[Emacs-diffs] trunk r117833: * keyboard.c (read_decoded_event_from_main_queue): Reinstitute alloca

[Paul Eggert]

------------------------------------------------------------
revno: 117833
revision-id: address@hidden
parent: address@hidden
author: Paul Eggert  <address@hidden>
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Sun 2014-09-07 06:27:33 -0700
message:
  * keyboard.c (read_decoded_event_from_main_queue): Reinstitute alloca
  
  here for destination buffer, to work around what appears to be a
  bug in decode_coding_c_string when the source and destination are
  both C strings.
  
  * keyboard.c (echo_add_key, menu_bar_items, tool_bar_items)
modified:
  src/ChangeLog                  changelog-20091113204419-o5vbwnq5f7feedwu-1438
  src/keyboard.c                 keyboard.c-20091113204419-o5vbwnq5f7feedwu-449

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2014-09-07 07:04:01 +0000
+++ b/src/ChangeLog     2014-09-07 13:27:33 +0000
@@ -1,5 +1,10 @@
 2014-09-07  Paul Eggert  <address@hidden>
 
+       * keyboard.c (read_decoded_event_from_main_queue): Reinstitute alloca
+       here for destination buffer, to work around what appears to be a
+       bug in decode_coding_c_string when the source and destination are
+       both C strings.
+
        Use SAFE_ALLOCA etc. to avoid unbounded stack allocation (Bug#18410).
        This follows up on the recent thread in emacs-devel on alloca; see:
        http://lists.gnu.org/archive/html/emacs-devel/2014-09/msg00042.html
@@ -24,7 +29,8 @@
        * ftfont.c (ftfont_get_charset, ftfont_check_otf, ftfont_drive_otf):
        * ftxfont.c (ftxfont_draw):
        * image.c (xbm_load, xpm_load, jpeg_load_body):
-       * keyboard.c (echo_add_key, menu_bar_items, tool_bar_items):
+       * keyboard.c (echo_add_key, menu_bar_items, tool_bar_items)
+
        * keymap.c (Fdescribe_buffer_bindings, describe_map):
        * lread.c (openp):
        * menu.c (digest_single_submenu, find_and_call_menu_selection)

=== modified file 'src/keyboard.c'
--- a/src/keyboard.c    2014-09-07 07:04:01 +0000
+++ b/src/keyboard.c    2014-09-07 13:27:33 +0000
@@ -2362,7 +2362,14 @@
              if (meta_key != 2)
                for (i = 0; i < n; i++)
                  src[i] &= ~0x80;
-             coding->destination = dest;
+
+             /* FIXME: For some reason decode_coding_c_string requires a
+                fresh output buffer each time, and reusing the old buffer can
+                make Emacs dump core.  Avoid triggering the problem for now
+                by allocating a new buffer each time through the loop.  */
+             bool please_fixme = true;
+             coding->destination = please_fixme ? alloca (n * 4) : dest;
+
              coding->dst_bytes = n * 4;
              decode_coding_c_string (coding, src, n, Qnil);
              eassert (coding->produced_char <= n);