Handle C stack overflow caused by too nested Lisp evaluation.

* configure.ac: Check for sigaltstack and related sigaction
support.  Unconditionally check for sigsetjmp and siglongjmp.
(HAVE_STACK_OVERFLOW_HANDLING): Define if we can support it.
* src/lisp.h (toplevel) [HAVE_STACK_OVERFLOW_HANDLING]: Declare
siglongjmp point to transfer control from SIGSEGV handler.
* src/keyboard.c (return_to_command_loop, recover_top_level_message)
[HAVE_STACK_OVERFLOW_HANDLING]: New variables.
(regular_top_level_message): New variable.
(command_loop) [HAVE_STACK_OVERFLOW_HANDLING]: Handle non-local
exit from SIGSEGV handler and adjust message displayed by Vtop_level
if appropriate.
(syms_of_keyboard): DEFVAR Vtop_level_message and initialize
new variables described above.
* src/sysdep.c [HAVE_SYS_RESOURCE_H]: Include sys/resource.h as such.
(stack_grows_down, sigsegv_stack, handle_sigsegv)
[HAVE_STACK_OVERFLOW_HANDLING]: New variables and function.
(init_sigsegv): New function.
(init_signals): Use it.
* lisp/startup.el (normal-top-level): Use top-level-message.

2 files changed, 5 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 65a59f4da6d..12d283e7120 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2014-08-26  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        * startup.el (normal-top-level): Use top-level-message.
+
 2014-08-25  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
         * net/shr.el (shr-copy-url): Encode copied URL to avoid getting
diff --git a/lisp/startup.el b/lisp/startup.el
index 144d732272f..1d5ae250505 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -497,7 +497,7 @@ It sets `command-line-processed', processes the command-line,
 reads the initialization files, etc.
 It is the default value of the variable `top-level'."
   (if command-line-processed
-      (message "Back to top level.")
+      (message top-level-message)
     (setq command-line-processed t)
 
     ;; Look in each dir in load-path for a subdirs.el file.  If we