sysdeps/mach/hurd/sendfile64.c

   1 /* sendfile -- copy data directly from one file descriptor to another
   2    Copyright (C) 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <sys/sendfile.h>
  21 #include <hurd.h>
  22 #include <hurd/fd.h>
  23 #include <sys/mman.h>
  24
  25 /* Send COUNT bytes from file associated with IN_FD starting at OFFSET to
  26    descriptor OUT_FD.  */
  27 ssize_t
  28 sendfile64 (int out_fd, int in_fd, off64_t *offset, size_t count)
  29 {
  30   /* We just do a vanilla io_read followed by a vanilla io_write here.
  31      In theory the IN_FD filesystem can return us out-of-line data that
  32      we then send out-of-line to the OUT_FD filesystem and no copying
  33      takes place until those pages need to be flushed or packaged by
  34      that filesystem (e.g. packetized by a network socket).  However,
  35      we momentarily consume COUNT bytes of our local address space,
  36      which might blow if it's huge or address space is real tight.  */
  37
  38   char *data = 0;
  39   size_t datalen = 0;
  40   error_t err = HURD_DPORT_USE (in_fd,
  41                                 __io_read (port, &data, &datalen,
  42                                            offset ? *offset : (off_t) -1,
  43                                            count));
  44   if (err == 0)
  45     {
  46       size_t nwrote;
  47       if (datalen == 0)
  48         return 0;
  49       err = HURD_DPORT_USE (out_fd, __io_write (port, data, datalen,
  50                                                 (off_t) -1, &nwrote));
  51       munmap (data, datalen);
  52       if (err == 0)
  53         {
  54           if (offset)
  55             *offset += datalen;
  56           return nwrote;
  57         }
  58     }
  59   return __hurd_fail (err);
  60 }