[PATCH] Return NULL for wildcard values in getnetgrent from nscd (BZ #16759)

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

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.

Tested on x86_64.

Siddhesh

	[BZ #16759]
	* inet/getnetgrent_r.c (get_nonempty_val): New function.
	(nscd_getnetgrent): Use it.

---
 inet/getnetgrent_r.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/inet/getnetgrent_r.c b/inet/getnetgrent_r.c
index 62cdfda..f6d064d 100644
--- a/inet/getnetgrent_r.c
+++ b/inet/getnetgrent_r.c
@@ -235,6 +235,14 @@ endnetgrent (void)
 }
 
 #ifdef USE_NSCD
+static const char *
+get_nonempty_val (const char *in)
+{
+  if (*in == '\0')
+    return NULL;
+  return in;
+}
+
 static enum nss_status
 nscd_getnetgrent (struct __netgrent *datap, char *buffer, size_t buflen,
 		  int *errnop)
@@ -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;
-- 
1.8.3.1

Attachment: pgprWls6_OL0K.pgp
Description: PGP signature