s3:registry: wrap reg_createkey() in a transaction

This is wrong layering (calling into regdb_transaction* in the reg_api code)
but fixes a potential race. It makes the multi-step create procedure atomic.

This should completely be done in the backend.

Signed-off-by: Andreas Schneider <asn@samba.org>

1 files changed, 30 insertions, 6 deletions

diff --git a/source3/registry/reg_api.c b/source3/registry/reg_api.c
index 3d051b3f2d..405a10591c 100644
--- a/source3/registry/reg_api.c
+++ b/source3/registry/reg_api.c
@@ -580,6 +580,13 @@ WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
 		goto done;
 	}
 
+	err = regdb_transaction_start();
+	if (!W_ERROR_IS_OK(err)) {
+		DEBUG(0, ("reg_createkey: failed to start transaction: %s\n",
+			  win_errstr(err)));
+		goto done;
+	}
+
 	while ((end = strchr(path, '\\')) != NULL) {
 		struct registry_key *tmp;
 		enum winreg_CreateAction action;
@@ -589,7 +596,7 @@ WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
 		err = reg_createkey(mem_ctx, key, path,
 				    KEY_ENUMERATE_SUB_KEYS, &tmp, &action);
 		if (!W_ERROR_IS_OK(err)) {
-			goto done;
+			goto trans_done;
 		}
 
 		if (key != parent) {
@@ -610,14 +617,14 @@ WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
 		if (paction != NULL) {
 			*paction = REG_OPENED_EXISTING_KEY;
 		}
-		goto done;
+		goto trans_done;
 	}
 
 	if (!W_ERROR_EQUAL(err, WERR_BADFILE)) {
 		/*
 		 * Something but "notfound" has happened, so bail out
 		 */
-		goto done;
+		goto trans_done;
 	}
 
 	/*
@@ -628,7 +635,7 @@ WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
 	err = reg_openkey(mem_ctx, key, "", KEY_CREATE_SUB_KEY,
 			  &create_parent);
 	if (!W_ERROR_IS_OK(err)) {
-		goto done;
+		goto trans_done;
 	}
 
 	/*
@@ -636,10 +643,14 @@ WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
 	 */
 
 	err = fill_subkey_cache(create_parent);
-	if (!W_ERROR_IS_OK(err)) goto done;
+	if (!W_ERROR_IS_OK(err)) {
+		goto trans_done;
+	}
 
 	err = create_reg_subkey(key->key, path);
-	W_ERROR_NOT_OK_GOTO_DONE(err);
+	if (!W_ERROR_IS_OK(err)) {
+		goto trans_done;
+	}
 
 	/*
 	 * Now open the newly created key
@@ -650,6 +661,19 @@ WERROR reg_createkey(TALLOC_CTX *ctx, struct registry_key *parent,
 		*paction = REG_CREATED_NEW_KEY;
 	}
 
+trans_done:
+	if (W_ERROR_IS_OK(err)) {
+		err = regdb_transaction_commit();
+		if (!W_ERROR_IS_OK(err)) {
+			DEBUG(0, ("reg_createkey: Error committing transaction: %s\n", win_errstr(err)));
+		}
+	} else {
+		WERROR err1 = regdb_transaction_cancel();
+		if (!W_ERROR_IS_OK(err1)) {
+			DEBUG(0, ("reg_createkey: Error cancelling transaction: %s\n", win_errstr(err1)));
+		}
+	}
+
  done:
 	TALLOC_FREE(mem_ctx);
 	return err;