349 lines
7.9 KiB
C
349 lines
7.9 KiB
C
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/*-
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* Copyright (c) 1999 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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* NASA Ames Research Center.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* Obtained from: $NetBSD: semtest.c,v 1.4 2002/07/20 08:36:25 grant Exp $
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* $FreeBSD$
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*/
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/*
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* Test the SVID-compatible Semaphore facility.
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*/
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#include <sys/param.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <sys/wait.h>
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#include <err.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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int main (int, char *[]);
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void print_semid_ds (struct semid_ds *, mode_t);
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void sigsys_handler (int);
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void sigchld_handler(int);
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void cleanup (void);
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void waiter (void);
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void usage (void);
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int sender_semid = -1;
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pid_t child_pid;
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int child_count;
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int signal_was_sigchld;
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key_t semkey;
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/*
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* This is the original semun union used by the sysvsem utility.
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* It is deliberately kept here under #if 0'ed condition for future
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* reference. PLEASE DO NOT REMOVE. The {SET,GET}ALL in FreeBSD
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* are signed values, so the default version in sys/sem.h suffices.
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*/
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#if 0
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds *buf; /* buffer for IPC_{STAT,SET} */
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u_short *array; /* array for GETALL & SETALL */
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};
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#endif
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int
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main(int argc, char *argv[])
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{
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struct sigaction sa;
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union semun sun;
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struct semid_ds s_ds;
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sigset_t sigmask;
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int i;
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if (argc != 2)
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usage();
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/*
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* Install a SIGSYS handler so that we can exit gracefully if
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* System V Semaphore support isn't in the kernel.
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*/
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sa.sa_handler = sigsys_handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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if (sigaction(SIGSYS, &sa, NULL) == -1)
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err(1, "sigaction SIGSYS");
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/*
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* Install and SIGCHLD handler to deal with all possible exit
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* conditions of the receiver.
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*/
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sa.sa_handler = sigchld_handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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if (sigaction(SIGCHLD, &sa, NULL) == -1)
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err(1, "sigaction SIGCHLD");
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semkey = ftok(argv[1], 4160);
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/*
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* Initialize child_pid to ourselves to that the cleanup function
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* works before we create the receiver.
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*/
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child_pid = getpid();
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/*
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* Make sure that when the sender exits, the message queue is
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* removed.
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*/
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if (atexit(cleanup) == -1)
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err(1, "atexit");
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if ((sender_semid = semget(semkey, 1, IPC_CREAT | 0640)) == -1)
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err(1, "semget");
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sun.buf = &s_ds;
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if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
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err(1, "semctl IPC_STAT");
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print_semid_ds(&s_ds, 0640);
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s_ds.sem_perm.mode = (s_ds.sem_perm.mode & ~0777) | 0600;
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sun.buf = &s_ds;
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if (semctl(sender_semid, 0, IPC_SET, sun) == -1)
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err(1, "semctl IPC_SET");
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memset(&s_ds, 0, sizeof(s_ds));
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sun.buf = &s_ds;
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if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
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err(1, "semctl IPC_STAT");
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if ((s_ds.sem_perm.mode & 0777) != 0600)
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err(1, "IPC_SET of mode didn't hold");
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print_semid_ds(&s_ds, 0600);
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for (child_count = 0; child_count < 5; child_count++) {
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switch ((child_pid = fork())) {
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case -1:
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err(1, "fork");
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/* NOTREACHED */
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case 0:
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waiter();
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break;
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default:
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break;
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}
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}
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/*
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* Wait for all of the waiters to be attempting to acquire the
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* semaphore.
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*/
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for (;;) {
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i = semctl(sender_semid, 0, GETNCNT);
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if (i == -1)
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err(1, "semctl GETNCNT");
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if (i == 5)
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break;
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}
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/*
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* Now set the thundering herd in motion by initializing the
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* semaphore to the value 1.
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*/
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sun.val = 1;
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if (semctl(sender_semid, 0, SETVAL, sun) == -1)
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err(1, "sender: semctl SETVAL to 1");
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/*
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* Suspend forever; when we get SIGCHLD, the handler will exit.
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*/
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sigemptyset(&sigmask);
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for (;;) {
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(void) sigsuspend(&sigmask);
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if (signal_was_sigchld)
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signal_was_sigchld = 0;
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else
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break;
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}
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/*
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* ...and any other signal is an unexpected error.
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*/
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errx(1, "sender: received unexpected signal");
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}
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void
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sigsys_handler(int signo)
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{
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errx(1, "System V Semaphore support is not present in the kernel");
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}
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void
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sigchld_handler(int signo)
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{
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union semun sun;
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struct semid_ds s_ds;
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int cstatus;
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/*
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* Reap the child; if it exited successfully, then we're on the
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* right track!
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*/
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if (wait(&cstatus) == -1)
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err(1, "wait");
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if (WIFEXITED(cstatus) == 0)
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errx(1, "receiver exited abnormally");
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if (WEXITSTATUS(cstatus) != 0)
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errx(1, "receiver exited with status %d",
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WEXITSTATUS(cstatus));
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/*
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* If we get here, the child has exited normally, and we should
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* decrement the child count. If the child_count reaches 0, we
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* should exit.
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*/
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sun.buf = &s_ds;
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if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
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err(1, "semctl IPC_STAT");
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print_semid_ds(&s_ds, 0600);
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if (--child_count != 0) {
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signal_was_sigchld = 1;
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return;
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}
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exit(0);
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}
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void
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cleanup()
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{
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/*
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* If we're the sender, and it exists, remove the message queue.
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*/
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if (child_pid != 0 && sender_semid != -1) {
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if (semctl(sender_semid, 0, IPC_RMID) == -1)
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warn("semctl IPC_RMID");
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}
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}
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void
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print_semid_ds(struct semid_ds *sp, mode_t mode)
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{
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uid_t uid = geteuid();
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gid_t gid = getegid();
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printf("PERM: uid %d, gid %d, cuid %d, cgid %d, mode 0%o\n",
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sp->sem_perm.uid, sp->sem_perm.gid,
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sp->sem_perm.cuid, sp->sem_perm.cgid,
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sp->sem_perm.mode & 0777);
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printf("nsems %u\n", sp->sem_nsems);
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printf("otime: %s", ctime(&sp->sem_otime));
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printf("ctime: %s", ctime(&sp->sem_ctime));
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/*
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* Sanity check a few things.
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*/
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if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
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errx(1, "uid mismatch");
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if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
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errx(1, "gid mismatch");
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if ((sp->sem_perm.mode & 0777) != mode)
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errx(1, "mode mismatch %o != %o",
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(sp->sem_perm.mode & 0777), mode);
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}
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void
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usage()
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{
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fprintf(stderr, "usage: %s keypath\n", getprogname());
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exit(1);
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}
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void
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waiter()
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{
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struct sembuf s;
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int semid;
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if ((semid = semget(semkey, 1, 0)) == -1)
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err(1, "waiter: semget");
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/*
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* Attempt to acquire the semaphore.
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*/
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s.sem_num = 0;
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s.sem_op = -1;
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s.sem_flg = SEM_UNDO;
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if (semop(semid, &s, 1) == -1)
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err(1, "waiter: semop -1");
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printf("WOO! GOT THE SEMAPHORE!\n");
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sleep(1);
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/*
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* Release the semaphore and exit.
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*/
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s.sem_num = 0;
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s.sem_op = 1;
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s.sem_flg = SEM_UNDO;
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if (semop(semid, &s, 1) == -1)
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err(1, "waiter: semop +1");
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exit(0);
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}
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