1 files changed, 32 insertions, 0 deletions
diff --git a/m4/unlinkdir.m4 b/m4/unlinkdir.m4
new file mode 100644
index 0000000..271083d
--- /dev/null
+++ b/m4/unlinkdir.m4
@@ -0,0 +1,32 @@
+# serial 7
+
+# Copyright (C) 2005-2007, 2009-2020 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.
+
+# Written by Paul Eggert.
+
+AC_DEFUN([gl_UNLINKDIR],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CHECK_HEADERS_ONCE([priv.h])
+
+  # The Hurd, the Linux kernel, the FreeBSD kernel version 2.2 and later,
+  # Cygwin, and mingw never let anyone (even root) unlink directories.
+  # If anyone knows of another system for which unlink can never
+  # remove a directory, please report it to <bug-coreutils@gnu.org>.
+  # Unfortunately this is difficult to test for, since it requires root access
+  # and might create garbage in the file system,
+  # so the code below simply relies on the kernel name and version number.
+  case $host_os in
+  gnu[[0-9]]* | \
+  linux-* | linux | \
+  freebsd2.2* | freebsd[[3-9]]* | freebsd[[1-9]][[0-9]]* | \
+  cygwin | \
+  mingw*)
+    AC_DEFINE([UNLINK_CANNOT_UNLINK_DIR], [1],
+      [Define to 1 if unlink (dir) cannot possibly succeed.]);;
+  esac
+])