sys-utils/setsid.c

   1 /*
   2  * No copyright is claimed.  This code is in the public domain; do with
   3  * it what you wish.
   4  *
   5  * Written by Rick Sladkey <jrs@world.std.com>
   6  *
   7  * setsid.c -- execute a command in a new session
   8  *
   9  * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
  10  * - added Native Language Support
  11  *
  12  * 2001-01-18 John Fremlin <vii@penguinpowered.com>
  13  * - fork in case we are process group leader
  14  *
  15  * 2008-08-20 Daniel Kahn Gillmor <dkg@fifthhorseman.net>
  16  * - if forked, wait on child process and emit its return code.
  17  */
  18 #include <getopt.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <sys/ioctl.h>
  23 #include <sys/types.h>
  24 #include <sys/wait.h>
  25
  26 #include "c.h"
  27 #include "nls.h"
  28 #include "closestream.h"
  29
  30 static void __attribute__((__noreturn__)) usage(void)
  31 {
  32         FILE *out = stdout;
  33         fputs(USAGE_HEADER, out);
  34         fprintf(out, _(
  35                 " %s [options] <program> [arguments ...]\n"),
  36                 program_invocation_short_name);
  37
  38         fputs(USAGE_SEPARATOR, out);
  39         fputs(_("Run a program in a new session.\n"), out);
  40
  41         fputs(USAGE_OPTIONS, out);
  42         fputs(_(" -c, --ctty     set the controlling terminal to the current one\n"), out);
  43         fputs(_(" -f, --fork     always fork\n"), out);
  44         fputs(_(" -w, --wait     wait program to exit, and use the same return\n"), out);
  45
  46         fprintf(out, USAGE_HELP_OPTIONS(16));
  47
  48         fprintf(out, USAGE_MAN_TAIL("setsid(1)"));
  49         exit(EXIT_SUCCESS);
  50 }
  51
  52 int main(int argc, char **argv)
  53 {
  54         int ch, forcefork = 0;
  55         int ctty = 0;
  56         pid_t pid;
  57         int status = 0;
  58
  59         static const struct option longopts[] = {
  60                 {"ctty", no_argument, NULL, 'c'},
  61                 {"fork", no_argument, NULL, 'f'},
  62                 {"wait", no_argument, NULL, 'w'},
  63                 {"version", no_argument, NULL, 'V'},
  64                 {"help", no_argument, NULL, 'h'},
  65                 {NULL, 0, NULL, 0}
  66         };
  67
  68         setlocale(LC_ALL, "");
  69         bindtextdomain(PACKAGE, LOCALEDIR);
  70         textdomain(PACKAGE);
  71         close_stdout_atexit();
  72
  73         while ((ch = getopt_long(argc, argv, "+Vhcfw", longopts, NULL)) != -1)
  74                 switch (ch) {
  75                 case 'c':
  76                         ctty=1;
  77                         break;
  78                 case 'f':
  79                         forcefork = 1;
  80                         break;
  81                 case 'w':
  82                         status = 1;
  83                         break;
  84
  85                 case 'h':
  86                         usage();
  87                 case 'V':
  88                         print_version(EXIT_SUCCESS);
  89                 default:
  90                         errtryhelp(EXIT_FAILURE);
  91                 }
  92
  93         if (argc - optind < 1) {
  94                 warnx(_("no command specified"));
  95                 errtryhelp(EXIT_FAILURE);
  96         }
  97
  98         if (forcefork || getpgrp() == getpid()) {
  99                 pid = fork();
 100                 switch (pid) {
 101                 case -1:
 102                         err(EXIT_FAILURE, _("fork"));
 103                 case 0:
 104                         /* child */
 105                         break;
 106                 default:
 107                         /* parent */
 108                         if (!status)
 109                                 return EXIT_SUCCESS;
 110                         if (wait(&status) != pid)
 111                                 err(EXIT_FAILURE, "wait");
 112                         if (WIFEXITED(status))
 113                                 return WEXITSTATUS(status);
 114                         err(status, _("child %d did not exit normally"), pid);
 115                 }
 116         }
 117         if (setsid() < 0)
 118                 /* cannot happen */
 119                 err(EXIT_FAILURE, _("setsid failed"));
 120
 121         if (ctty && ioctl(STDIN_FILENO, TIOCSCTTY, 1))
 122                 err(EXIT_FAILURE, _("failed to set the controlling terminal"));
 123         execvp(argv[optind], argv + optind);
 124         errexec(argv[optind]);
 125 }