glibc/misc/daemon.c

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)daemon.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <unistd.h>
#include <sys/stat.h>

#include <device-nrs.h>
#include <not-cancel.h>

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)
    (void) __chdir ("/");

  if (!noclose)
    {
      struct __stat64_t64 st;

      fd = __open_nocancel (_PATH_DEVNULL, O_RDWR, 0);
      if (fd != -1 && __glibc_likely (__fstat64_time64 (fd, &st) == 0))
        {
          if (__builtin_expect (S_ISCHR (st.st_mode), 1) != 0
#if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
              && (st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR))
#endif
             )
            {
              (void) __dup2 (fd, STDIN_FILENO);
              (void) __dup2 (fd, STDOUT_FILENO);
              (void) __dup2 (fd, STDERR_FILENO);
              if (fd > 2)
                (void) __close (fd);
            }
          else
            {
              /* We must set an errno value since no function call
                 actually failed.  */
              __close_nocancel_nostatus (fd);
              __set_errno (ENODEV);
              return -1;
            }
        }
      else
        {
          __close_nocancel_nostatus (fd);
          return -1;
        }
    }

  return 0;
}