1 files changed, 64 insertions, 0 deletions
diff --git a/m4/putenv.m4 b/m4/putenv.m4
new file mode 100644
index 0000000..d37a602
--- /dev/null
+++ b/m4/putenv.m4
@@ -0,0 +1,64 @@
+# putenv.m4 serial 26
+dnl Copyright (C) 2002-2023 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.
+
+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_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([for putenv compatible with GNU and SVID],
+    [gl_cv_func_svid_putenv],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [AC_INCLUDES_DEFAULT
+           GL_MDA_DEFINES],
+          [[
+            /* Put it in env.  */
+            if (putenv ("CONFTEST_putenv=val"))
+              return 1;
+
+            /* Try to remove it.  */
+            if (putenv ("CONFTEST_putenv"))
+              return 2;
+
+            /* Make sure it was deleted.  */
+            if (getenv ("CONFTEST_putenv") != 0)
+              return 3;
+
+            return 0;
+          ]])],
+       [gl_cv_func_svid_putenv=yes],
+       [gl_cv_func_svid_putenv=no],
+       [dnl When crosscompiling, assume putenv is broken.
+        case "$host_os" in
+                              # Guess yes on glibc systems.
+          *-gnu* | gnu*)      gl_cv_func_svid_putenv="guessing yes" ;;
+                              # Guess yes on musl systems.
+          *-musl* | midipix*) gl_cv_func_svid_putenv="guessing yes" ;;
+                              # Guess no on native Windows.
+          mingw*)             gl_cv_func_svid_putenv="guessing no" ;;
+                              # If we don't know, obey --enable-cross-guesses.
+          *)                  gl_cv_func_svid_putenv="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+  case "$gl_cv_func_svid_putenv" in
+    *yes) ;;
+    *)
+      REPLACE_PUTENV=1
+      ;;
+  esac
+])
+
+# Prerequisites of lib/putenv.c.
+AC_DEFUN([gl_PREREQ_PUTENV],
+[
+  AC_CHECK_DECLS([_putenv])
+])