commands/simple/intr.c

   1 /*      intr 1.4 - run a command with interrupts enabled
   2  *                                                      Author: Kees J. Bot
   3  *                                                              17 Dec 1992
   4  */
   5 #define nil 0
   6 #ifndef _POSIX_SOURCE
   7 #define _POSIX_SOURCE 1
   8 #endif
   9 #include <sys/types.h>
  10 #include <errno.h>
  11 #include <fcntl.h>
  12 #include <signal.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17
  18 #if __minix
  19 static char DEV_LOG[]= "/dev/log";
  20 #else
  21 static char DEV_LOG[]= "/dev/console";
  22 #endif
  23
  24 static void say(const char *s)
  25 {
  26         write(2, s, strlen(s));
  27 }
  28
  29 static void fatal(const char *label)
  30 {
  31         int err= errno;
  32
  33         say("intr: ");
  34         say(label);
  35         say(": ");
  36         say(strerror(err));
  37         say("\n");
  38         exit(1);
  39 }
  40
  41 static void usage(void)
  42 {
  43         say("Usage: intr [-d] [-t seconds] command [arg ...]\n");
  44         exit(1);
  45 }
  46
  47 int main(int argc, char **argv)
  48 {
  49         int fd;
  50         unsigned n= 0;
  51         int daemonize= 0;
  52         int i;
  53
  54         i= 1;
  55         while (i < argc && argv[i][0] == '-') {
  56                 char *opt= argv[i++]+1, *end;
  57                 unsigned long sec;
  58
  59                 if (opt[0] == '-' && opt[1] == 0) break;
  60
  61                 while (*opt != 0) switch (*opt++) {
  62                 case 'd':
  63                         /* -d */
  64                         daemonize= 1;
  65                         break;
  66                 case 't':
  67                         /* -t n: alarm in n seconds. */
  68                         if (*opt == 0) {
  69                                 if (i == argc) usage();
  70                                 opt= argv[i++];
  71                         }
  72                         sec= strtoul(opt, &end, 10);
  73                         if (end == opt || *end != 0 || (n= sec) != sec)
  74                                 usage();
  75                         opt= "";
  76                         break;
  77                 default:
  78                         usage();
  79                 }
  80         }
  81
  82         if ((argc - i) < 1) usage();
  83
  84         /* Try to open the controlling tty. */
  85         if ((fd= open("/dev/tty", O_RDWR)) < 0) {
  86                 if (errno != ENXIO) fatal("/dev/tty");
  87         }
  88
  89         if (!daemonize) {
  90                 /* Bring to the foreground.  If we already have a controlling
  91                  * tty then use it.  Otherwise try to allocate the console as
  92                  * controlling tty and begin a process group.
  93                  */
  94                 if (fd < 0) {
  95                         if (setsid() < 0) fatal("setsid()");
  96
  97                         fd= open("/dev/console", O_RDWR);
  98                 }
  99
 100                 if (fd >= 0) {
 101                         if (fd != 0) {
 102                                 dup2(fd, 0);
 103                                 close(fd);
 104                         }
 105                         dup2(0, 1);
 106                         dup2(0, 2);
 107                 }
 108
 109                 /* Set the usual signals back to the default. */
 110                 signal(SIGHUP, SIG_DFL);
 111                 signal(SIGINT, SIG_DFL);
 112                 signal(SIGQUIT, SIG_DFL);
 113                 signal(SIGTERM, SIG_DFL);
 114         } else {
 115                 /* Send to the background.  Redirect input to /dev/null, and
 116                  * output to the log device.  Detach from the process group.
 117                  */
 118                 if (fd >= 0) {
 119                         close(fd);
 120
 121                         if (setsid() < 0) fatal("setsid()");
 122                 }
 123                 if ((fd= open("/dev/null", O_RDWR)) < 0) fatal("/dev/null");
 124                 if (fd != 0) {
 125                         dup2(fd, 0);
 126                         close(fd);
 127                 }
 128                 if ((fd= open(DEV_LOG, O_WRONLY)) < 0) fatal(DEV_LOG);
 129                 if (fd != 1) {
 130                         dup2(fd, 1);
 131                         close(fd);
 132                 }
 133                 dup2(1, 2);
 134
 135                 /* Move to the root directory. */
 136                 (void) chdir("/");
 137         }
 138
 139         /* Schedule the alarm.  (It is inherited over execve.) */
 140         if (n != 0) alarm(n);
 141
 142         /* Call program. */
 143         execvp(argv[i], argv + i);
 144
 145         /* Complain. */
 146         fatal(argv[i]);
 147         return 0;
 148 }