diplodocus.org Git - nmh/blob - sbr/push.c

   1
   2 /*
   3  * push.c -- push a fork into the background
   4  *
   5  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   6  * COPYRIGHT file in the root directory of the nmh distribution for
   7  * complete copyright information.
   8  */
   9
  10 #include <h/mh.h>
  11 #include <h/signals.h>
  12
  13
  14 void
  15 push(void)
  16 {
  17     pid_t pid;
  18     int i;
  19
  20     for (i = 0; (pid = fork()) == -1 && i < 5; i++)
  21         sleep (5);
  22
  23     switch (pid) {
  24         case -1:
  25             /* fork error */
  26             advise (NULL, "unable to fork, so can't push...");
  27             break;
  28
  29         case 0:
  30             /* child, block a few signals and continue */
  31             SIGNAL (SIGHUP, SIG_IGN);
  32             SIGNAL (SIGINT, SIG_IGN);
  33             SIGNAL (SIGQUIT, SIG_IGN);
  34             SIGNAL (SIGTERM, SIG_IGN);
  35 #ifdef SIGTSTP
  36             SIGNAL (SIGTSTP, SIG_IGN);
  37             SIGNAL (SIGTTIN, SIG_IGN);
  38             SIGNAL (SIGTTOU, SIG_IGN);
  39 #endif
  40
  41             unregister_for_removal(0);
  42
  43             if (freopen ("/dev/null", "r", stdin) == NULL) {
  44                 advise ("stdin", "freopen");
  45             }
  46             if (freopen ("/dev/null", "w", stdout) == NULL) {
  47                 advise ("stdout", "freopen");
  48             }
  49             break;
  50
  51         default:
  52             /* parent, just exit */
  53             done (0);
  54     }
  55 }
  56