/*      $NetBSD: semtest.c,v 1.3 2001/02/19 22:44:41 cgd Exp $  */

/*-
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Test the SVID-compatible Semaphore facility.
 */

#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

int     main(int, char *[]);
void    print_semid_ds(struct semid_ds *, mode_t);
void    sigsys_handler(int);
void    sigchld_handler(int);
void    cleanup(void);
void    waiter(void);

int     sender_semid = -1;
pid_t   child_pid;
int     child_count;
volatile sig_atomic_t signal_was_sigchld;

key_t   semkey;

char keyname[] = "/tmp/msgtestXXXXXXXX";

int verbose;

union mysemun {
        int     val;            /* value for SETVAL */
        struct  semid_ds *buf;  /* buffer for IPC_{STAT,SET} */
        u_short *array;         /* array for GETALL & SETALL */
};

int
main(argc, argv)
        int argc;
        char *argv[];
{
        struct sigaction sa;
        union mysemun sun;
        struct semid_ds s_ds;
        sigset_t sigmask;
        int i;

        int fd, ch;

        if ((fd = mkstemp(keyname)) < 0)
                err(1, "mkstemp");

        close(fd);

        while ((ch = getopt(argc, argv, "v")) != -1) {
                switch (ch) {
                case 'v':
                        verbose = 1;
                        break;
                default:
                        fprintf(stderr, "Usage: semtest [-v]\n");
                        exit(1);
                }
        }

        /*
         * Install a SIGSYS handler so that we can exit gracefully if
         * System V Semaphore support isn't in the kernel.
         */
        sa.sa_handler = sigsys_handler;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;
        if (sigaction(SIGSYS, &sa, NULL) == -1)
                err(1, "sigaction SIGSYS");

        /*
         * Install and SIGCHLD handler to deal with all possible exit
         * conditions of the receiver.
         */
        sa.sa_handler = sigchld_handler;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;
        if (sigaction(SIGCHLD, &sa, NULL) == -1)
                err(1, "sigaction SIGCHLD");

        semkey = ftok(keyname, arc4random() & INT_MAX);

        /*
         * Initialize child_pid to ourselves to that the cleanup function
         * works before we create the receiver.
         */
        child_pid = getpid();

        /*
         * Make sure that when the sender exits, the message queue is
         * removed.
         */
        if (atexit(cleanup) == -1)
                err(1, "atexit");

        sender_semid = semget(semkey, 1, IPC_CREAT | IPC_EXCL | 0640);
        if (sender_semid == -1)
                err(1, "semget");

        
        sun.buf = &s_ds;
        if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
                err(1, "semctl IPC_STAT");

        if (verbose)
                print_semid_ds(&s_ds, 0640);

        s_ds.sem_perm.mode = (s_ds.sem_perm.mode & ~0777) | 0600;

        sun.buf = &s_ds;
        if (semctl(sender_semid, 0, IPC_SET, sun) == -1)
                err(1, "semctl IPC_SET");

        memset(&s_ds, 0, sizeof(s_ds));

        sun.buf = &s_ds;
        if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
                err(1, "semctl IPC_STAT");

        if ((s_ds.sem_perm.mode & 0777) != 0600)
                err(1, "IPC_SET of mode didn't hold");

        if (verbose)
                print_semid_ds(&s_ds, 0600);

        for (child_count = 0; child_count < 5; child_count++) {
                switch ((child_pid = fork())) {
                case -1:
                        err(1, "fork");
                        /* NOTREACHED */

                case 0:
                        waiter();
                        break;

                default:
                        break;
                }
        }

        /*
         * Wait for all of the waiters to be attempting to acquire the
         * semaphore.
         */
        for (;;) {
                i = semctl(sender_semid, 0, GETNCNT);
                if (i == -1)
                        err(1, "semctl GETNCNT");
                if (i == 5)
                        break;
        }

        /*
         * Now set the thundering herd in motion by initializing the
         * semaphore to the value 1.
         */
        sun.val = 1;
        if (semctl(sender_semid, 0, SETVAL, sun) == -1)
                err(1, "sender: semctl SETVAL to 1");

        /*
         * Suspend forever; when we get SIGCHLD, the handler will exit.
         */
        sigemptyset(&sigmask);
        for (;;) {
                (void) sigsuspend(&sigmask);
                if (signal_was_sigchld)
                        signal_was_sigchld = 0;
                else
                        break;
        }

        /*
         * ...and any other signal is an unexpected error.
         */
        errx(1, "sender: received unexpected signal");
}

void
sigsys_handler(signo)
        int signo;
{

        errx(1, "System V Semaphore support is not present in the kernel");
}

void
sigchld_handler(signo)
        int signo;
{
        union mysemun sun;
        struct semid_ds s_ds;
        int cstatus;

        /*
         * Reap the child; if it exited successfully, then we're on the
         * right track!
         */
        if (wait(&cstatus) == -1)
                err(1, "wait");

        if (WIFEXITED(cstatus) == 0)
                errx(1, "receiver exited abnormally");

        if (WEXITSTATUS(cstatus) != 0)
                errx(1, "receiver exited with status %d",
                    WEXITSTATUS(cstatus));

        /*
         * If we get here, the child has exited normally, and we should
         * decrement the child count.  If the child_count reaches 0, we
         * should exit.
         */

        sun.buf = &s_ds;
        if (semctl(sender_semid, 0, IPC_STAT, sun) == -1)
                err(1, "semctl IPC_STAT");

        if (verbose)
                print_semid_ds(&s_ds, 0600);

        if (--child_count != 0) {
                signal_was_sigchld = 1;
                return;
        }

        exit(0);
}

void
cleanup()
{

        /*
         * If we're the sender, and it exists, remove the message queue.
         */
        if (child_pid != 0 && sender_semid != -1) {
                if (semctl(sender_semid, 0, IPC_RMID) == -1)
                        warn("semctl IPC_RMID");
        }
        remove(keyname);
}

void
print_semid_ds(sp, mode)
        struct semid_ds *sp;
        mode_t mode;
{
        uid_t uid = geteuid();
        gid_t gid = getegid();

        printf("PERM: uid %u, gid %u, cuid %u, cgid %u, mode 0%o\n",
            sp->sem_perm.uid, sp->sem_perm.gid,
            sp->sem_perm.cuid, sp->sem_perm.cgid,
            sp->sem_perm.mode & 0777);

        printf("nsems %u\n", sp->sem_nsems);

        printf("otime: %s", ctime(&sp->sem_otime));
        printf("ctime: %s", ctime(&sp->sem_ctime));

        /*
         * Sanity check a few things.
         */

        if (sp->sem_perm.uid != uid || sp->sem_perm.cuid != uid)
                errx(1, "uid mismatch");

        if (sp->sem_perm.gid != gid || sp->sem_perm.cgid != gid)
                errx(1, "gid mismatch");

        if ((sp->sem_perm.mode & 0777) != mode)
                errx(1, "mode mismatch %o != %o",
                    (sp->sem_perm.mode & 0777), mode);
}

void
waiter()
{
        struct sembuf s;
        int semid;

        if ((semid = semget(semkey, 1, 0)) == -1)
                err(1, "waiter: semget");

        /*
         * Attempt to acquire the semaphore.
         */
        s.sem_num = 0;
        s.sem_op = -1;
        s.sem_flg = SEM_UNDO;

        if (semop(semid, &s, 1) == -1)
                err(1, "waiter: semop -1");

        if (verbose)
                printf("WOO!  GOT THE SEMAPHORE!\n");
        sleep(1);

        /*
         * Release the semaphore and exit.
         */
        s.sem_num = 0;
        s.sem_op = 1;
        s.sem_flg = SEM_UNDO;

        if (semop(semid, &s, 1) == -1)
                err(1, "waiter: semop +1");

        exit(0);
}