From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 7 Sep 2014 13:27:33 +0000 (-0700)
Subject: * keyboard.c (read_decoded_event_from_main_queue): Reinstitute alloca
X-Git-Tag: emacs-25.0.90~2635^2~679^2~338
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=2b95a8efed84d6ec8f178a3bfbbcbfdee3ab35ef;p=emacs.git

* 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)
---

diff --git a/src/ChangeLog b/src/ChangeLog
index 72bdb87fc70..e9c3fe0dea4 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,10 @@
 2014-09-07  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* 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)
diff --git a/src/keyboard.c b/src/keyboard.c
index 9e14560404b..eef0770684e 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -2362,7 +2362,14 @@ read_decoded_event_from_main_queue (struct timespec *end_time,
 	      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);