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

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