/*
 * $Id: lock.c,v 1.4 2007/07/11 16:37:35 cparker Exp $
 *
 * Copyright (C) 1997 Lars Fenneberg
 *
 * See the file COPYRIGHT for the respective terms and conditions.
 * If the file is missing contact me at lf@elemental.net
 * and I'll send you a copy.
 *
 */

#include "config.h"
#include "includes.h"

#if defined(HAVE_FLOCK)

int do_lock_exclusive(FILE * fd)
{
  return flock(fileno(fd), LOCK_EX|LOCK_NB);
}

int do_unlock(FILE * fd)
{
  return flock(fileno(fd), LOCK_UN);
}

#elif defined(WIN32)

int do_lock_exclusive(FILE * fd)
{
  _lock_file(fd);
  return 1;
}

int do_unlock(FILE * fd)
{
  _unlock_file(fd);
  return 1;
}

#elif defined(HAVE_FCNTL)

int do_lock_exclusive(FILE * fd)
{
  flock_t fl;
  int res;

  memset((void *)&fl, 0, sizeof(fl));

  fl.l_type = F_WRLCK;
  fl.l_whence = fl.l_start = 0;
  fl.l_len = 0; /* 0 means "to end of file" */

  res = fcntl(fileno(fd), F_SETLK, &fl);

  if ((res == -1) && (errno == EAGAIN))
    errno = EWOULDBLOCK;

  return res;
}

int do_unlock(FILE * fd)
{
  flock_t fl;

  memset((void *)&fl, 0, sizeof(fl));

  fl.l_type = F_UNLCK;
  fl.l_whence = fl.l_start = 0;
  fl.l_len = 0; /* 0 means "to end of file" */

  return fcntl(fileno(fd), F_SETLK, &fl);
}

#else
#error YOU_LOSE "need either flock(2) or fcntl(2)"
#endif

