# strsignal.m4
# serial 10
dnl Copyright (C) 2008-2024 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.

AC_DEFUN([gl_FUNC_STRSIGNAL],
[
  dnl Persuade glibc <string.h> to declare strsignal().
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  AC_REQUIRE([gl_STRING_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  AC_CHECK_DECLS_ONCE([strsignal])
  if test $ac_cv_have_decl_strsignal = no; then
    HAVE_DECL_STRSIGNAL=0
  fi

  AC_CHECK_FUNCS([strsignal])
  if test $ac_cv_func_strsignal = yes; then
    HAVE_STRSIGNAL=1
    dnl Check if strsignal behaves reasonably for out-of-range signal numbers.
    dnl On Solaris it returns NULL; on AIX 5.1 it returns (char *) -1.
    AC_CACHE_CHECK([whether strsignal always returns a string],
      [gl_cv_func_working_strsignal],
      [AC_RUN_IFELSE(
         [AC_LANG_PROGRAM(
            [[#include <string.h>
#include <unistd.h> /* NetBSD 5.0 declares it in wrong header. */
            ]],
            [[int result = 0;
              char *s = strsignal (-1);
              if (s == (char *) 0)
                result |= 1;
              if (s == (char *) -1)
                result |= 2;
              return result;
            ]])],
         [gl_cv_func_working_strsignal=yes],
         [gl_cv_func_working_strsignal=no],
         [case "$host_os" in
            solaris* | aix*) gl_cv_func_working_strsignal=no;;
            *)               gl_cv_func_working_strsignal="guessing yes";;
          esac])])
    if test "$gl_cv_func_working_strsignal" = no; then
      REPLACE_STRSIGNAL=1
    fi
  else
    HAVE_STRSIGNAL=0
  fi
])

# Prerequisites of lib/strsignal.c.
AC_DEFUN([gl_PREREQ_STRSIGNAL], [
  AC_CHECK_HEADERS_ONCE([unistd.h])
  AC_CHECK_DECLS([sys_siglist], [], [], [[#include <signal.h>]])
  AC_CHECK_DECLS([_sys_siglist], [], [], [[#include <signal.h>]])
])
