/* sendfile -- copy data directly from one file descriptor to another

   Copyright (C) 2002-2018 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/sendfile.h>

#include <hurd.h>

#include <hurd/fd.h>

#include <sys/mman.h>

/* Send COUNT bytes from file associated with IN_FD starting at OFFSET to

   descriptor OUT_FD.  */

ssize_t

__sendfile64 (int out_fd, int in_fd, off64_t *offset, size_t count)

{

  /* We just do a vanilla io_read followed by a vanilla io_write here.

     In theory the IN_FD filesystem can return us out-of-line data that

     we then send out-of-line to the OUT_FD filesystem and no copying

     takes place until those pages need to be flushed or packaged by

     that filesystem (e.g. packetized by a network socket).  However,

     we momentarily consume COUNT bytes of our local address space,

     which might blow if it's huge or address space is real tight.  */

  char *data = 0;

  size_t datalen = 0;

  error_t err = HURD_DPORT_USE (in_fd,

				__io_read (port, &data, &datalen,

					   offset ? *offset : (off_t) -1,

					   count));

  if (err == 0)

    {

      size_t nwrote;

      if (datalen == 0)

	return 0;

      err = HURD_DPORT_USE (out_fd, __io_write (port, data, datalen,

						(off_t) -1, &nwrote));

      __munmap (data, datalen);

      if (err == 0)

	{

	  if (offset)

	    *offset += datalen;

	  return nwrote;

	}

    }

  return __hurd_fail (err);

}

strong_alias (__sendfile64, sendfile64)