2589. [bug] dns_db_unregister() failed to clear '*dbimp'.

[RT #19626]

CHANGES

@@ -1,6 +1,9 @@
 2613.	[bug]		Option argument validation was missing for
 			dnssec-dsfromkey. [RT #19828]
 
+2589.	[bug]		dns_db_unregister() failed to clear '*dbimp'.
+		        [RT #19626]
+
 2581.	[contrib]	dlz/mysql set MYSQL_OPT_RECONNECT option on connection.
 			Requires MySQL 5.0.19 or later. [RT #19084]
 

lib/dns/db.c

@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: db.c,v 1.88 2008/09/24 02:46:22 marka Exp $ */
+/* $Id: db.c,v 1.88.50.1 2009/06/22 03:53:05 marka Exp $ */
 
 /*! \file */
 
@@ -854,12 +854,14 @@ dns_db_unregister(dns_dbimplementation_t **dbimp) {
 	RUNTIME_CHECK(isc_once_do(&once, initialize) == ISC_R_SUCCESS);
 
 	imp = *dbimp;
+	*dbimp = NULL;
 	RWLOCK(&implock, isc_rwlocktype_write);
 	ISC_LIST_UNLINK(implementations, imp, link);
 	mctx = imp->mctx;
 	isc_mem_put(mctx, imp, sizeof(dns_dbimplementation_t));
 	isc_mem_detach(&mctx);
 	RWUNLOCK(&implock, isc_rwlocktype_write);
+	ENSURE(*dbimp == NULL);
 }
 
 isc_result_t