ldb: make ldb module programming less error prone

When a top level method in a module returns an error, it is supposed
to call ldb_module_done(). We ran across a case where this wasn't
done, and then found that in fact that are hundreds of similar cases
in our modules. It took Andrew and I a full day to work out that this
was the cause of a subtle segv in another part of the code.

To try to prevent this happening again, this patch changes
ldb_next_request() to catch the error by checking if a module
returning an error has called ldb_module_done(). If it hasn't then the
call is made on behalf of the module.

1 files changed, 3 insertions, 0 deletions

diff --git a/source4/lib/ldb/include/ldb_private.h b/source4/lib/ldb/include/ldb_private.h
index 3cda9a3e33..a70d9c704d 100644
--- a/source4/lib/ldb/include/ldb_private.h
+++ b/source4/lib/ldb/include/ldb_private.h
@@ -47,10 +47,13 @@ struct ldb_module_ops;
 
 struct ldb_backend_ops;
 
+#define LDB_HANDLE_FLAG_DONE_CALLED 1
+
 struct ldb_handle {
 	int status;
 	enum ldb_state state;
 	struct ldb_context *ldb;
+	unsigned flags;
 };
 
 /* basic module structure */