coreutils/m4/putenv.m4

# putenv.m4 serial 8
dnl Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
dnl This file is free software, distributed under the terms of the GNU
dnl General Public License.  As a special exception to the GNU General
dnl Public License, this file may be distributed as part of a program
dnl that contains a configuration script generated by Autoconf, under
dnl the same distribution terms as the rest of that program.

dnl From Jim Meyering.
dnl
dnl Check whether putenv ("FOO") removes FOO from the environment.
dnl The putenv in libc on at least SunOS 4.1.4 does *not* do that.

AC_DEFUN([gl_FUNC_PUTENV],
[AC_CACHE_CHECK([for SVID conformant putenv], jm_cv_func_svid_putenv,
  [AC_TRY_RUN([
    int
    main ()
    {
      /* Put it in env.  */
      if (putenv ("CONFTEST_putenv=val"))
        exit (1);

      /* Try to remove it.  */
      if (putenv ("CONFTEST_putenv"))
        exit (1);

      /* Make sure it was deleted.  */
      if (getenv ("CONFTEST_putenv") != 0)
        exit (1);

      exit (0);
    }
	      ],
	     jm_cv_func_svid_putenv=yes,
	     jm_cv_func_svid_putenv=no,
	     dnl When crosscompiling, assume putenv is broken.
	     jm_cv_func_svid_putenv=no)
  ])
  if test $jm_cv_func_svid_putenv = no; then
    AC_LIBOBJ(putenv)
    AC_DEFINE(putenv, rpl_putenv,
      [Define to rpl_putenv if the replacement function should be used.])
    gl_PREREQ_PUTENV
  fi
])

# Prerequisites of lib/putenv.c.
AC_DEFUN([gl_PREREQ_PUTENV], [
  AC_CHECK_HEADERS_ONCE(unistd.h)
])