Markus Armbruster
aae823507c
sigismember() fails when passed an invalid or unsupported signal number. lwpInitSigWait() and lwpGetSig() treat sigismember() failure like "is a member". lwpInitSigWait() will then sigaction() unsuccessfully. Harmless. lwpGetSig() returns the bad signal number when it's greater than any caught signal's number. The bad signal number then gets returned to main(), which shuts down the server. Fix by treating failure like "is not a member". Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
145 lines
3.2 KiB
C
145 lines
3.2 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 <signal.h>
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#include "lwp.h"
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#include "lwpint.h"
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/*
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* Signals caught so far.
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* Access only with signals blocked!
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*/
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static sigset_t LwpSigCaught;
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/*
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* LwpSigCaught changed since last
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*/
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static 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 lwpCatchAwaitedSig(int);
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/*
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* Initialize waiting for signals in @set.
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*/
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void
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lwpInitSigWait(sigset_t *set)
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{
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struct sigaction act;
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int i;
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sigemptyset(&LwpSigCaught);
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act.sa_flags = 0;
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act.sa_mask = *set;
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act.sa_handler = lwpCatchAwaitedSig;
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for (i = 0; i < NSIG; i++) {
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if (sigismember(set, i) > 0)
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sigaction(i, &act, NULL);
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}
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}
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static void
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lwpCatchAwaitedSig(int sig)
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{
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sigaddset(&LwpSigCaught, sig);
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LwpSigCheck = 1;
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}
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/*
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* Test whether a signal from @set has been caught.
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* If yes, delete that signal from the set of caught 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(sigset_t *set)
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{
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sigset_t save;
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int i;
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sigprocmask(SIG_BLOCK, set, &save);
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for (i = NSIG - 1; i > 0; i--) {
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if (sigismember(set, i) > 0 && sigismember(&LwpSigCaught, i) > 0) {
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lwpStatus(LwpCurrent, "Got awaited signal %d", i);
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sigdelset(&LwpSigCaught, i);
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break;
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}
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}
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sigprocmask(SIG_SETMASK, &save, NULL);
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return i;
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}
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/*
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* Wait until a signal from @set 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(sigset_t *set, 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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LwpSigCheck = 0;
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res = lwpGetSig(set);
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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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