# HG changeset patch
# User Bruno Haible <bruno@clisp.org>
# Date 1194202327 -3600
# Node ID f7e0638b709fc105374b49b10d57bd809070b738
# Parent  6d73d8d1aecb6e6b4dc4baf33d005e32d2c56595
New module 'nocrash'.

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2007-11-04  Bruno Haible  <bruno@clisp.org>
+
+	* modules/nocrash: New file.
+	* m4/nocrash.m4: New file, taken from GNU clisp. Code taken from
+	GNU libsigsegv, with permission of GNU libsigsegv's copyright holders.
+
 2007-11-04  Bruno Haible  <bruno@clisp.org>
 
 	* tests/test-vasnprintf-posix.c (test_function): Add some tests of
diff --git a/m4/nocrash.m4 b/m4/nocrash.m4
new file mode 100644
--- /dev/null
+++ b/m4/nocrash.m4
@@ -0,0 +1,102 @@
+# nocrash.m4 serial 1
+dnl Copyright (C) 2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Based on libsigsegv, from Bruno Haible and Paolo Bonzini.
+
+AC_PREREQ(2.13)
+
+dnl Expands to some code for use in .c programs that will cause the configure
+dnl test to exit instead of crashing. This is useful to avoid triggering
+dnl action from a background debugger and to avoid core dumps.
+dnl Usage:   ...
+dnl          ]GL_NOCRASH[
+dnl          ...
+dnl          int main() { nocrash_init(); ... }
+AC_DEFUN([GL_NOCRASH],[[
+#include <stdlib.h>
+#if defined __MACH__ && defined __APPLE__
+/* Avoid a crash on MacOS X.  */
+#include <mach/mach.h>
+#include <mach/mach_error.h>
+#include <mach/thread_status.h>
+#include <mach/exception.h>
+#include <mach/task.h>
+#include <pthread.h>
+/* The exception port on which our thread listens.  */
+static mach_port_t our_exception_port;
+/* The main function of the thread listening for exceptions of type
+   EXC_BAD_ACCESS.  */
+static void *
+mach_exception_thread (void *arg)
+{
+  /* Buffer for a message to be received.  */
+  struct {
+    mach_msg_header_t head;
+    mach_msg_body_t msgh_body;
+    char data[1024];
+  } msg;
+  mach_msg_return_t retval;
+  /* Wait for a message on the exception port.  */
+  retval = mach_msg (&msg.head, MACH_RCV_MSG | MACH_RCV_LARGE, 0, sizeof (msg),
+                     our_exception_port, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
+  if (retval != MACH_MSG_SUCCESS)
+    abort ();
+  exit (1);
+}
+static void
+nocrash_init (void)
+{
+  mach_port_t self = mach_task_self ();
+  /* Allocate a port on which the thread shall listen for exceptions.  */
+  if (mach_port_allocate (self, MACH_PORT_RIGHT_RECEIVE, &our_exception_port)
+      == KERN_SUCCESS) {
+    /* See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/mach_port_insert_right.html.  */
+    if (mach_port_insert_right (self, our_exception_port, our_exception_port,
+                                MACH_MSG_TYPE_MAKE_SEND)
+        == KERN_SUCCESS) {
+      /* The exceptions we want to catch.  Only EXC_BAD_ACCESS is interesting
+         for us.  */
+      exception_mask_t mask = EXC_MASK_BAD_ACCESS;
+      /* Create the thread listening on the exception port.  */
+      pthread_attr_t attr;
+      pthread_t thread;
+      if (pthread_attr_init (&attr) == 0
+          && pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED) == 0
+          && pthread_create (&thread, &attr, mach_exception_thread, NULL) == 0) {
+        pthread_attr_destroy (&attr);
+        /* Replace the exception port info for these exceptions with our own.
+           Note that we replace the exception port for the entire task, not only
+           for a particular thread.  This has the effect that when our exception
+           port gets the message, the thread specific exception port has already
+           been asked, and we don't need to bother about it.
+           See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/task_set_exception_ports.html.  */
+        task_set_exception_ports (self, mask, our_exception_port,
+                                  EXCEPTION_DEFAULT, MACHINE_THREAD_STATE);
+      }
+    }
+  }
+}
+#else
+/* Avoid a crash on POSIX systems.  */
+#include <signal.h>
+/* A POSIX signal handler.  */
+static void
+exception_handler (int sig)
+{
+  exit (1);
+}
+static void
+nocrash_init (void)
+{
+#ifdef SIGSEGV
+  signal (SIGSEGV, exception_handler);
+#endif
+#ifdef SIGBUS
+  signal (SIGBUS, exception_handler);
+#endif
+}
+#endif
+]])
diff --git a/modules/nocrash b/modules/nocrash
new file mode 100644
--- /dev/null
+++ b/modules/nocrash
@@ -0,0 +1,20 @@
+Description:
+Macro that avoids crashes in configure tests.
+
+Files:
+m4/nocrash.m4
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+
+Include:
+
+License:
+unlimited
+
+Maintainer:
+Bruno Haible, Paolo Bonzini
+