (current_buffer->modtime);
+  if (ns < 0)
+    return make_number (UNKNOWN_MODTIME_NSECS - ns);
   return make_lisp_time (current_buffer->modtime);
 }
 
@@ -5415,12 +5398,22 @@
 or if the file itself has been changed for some known benign reason.
 An argument specifies the modification time value to use
 \(instead of that of the visited file), in the form of a list
-\(HIGH LOW USEC PSEC) as returned by `current-time'.  */)
-  (Lisp_Object time_list)
+\(HIGH LOW USEC PSEC) or an integer flag as returned by
+`visited-file-modtime'.  */)
+  (Lisp_Object time_flag)
 {
-  if (!NILP (time_list))
+  if (!NILP (time_flag))
     {
-      current_buffer->modtime = lisp_time_argument (time_list);
+      EMACS_TIME mtime;
+      if (INTEGERP (time_flag))
+       {
+         CHECK_RANGED_INTEGER (time_flag, -1, 0);
+         mtime = make_emacs_time (0, UNKNOWN_MODTIME_NSECS - XINT (time_flag));
+       }
+      else
+       mtime = lisp_time_argument (time_flag);
+
+      current_buffer->modtime = mtime;
       current_buffer->modtime_size = -1;
     }
   else
@@ -6121,7 +6114,6 @@
   defsubr (&Swrite_region);
   defsubr (&Scar_less_than_car);
   defsubr (&Sverify_visited_file_modtime);
-  defsubr (&Sclear_visited_file_modtime);
   defsubr (&Svisited_file_modtime);
   defsubr (&Sset_visited_file_modtime);
   defsubr (&Sdo_auto_save);

=== modified file 'src/systime.h'
--- a/src/systime.h     2013-04-27 15:34:28 +0000
+++ b/src/systime.h     2013-07-10 06:26:23 +0000
@@ -67,7 +67,9 @@
 SYSTIME_INLINE EMACS_TIME
 make_emacs_time (time_t s, int ns)
 {
-  EMACS_TIME r = { s, ns };
+  EMACS_TIME r;
+  r.tv_sec = s;
+  r.tv_nsec = ns;
   return r;
 }
 
@@ -75,7 +77,9 @@
 SYSTIME_INLINE EMACS_TIME
 invalid_emacs_time (void)
 {
-  EMACS_TIME r = { 0, -1 };
+  EMACS_TIME r;
+  r.tv_sec = 0;
+  r.tv_nsec = -1;
   return r;
 }
 
@@ -166,21 +170,6 @@
   return timespec_cmp (t1, t2) == 0;
 }
 SYSTIME_INLINE int
-EMACS_TIME_NE (EMACS_TIME t1, EMACS_TIME t2)
-{
-  return timespec_cmp (t1, t2) != 0;
-}
-SYSTIME_INLINE int
-EMACS_TIME_GT (EMACS_TIME t1, EMACS_TIME t2)
-{
-  return timespec_cmp (t1, t2) > 0;
-}
-SYSTIME_INLINE int
-EMACS_TIME_GE (EMACS_TIME t1, EMACS_TIME t2)
-{
-  return timespec_cmp (t1, t2) >= 0;
-}
-SYSTIME_INLINE int
 EMACS_TIME_LT (EMACS_TIME t1, EMACS_TIME t2)
 {
   return timespec_cmp (t1, t2) < 0;

=== modified file 'src/undo.c'
--- a/src/undo.c        2013-05-18 05:32:17 +0000
+++ b/src/undo.c        2013-07-10 06:26:23 +0000
@@ -229,10 +229,9 @@
   if (base_buffer->base_buffer)
     base_buffer = base_buffer->base_buffer;
 
-  bset_undo_list
-    (current_buffer,
-     Fcons (Fcons (Qt, make_lisp_time (base_buffer->modtime)),
-           BVAR (current_buffer, undo_list)));
+  bset_undo_list (current_buffer,
+                 Fcons (Fcons (Qt, Fvisited_file_modtime ()),
+                        BVAR (current_buffer, undo_list)));
 }
 
 /* Record a change in property PROP (whose old value was VAL)