Re: Trapping Control-C in an interactive Lua program

[steve donovan <steve.j.donovan@...>]

On Mon, Apr 12, 2010 at 12:19 PM, steve donovan
<steve.j.donovan@gmail.com> wrote:
> Thanks, Jerome, that does seem to help.

The final solution is a little ... bizarre. Here is the function that
grabs user input:

		local stat,res = pcall(io.read)
		pcall(io.write,'')
		if not res then
			print 'ctrl-c caught'
			signal(2,1) -- SIGINT,SIG_IGN
			return ''
		end
		return res

This is compensating for the following SIGINT handler in lua.c:

static void lstop (lua_State *L, lua_Debug *ar) {
  (void)ar;  /* unused arg. */
  lua_sethook(L, NULL, 0, 0);
  luaL_error(L, "interrupted!");
}


static void laction (int i) {
  signal(i, SIG_DFL); /* if another SIGINT happens before lstop,
                              terminate process (default action) */
  lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}

So we catch 'interrupted!' in the protected io.write() call , and can
then switch off ctrl-C handling.

This is on Windows, don't know if the trickery is portable yet.

steve d.