triple.c

/*
 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
 *      The President and Fellows of Harvard College.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY 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 UNIVERSITY 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.
 */

/*
 * triple.c
 *
 *      Runs three copies of some subprogram.
 */

#include <stdio.h>
#include <unistd.h>
#include <err.h>
#include "triple.h"

static
pid_t
spawnv(const char *prog, char **argv)
{
        pid_t pid = fork();
        switch (pid) {
            case -1:
                err(1, "fork");
            case 0:
                /* child */
                execv(prog, argv);
                err(1, "%s: execv", prog);
            default:
                /* parent */
                break;
        }
        return pid;
}

static
int
dowait(int index, int pid)
{
        int status;

        if (waitpid(pid, &status, 0)<0) {
                warn("waitpid for copy #%d (pid %d)", index, pid);
                return 1;
        }
        else if (WIFSIGNALED(status)) {
                warnx("copy #%d (pid %d): signal %d", index, pid,
                      WTERMSIG(status));
                return 1;
        }
        else if (WEXITSTATUS(status) != 0) {
                warnx("copy #%d (pid %d): exit %d", index, pid,
                      WEXITSTATUS(status));
                return 1;
        }
        return 0;
}

void
triple(const char *prog)
{
        pid_t pids[3];
        int i, failures = 0;
        char *args[2];

        /* set up the argv */
        args[0]=(char *)prog;
        args[1]=NULL;

        warnx("Starting: running three copies of %s...", prog);

        for (i=0; i<3; i++) {
                pids[i]=spawnv(args[0], args);
        }

        for (i=0; i<3; i++) {
                failures += dowait(i, pids[i]);
        }

        if (failures > 0) {
                warnx("%d failures", failures);
        }
        else {
                warnx("Congratulations! You passed.");
        }
}