[PATCH] acl_extended_file(): add basic support for NFSv4

[Ondrej Valousek]

Hi Andreas/all
I am wondering if there is a chance to accept the patch below?
I want to make the acl_extended_file() function NFSv4 aware so that we can 
(re-)use it in GNULIB's file-has-acl() function.
The reasoning for this is I really want to see the (+) sign long list (ls -l) 
for files/directories that have
either Posix or NFSv4 style ACLs on them
So this is 1st step to make this library NFSv4 ACLs aware.

---
 libacl/__acl_extended_file.c | 37 ++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/libacl/__acl_extended_file.c b/libacl/__acl_extended_file.c
index f10beec..6f9a666 100644
--- a/libacl/__acl_extended_file.c
+++ b/libacl/__acl_extended_file.c
@@ -22,12 +22,44 @@
 #include "config.h"
 #include <unistd.h>
 #include <sys/xattr.h>
+#include <arpa/inet.h>
+#ifndef XATTR_NAME_NFSV4_ACL
+#define XATTR_NAME_NFSV4_ACL "system.nfs4_acl"
+#endif
+
 #include "libacl.h"
 
 #include "byteorder.h"
 #include "acl_ea.h"
 #include "__acl_extended_file.h"
 
+int __nfs4_acls_exists(const char *name,
+                      ssize_t (*fun)(const char *, const char *,
+                              void *, size_t))
+{
+       int ret;
+
+        ret = fun (name, XATTR_NAME_NFSV4_ACL, NULL, 0);
+        if (ret < 0 && errno == ENODATA)
+              ret = 0;
+        else if (ret > 0) {
+             char *xattr = malloc(ret);
+             if (!xattr) {
+               ret = -1;
+             } else {
+                ret = fun (name, XATTR_NAME_NFSV4_ACL, xattr, ret);
+               if (ret < 0) ret = -1;
+               else {
+                   u_int32_t num_aces = 
(u_int32_t)ntohl(*((u_int32_t*)(xattr))); /* Grab the number of aces in the acl 
*/
+                   ret = num_aces > 3;
+               }
+               free(xattr);
+            }
+        }
+
+       return ret;
+}
+
 int
 __acl_extended_file(const char *path_p,
                    ssize_t (*fun)(const char *, const char *,
@@ -37,8 +69,9 @@ __acl_extended_file(const char *path_p,
        int retval;
 
        retval = fun(path_p, ACL_EA_ACCESS, NULL, 0);
-       if (retval < 0 && errno != ENOATTR && errno != ENODATA)
-               return -1;
+       if (retval < 0 && errno != ENOATTR && errno != ENODATA){ /* we might be 
on NFS, so try to check NFSv4 ACLs too */
+               return __nfs4_acls_exists(path_p,fun);
+       }       
        if (retval > base_size)
                return 1;
        retval = fun(path_p, ACL_EA_DEFAULT, NULL, 0);
-- 
2.37.3