Re: Patch for lua-5.2.0-beta-rc2

[François Perrad <francois.perrad@...>]

2011/6/24 Roberto Ierusalimschy <roberto@inf.puc-rio.br>:
>> a minor improvement/optimization of setpath().
>
>     /* replace ";;" by ";AUXMARK;" and then AUXMARK by default path */
>     path = luaL_gsub(L, path, LUA_PATH_SEP LUA_PATH_SEP,
>                               LUA_PATH_SEP AUXMARK LUA_PATH_SEP);
> +    lua_remove(L, -1);
>     luaL_gsub(L, path, AUXMARK, def);
> -    lua_remove(L, -2);
>   }
>
> This "improvement" seems to have a subtle bug. With the first remove,
> the string 'path' may not be anchored in Lua anymore. If the next gsub
> triggers some garbage-collection cycles, 'path' may be collected while
> still being used by gsub.

setpath is a static function called only by luaopen_package,
and the GC is stopped during the initialization of std libraries (in lua.c).
But an embedder could call luaL_openlibs without this precaution.

François

>
> -- Roberto
>
>