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/* sendfile -- copy data directly from one file descriptor to another
Copyright (C) 2002 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#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
sendfile (int out_fd, int in_fd, off_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);
}
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