/* Copyright (C) 1993-2018 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 <errno.h>

#include <unistd.h>

#include <hurd.h>

#include <hurd/fd.h>

#include <string.h>

error_t

_hurd_fd_read (struct hurd_fd *fd, void *buf, size_t *nbytes, loff_t offset)

{

  error_t err;

  char *data;

  mach_msg_type_number_t nread;

  error_t readfd (io_t port)

    {

      return __io_read (port, &data, &nread, offset, *nbytes);

    }

  data = buf;

  nread = *nbytes;

  if (err = HURD_FD_PORT_USE (fd, _hurd_ctty_input (port, ctty, readfd)))

    return err;

  if (data != buf)

    {

      if (nread > *nbytes)	/* Sanity check for bogus server.  */

	{

	  __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread);

	  return EGRATUITOUS;

	}

      memcpy (buf, data, nread);

      __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread);

    }

  *nbytes = nread;

  return 0;

}