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

   1 /* Copyright (C) 1996, 1997 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 #ifndef _SYS_UIO_H
  20 # error "Never include <bits/uio.h> directly; use <sys/uio.h> instead."
  21 #endif
  22
  23
  24 #include <sys/types.h>
  25
  26
  27 /* We should normally use the Linux kernel header file to define this
  28    type and macros but this calls for trouble because of the header
  29    includes other kernel headers.  */
  30
  31 /* Size of object which can be written atomically.
  32
  33    This macro has different values in different kernel versions.  The
  34    latest versions of ther kernel use 1024 and this is good choice.  Since
  35    the C library implementation of readv/writev is able to emulate the
  36    functionality even if the currently running kernel does not support
  37    this large value the readv/writev call will not fail because of this.  */
  38 #define UIO_MAXIOV      1024
  39
  40
  41 /* Structure for scatter/gather I/O.  */
  42 struct iovec
  43   {
  44     void *iov_base;     /* Pointer to data.  */
  45     size_t iov_len;     /* Length of data.  */
  46   };