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- Subject: Re: Patch for lua-5.2.0-beta-rc2
- From: Patrick Donnelly <batrick@...>
- Date: Fri, 24 Jun 2011 13:55:29 -0400
On Fri, Jun 24, 2011 at 11:57 AM, François Perrad
> 2011/6/24 Roberto Ierusalimschy <email@example.com>:
>>> 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.
This isn't an improvement or an optimization. 'path' must exist on the
stack before calling luaL_gsub to be correct. Your patch is wrong.
- Patrick Donnelly