sysdeps/unix/sysv/linux/bits/uio.h

   1 /* Copyright (C) 1996, 1997, 2006 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #if !defined _SYS_UIO_H && !defined _FCNTL_H
  20 # error "Never include <bits/uio.h> directly; use <sys/uio.h> instead."
  21 #endif
  22
  23 #ifndef _BITS_UIO_H
  24 #define _BITS_UIO_H     1
  25
  26 #include <sys/types.h>
  27
  28
  29 /* We should normally use the Linux kernel header file to define this
  30    type and macros but this calls for trouble because of the header
  31    includes other kernel headers.  */
  32
  33 /* Size of object which can be written atomically.
  34
  35    This macro has different values in different kernel versions.  The
  36    latest versions of the kernel use 1024 and this is good choice.  Since
  37    the C library implementation of readv/writev is able to emulate the
  38    functionality even if the currently running kernel does not support
  39    this large value the readv/writev call will not fail because of this.  */
  40 #define UIO_MAXIOV      1024
  41
  42
  43 /* Structure for scatter/gather I/O.  */
  44 struct iovec
  45   {
  46     void *iov_base;     /* Pointer to data.  */
  47     size_t iov_len;     /* Length of data.  */
  48   };
  49
  50 #endif