43e0efbdeb
difficult to read and understand. Most manuals of English style therefore say that you should use "use".
135 lines
4.5 KiB
Groff
135 lines
4.5 KiB
Groff
.\" $NetBSD: dofileread.9,v 1.4 2003/02/04 22:38:18 perry Exp $
|
|
.\"
|
|
.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Gregory McGarry.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the NetBSD
|
|
.\" Foundation, Inc. and its contributors.
|
|
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
|
|
.\" contributors may be used to endorse or promote products derived
|
|
.\" from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd October 20, 2002
|
|
.Dt DOFILEREAD 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm dofileread ,
|
|
.Nm dofilereadv ,
|
|
.Nm dofilewrite ,
|
|
.Nm dofilewritev ,
|
|
.Nd high-level file operations
|
|
.Sh SYNOPSIS
|
|
.Fd #include \*[Lt]sys/file.h\*[Gt]
|
|
.Ft int
|
|
.Fn dofileread "struct proc *p" "int fd" "struct file *fp" "void *buf" \
|
|
"size_t nbyte" "off_t *offset" "int flags" "register_t *retval"
|
|
.Ft int
|
|
.Fn dofilewrite "struct proc *p" "int fd" "struct file *fp" \
|
|
"const void *buf" "size_t nbyte" "off_t *offset" "int flags" \
|
|
"register_t *retval"
|
|
.Ft int
|
|
.Fn dofilereadv "struct proc *p" "int fd" "struct file *fp" \
|
|
"const struct iovec *iovp" "int iovcnt" "off_t *offset" "int flags" \
|
|
"register_t *retval"
|
|
.Ft int
|
|
.Fn dofilewritev "struct proc *p" "int fd" "struct file *fp" \
|
|
"const struct iovec *iovp" "int iovcnt" "off_t *offset" "int flags" \
|
|
"register_t *retval"
|
|
.Sh DESCRIPTION
|
|
The functions implement the underlying functionality of the
|
|
.Xr read 2 ,
|
|
.Xr write 2 ,
|
|
.Xr readv 2 ,
|
|
and
|
|
.Xr writev 2
|
|
system calls.
|
|
They are also used throughout the kernel as high-level access routines
|
|
for file I/O.
|
|
.Pp
|
|
The
|
|
.Fn dofileread
|
|
function attempts to read
|
|
.Fa nbytes
|
|
of data from the object referenced by file entry
|
|
.Fa fp
|
|
into the buffer pointed to by
|
|
.Fa buf .
|
|
The
|
|
.Fn dofilewrite
|
|
function attempts to write
|
|
.Fa nbytes
|
|
of data to the object referenced by file entry
|
|
.Fa fp
|
|
from the buffer pointed to by
|
|
.Fa buf .
|
|
.Pp
|
|
The
|
|
.Fn dofilereadv
|
|
and
|
|
.Fn dofilewritev
|
|
functions perform the same operations, but scatter the data with the
|
|
.Fa iovcnt
|
|
buffers specified by the members of the
|
|
.Fa iov
|
|
array.
|
|
.Pp
|
|
The offset of the file operations is explicitly specified by
|
|
.Fa *offset .
|
|
The new file offset after the file operation is returned in
|
|
.Fa *offset .
|
|
If the FOF_UPDATE_OFFSET flag is specified in the
|
|
.Fa flags
|
|
argument, the file offset in the file entry
|
|
.Fa fp
|
|
is updated to reflect the new file offset, otherwise it remains
|
|
unchanged after the operation.
|
|
.Pp
|
|
The file descriptor
|
|
.Fa fd
|
|
is largely unused except for use by the ktrace framework for reporting
|
|
to userlevel the process's file descriptor.
|
|
.Pp
|
|
Upon successful completion the number of bytes which were transferred
|
|
is returned in
|
|
.Fa *retval .
|
|
.Sh RETURN VALUES
|
|
Upon successful completion zero is returned, otherwise an appropriate
|
|
error is returned.
|
|
.Sh CODE REFERENCES
|
|
This section describes places within the
|
|
.Nx
|
|
source tree where actual code implementing or using these file
|
|
operations can be found.
|
|
All pathnames are relative to
|
|
.Pa /usr/src .
|
|
.Pp
|
|
The framework for these file operations is implemented within the file
|
|
.Pa sys/kern/sys_generic.c .
|
|
.Sh SEE ALSO
|
|
.Xr file 9
|