source: trunk/minix/commands/simple/intr.c@ 15

/*      intr 1.4 - run a command with interrupts enabled
 *                                                      Author: Kees J. Bot
 *                                                              17 Dec 1992
 */
#define nil 0
#ifndef _POSIX_SOURCE
#define _POSIX_SOURCE 1
#endif
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#if __minix
static char DEV_LOG[]= "/dev/log";
#else
static char DEV_LOG[]= "/dev/console";
#endif

static void say(const char *s)
{
        write(2, s, strlen(s));
}

static void fatal(const char *label)
{
        int err= errno;

        say("intr: ");
        say(label);
        say(": ");
        say(strerror(err));
        say("\n");
        exit(1);
}

static void usage(void)
{
        say("Usage: intr [-d] [-t seconds] command [arg ...]\n");
        exit(1);
}

int main(int argc, char **argv)
{
        int fd;
        unsigned n= 0;
        int daemonize= 0;
        int i;

        i= 1;
        while (i < argc && argv[i][0] == '-') {
                char *opt= argv[i++]+1, *end;
                unsigned long sec;

                if (opt[0] == '-' && opt[1] == 0) break;

                while (*opt != 0) switch (*opt++) {
                case 'd':
                        /* -d */
                        daemonize= 1;
                        break;
                case 't':
                        /* -t n: alarm in n seconds. */
                        if (*opt == 0) {
                                if (i == argc) usage();
                                opt= argv[i++];
                        }
                        sec= strtoul(opt, &end, 10);
                        if (end == opt || *end != 0 || (n= sec) != sec)
                                usage();
                        opt= "";
                        break;
                default:
                        usage();
                }
        }

        if ((argc - i) < 1) usage();

        /* Try to open the controlling tty. */
        if ((fd= open("/dev/tty", O_RDWR)) < 0) {
                if (errno != ENXIO) fatal("/dev/tty");
        }

        if (!daemonize) {
                /* Bring to the foreground.  If we already have a controlling
                 * tty then use it.  Otherwise try to allocate the console as
                 * controlling tty and begin a process group.
                 */
                if (fd < 0) {
                        if (setsid() < 0) fatal("setsid()");

                        fd= open("/dev/console", O_RDWR);
                }

                if (fd >= 0) {
                        if (fd != 0) {
                                dup2(fd, 0);
                                close(fd);
                        }
                        dup2(0, 1);
                        dup2(0, 2);
                }

                /* Set the usual signals back to the default. */
                signal(SIGHUP, SIG_DFL);
                signal(SIGINT, SIG_DFL);
                signal(SIGQUIT, SIG_DFL);
                signal(SIGTERM, SIG_DFL);
        } else {
                /* Send to the background.  Redirect input to /dev/null, and
                 * output to the log device.  Detach from the process group.
                 */
                if (fd >= 0) {
                        close(fd);

                        if (setsid() < 0) fatal("setsid()");
                }
                if ((fd= open("/dev/null", O_RDWR)) < 0) fatal("/dev/null");
                if (fd != 0) {
                        dup2(fd, 0);
                        close(fd);
                }
                if ((fd= open(DEV_LOG, O_WRONLY)) < 0) fatal(DEV_LOG);
                if (fd != 1) {
                        dup2(fd, 1);
                        close(fd);
                }
                dup2(1, 2);

                /* Move to the root directory. */
                (void) chdir("/");
        }

        /* Schedule the alarm.  (It is inherited over execve.) */
        if (n != 0) alarm(n);

        /* Call program. */
        execvp(argv[i], argv + i);

        /* Complain. */
        fatal(argv[i]);
        return 0;
}