/*
* Empire - A multi-player, client/server Internet based war game.
* Copyright (C) 1994-2020, Dave Pare, Jeff Bailey, Thomas Ruschak,
* Ken Stevens, Steve McClure, Markus Armbruster
*
* Empire is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
* ---
*
* See files README, COPYING and CREDITS in the root of the source
* tree for related information and legal notices. It is expected
* that future projects/authors will amend these files as needed.
*
* ---
*
* sig.c: Wait for signals
*
* Known contributors to this file:
* Markus Armbruster, 2006-2020
*/
#include
#include
#include
#include
#include "lwp.h"
#include "lwpint.h"
/*
* Signals caught so far.
* Access only with signals blocked!
*/
static sigset_t LwpSigCaught;
/*
* LwpSigCaught changed since last
*/
static sig_atomic_t LwpSigCheck;
/* The thread waiting for signals in lwpSigWait() */
static struct lwpProc *LwpSigWaiter;
static void lwpCatchAwaitedSig(int);
/*
* Initialize waiting for signals in @set.
*/
void
lwpInitSigWait(sigset_t *set)
{
struct sigaction act;
int i;
sigemptyset(&LwpSigCaught);
act.sa_flags = 0;
act.sa_mask = *set;
sigemptyset(&act.sa_mask);
act.sa_handler = lwpCatchAwaitedSig;
for (i = 0; i < NSIG; i++) {
if (sigismember(set, i))
sigaction(i, &act, NULL);
}
}
static void
lwpCatchAwaitedSig(int sig)
{
sigaddset(&LwpSigCaught, sig);
LwpSigCheck = 1;
}
/*
* Test whether a signal from @set has been caught.
* If yes, delete that signal from the set of caught signals, and
* return its number.
* Else return 0.
*/
static int
lwpGetSig(sigset_t *set)
{
sigset_t save;
int i;
sigprocmask(SIG_BLOCK, set, &save);
for (i = NSIG - 1; i > 0; i--) {
if (sigismember(set, i) && sigismember(&LwpSigCaught, i)) {
lwpStatus(LwpCurrent, "Got awaited signal %d", i);
sigdelset(&LwpSigCaught, i);
break;
}
}
sigprocmask(SIG_SETMASK, &save, NULL);
return i;
}
/*
* Wait until a signal from @set arrives.
* Assign its number to *@sig and return 0.
* If another thread is already waiting for signals, return EBUSY
* without waiting.
*/
int
lwpSigWait(sigset_t *set, int *sig)
{
int res;
if (LwpSigWaiter)
return EBUSY;
for (;;) {
LwpSigCheck = 0;
res = lwpGetSig(set);
if (res > 0)
break;
lwpStatus(LwpCurrent, "Waiting for signals");
LwpSigWaiter = LwpCurrent;
lwpReschedule();
}
*sig = res;
return 0;
}
/*
* Wake up the thread awaiting signals if one arrived.
* To be called from lwpReschedule().
*/
void
lwpSigWakeup(void)
{
if (LwpSigWaiter && LwpSigCheck) {
lwpReady(LwpSigWaiter);
LwpSigWaiter = NULL;
}
}