[Tarantool-patches] [PATCH v3 2/2] iproto: add an empty body to the unprepare response

[Chris Sosnin]

Absence of the body in the unprepare response forces users to perform
additional checks to avoid errors. Adding an empty body fixes this problem.

Closes #4769
---
 src/box/iproto.cc                             | 19 +++---
 .../gh-4769-unprepare-response-body.result    | 62 +++++++++++++++++++
 .../gh-4769-unprepare-response-body.test.lua  | 30 +++++++++
 3 files changed, 103 insertions(+), 8 deletions(-)
 create mode 100644 test/box/gh-4769-unprepare-response-body.result
 create mode 100644 test/box/gh-4769-unprepare-response-body.test.lua

diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index f313af6ae..5a3fb5d0b 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -1780,21 +1780,24 @@ tx_process_sql(struct cmsg *m)
 	 * become out of date during yield.
 	 */
 	out = msg->connection->tx.p_obuf;
+	if (is_unprepare) {
+		if (iproto_reply_ok(out, msg->header.sync, schema_version) != 0)
+			goto error;
+		iproto_wpos_create(&msg->wpos, out);
+		return;
+	}
 	struct obuf_svp header_svp;
 	/* Prepare memory for the iproto header. */
 	if (iproto_prepare_header(out, &header_svp, IPROTO_HEADER_LEN) != 0) {
 		port_destroy(&port);
 		goto error;
 	}
-	/* Nothing to dump in case of UNPREPARE request. */
-	if (!is_unprepare) {
-		if (port_dump_msgpack(&port, out) != 0) {
-			port_destroy(&port);
-			obuf_rollback_to_svp(out, &header_svp);
-			goto error;
-		}
+	if (port_dump_msgpack(&port, out) != 0) {
 		port_destroy(&port);
+		obuf_rollback_to_svp(out, &header_svp);
+		goto error;
 	}
+	port_destroy(&port);
 	iproto_reply_sql(out, &header_svp, msg->header.sync, schema_version);
 	iproto_wpos_create(&msg->wpos, out);
 	return;
@@ -1871,7 +1874,7 @@ net_send_msg(struct cmsg *m)
 }
 
 /**
- * Complete sending an iproto error: 
+ * Complete sending an iproto error:
  * recycle the error object and flush output.
  */
 static void
diff --git a/test/box/gh-4769-unprepare-response-body.result b/test/box/gh-4769-unprepare-response-body.result
new file mode 100644
index 000000000..a5230fad1
--- /dev/null
+++ b/test/box/gh-4769-unprepare-response-body.result
@@ -0,0 +1,62 @@
+-- test-run result file version 2
+test_run = require('test_run').new()
+ | ---
+ | ...
+test_run:cmd("setopt delimiter ';'")
+ | ---
+ | - true
+ | ...
+
+net_box = require('net.box')
+msgpack = require('msgpack')
+urilib = require('uri')
+
+IPROTO_REQUEST_TYPE = 0x00
+IPROTO_PREPARE      = 13
+IPROTO_SQL_TEXT     = 0x40
+IPROTO_STMT_ID      = 0x43
+
+test_run:cmd("setopt delimiter ''");
+ | ---
+ | ...
+
+box.schema.user.grant('guest', 'read, write, execute', 'universe')
+ | ---
+ | ...
+uri = urilib.parse(box.cfg.listen)
+ | ---
+ | ...
+socket = net_box.establish_connection(uri.host, uri.service)
+ | ---
+ | ...
+
+header = { [IPROTO_REQUEST_TYPE] = IPROTO_PREPARE }
+ | ---
+ | ...
+body = { [IPROTO_SQL_TEXT] = 'SELECT 1' }
+ | ---
+ | ...
+response = iproto_request(socket, header, body)
+ | ---
+ | ...
+
+body = { [IPROTO_STMT_ID] = response['body'][IPROTO_STMT_ID] }
+ | ---
+ | ...
+-- Decoding of the response will fail if there's no body.
+response = iproto_request(socket, header, body)
+ | ---
+ | ...
+response.body
+ | ---
+ | - {}
+ | ...
+
+box.schema.user.revoke('guest', 'read, write, execute', 'universe')
+ | ---
+ | ...
+socket:close()
+ | ---
+ | - true
+ | ...
+
diff --git a/test/box/gh-4769-unprepare-response-body.test.lua b/test/box/gh-4769-unprepare-response-body.test.lua
new file mode 100644
index 000000000..70e41b3e5
--- /dev/null
+++ b/test/box/gh-4769-unprepare-response-body.test.lua
@@ -0,0 +1,30 @@
+test_run = require('test_run').new()
+test_run:cmd("setopt delimiter ';'")
+
+net_box = require('net.box')
+msgpack = require('msgpack')
+urilib = require('uri')
+
+IPROTO_REQUEST_TYPE = 0x00
+IPROTO_PREPARE      = 13
+IPROTO_SQL_TEXT     = 0x40
+IPROTO_STMT_ID      = 0x43
+
+test_run:cmd("setopt delimiter ''");
+
+box.schema.user.grant('guest', 'read, write, execute', 'universe')
+uri = urilib.parse(box.cfg.listen)
+socket = net_box.establish_connection(uri.host, uri.service)
+
+header = { [IPROTO_REQUEST_TYPE] = IPROTO_PREPARE }
+body = { [IPROTO_SQL_TEXT] = 'SELECT 1' }
+response = iproto_request(socket, header, body)
+
+body = { [IPROTO_STMT_ID] = response['body'][IPROTO_STMT_ID] }
+-- Decoding of the response will fail if there's no body.
+response = iproto_request(socket, header, body)
+response.body
+
+box.schema.user.revoke('guest', 'read, write, execute', 'universe')
+socket:close()
+
-- 
2.21.1 (Apple Git-122.3)