From 0c9d67d8154069c76e04e838bb30114080481cd2 Mon Sep 17 00:00:00 2001
From: Nalin Dahyabhai <nalin@dahyabhai.net>
Date: Wed, 7 Aug 2013 10:26:32 -0400
Subject: Handle locking failures

Handle cases where we fail to acquire locks.
---
 src/back-sch.c | 101 ++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 64 insertions(+), 37 deletions(-)

diff --git a/src/back-sch.c b/src/back-sch.c
index 0b90ff6..a2ea291 100644
--- a/src/back-sch.c
+++ b/src/back-sch.c
@@ -1291,8 +1291,7 @@ backend_search_cb(Slapi_PBlock *pb)
 	} else {
 		slapi_log_error(SLAPI_LOG_PLUGIN,
 				cbdata.state->plugin_desc->spd_id,
-				"unable to acquire read lock, "
-				"ignoring search\n");
+				"unable to acquire read lock\n");
 	}
 	wrap_dec_call_level();
 #ifdef USE_NSSWITCH
@@ -1313,48 +1312,76 @@ backend_search_cb(Slapi_PBlock *pb)
 			}
 			staged = staged->next;
 		}
+		cbdata.nsswitch_buffer_len = 0;
+		free(cbdata.nsswitch_buffer);
 		/* Add the entries to the map cache */
 		wrap_inc_call_level();
-		map_wrlock();
-		staged = cbdata.staged;
-		while (staged != NULL) {
-			if (staged->entries != NULL) {
-				cbdata.cur_staged = staged;
-				/* We actually need to find the original set first */
-				map_data_foreach_domain(cbdata.state, backend_search_find_set_data_cb, &cbdata);
-				for (i = 0; i < staged->count ; i++) {
-					if (staged->entries[i] != NULL) {
-						if ((cbdata.cur_staged->set_data != NULL) &&
-						    !map_data_check_entry(cbdata.state,
-									  staged->map_group, staged->map_set,
-									  slapi_sdn_get_ndn(slapi_entry_get_sdn(staged->entries[i])))) {
-							backend_set_entry_from(cbdata.pb, backend_entry_source_nsswitch,
-									       staged->entries[i], staged->set_data);
+		if (map_wrlock() == 0) {
+			staged = cbdata.staged;
+			while (staged != NULL) {
+				if (staged->entries != NULL) {
+					cbdata.cur_staged = staged;
+					/* We actually need to find the original set first */
+					map_data_foreach_domain(cbdata.state, backend_search_find_set_data_cb, &cbdata);
+					for (i = 0; i < staged->count; i++) {
+						if (staged->entries[i] != NULL) {
+							if ((cbdata.cur_staged->set_data != NULL) &&
+							    !map_data_check_entry(cbdata.state,
+										  staged->map_group, staged->map_set,
+										  slapi_sdn_get_ndn(slapi_entry_get_sdn(staged->entries[i])))) {
+								backend_set_entry_from(cbdata.pb, backend_entry_source_nsswitch,
+										       staged->entries[i], staged->set_data);
+							}
+							slapi_entry_free(staged->entries[i]);
+							staged->entries[i] = NULL;
 						}
-						slapi_entry_free(staged->entries[i]);
-						staged->entries[i] = NULL;
 					}
+					free(staged->entries);
+					staged->count = 0;
+					staged->entries = NULL;
+				}
+				slapi_ch_free_string(&staged->map_group);
+				slapi_ch_free_string(&staged->map_set);
+				slapi_ch_free_string(&staged->name);
+				slapi_ch_free_string(&staged->container_sdn);
+				next = staged->next;
+				free(staged);
+				staged = next;
+			}
+			cbdata.staged = NULL;
+			map_unlock();
+		} else {
+			slapi_log_error(SLAPI_LOG_PLUGIN,
+					cbdata.state->plugin_desc->spd_id,
+					"unable to acquire write lock\n");
+			while (staged != NULL) {
+				for (i = 0;
+				     (i < staged->count) &&
+				     (staged->entries != NULL) &&
+				     (staged->entries[i] != NULL);
+				     i++) {
+					slapi_entry_free(staged->entries[i]);
+					staged->entries[i] = NULL;
 				}
-				free(staged->entries);
-				staged->count = 0;
-				staged->entries = NULL;
+				slapi_ch_free_string(&staged->map_group);
+				slapi_ch_free_string(&staged->map_set);
+				slapi_ch_free_string(&staged->name);
+				slapi_ch_free_string(&staged->container_sdn);
+				next = staged->next;
+				free(staged);
+				staged = next;
 			}
-			slapi_ch_free_string(&staged->map_group);
-			slapi_ch_free_string(&staged->map_set);
-			slapi_ch_free_string(&staged->name);
-			slapi_ch_free_string(&staged->container_sdn);
-			next = staged->next;
-			free(staged);
-			staged = next;
 		}
-		cbdata.staged = NULL;
-		map_unlock();
-		cbdata.nsswitch_buffer_len = 0;
-		free(cbdata.nsswitch_buffer);
 		/* Perform search again, this time to collect the data added by the NSSWITCH search */
-		map_rdlock();
-		map_data_foreach_domain(cbdata.state, backend_search_group_cb, &cbdata);
-		map_unlock();
+		if (map_rdlock() == 0) {
+			map_data_foreach_domain(cbdata.state, backend_search_group_cb, &cbdata);
+			map_unlock();
+		} else {
+			slapi_log_error(SLAPI_LOG_PLUGIN,
+					cbdata.state->plugin_desc->spd_id,
+					"unable to acquire read lock, "
+					"ignoring search\n");
+		}
 		wrap_dec_call_level();
 	}
 #endif
@@ -1691,8 +1718,8 @@ backend_bind_cb(Slapi_PBlock *pb)
 		slapi_ch_free_string(&group);
 		slapi_ch_free_string(&username);
 	} else {
-done_with_lock:
 		map_unlock();
+done_with_lock:
 		wrap_dec_call_level();
 		if (backend_check_scope_pb(pb)) {
 			slapi_send_ldap_result(pb, LDAP_INVALID_CREDENTIALS,
-- 
cgit