2 files changed, 24 insertions, 12 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index b3410b1c69e..e15c3e7937f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,12 @@
 2009-07-21  Chong Yidong  <cyd@stupidchicken.com>
 
+        * fileio.c: Revert 2009-07-16 changes.
+        (Vauto_save_include_big_deletions): New variable.
+        (Fdo_auto_save): Disable auto-save only if
+        auto-save-include-big-deletions is nil.
+
+2009-07-21  Chong Yidong  <cyd@stupidchicken.com>
+
         * xdisp.c (move_it_to): For continued lines ending in a tab, take
         the overflowed pixels into account (Bug#3879).
 
diff --git a/src/fileio.c b/src/fileio.c
index 43872d59472..3702d4cc1b8 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -193,6 +193,9 @@ Lisp_Object Vauto_save_list_file_name;
 /* Whether or not files are auto-saved into themselves.  */
 Lisp_Object Vauto_save_visited_file_name;
 
+/* Whether or not to continue auto-saving after a large deletion.  */
+Lisp_Object Vauto_save_include_big_deletions;
+
 /* On NT, specifies the directory separator character, used (eg.) when
    expanding file names.  This can be bound to / or \. */
 Lisp_Object Vdirectory_sep_char;
@@ -4492,8 +4495,7 @@ This calls `write-region-annotate-functions' at the start, and
       if (visiting)
         {
           SAVE_MODIFF = MODIFF;
-          if (XINT (current_buffer->save_length) != -2)
-            XSETFASTINT (current_buffer->save_length, Z - BEG);
+          XSETFASTINT (current_buffer->save_length, Z - BEG);
           current_buffer->filename = visit_file;
         }
       UNGCPRO;
@@ -4704,8 +4706,7 @@ This calls `write-region-annotate-functions' at the start, and
   if (visiting)
     {
       SAVE_MODIFF = MODIFF;
-      if (XINT (current_buffer->save_length) != -2)
-        XSETFASTINT (current_buffer->save_length, Z - BEG);
+      XSETFASTINT (current_buffer->save_length, Z - BEG);
       current_buffer->filename = visit_file;
       update_mode_lines++;
     }
@@ -5309,7 +5310,7 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
             && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)
             && b->auto_save_modified < BUF_MODIFF (b)
             /* -1 means we've turned off autosaving for a while--see below.  */
-            && XINT (b->save_length) != -1
+            && XINT (b->save_length) >= 0
             && (do_handled_files
                 || NILP (Ffind_file_name_handler (b->auto_save_file_name,
                                                   Qwrite_region))))
@@ -5323,8 +5324,8 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
                 && EMACS_SECS (before_time) - b->auto_save_failure_time < 1200)
               continue;
 
-            if (XINT (b->save_length) != -2
-                /* -2 is a magic flag turning off this feature in a buffer.  */
+            set_buffer_internal (b);
+            if (NILP (Vauto_save_include_big_deletions)
                 && (XFASTINT (b->save_length) * 10
                     > (BUF_Z (b) - BUF_BEG (b)) * 13)
                 /* A short file is likely to change a large fraction;
@@ -5345,14 +5346,12 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
                 Fsleep_for (make_number (1), Qnil);
                 continue;
               }
-            set_buffer_internal (b);
             if (!auto_saved && NILP (no_message))
               message1 ("Auto-saving...");
             internal_condition_case (auto_save_1, Qt, auto_save_error);
             auto_saved++;
             b->auto_save_modified = BUF_MODIFF (b);
-            if (XINT (current_buffer->save_length) != -2)
-              XSETFASTINT (current_buffer->save_length, Z - BEG);
+            XSETFASTINT (current_buffer->save_length, Z - BEG);
             set_buffer_internal (old);
 
             EMACS_GET_TIME (after_time);
@@ -5397,8 +5396,7 @@ No auto-save file will be written until the buffer changes again.  */)
      ()
 {
   current_buffer->auto_save_modified = MODIFF;
-  if (XINT (current_buffer->save_length) != -2)
-    XSETFASTINT (current_buffer->save_length, Z - BEG);
+  XSETFASTINT (current_buffer->save_length, Z - BEG);
   current_buffer->auto_save_failure_time = -1;
   return Qnil;
 }
@@ -5710,6 +5708,13 @@ a non-nil value.  */);
 Normally auto-save files are written under other names.  */);
   Vauto_save_visited_file_name = Qnil;
 
+  DEFVAR_LISP ("auto-save-include-big-deletions", &Vauto_save_include_big_deletions,
+               doc: /* If non-nil, auto-save even if a large part of the text is deleted.
+If nil, deleting a substantial portion of the text disables auto-save
+in the buffer; this is the default behavior, because the auto-save
+file is usually more useful if it contains the deleted text.  */);
+  Vauto_save_include_big_deletions = Qnil;
+
 #ifdef HAVE_FSYNC
   DEFVAR_BOOL ("write-region-inhibit-fsync", &write_region_inhibit_fsync,
                doc: /* *Non-nil means don't call fsync in `write-region'.