/* Linux implementation of preadv2.

   Copyright (C) 2017-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <sys/uio.h>

#include <sysdep-cancel.h>

#ifndef __OFF_T_MATCHES_OFF64_T

# if !defined (__NR_preadv2) && defined (__NR_pread64v2)

#  define __NR_preadv2 __NR_pread64v2

# endif

ssize_t

preadv2 (int fd, const struct iovec *vector, int count, off_t offset,

	 int flags)

{

# ifdef __NR_preadv2

  ssize_t result = SYSCALL_CANCEL (preadv2, fd, vector, count,

				   LO_HI_LONG (offset), flags);

  if (result >= 0 || errno != ENOSYS)

    return result;

# endif

  /* Trying to emulate the preadv2 syscall flags is troublesome:

     * We can not temporary change the file state of the O_DSYNC and O_SYNC

       flags to emulate RWF_{D}SYNC (attempts to change the state of using

       fcntl are silently ignored).

     * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal

       semantic not provided by any other flag (O_NONBLOCK for instance).  */

  if (flags != 0)

    {

      __set_errno (ENOTSUP);

      return -1;

    }

  if (offset == -1)

    return __readv (fd, vector, count);

  else

    return preadv (fd, vector, count, offset);

}

#endif