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glibc  2.9
uio.h
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00001 /* Copyright (C) 1996, 1997, 2006 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #if !defined _SYS_UIO_H && !defined _FCNTL_H
00020 # error "Never include <bits/uio.h> directly; use <sys/uio.h> instead."
00021 #endif
00022 
00023 #ifndef _BITS_UIO_H
00024 #define _BITS_UIO_H  1
00025 
00026 #include <sys/types.h>
00027 
00028 
00029 /* We should normally use the Linux kernel header file to define this
00030    type and macros but this calls for trouble because of the header
00031    includes other kernel headers.  */
00032 
00033 /* Size of object which can be written atomically.
00034 
00035    This macro has different values in different kernel versions.  The
00036    latest versions of the kernel use 1024 and this is good choice.  Since
00037    the C library implementation of readv/writev is able to emulate the
00038    functionality even if the currently running kernel does not support
00039    this large value the readv/writev call will not fail because of this.  */
00040 #define UIO_MAXIOV   1024
00041 
00042 
00043 /* Structure for scatter/gather I/O.  */
00044 struct iovec
00045   {
00046     void *iov_base;  /* Pointer to data.  */
00047     size_t iov_len;  /* Length of data.  */
00048   };
00049 
00050 #endif