More configurability for secondary group lookup

Together with a previous patch which introduced the initgroups
entry in nsswitch.conf this patch allows more customization of
the lookups for initgroups/getgrouplist.  Nothing changes if
the groups entry in nsswitch.conf is used.  If the initgroups entry
is used instead the code now doesn't automatically continue looking
for more entries aftedr a successful lookup.  Instead the normal
rules are followed which do specify that by default no more
service is consulted.  This can be overwritten with
	[SUCCESS=continue]
appropriately placed in the line.

ChangeLog

@@ -1,3 +1,13 @@
+2011-05-10  Ulrich Drepper  <drepper@gmail.com>
+
+	[BZ #11257]
+	* grp/initgroups.c (internal_getgrouplist): When we found the service
+	list through the initgroups entry in nsswitch.conf do not always
+	continue on a successful lookup.  Don't always use the
+	__nss_group_data-ase value if it is set.
+	* nss/nsswitch.conf (initgroups): Change action for successful db
+	lookup to continue for compatibility.
+
 2011-05-09  Ulrich Drepper  <drepper@gmail.com>
 
 	[BZ #11532]

NEWS

@@ -1,4 +1,4 @@
-GNU C Library NEWS -- history of user-visible changes.  2011-5-9
+GNU C Library NEWS -- history of user-visible changes.  2011-5-10
 Copyright (C) 1992-2009, 2010, 2011 Free Software Foundation, Inc.
 See the end for copying conditions.
 
@@ -9,11 +9,11 @@ Version 2.14
 
 * The following bugs are resolved with this release:
 
-  11258, 11487, 11532, 11578, 11653, 11668, 11724, 11945, 11947, 12158,
-  12178, 12200, 12346, 12393, 12420, 12445, 12449, 12454, 12460, 12469,
-  12489, 12509, 12510, 12518, 12541, 12545, 12551, 12583, 12587, 12597,
-  12611, 12631, 12650, 12653, 12655, 12660, 12681, 12685, 12711, 12713,
-  12714, 12717, 12723, 12734, 12738
+  11257, 11258, 11487, 11532, 11578, 11653, 11668, 11724, 11945, 11947,
+  12158, 12178, 12200, 12346, 12393, 12420, 12445, 12449, 12454, 12460,
+  12469, 12489, 12509, 12510, 12518, 12541, 12545, 12551, 12583, 12587,
+  12597, 12611, 12631, 12650, 12653, 12655, 12660, 12681, 12685, 12711,
+  12713, 12714, 12717, 12723, 12734, 12738
 
 * The RPC implementation in libc is obsoleted.  Old programs keep working
   but new programs cannot be linked with the routines in libc anymore.

grp/initgroups.c

@@ -44,6 +44,8 @@ extern int __nss_group_lookup (service_user **nip, const char *name,
 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
 
 extern service_user *__nss_group_database attribute_hidden;
+static service_user *initgroups_database;
+static bool use_initgroups_entry;
 
 
 #include "compat-initgroups.c"
@@ -69,32 +71,41 @@ internal_getgrouplist (const char *user, gid_t group, long int *size,
     }
 #endif
 
-  service_user *nip = NULL;
-  initgroups_dyn_function fct;
   enum nss_status status = NSS_STATUS_UNAVAIL;
-  int no_more;
-  /* Start is one, because we have the first group as parameter.  */
-  long int start = 1;
+  int no_more = 0;
 
   /* Never store more than the starting *SIZE number of elements.  */
   assert (*size > 0);
   (*groupsp)[0] = group;
+  /* Start is one, because we have the first group as parameter.  */
+  long int start = 1;
 
-  if (__nss_group_database != NULL)
+  if (initgroups_database == NULL)
     {
-      no_more = 0;
-      nip = __nss_group_database;
+      no_more = __nss_database_lookup ("initgroups", NULL, "",
+				       &initgroups_database);
+      if (no_more == 0 && initgroups_database == NULL)
+	{
+	  if (__nss_group_database == NULL)
+	    no_more = __nss_database_lookup ("group", NULL, "compat files",
+					     &__nss_group_database);
+
+	  initgroups_database = __nss_group_database;
+	}
+      else if (initgroups_database != NULL)
+	{
+	  assert (no_more == 0);
+	  use_initgroups_entry = true;
+	}
     }
-  else
-    no_more = __nss_database_lookup ("initgroups", "group",
-				     "compat [NOTFOUND=return] files", &nip);
 
+  service_user *nip = initgroups_database;
   while (! no_more)
     {
       long int prev_start = start;
 
-      fct = __nss_lookup_function (nip, "initgroups_dyn");
-
+      initgroups_dyn_function fct = __nss_lookup_function (nip,
+							   "initgroups_dyn");
       if (fct == NULL)
 	status = compat_call (nip, user, group, &start, size, groupsp,
 			      limit, &errno);
@@ -121,7 +132,13 @@ internal_getgrouplist (const char *user, gid_t group, long int *size,
       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 	__libc_fatal ("illegal status in internal_getgrouplist");
 
-      if (status != NSS_STATUS_SUCCESS
+      /* For compatibility reason we will continue to look for more
+	 entries using the next service even though data has already
+	 been found if the nsswitch.conf file contained only a 'groups'
+	 line and no 'initgroups' line.  If the latter is available
+	 we always respect the status.  This means that the default
+	 for successful lookups is to return.  */
+      if ((use_initgroups_entry || status != NSS_STATUS_SUCCESS)
 	  && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 	 break;
 

nss/nsswitch.conf

@@ -5,7 +5,7 @@
 
 passwd:		db files
 group:		db files
-initgroups:	db files
+initgroups:	db [SUCCESS=continue] files
 shadow:		db files
 gshadow:	files