Use NSS_STATUS_TRYAGAIN to indicate insufficient buffer (BZ #16878)

The netgroups nss modules in the glibc tree use NSS_STATUS_UNAVAIL
(with errno as ERANGE) when the supplied buffer does not have
sufficient space for the result.  This is wrong, because the canonical
way to indicate insufficient buffer is to set the errno to ERANGE and
the status to NSS_STATUS_TRYAGAIN, as is used by all other modules.

This fixes nscd behaviour when the nss_ldap module returns
NSS_STATUS_TRYAGAIN to indicate that a netgroup entry is too long to
fit into the supplied buffer.

ChangeLog

@@ -1,3 +1,11 @@
+2014-05-26  Siddhesh Poyarekar  <siddhesh@redhat.com>
+
+	[BZ #16878]
+	* nscd/netgroupcache.c (addgetnetgrentX): Look for
+	NSS_STATUS_TRYAGAIN to indicate insufficient buffer space.
+	* nscd/nss_files/files-netgrp.c (_nss_netgroup_parseline): Use
+	NSS_STATUS_TRYAGAIN to indicate insufficient buffer space.
+
 2014-05-25  Richard Henderson  <rth@twiddle.net>
 
 	* sysdeps/unix/sysv/linux/aarch64/nptl/sysdep-cancel.h

NEWS

@@ -16,9 +16,9 @@ Version 2.20
   16670, 16674, 16677, 16680, 16683, 16689, 16695, 16701, 16706, 16707,
   16712, 16713, 16714, 16731, 16739, 16740, 16743, 16754, 16758, 16759,
   16760, 16770, 16786, 16789, 16791, 16799, 16800, 16815, 16823, 16824,
-  16831, 16838, 16849, 16854, 16876, 16877, 16885, 16888, 16890, 16912,
-  16915, 16916, 16917, 16922, 16927, 16928, 16932, 16943, 16958, 16966,
-  16967, 16965, 16977, 16978.
+  16831, 16838, 16849, 16854, 16876, 16877, 16878, 16885, 16888, 16890,
+  16912, 16915, 16916, 16917, 16922, 16927, 16928, 16932, 16943, 16958,
+  16966, 16967, 16965, 16977, 16978.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.

nscd/netgroupcache.c

@@ -197,11 +197,6 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 		    int e;
 		    status = getfct.f (&data, buffer + buffilled,
 				       buflen - buffilled - req->key_len, &e);
-		    if (status == NSS_STATUS_RETURN
-			|| status == NSS_STATUS_NOTFOUND)
-		      /* This was either the last one for this group or the
-			 group was empty.  Look at next group if available.  */
-		      break;
 		    if (status == NSS_STATUS_SUCCESS)
 		      {
 			if (data.type == triple_val)
@@ -320,11 +315,18 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 			      }
 			  }
 		      }
-		    else if (status == NSS_STATUS_UNAVAIL && e == ERANGE)
+		    else if (status == NSS_STATUS_TRYAGAIN && e == ERANGE)
 		      {
 			buflen *= 2;
 			buffer = xrealloc (buffer, buflen);
 		      }
+		    else if (status == NSS_STATUS_RETURN
+			     || status == NSS_STATUS_NOTFOUND
+			     || status == NSS_STATUS_UNAVAIL)
+		      /* This was either the last one for this group or the
+			 group was empty or the NSS module had an internal
+			 failure.  Look at next group if available.  */
+		      break;
 		  }
 
 	      enum nss_status (*endfct) (struct __netgrent *);

nss/nss_files/files-netgrp.c

@@ -252,7 +252,7 @@ _nss_netgroup_parseline (char **cursor, struct __netgrent *result,
   if (cp - host > buflen)
     {
       *errnop = ERANGE;
-      status = NSS_STATUS_UNAVAIL;
+      status = NSS_STATUS_TRYAGAIN;
     }
   else
     {