sql: decode ARRAY and MAP types after SELECT

Before this patch MSGPACK received using SELECT statement through
net.box was unpacked. Fixed in this patch.

src/box/execute.c

@@ -351,13 +351,21 @@ sql_column_to_messagepack(struct sqlite3_stmt *stmt, int i,
 	}
 	case SQLITE_BLOB: {
 		uint32_t len = sqlite3_column_bytes(stmt, i);
-		size = mp_sizeof_bin(len);
-		char *pos = (char *) region_alloc(region, size);
-		if (pos == NULL)
-			goto oom;
-		const char *s;
-		s = (const char *)sqlite3_column_blob(stmt, i);
-		mp_encode_bin(pos, s, len);
+		const char *s =
+			(const char *)sqlite3_column_blob(stmt, i);
+		if (sql_column_subtype(stmt, i) == SQL_SUBTYPE_MSGPACK) {
+			size = len;
+			char *pos = (char *)region_alloc(region, size);
+			if (pos == NULL)
+				goto oom;
+			memcpy(pos, s, len);
+		} else {
+			size = mp_sizeof_bin(len);
+			char *pos = (char *)region_alloc(region, size);
+			if (pos == NULL)
+				goto oom;
+			mp_encode_bin(pos, s, len);
+		}
 		break;
 	}
 	case SQLITE_NULL: {

test/sql/iproto.result

@@ -811,6 +811,38 @@ cn:execute("PRAGMA TABLE_INFO(test);")
 box.sql.execute('DROP TABLE test')
 ---
 ...
+-- SELECT returns unpacked msgpack.
+format = {{name = 'id', type = 'integer'}, {name = 'x', type = 'any'}}
+---
+...
+s = box.schema.space.create('test', {format=format})
+---
+...
+i1 = s:create_index('i1', {parts = {1, 'int'}})
+---
+...
+s:insert({1, {1,2,3}})
+---
+- [1, [1, 2, 3]]
+...
+s:insert({2, {a = 3}})
+---
+- [2, {'a': 3}]
+...
+cn:execute('select * from "test"')
+---
+- metadata:
+  - name: id
+    type: UNKNOWN
+  - name: x
+    type: UNKNOWN
+  rows:
+  - [1, [1, 2, 3]]
+  - [2, {'a': 3}]
+...
+s:drop()
+---
+...
 cn:close()
 ---
 ...

test/sql/iproto.test.lua

@@ -263,6 +263,15 @@ box.sql.execute('CREATE TABLE test (id INT PRIMARY KEY)')
 cn:execute("PRAGMA TABLE_INFO(test);")
 box.sql.execute('DROP TABLE test')
 
+-- SELECT returns unpacked msgpack.
+format = {{name = 'id', type = 'integer'}, {name = 'x', type = 'any'}}
+s = box.schema.space.create('test', {format=format})
+i1 = s:create_index('i1', {parts = {1, 'int'}})
+s:insert({1, {1,2,3}})
+s:insert({2, {a = 3}})
+cn:execute('select * from "test"')
+s:drop()
+
 cn:close()
 
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')