# SYNOPSIS

#

#   AX_CHECK_CATCHABLE_SEGV

#

# DESCRIPTION

#

#  Check whether segmentation violations can be caught using signal handlers.

#serial 1

AC_DEFUN([AX_CHECK_CATCHABLE_SEGV], [dnl

    AC_PREREQ(2.64)

    AS_VAR_PUSHDEF([CACHEVAR], [ax_cv_check_[]_AC_LANG_ABBREV[]CATCHABLE_SEGV])dnl

    AC_CACHE_CHECK([whether segmentation violations can be caught when using the _AC_LANG compiler], CACHEVAR, [

        AC_RUN_IFELSE([

            AC_LANG_PROGRAM([[

#include <signal.h>

#include <stdlib.h>

static void sig(int _) { exit(0); }

            ]], [[

volatile unsigned char * volatile x = (volatile unsigned char *) malloc(8);

size_t i;

signal(SIGSEGV, sig);

signal(SIGBUS, sig);

#if !defined(__SANITIZE_ADDRESS__) && !defined(__EMSCRIPTEN__)

for (i = 0; i < 10000000; i += 1024) { x[-i] = x[i] = (unsigned char) i; }

#endif

free((void *) x);

exit(1)

            ]])],

            [AS_VAR_SET(CACHEVAR, [yes])],

            [AS_VAR_SET(CACHEVAR, [no])],

            [AS_VAR_SET(CACHEVAR, [unknown])]

        )

    ])

    AS_VAR_IF(CACHEVAR, yes,

        [AC_DEFINE([HAVE_CATCHABLE_SEGV], [1], [Define if segmentation violations can be caught using signal handlers])],

        [AC_MSG_WARN([On this platform, segmentation violations cannot be caught using signal handlers. This is expected if you enabled a tool such as Address Sanitizer (-fsanitize=address), but be aware that using Address Sanitizer may also significantly reduce performance.])]

    )

    AS_VAR_POPDEF([CACHEVAR])dnl

])