[PATCH] Basic support for checking NFSv4 ACLs in Linux

[Ondrej Valousek]

As per suggestions from Andreas, I am attaching a simplified version of the 
patch implementing basic
checks for non-trivial NFSv4 acls

---
 lib/file-has-acl.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/lib/file-has-acl.c b/lib/file-has-acl.c
index e02f0626a..37b3aaa30 100644
--- a/lib/file-has-acl.c
+++ b/lib/file-has-acl.c
@@ -32,6 +32,11 @@
 #if GETXATTR_WITH_POSIX_ACLS
 # include <sys/xattr.h>
 # include <linux/xattr.h>
+# include <arpa/inet.h>
+#ifndef XATTR_NAME_NFSV4_ACL
+#define XATTR_NAME_NFSV4_ACL "system.nfs4_acl"
+#endif
+#define TRIVIAL_NFS4_ACL_LENGTH 80
 #endif
 
 /* Return 1 if NAME has a nontrivial access control list,
@@ -67,6 +72,14 @@ file_has_acl (char const *name, struct stat const *sb)
             return 1;
         }
 
+      if (ret < 0) { /* we might be on NFS, so try to check NFSv4 ACLs too */
+         char xattr[TRIVIAL_NFS4_ACL_LENGTH];
+
+         ret = getxattr (name, XATTR_NAME_NFSV4_ACL, xattr, 
TRIVIAL_NFS4_ACL_LENGTH);
+         if (ret < 0 && errno == ENODATA)
+              ret = 0;
+         else ret = errno == ERANGE;  /* we won't fit into the buffer, so 
non-trivial ACL is presented */
+      }  
       if (ret < 0)
         return - acl_errno_valid (errno);
       return ret;
-- 
2.37.3