[tarantool-patches] Re: [PATCH v1 1/1] box: fix empty tuple invalid update

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

 > A few lines above you allocate struct update_field, which
> is unused when field == end. Please, move this check before
> update->alloc().
You are right. Thank you.
====================================
The tuple:update() used to work incorrectly in case of empty
tuple produced with box.tuple.new{} because update_create_rope
unconditionally initialized a new rope with [tuple_data,
mp_next(tuple_data)] field that might not exists.

Closes #4041
---
 src/box/tuple_update.c  |  3 +++
 test/box/tuple.result   | 21 +++++++++++++++++++++
 test/box/tuple.test.lua | 10 ++++++++++
 3 files changed, 34 insertions(+)

diff --git a/src/box/tuple_update.c b/src/box/tuple_update.c
index 01c55fb1a..b879d50f9 100644
--- a/src/box/tuple_update.c
+++ b/src/box/tuple_update.c
@@ -826,6 +826,9 @@ update_create_rope(struct tuple_update *update, const char *tuple_data,
 				region_alloc_free_stub, update->alloc_ctx);
 	if (update->rope == NULL)
 		return -1;
+	if (tuple_data == tuple_data_end)
+		return 0;
+
 	/* Initialize the rope with the old tuple. */
 
 	struct update_field *first = (struct update_field *)
diff --git a/test/box/tuple.result b/test/box/tuple.result
index 82ad8404d..2561ebc35 100644
--- a/test/box/tuple.result
+++ b/test/box/tuple.result
@@ -859,6 +859,27 @@ t
 t = nil
 ---
 ...
+--
+-- gh-4041: Invalid field on empty tuple update.
+--
+t = box.tuple.new{}
+---
+...
+t:update({{'=', 1, 1}})
+---
+- [1]
+...
+t:upsert({{'=', 1, 1}})
+---
+- [1]
+...
+t:update({{'+', 1, 1}})
+---
+- error: Field 1 was not found in the tuple
+...
+t = nil
+---
+...
 --------------------------------------------------------------------------------
 -- test msgpack.encode + tuple
 --------------------------------------------------------------------------------
diff --git a/test/box/tuple.test.lua b/test/box/tuple.test.lua
index 8030b0884..b0a4ab173 100644
--- a/test/box/tuple.test.lua
+++ b/test/box/tuple.test.lua
@@ -270,6 +270,16 @@ t = box.tuple.new(require('yaml').decode("[17711728, {1000: 'xxx'}]"))
 t:update({{'=', 2, t[2]}})
 t
 t = nil
+
+--
+-- gh-4041: Invalid field on empty tuple update.
+--
+t = box.tuple.new{}
+t:update({{'=', 1, 1}})
+t:upsert({{'=', 1, 1}})
+t:update({{'+', 1, 1}})
+t = nil
+
 --------------------------------------------------------------------------------
 -- test msgpack.encode + tuple
 --------------------------------------------------------------------------------
-- 
2.21.0