1 files changed, 52 insertions, 0 deletions
diff --git a/lib/acl-errno-valid.c b/lib/acl-errno-valid.c
new file mode 100644
index 0000000..96577eb
--- /dev/null
+++ b/lib/acl-errno-valid.c
@@ -0,0 +1,52 @@
+/* Test whether ACLs are well supported on this system.
+
+   Copyright 2013-2018 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+   Written by Paul Eggert.  */
+
+#include <config.h>
+
+#include <acl.h>
+
+#include <errno.h>
+
+/* Return true if errno value ERRNUM indicates that ACLs are well
+   supported on this system.  ERRNUM should be an errno value obtained
+   after an ACL-related system call fails.  */
+bool
+acl_errno_valid (int errnum)
+{
+  /* Recognize some common errors such as from an NFS mount that does
+     not support ACLs, even when local drives do.  */
+  switch (errnum)
+    {
+    case EBUSY: return false;
+    case EINVAL: return false;
+#if defined __APPLE__ && defined __MACH__
+    case ENOENT: return false;
+#endif
+    case ENOSYS: return false;
+
+#if defined ENOTSUP && ENOTSUP != EOPNOTSUPP
+# if ENOTSUP != ENOSYS /* Needed for the MS-Windows port of GNU Emacs.  */
+    case ENOTSUP: return false;
+# endif
+#endif
+
+    case EOPNOTSUPP: return false;
+    default: return true;
+    }
+}