cosmopolitan/libc/runtime/daemon.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/paths.h"
#include "libc/sysv/consts/o.h"

/**
 * Daemonizes process.
 */
int daemon(int nochdir, int noclose) {
  int fd;

  switch (fork()) {
    case -1:
      return (-1);
    case 0:
      break;
    default:
      _Exit(0);
  }

  if (setsid() == -1) {
    return -1;
  }

  if (!nochdir) {
    chdir("/");
  }

  if (!noclose && (fd = open(_PATH_DEVNULL, O_RDWR)) != -1) {
    dup2(fd, 0);
    dup2(fd, 1);
    dup2(fd, 2);
    if (fd > 2) {
      close(fd);
    }
  }

  return 0;
}