/*
 * Process id output.
 * Copyright (C) 1998, 1999 Kunihiro Ishiguro
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * GNU Zebra is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Zebra; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.  
 */

#include <zebra.h>
#include <fcntl.h>
#include <log.h>
#include "version.h"

#define PIDFILE_MASK 0644

int pidfile_acquire (const char *path)
{
  int fd;
  mode_t oldumask;

  fd = open (path, O_RDWR | O_CREAT, PIDFILE_MASK);
  if (fd < 0)
  {
    zlog_err ("Can't create pid lock file %s (%s), exiting",
	    path, safe_strerror (errno));
    exit (1);
  }
  umask (oldumask);

#ifdef HAVE_FCNTL
  {
    struct flock lock;
    memset (&lock, 0, sizeof (lock));
    lock.l_type = F_WRLCK;
    lock.l_whence = SEEK_SET;
    if (fcntl (fd, F_SETLK, &lock) < 0)
    {
      zlog_err ("Could not lock pid_file %s, exiting", path);
      exit (1);
    }
  }
#endif

  return fd;
}

void pidfile_fill (const int fd)
{
  int tmp;
  char buf[BUFSIZ];
  size_t pidsize;

  pidsize = snprintf (buf, BUFSIZ, "%u\n", getpid());
  if ((tmp = write (fd, buf, pidsize)) != (int)pidsize)
    zlog_err ("Could not write pid %u to FD %d, rc was %d: %s",
      getpid(), fd, tmp, safe_strerror(errno));
  else if (ftruncate(fd, pidsize) < 0)
    zlog_err ("Could not truncate FD %d to %u bytes: %s",
      fd, pidsize, safe_strerror (errno));
  /* Do not close the pidfile, let the lock remain. */
}

pid_t pid_output (const char *path)
{
  pidfile_fill (pidfile_acquire (path));
  /* There is little sense in returning the PID (especially when no other
   * function really uses returned value), but to keep function spec
   * unchanged let's just do it.
   */
  return getpid();
}