flock.c

/*
 * Copyright (c) 1995, 1996, 1997 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * 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.
 *
 * 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
 */

#include <config.h>

#ifndef HAVE_FLOCK

#include "roken.h"

#define OP_MASK (LOCK_SH | LOCK_EX | LOCK_UN)


ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
rk_flock(int fd, int operation)
{
#if defined(HAVE_FCNTL) && defined(F_SETLK)
  struct flock arg;
  int code, cmd;

  arg.l_whence = SEEK_SET;
  arg.l_start = 0;
  arg.l_len = 0;		/* means to EOF */

  if (operation & LOCK_NB)
    cmd = F_SETLK;
  else
    cmd = F_SETLKW;		/* Blocking */

  switch (operation & OP_MASK) {
  case LOCK_UN:
    arg.l_type = F_UNLCK;
    code = fcntl(fd, F_SETLK, &arg);
    break;
  case LOCK_SH:
    arg.l_type = F_RDLCK;
    code = fcntl(fd, cmd, &arg);
    break;
  case LOCK_EX:
    arg.l_type = F_WRLCK;
    code = fcntl(fd, cmd, &arg);
    break;
  default:
    errno = EINVAL;
    code = -1;
    break;
  }
  return code;

#elif defined(_WIN32)
  /* Windows */

#define FLOCK_OFFSET_LOW  0
#define FLOCK_OFFSET_HIGH 0
#define FLOCK_LENGTH_LOW  0x00000000
#define FLOCK_LENGTH_HIGH 0x80000000

  HANDLE hFile;
  OVERLAPPED ov;
  BOOL rv = FALSE;
  DWORD f = 0;

  hFile = (HANDLE) _get_osfhandle(fd);
  if (hFile == NULL || hFile == INVALID_HANDLE_VALUE) {
      _set_errno(EBADF);
      return -1;
  }

  ZeroMemory(&ov, sizeof(ov));
  ov.hEvent = NULL;
  ov.Offset = FLOCK_OFFSET_LOW;
  ov.OffsetHigh = FLOCK_OFFSET_HIGH;

  if (operation & LOCK_NB)
      f = LOCKFILE_FAIL_IMMEDIATELY;

  switch (operation & OP_MASK) {
  case LOCK_UN:			/* Unlock */
      rv = UnlockFileEx(hFile, 0,
			FLOCK_LENGTH_LOW, FLOCK_LENGTH_HIGH, &ov);
      break;

  case LOCK_SH:			/* Shared lock */
      rv = LockFileEx(hFile, f, 0,
		      FLOCK_LENGTH_LOW, FLOCK_LENGTH_HIGH, &ov);
      break;

  case LOCK_EX:			/* Exclusive lock */
      rv = LockFileEx(hFile, f|LOCKFILE_EXCLUSIVE_LOCK, 0,
		      FLOCK_LENGTH_LOW, FLOCK_LENGTH_HIGH,
		      &ov);
      break;

  default:
      _set_errno(EINVAL);
      return -1;
  }

  if (!rv) {
      switch (GetLastError()) {
      case ERROR_SHARING_VIOLATION:
      case ERROR_LOCK_VIOLATION:
      case ERROR_IO_PENDING:
	  _set_errno(EWOULDBLOCK);
	  break;

      case ERROR_ACCESS_DENIED:
	  _set_errno(EACCES);
	  break;

      default:
	  _set_errno(ENOLCK);
      }
      return -1;
  }

  return 0;

#else
  return -1;
#endif
}

#endif