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- Subject: RE: Proper Stack Cleaning
- From: "Incley, Mark" <mark.incley@...>
- Date: Mon, 13 Sep 2004 14:49:15 +0100
I wrote the following macros which I use in most functions that call Lua.
They've proved very useful and have caught quite a few stack "leaks" as well
as drawing my attention to the way that the lua_xxlibopen() functions leave
a value on the stack.
#define STACKCHECKSTART(ls) int __stackTopEnd_##ls = 0; int
__stackTopStart_##ls = lua_gettop(ls);
#define STACKCHECKEND(ls) STACKCHECKENDPLUS(ls, 0)
#define STACKCHECKENDPLUS(ls,a) assert((__stackTopEnd_##ls = lua_gettop(ls))
== __stackTopStart_##ls + a);
void egfunction(lua_State *ls)
<use the Lua API>
- or -
STACKCHECKENDPLUS(ls, 2) /* Should leave fn with 2 extra
values on Lua stack */
[mailto:firstname.lastname@example.org] On Behalf Of Matthew Harmon
Sent: 13 September 2004 14:29
To: 'Lua list'
Subject: Proper Stack Cleaning
I recently activated the runtime checks/tests and found that one of my bugs
was likely due to a stack overflow. I soon realized that there were some
operations I was performing that left values on the stack. For example,
loading libraries with lua_xxxlibopen(), etc. may push values onto the
stack, according to lua_gettop() anyway. In fact, by the time I got to do
any "real" work, the stack had 13 items on it.
In the examples and docs, I don't see mention of cleaning up the stack after
operations like these. Is it good practice to simply do a lua_settop(l, 0)
after a bunch of such operations?
Also, what is the proper procedure for enabling the runtime checks? I
manually included luauser_tests.h and added ltests.c to my project. That
seemed to work, but I'm not sure if that is the recommend method.