commit dd3022d75e6fb8957843d6d84257a5d8457822d5
Author: Siddhesh Poyarekar <siddhesh@redhat.com>
Date:   Thu Mar 27 19:49:51 2014 +0530

    Return NULL for wildcard values in getnetgrent from nscd (BZ #16759)
    
    getnetgrent is supposed to return NULL for values that are wildcards
    in the (host, user, domain) triplet.  This works correctly with nscd
    disabled, but with it enabled, it returns a blank ("") instead of a
    NULL.  This is easily seen with the output of `getent netgroup foonet`
    for a netgroup foonet defined as follows in /etc/netgroup:
    
        foonet (,foo,)
    
    The output with nscd disabled is:
    
        foonet ( ,foo,)
    
    while with nscd enabled, it is:
    
        foonet (,foo,)
    
    The extra space with nscd disabled is due to the fact that `getent
    netgroup` adds it if the return value from getnetgrent is NULL for
    either host or user.

diff --git glibc-2.17-c758a686/inet/getnetgrent_r.c glibc-2.17-c758a686/inet/getnetgrent_r.c
index 62cdfda..f6d064d 100644
--- glibc-2.17-c758a686/inet/getnetgrent_r.c
+++ glibc-2.17-c758a686/inet/getnetgrent_r.c
@@ -235,6 +235,14 @@ endnetgrent (void)
   __libc_lock_unlock (lock);
 }
 
+static const char *
+get_nonempty_val (const char *in)
+{
+  if (*in == '\0')
+    return NULL;
+  return in;
+}
+
 #ifdef USE_NSCD
 static enum nss_status
 nscd_getnetgrent (struct __netgrent *datap, char *buffer, size_t buflen,
@@ -243,11 +251,11 @@ nscd_getnetgrent (struct __netgrent *datap, char *buffer, size_t buflen,
     return NSS_STATUS_UNAVAIL;
 
   datap->type = triple_val;
-  datap->val.triple.host = datap->cursor;
+  datap->val.triple.host = get_nonempty_val (datap->cursor);
   datap->cursor = (char *) __rawmemchr (datap->cursor, '\0') + 1;
-  datap->val.triple.user = datap->cursor;
+  datap->val.triple.user = get_nonempty_val (datap->cursor);
   datap->cursor = (char *) __rawmemchr (datap->cursor, '\0') + 1;
-  datap->val.triple.domain = datap->cursor;
+  datap->val.triple.domain = get_nonempty_val (datap->cursor);
   datap->cursor = (char *) __rawmemchr (datap->cursor, '\0') + 1;
 
   return NSS_STATUS_SUCCESS;