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Mon, 10 Feb 2020 16:08:25 +0300 (MSK)
Date: Mon, 10 Feb 2020 16:08:23 +0300
From: Nikita Pettik <korablev@tarantool.org>
Message-ID: <20200210130823.GF1110@tarantool.org>
References: <20200210075707.86953-1-arkholga@tarantool.org>
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In-Reply-To: <20200210075707.86953-1-arkholga@tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH] json: fix silent change of global
json settings
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To: Olga Arkhangelskaia <arkholga@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
On 10 Feb 10:57, Olga Arkhangelskaia wrote:
> When json.decode is used with 2 arguments, 2nd argument seeps out to global
> json settings. Morover,
Nit: Moreover.
> due to current serialier.cfg implementation it
-> serializer
> remains invisible while checking settings by json.cfg. To prevent sucj
-> such
> behaviour we stop writing to global serializer struct and use local one,
> to get one-time action.
> As was mention before json.cfg can not be trusted in this case, so to check that
> everything remained unchanged we call decode twice with and without 2nd
> argument.
>
> Closes #4761
Note that there's no 'Closes #4761' label on your actual branch.
I guess you simply forgot to push updated branch.
> ---
> + --
> + -- gh-4761 json.decode silently changes global settings of json when called
> + -- with 2d parameter
> + --
> + test:ok(pcall(serializer.decode,'{"1":{"b":{"c":1,"d":null}},"a":1}'))
>
> --
> -- gh-3514: fix parsing integers with exponent in json
> diff --git a/third_party/lua-cjson/lua_cjson.c b/third_party/lua-cjson/lua_cjson.c
> index 3d25814f3..f855cbd80 100644
> --- a/third_party/lua-cjson/lua_cjson.c
> +++ b/third_party/lua-cjson/lua_cjson.c
> @@ -1004,13 +1004,13 @@ static int json_decode(lua_State *l)
> luaL_argcheck(l, lua_gettop(l) == 2 || lua_gettop(l) == 1, 1,
> "expected 1 or 2 arguments");
>
> + struct luaL_serializer *cfg = luaL_checkserializer(l);
Nit: I'd add a brief comment here (to avoid any confusions concerning
copying object on the stack):
diff --git a/third_party/lua-cjson/lua_cjson.c b/third_party/lua-cjson/lua_cjson.c
index f855cbd80..c9c987c8c 100644
--- a/third_party/lua-cjson/lua_cjson.c
+++ b/third_party/lua-cjson/lua_cjson.c
@@ -1006,6 +1006,14 @@ static int json_decode(lua_State *l)
struct luaL_serializer *cfg = luaL_checkserializer(l);
struct luaL_serializer user_cfg = *cfg;
+ /*
+ * user_cfg is per-call local version of global cfg: it is
+ * used if user passes custom options to :decode() method
+ * as a separate arguments. In this case it is required
+ * to avoid modifying global parameters. Life span of
+ * user_cfg is restricted by the scope of :decode() so it
+ * is enough to allocate it on the stack.
+ */
json.cfg = cfg;
if (lua_gettop(l) == 2) {
> + struct luaL_serializer user_cfg = *cfg;
> + json.cfg = cfg;
What is more, you can avoid premature copying on the stack:
@@ -1005,9 +1005,10 @@ static int json_decode(lua_State *l)
"expected 1 or 2 arguments");
struct luaL_serializer *cfg = luaL_checkserializer(l);
- struct luaL_serializer user_cfg = *cfg;
+ struct luaL_serializer user_cfg;
json.cfg = cfg;
if (lua_gettop(l) == 2) {
+ user_cfg = *cfg;
luaL_serializer_parse_options(l, &user_cfg);
lua_pop(l, 1);
json.cfg = &user_cfg;
> if (lua_gettop(l) == 2) {
> - struct luaL_serializer *user_cfg = luaL_checkserializer(l);
> - luaL_serializer_parse_options(l, user_cfg);
> + luaL_serializer_parse_options(l, &user_cfg);