Re: [Tarantool-patches] [PATCH 2/5] info: use luaL_pushuuidstr() for box.info uuids

[Sergey Ostanevich via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi!

Thanks for the patch, just one comment below.

Sergos


> On 28 Jul 2021, at 00:24, Vladislav Shpilevoy <v.shpilevoy@tarantool.org> wrote:
> 
> box.info.uuid, box.info.cluster.uuid, and box.info.* replica UUIDs
> used tt_uuid_str() function. The function is not safe to use in
> preemptive context like Lua, where any attempt to push something
> onto the Lua stack might trigger GC, which in turn might invoke
> any other code.
> 
> It is not safe because uses the static buffer, which is global and
> cyclic. Newer allocations can override the old data without any
> warning.
> 
> Follow up #5632
> Follow up #6050
> Part of #6259
> ---
> src/box/lua/info.c                            |  8 ++--
> ...> gh-5632-6050-6259-gc-buf-reuse.test.lua} | 48 ++++++++++++++++---
> 2 files changed, 46 insertions(+), 10 deletions(-)
> rename test/app-tap/{gh-5632-6050-gc-buf-reuse.test.lua => gh-5632-6050-6259-gc-buf-reuse.test.lua} (79%)
> 
> diff --git a/src/box/lua/info.c b/src/box/lua/info.c
> index 1d8fe7938..d297ec6f6 100644
> --- a/src/box/lua/info.c
> +++ b/src/box/lua/info.c
> @@ -176,7 +176,7 @@ lbox_pushreplica(lua_State *L, struct replica *replica)
> 	lua_settable(L, -3);
> 
> 	lua_pushstring(L, "uuid");
> -	lua_pushstring(L, tt_uuid_str(&replica->uuid));
> +	luaL_pushuuidstr(L, &replica->uuid);
> 	lua_settable(L, -3);
> 
> 	lua_pushstring(L, "lsn");
> @@ -235,7 +235,7 @@ lbox_info_replication_anon_call(struct lua_State *L)
> 		if (!replica->anon)
> 			continue;
> 
> -		lua_pushstring(L, tt_uuid_str(&replica->uuid));
> +		luaL_pushuuidstr(L, &replica->uuid);
> 		lbox_pushreplica(L, replica);
> 
> 		lua_settable(L, -3);
> @@ -290,7 +290,7 @@ lbox_info_id(struct lua_State *L)
> static int
> lbox_info_uuid(struct lua_State *L)
> {
> -	lua_pushlstring(L, tt_uuid_str(&INSTANCE_UUID), UUID_STR_LEN);
> +	luaL_pushuuidstr(L, &INSTANCE_UUID);
> 	return 1;
> }
> 
> @@ -376,7 +376,7 @@ lbox_info_cluster(struct lua_State *L)
> {
> 	lua_createtable(L, 0, 2);
> 	lua_pushliteral(L, "uuid");
> -	lua_pushlstring(L, tt_uuid_str(&REPLICASET_UUID), UUID_STR_LEN);
> +	luaL_pushuuidstr(L, &REPLICASET_UUID);
> 	lua_settable(L, -3);
> 	return 1;
> }
> diff --git a/test/app-tap/gh-5632-6050-gc-buf-reuse.test.lua b/test/app-tap/gh-5632-6050-6259-gc-buf-reuse.test.lua
> similarity index 79%
> rename from test/app-tap/gh-5632-6050-gc-buf-reuse.test.lua
> rename to test/app-tap/gh-5632-6050-6259-gc-buf-reuse.test.lua
> index bf7590a14..f806ba6b7 100755
> --- a/	
> +++ b/test/app-tap/gh-5632-6050-6259-gc-buf-reuse.test.lua
> @@ -1,10 +1,10 @@
> #!/usr/bin/env tarantool
> 
> --
> --- gh-5632, gh-6050: Lua code should not use any global buffers or objects
> --- without proper ownership protection. Otherwise these items might be suddenly
> --- reused during Lua GC which happens almost at any moment. That might lead to
> --- data corruption.
> +-- gh-5632, gh-6050, gh-6259: Lua code should not use any global buffers or
> +-- objects without proper ownership protection. Otherwise these items might be
> +-- suddenly reused during Lua GC which happens almost at any moment. That might
> +-- lead to data corruption.
> --
> 
> local tap = require('tap')
> @@ -190,11 +190,47 @@ local function test_json(test)
>    test:ok(is_success, 'json in gc')
> end
> 
> -local test = tap.test('gh-5632-6050-gc-buf-reuse')
> -test:plan(4)
> +local function test_info_uuid(test)
> +    test:plan(1)
> +
> +    local gc_count = 100
> +    local iter_count = 1000
> +    local is_success = true
> +
> +    local function uuid_to_str()
> +        local uu = uuid.new()
> +        local str1 = box.info.uuid
> +        local str2 = box.info.cluster.uuid
> +        local str3 = box.info.uuid
> +        local str4 = box.info.cluster.uuid
> +        if str1 ~= str3 or str2 ~= str4 then
> +            is_success = false
> +            assert(false)

Why did you keep the assert? I believe there should be just a non-ok in test?

> +        end
> +    end
> +
> +    local function create_gc()
> +        for _ = 1, gc_count do
> +            ffi.gc(ffi.new('char[1]'), function() uuid_to_str() end)
> +        end
> +    end
> +
> +    for _ = 1, iter_count do
> +        create_gc()
> +        uuid_to_str()
> +    end
> +
> +    test:ok(is_success, 'info uuid in gc')
> +end
> +
> +box.cfg{}
> +
> +local test = tap.test('gh-5632-6050-6259-gc-buf-reuse')
> +test:plan(5)
> test:test('uuid in __gc', test_uuid)
> test:test('uri in __gc', test_uri)
> test:test('msgpackffi in __gc', test_msgpackffi)
> test:test('json in __gc', test_json)
> +test:test('info uuid in __gc', test_info_uuid)
> 
> os.exit(test:check() and 0 or 1)
> -- 
> 2.24.3 (Apple Git-128)
>