sys-utils/setsid.c

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