[PATCH v2 1/1] lua: wrong 'tomap' work with nullable fields

[imeevma@tarantool.org]

Tuple method 'tomap' in some cases worked improperly if tuple
length less than it should be according to space format. Fixed
in this patch.

Closes #3631
---
Branch: https://github.com/tarantool/tarantool/tree/imeevma/gh-3631-wrong-tomap-work-with-nullable-fields
Issue: https://github.com/tarantool/tarantool/issues/3631

 src/box/lua/tuple.c        |  4 +--
 test/engine/tuple.result   | 63 ++++++++++++++++++++++++++++++++++++++++++++++
 test/engine/tuple.test.lua | 23 +++++++++++++++++
 3 files changed, 88 insertions(+), 2 deletions(-)

diff --git a/src/box/lua/tuple.c b/src/box/lua/tuple.c
index 7ca4299..5acbecb 100644
--- a/src/box/lua/tuple.c
+++ b/src/box/lua/tuple.c
@@ -284,12 +284,12 @@ lbox_tuple_to_map(struct lua_State *L)
 		luaL_error(L, "Usage: tuple:tomap()");
 	const struct tuple *tuple = lua_checktuple(L, 1);
 	const struct tuple_format *format = tuple_format(tuple);
-	const struct tuple_field *field = &format->fields[0];
 	const char *pos = tuple_data(tuple);
 	int field_count = (int)mp_decode_array(&pos);
 	int n_named = format->dict->name_count;
 	lua_createtable(L, field_count, n_named);
-	for (int i = 0; i < n_named; ++i, ++field) {
+	int named_and_presented = MIN(field_count, n_named);
+	for (int i = 0; i < named_and_presented; ++i) {
 		/* Access by name. */
 		const char *name = format->dict->names[i];
 		lua_pushstring(L, name);
diff --git a/test/engine/tuple.result b/test/engine/tuple.result
index b3b23b2..88bb3b4 100644
--- a/test/engine/tuple.result
+++ b/test/engine/tuple.result
@@ -590,6 +590,69 @@ maplen(t1map), t1map[1], t1map[2], t1map[3]
 s:drop()
 ---
 ...
+--
+-- gh-3631: Wrong 'tomap' work with nullable fields
+--
+format = {}
+---
+...
+format[1] = {'first', 'unsigned'}
+---
+...
+format[2] = {'second', 'unsigned'}
+---
+...
+format[3] = {'third', 'unsigned'}
+---
+...
+format[4] = {'fourth', 'string', is_nullable = true}
+---
+...
+s = box.schema.space.create('test', {format = format, engine = engine})
+---
+...
+pk = s:create_index('primary', {parts = {1, 'unsigned'}})
+---
+...
+s:insert({1, 2, 3})
+---
+- [1, 2, 3]
+...
+tuple = s:get(1)
+---
+...
+tuple
+---
+- [1, 2, 3]
+...
+-- Should be NULL
+tuple.fourth
+---
+- null
+...
+-- Should have only three named fields
+tuple:tomap()
+---
+- 1: 1
+  2: 2
+  3: 3
+  third: 3
+  second: 2
+  first: 1
+...
+-- Should be NULL
+tuple:tomap().fourth
+---
+- null
+...
+-- Should be nil
+type(tuple:tomap().fourth)
+---
+- nil
+...
+s:drop()
+---
+...
 engine = nil
 ---
 ...
diff --git a/test/engine/tuple.test.lua b/test/engine/tuple.test.lua
index 6d7d254..723dde4 100644
--- a/test/engine/tuple.test.lua
+++ b/test/engine/tuple.test.lua
@@ -200,5 +200,28 @@ t1map = t1:tomap()
 maplen(t1map), t1map[1], t1map[2], t1map[3]
 s:drop()
 
+--
+-- gh-3631: Wrong 'tomap' work with nullable fields
+--
+format = {}
+format[1] = {'first', 'unsigned'}
+format[2] = {'second', 'unsigned'}
+format[3] = {'third', 'unsigned'}
+format[4] = {'fourth', 'string', is_nullable = true}
+s = box.schema.space.create('test', {format = format, engine = engine})
+pk = s:create_index('primary', {parts = {1, 'unsigned'}})
+s:insert({1, 2, 3})
+tuple = s:get(1)
+tuple
+-- Should be NULL
+tuple.fourth
+-- Should have only three named fields
+tuple:tomap()
+-- Should be NULL
+tuple:tomap().fourth
+-- Should be nil
+type(tuple:tomap().fourth)
+s:drop()
+
 engine = nil
 test_run = nil
-- 
2.7.4