1# putenv.m4 serial 24
2dnl Copyright (C) 2002-2020 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7dnl From Jim Meyering.
8dnl
9dnl Check whether putenv ("FOO") removes FOO from the environment.
10dnl The putenv in libc on at least SunOS 4.1.4 does *not* do that.
11
12AC_DEFUN([gl_FUNC_PUTENV],
13[
14  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
15  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
16  AC_CACHE_CHECK([for putenv compatible with GNU and SVID],
17   [gl_cv_func_svid_putenv],
18   [AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],[[
19    /* Put it in env.  */
20    if (putenv ("CONFTEST_putenv=val"))
21      return 1;
22
23    /* Try to remove it.  */
24    if (putenv ("CONFTEST_putenv"))
25      return 2;
26
27    /* Make sure it was deleted.  */
28    if (getenv ("CONFTEST_putenv") != 0)
29      return 3;
30
31    return 0;
32              ]])],
33             gl_cv_func_svid_putenv=yes,
34             gl_cv_func_svid_putenv=no,
35             dnl When crosscompiling, assume putenv is broken.
36             [case "$host_os" in
37                               # Guess yes on glibc systems.
38                *-gnu* | gnu*) gl_cv_func_svid_putenv="guessing yes" ;;
39                               # Guess yes on musl systems.
40                *-musl*)       gl_cv_func_svid_putenv="guessing yes" ;;
41                               # Guess no on native Windows.
42                mingw*)        gl_cv_func_svid_putenv="guessing no" ;;
43                               # If we don't know, obey --enable-cross-guesses.
44                *)             gl_cv_func_svid_putenv="$gl_cross_guess_normal" ;;
45              esac
46             ])
47   ])
48  case "$gl_cv_func_svid_putenv" in
49    *yes) ;;
50    *)
51      REPLACE_PUTENV=1
52      ;;
53  esac
54])
55
56# Prerequisites of lib/putenv.c.
57AC_DEFUN([gl_PREREQ_PUTENV],
58[
59  AC_CHECK_DECLS([_putenv])
60])
61