Let users disable unsafe signal handling code

* src/keyboard.c (syms_of_keyboard): New user variables
`attempt-stack-overflow-recovery' and
`attempt-orderly-shutdown-on-fatal-signal'.
* src/sysdep.c (stack_overflow): Check
`attempt-stack-overflow-recovery'.
* src/emacs.c (terminate_due_to_signal): Check
`attempt-orderly-shutdown-on-fatal-signal'.

1 files changed, 11 insertions, 8 deletions

diff --git a/src/emacs.c b/src/emacs.c
index 926aa989e6a..d13413d880b 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -370,17 +370,20 @@ terminate_due_to_signal (int sig, int backtrace_limit)
 {
   signal (sig, SIG_DFL);
 
-  /* If fatal error occurs in code below, avoid infinite recursion.  */
-  if (! fatal_error_in_progress)
+  if (attempt_orderly_shutdown_on_fatal_signal)
     {
-      fatal_error_in_progress = 1;
+      /* If fatal error occurs in code below, avoid infinite recursion.  */
+      if (! fatal_error_in_progress)
+        {
+          fatal_error_in_progress = 1;
 
-      totally_unblock_input ();
-      if (sig == SIGTERM || sig == SIGHUP || sig == SIGINT)
-        Fkill_emacs (make_number (sig));
+          totally_unblock_input ();
+          if (sig == SIGTERM || sig == SIGHUP || sig == SIGINT)
+            Fkill_emacs (make_number (sig));
 
-      shut_down_emacs (sig, Qnil);
-      emacs_backtrace (backtrace_limit);
+          shut_down_emacs (sig, Qnil);
+          emacs_backtrace (backtrace_limit);
+        }
     }
 
   /* Signal the same code; this time it will really be fatal.