From b42302f52ada1db87a28905310818eb32d92e1f1 Mon Sep 17 00:00:00 2001
From: Vladimir Davydov <vdavydov@tarantool.org>
Date: Thu, 2 Feb 2023 15:21:56 +0300
Subject: [PATCH] lua-yaml: enable aliasing for objects returned by __serialize
The YAML serializer fails to detect aliases in objects returned by
the __serialize method:
tarantool> x = {}
---
...
tarantool> {a = x, b = x}
---
- a: &0 []
b: *0
...
tarantool> setmetatable({}, {
> __serialize = function() return {a = x, b = x} end,
> })
---
- a: []
b: []
...
Fix this by scanning the object returned by the __serialize method
(called by luaL_checkfield) for references.
Closes #8240
NO_DOC=bug fix
---
.../unreleased/gh-8240-yaml-alias-serialize-fix.md | 4 ++++
src/lua/serializer.c | 9 ++++++---
src/lua/serializer.h | 2 ++
.../gh_8240_yaml_alias_serialize_test.lua | 14 ++++++++++++++
third_party/lua-yaml/lyaml.cc | 4 ++++
5 files changed, 30 insertions(+), 3 deletions(-)
create mode 100644 changelogs/unreleased/gh-8240-yaml-alias-serialize-fix.md
diff --git a/changelogs/unreleased/gh-8240-yaml-alias-serialize-fix.md b/changelogs/unreleased/gh-8240-yaml-alias-serialize-fix.md
new file mode 100644
index 0000000000..dc99402e77
--- /dev/null
+++ b/changelogs/unreleased/gh-8240-yaml-alias-serialize-fix.md
@@ -0,0 +1,4 @@
+## bugfix/lua
+
+* Fixed alias detection in the YAML serializer in case the input contains
+ objects that implement the `__serialize` meta method (gh-8240).
diff --git a/src/lua/serializer.c b/src/lua/serializer.c
index c2e0229c74..231a973a3c 100644
--- a/src/lua/serializer.c
+++ b/src/lua/serializer.c
@@ -324,6 +324,7 @@ lua_field_try_serialize(struct lua_State *L, struct luaL_serializer *cfg,
if (luaL_tofield(L, cfg, -1, field) != 0)
return -1;
lua_replace(L, idx);
+ field->serialized = true;
return 0;
}
if (!lua_isstring(L, -1)) {
@@ -433,6 +434,11 @@ int
luaL_tofield(struct lua_State *L, struct luaL_serializer *cfg, int index,
struct luaL_field *field)
{
+ field->type = MP_NIL;
+ field->ext_type = MP_UNKNOWN_EXTENSION;
+ field->compact = false;
+ field->serialized = false;
+
if (index < 0)
index = lua_gettop(L) + index + 1;
@@ -568,10 +574,7 @@ luaL_tofield(struct lua_State *L, struct luaL_serializer *cfg, int index,
field->type = MP_STR;
return 0;
case LUA_TTABLE:
- {
- field->compact = false;
return lua_field_inspect_table(L, cfg, index, field);
- }
case LUA_TLIGHTUSERDATA:
case LUA_TUSERDATA:
field->sval.data = NULL;
diff --git a/src/lua/serializer.h b/src/lua/serializer.h
index aa143153a9..2e73aecc01 100644
--- a/src/lua/serializer.h
+++ b/src/lua/serializer.h
@@ -241,6 +241,8 @@ struct luaL_field {
/* subtypes of MP_EXT */
enum mp_extension_type ext_type;
bool compact; /* a flag used by YAML serializer */
+ /** Set if __serialize metamethod was called for this field. */
+ bool serialized;
};
/**
diff --git a/test/app-luatest/gh_8240_yaml_alias_serialize_test.lua b/test/app-luatest/gh_8240_yaml_alias_serialize_test.lua
index 274254e4b8..e08e4bf74a 100644
--- a/test/app-luatest/gh_8240_yaml_alias_serialize_test.lua
+++ b/test/app-luatest/gh_8240_yaml_alias_serialize_test.lua
@@ -27,3 +27,17 @@ g.test_objects_that_implement_serialize_are_aliased = function()
t.assert_is(nested2[1], nested2.a[1][1])
t.assert_is(nested2[1], nested2.a.b.c)
end
+
+g.test_objects_returned_by_serialize_are_aliased = function()
+ local o1 = {}
+ local o2 = serialize(setmetatable({}, {
+ __serialize = function() return {o1, {a = o1}} end,
+ }))
+ local o3 = serialize(setmetatable({}, {
+ __serialize = function() return {o2, o2} end
+ }))
+ t.assert_equals(o2, {o1, {a = o1}})
+ t.assert_is(o2[1], o2[2].a)
+ t.assert_equals(o3, {{o1, {a = o1}}, {o1, {a = o1}}})
+ t.assert_is(o3[1], o3[2])
+end
diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc
index 2a18730b0d..762d85bca5 100644
--- a/third_party/lua-yaml/lyaml.cc
+++ b/third_party/lua-yaml/lyaml.cc
@@ -616,6 +616,8 @@ static int yaml_is_flow_mode(struct lua_yaml_dumper *dumper) {
return 0;
}
+static void find_references(struct lua_yaml_dumper *dumper);
+
static int dump_node(struct lua_yaml_dumper *dumper)
{
size_t len = 0;
@@ -635,6 +637,8 @@ static int dump_node(struct lua_yaml_dumper *dumper)
int top = lua_gettop(dumper->L);
luaL_checkfield(dumper->L, dumper->cfg, top, &field);
+ if (field.serialized)
+ find_references(dumper);
switch(field.type) {
case MP_UINT:
snprintf(buf, sizeof(buf) - 1, "%" PRIu64, field.ival);
--
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