From: Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: Sergey Kaplun <skaplun@tarantool.org>, Sergey Bronnikov <estetus@gmail.com> Cc: tarantool-patches@dev.tarantool.org, max.kokryashkin@gmail.com Subject: Re: [Tarantool-patches] [PATCH luajit][v2] LJ_GC64: Fix lua_concat(). Date: Tue, 10 Oct 2023 15:33:45 +0300 [thread overview] Message-ID: <a511a8ab-e816-4f63-bac6-2f493fa4fc6b@tarantool.org> (raw) In-Reply-To: <ZSQJ_ZQreDsbmKAe@root> Hi, Sergey On 09.10.2023 17:11, Sergey Kaplun wrote: > Hi, Sergey! > Thanks for the patch! > LGTM, after fixing a few nits mentioned below. > > On 06.10.23, Sergey Bronnikov wrote: >> From: Sergey Bronnikov <sergeyb@tarantool.org> >> >> Reported by Mathias Westerdahl. >> >> (cherry picked from commit 633f265f67f322cbe2c5fd11d3e46d968ac220f7) >> >> Lua 5.1 Reference Manual [1] defines a function `lua_concat`, that: >> >>> void lua_concat (lua_State *L, int n); >>> >>> Concatenates the n values at the top of the stack, pops them, and leaves >>> the result at the top. >> Without the patch `lua_concat()` behaved incorrectly with userdata with > Typo: s/patch/patch,/ Fixed. > >> defined `__concat` metamethod. The problem is GC64-specific. > Typo: s/defined/the defined/ Fixed. > >> Assuming we have three literals and a userdata with defined "__concat" > Typo: s/defined/the defined/ Fixed. > >> metamethod on top of the Lua stack: >> >> 1 [string] >> 2 [string] >> 3 [string] >> 4 [string] >> 5 [userdata] <--- top >> >> On attempt to concatenate *two* items on top of the Lua stack, >> `lua_concat()` concatenates *four* items and leaves result on the top: > Typo: s/result/the result/ > Typo: s/the top/top of the Lua stack/ > or s/on the top/at the top of the Lua stack/ Fixed. > >> 1 [string] >> 2 [string][string][string][userdata] <--- top >> >> The problem is in incorrect calculation of `n` counter in the loop in > Typo: s/in incorrect/in the incorrect/ Fixed. > >> implementation of function `lua_concat`. Without the fix `n` is equal to > Typo: s/in implementation/in the implementation/ > Typo: s/fix/fix,/ Fixed. > >> 3 at the end of the first iteration and therefore it goes to the next > Typo: s/ and/, and/ Fixed. > >> iteration of concatenation. In the fixed implementation of >> `lua_concat()` `n` is equal to 1 at the end of the first loop iteration, > Typo: s/`lua_concat()`/`lua_concat()`,/ Fixed. > >> decremented in a loop postcondition and breaks the loop. > Typo: s/ and/, and/ Fixed. > Minor: Also, we can mention that for details, the reader can see > `lj_meta_cat()` implementation in <src/lj_meta.c>. > Feel free to ignore. Added. >> The patch fixes incorrect behaviour. >> >> 1. https://www.lua.org/manual/5.1/manual.html >> >> Sergey Bronnikov: >> * added the description and the test for the problem >> >> Part of tarantool/tarantool#8825 > I suppose this should be #9145. Done. > >> --- >> PR: https://github.com/tarantool/tarantool/pull/9176 >> Branch: https://github.com/tarantool/luajit/commits/ligurio/lj-881-fix-concat >> Issues: >> - https://github.com/LuaJIT/LuaJIT/issues/881 >> - https://github.com/tarantool/tarantool/issues/8825 > <snipped> > >> diff --git a/test/tarantool-c-tests/lj-881-fix-lua-concat.test.c b/test/tarantool-c-tests/lj-881-fix-lua-concat.test.c >> new file mode 100644 >> index 00000000..1b1f146f >> --- /dev/null >> +++ b/test/tarantool-c-tests/lj-881-fix-lua-concat.test.c >> @@ -0,0 +1,95 @@ >> +#include <string.h> >> + >> +#include "lua.h" >> +#include "lauxlib.h" >> + >> +#include "test.h" >> +#include "utils.h" >> + >> +/* >> + * This test demonstrates LuaJIT's incorrect behaviour, when > Typo: s/,// Fixed. > >> + * calling `lua_concat()` with userdata with __concat metamethod. > Typo: s/__concat/the __concat/ Fixed. > >> + * See https://github.com/LuaJIT/LuaJIT/issues/881 for details. >> + */ >> + >> +#define MT_NAME "int" >> + >> +static int INFO_concat(lua_State *L) >> +{ >> + const char *s = luaL_checkstring(L, 1); >> + int *n = (int *)luaL_checkudata(L, 2, MT_NAME); >> + /* Do non-default concatenation. */ >> + lua_pushfstring(L, "%s + %d", s, *n); >> + return 1; >> +} >> + >> +static const luaL_Reg mt[] = >> +{ > Minor: I suppose this line may be joined with the previous one, as far > as this is not a function's body. Joined. > >> + {"__concat", INFO_concat}, > Typo: s/, /, / Fixed. > >> + {NULL, NULL} >> +}; >> + >> +static int lua_concat_testcase(void *test_state) >> +{ > <snipped> > >> + >> + int *n = (int *)lua_newuserdata(L, sizeof(int)); > I suggest to use `sizeof(*n)` here to avoid type duplication. Fixed. > >> + *n = 100; > I suppose we can use something like the following: > > | #define TEST_VALUE 100 > | #define STR(s) #s > | #define XSTR(s) STR(s) > | #define TEST_VALUE_STR XSTR(TEST_VALUE) > > or just use #TEST_VALUE in the `expected_str[]` declaration. > This helps to avoid the duplication of the magic number `100`. Updated: #define TYPE_NAME "int" +#define TEST_VALUE 100 +#define TOSTR(s) #s +#define CONCAT(A, B) A TOSTR(B) + static int __concat(lua_State *L) { const char *s = luaL_checkstring(L, 1); @@ -73,7 +76,7 @@ static int lua_concat_testcase(void *test_state) const char *str = lua_tostring(L, -1); assert_int_equal(lua_gettop(L), top - 2 + 1); - const char expected_str[] = "A + 100"; + const char expected_str[] = CONCAT("A + ", TEST_VALUE); assert_str_equal(str, expected_str, strlen(expected_str)); /* Teardown. */ > >> + > <snipped> > >> + const char expected_str[] = "A + 100"; >> + assert_str_equal(str, expected_str, strlen(expected_str)); > <snipped> > >> -- >> 2.34.1 >>
next prev parent reply other threads:[~2023-10-10 12:33 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-10-06 14:15 Sergey Bronnikov via Tarantool-patches 2023-10-08 14:58 ` Maxim Kokryashkin via Tarantool-patches 2023-10-09 14:11 ` Sergey Kaplun via Tarantool-patches 2023-10-10 12:33 ` Sergey Bronnikov via Tarantool-patches [this message] 2023-10-31 16:00 ` Igor Munkin via Tarantool-patches 2023-10-31 18:14 ` Sergey Bronnikov via Tarantool-patches 2023-10-31 19:22 ` Igor Munkin via Tarantool-patches
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