Markus Armbruster
d89bda9998
Rename LwpSigCaught to LwpPendingSig, and lwpCatchAwaitedSig() to lwpHandleAwaitedSig(). Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
175 lines
3.9 KiB
C
175 lines
3.9 KiB
C
/*
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* Empire - A multi-player, client/server Internet based war game.
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* Copyright (C) 1994-2020, Dave Pare, Jeff Bailey, Thomas Ruschak,
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* Ken Stevens, Steve McClure, Markus Armbruster
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*
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* Empire is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* ---
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*
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* See files README, COPYING and CREDITS in the root of the source
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* tree for related information and legal notices. It is expected
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* that future projects/authors will amend these files as needed.
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*
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* ---
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*
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* sig.c: Wait for signals
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*
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* Known contributors to this file:
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* Markus Armbruster, 2006-2020
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*/
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#include <config.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <signal.h>
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#include "lwp.h"
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#include "lwpint.h"
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/*
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* Awaited signal numbers, terminated with 0.
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*/
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static int *LwpAwaitedSig;
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/*
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* Pending awaited signals.
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* Access only with signals blocked!
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*/
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static volatile int *LwpPendingSig;
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/*
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* Is there anything in LwpPendingSig[]?
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*/
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static volatile sig_atomic_t LwpSigCheck;
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/* The thread waiting for signals in lwpSigWait() */
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static struct lwpProc *LwpSigWaiter;
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static void lwpHandleAwaitedSig(int);
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/*
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* Initialize waiting for signals in @sig[].
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* @sig[] contains signal numbers, terminated with 0. It must have
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* static storage duration.
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*/
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void
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lwpInitSigWait(int sig[])
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{
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struct sigaction act;
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int i;
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LwpAwaitedSig = sig;
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act.sa_flags = 0;
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act.sa_handler = lwpHandleAwaitedSig;
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sigemptyset(&act.sa_mask);
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for (i = 0; sig[i]; i++)
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sigaddset(&act.sa_mask, sig[i]);
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LwpPendingSig = calloc(i, sizeof(*LwpPendingSig));
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for (i = 0; sig[i]; i++)
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sigaction(sig[i], &act, NULL);
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}
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/*
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* Signal handler for awaited signals.
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* Set @LwpPendingSig[] for @sig, and set @LwpSigCheck.
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* Not reentrant; lwpInitSigWait() guards.
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*/
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static void
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lwpHandleAwaitedSig(int sig)
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{
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int i;
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for (i = 0; LwpAwaitedSig[i]; i++) {
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if (sig == LwpAwaitedSig[i])
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LwpPendingSig[i] = 1;
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}
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LwpSigCheck = 1;
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}
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/*
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* Test whether an awaited signal is pending.
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* If yes, remove that signal from the set of pending signals, and
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* return its number.
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* Else return 0.
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*/
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static int
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lwpGetSig(void)
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{
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int ret = 0;
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sigset_t set, save;
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int i;
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sigemptyset(&set);
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for (i = 0; LwpAwaitedSig[i]; i++)
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sigaddset(&set, LwpAwaitedSig[i]);
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sigprocmask(SIG_BLOCK, &set, &save);
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for (i = 0; LwpAwaitedSig[i]; i++) {
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if (LwpPendingSig[i]) {
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lwpStatus(LwpCurrent, "Got awaited signal %d", LwpPendingSig[i]);
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ret = LwpAwaitedSig[i];
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LwpPendingSig[i] = 0;
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}
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}
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for (; LwpAwaitedSig[i] && LwpPendingSig[i]; i++) ;
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if (!LwpPendingSig[i])
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LwpSigCheck = 0;
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sigprocmask(SIG_SETMASK, &save, NULL);
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return ret;
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}
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/*
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* Wait until one of the signals passed to lwpInitSigWait() arrives.
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* Assign its number to *@sig and return 0.
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* If another thread is already waiting for signals, return EBUSY
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* without waiting.
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*/
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int
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lwpSigWait(int *sig)
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{
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int res;
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if (LwpSigWaiter)
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return EBUSY;
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for (;;) {
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res = lwpGetSig();
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if (res > 0)
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break;
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lwpStatus(LwpCurrent, "Waiting for signals");
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LwpSigWaiter = LwpCurrent;
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lwpReschedule();
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}
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*sig = res;
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return 0;
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}
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/*
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* Wake up the thread awaiting signals if one arrived.
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* To be called from lwpReschedule().
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*/
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void
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lwpSigWakeup(void)
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{
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if (LwpSigWaiter && LwpSigCheck) {
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lwpReady(LwpSigWaiter);
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LwpSigWaiter = NULL;
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}
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}
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