# getprogname.m4 - check for getprogname or replacements for it

# Copyright (C) 2016-2018 Free Software Foundation, Inc.

# This file is free software; the Free Software Foundation

# gives unlimited permission to copy and/or distribute it,

# with or without modifications, as long as this notice is preserved.

# serial 4

AC_DEFUN([gl_FUNC_GETPROGNAME],

[

  AC_CHECK_FUNCS_ONCE([getprogname getexecname])

  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  ac_found=0

  AC_CHECK_DECLS([program_invocation_name], [ac_found=1], [],

    [#include <errno.h>])

  AC_CHECK_DECLS([program_invocation_short_name], [ac_found=1], [],

    [#include <errno.h>])

  AC_CHECK_DECLS([__argv], [ac_found=1], [], [#include <stdlib.h>])

  # Incur the cost of this test only if none of the above worked.

  if test $ac_found = 0; then

    # On OpenBSD 5.1, using the global __progname variable appears to be

    # the only way to implement getprogname.

    AC_CACHE_CHECK([whether __progname is defined in default libraries],

      [gl_cv_var___progname],

      [

        gl_cv_var___progname=

        AC_LINK_IFELSE(

          [AC_LANG_PROGRAM(

            [[extern char *__progname;]],

            [[return *__progname;]]

          )],

          [gl_cv_var___progname=yes]

        )

      ]

    )

    if test "$gl_cv_var___progname" = yes; then

      AC_DEFINE([HAVE_VAR___PROGNAME], 1,

        [Define if you have a global __progname variable])

    fi

  fi

])