source: vendor/3.6.9/source3/script/tests/timelimit.c

/* run a command with a limited timeout
   tridge@samba.org, June 2005
   metze@samba.org, March 2006

   attempt to be as portable as possible (fighting posix all the way)
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>

static pid_t child_pid;

static void usage(void)
{
        printf("usage: timelimit <time> <command>\n");
        printf("   SIGUSR1 - passes SIGTERM to command's process group\n");
        printf("   SIGALRM - passes SIGTERM to command's process group\n");
        printf("             after 5s SIGKILL will be passed and exit(1)\n");
        printf("   SIGTERM - passes SIGTERM to command's process group\n");
        printf("             after 1s SIGKILL will be passed and exit(1)\n");
}

static void sig_alrm_kill(int sig)
{
        fprintf(stderr, "\nMaximum time expired in timelimit - killing\n");
        kill(-child_pid, SIGKILL);
        exit(1);
}

static void sig_alrm_term(int sig)
{
        kill(-child_pid, SIGTERM);
        alarm(5);
        signal(SIGALRM, sig_alrm_kill);
}

static void sig_term(int sig)
{
        kill(-child_pid, SIGTERM);
        alarm(1);
        signal(SIGALRM, sig_alrm_kill);
}

static void sig_usr1(int sig)
{
        kill(-child_pid, SIGTERM);
}

static void new_process_group(void)
{
        if (setpgid(0,0) == -1) {
                perror("setpgid");
                exit(1);
        }
}


int main(int argc, char *argv[])
{
        int maxtime, ret=1;

        if (argc < 3) {
                usage();
                exit(1);
        }

        maxtime = atoi(argv[1]);

        child_pid = fork();
        if (child_pid == 0) {
                new_process_group();
                execvp(argv[2], argv+2);
                perror(argv[2]);
                exit(1);
        }

        signal(SIGTERM, sig_term);
        signal(SIGINT,  sig_term);
        signal(SIGQUIT, sig_term);
        signal(SIGUSR1, sig_usr1);
        signal(SIGALRM, sig_alrm_term);
        alarm(maxtime);

        do {
                int status;
                pid_t pid = wait(&status);
                if (pid != -1) {
                        ret = WEXITSTATUS(status);
                } else if (errno == ECHILD) {
                        break;
                }
        } while (1);

        kill(-child_pid, SIGKILL);

        exit(ret);
}