Re: Breaking infinite loops / stopping code execution from C

[read.beyond.data@...]

At 16:28 20.08.2002 -0500, Kelmar wrote:

> lua_error() doesn't appear to call exit() to me; however, lua_error()
> can be easily replaced using lua_register().  You can define your
> own custom error handler this way.  This allows you to redirect the
> output to say, a window, instaead of stderr.

Thanks Kelmar, but this is not my problem after all. I already replaced 
error-msg output to a window in my gui application, but this has never been 
the problem ;)
If you take a look at the lua_error() implementation in the LUA source:

LUA_API void lua_error (lua_State *L, const char *s) {
  if (s) message(L, s);
  luaD_breakrun(L, LUA_ERRRUN);
}

void luaD_breakrun (lua_State *L, int errcode) {
  if (L->errorJmp) {
    L->errorJmp->status = errcode;
    longjmp(L->errorJmp->b, 1);
  }
  else {
    if (errcode != LUA_ERRMEM)
      message(L, "unable to recover; exiting\n");
    exit(EXIT_FAILURE);
  }
}

You'll see that it WILL call exit(EXIT_FAILURE), which is by the way also 
in the docs:

"If lua_error is called from a C function that has been called from Lua, 
then the corresponding Lua execution terminates, as if an error had 
occurred inside Lua code. Otherwise, the whole host program terminates with 
a call to exit(EXIT_FAILURE). "

Actually, my problem is, I'm using LUA to develop an application which is 
completely driven by user scripts. It's targeted for an audience with 
almost no knowledge in programming/scripting, so there definitely will be a 
lot of errors. I'm now in dire need for a way to STOP EXECUTION immediately 
if the user clicks a button on the gui. This should stop the whole script 
and reset LUA back to a fresh state, breaking out from infinite loops etc., 
but neither terminate nor corrupt the application in another way except for 
just stopping script execution. lua_error() WILL terminate the whole host 
programm, which is not acceptable. Setting up a timer / counter may work 
for infinite loops, but there are other situations when the script needs to 
be stopped. Imagine the common Ctrl-Break, which is exactly what I'd need....
I'm almost desperate as I can't seem to find a way on my own, development 
has stagnated since I stumpled upon this...hope anyone has an idea, I'd 
REALLY appreciate it....
Thanks, Celvin