125 lines
3.6 KiB
Groff
125 lines
3.6 KiB
Groff
.\" Copyright (c) 2008 Konstantin Belousov
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd August 20, 2015
|
|
.Dt DEVFS_CDEVPRIV 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm devfs_set_cdevpriv ,
|
|
.Nm devfs_get_cdevpriv ,
|
|
.Nm devfs_clear_cdevpriv
|
|
.Nd manage per-open filedescriptor data for devices
|
|
.Sh SYNOPSIS
|
|
.In sys/param.h
|
|
.In sys/conf.h
|
|
.Bd -literal
|
|
typedef void (*cdevpriv_dtr_t)(void *data);
|
|
.Ed
|
|
.Ft int
|
|
.Fn devfs_get_cdevpriv "void **datap"
|
|
.Ft int
|
|
.Fn devfs_set_cdevpriv "void *priv" "cdevpriv_dtr_t dtr"
|
|
.Ft void
|
|
.Fn devfs_clear_cdevpriv "void"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn devfs_xxx_cdevpriv
|
|
family of functions allows the
|
|
.Fa cdev
|
|
driver methods to associate some driver-specific data with each
|
|
user process
|
|
.Xr open 2
|
|
of the device special file.
|
|
Currently, functioning of these functions is restricted to the context
|
|
of the
|
|
.Fa cdevsw
|
|
switch method calls performed as
|
|
.Xr devfs 5
|
|
operations in response to system calls that use filedescriptors.
|
|
.Pp
|
|
The
|
|
.Fn devfs_set_cdevpriv
|
|
function associates a data pointed by
|
|
.Va priv
|
|
with current calling context (filedescriptor).
|
|
The data may be retrieved later, possibly from another call
|
|
performed on this filedescriptor, by the
|
|
.Fn devfs_get_cdevpriv
|
|
function.
|
|
The
|
|
.Fn devfs_clear_cdevpriv
|
|
disassociates previously attached data from context.
|
|
Immediately after
|
|
.Fn devfs_clear_cdevpriv
|
|
finished operating, the
|
|
.Va dtr
|
|
callback is called, with private data supplied
|
|
.Va data
|
|
argument.
|
|
The
|
|
.Fn devfs_clear_cdevpriv
|
|
function will be also be called if the open callback
|
|
function returns an error code.
|
|
.Pp
|
|
On the last filedescriptor close, system automatically arranges
|
|
.Fn devfs_clear_cdevpriv
|
|
call.
|
|
.Pp
|
|
If successful, the functions return 0.
|
|
.Pp
|
|
The function
|
|
.Fn devfs_set_cdevpriv
|
|
returns the following values on error:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENOENT
|
|
The current call is not associated with some filedescriptor.
|
|
.It Bq Er EBUSY
|
|
The private driver data is already associated with current
|
|
filedescriptor.
|
|
.El
|
|
.Pp
|
|
The function
|
|
.Fn devfs_get_cdevpriv
|
|
returns the following values on error:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The current call is not associated with some filedescriptor.
|
|
.It Bq Er ENOENT
|
|
The private driver data was not associated with current
|
|
filedescriptor, or
|
|
.Fn devfs_clear_cdevpriv
|
|
was called.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr close 2 ,
|
|
.Xr open 2 ,
|
|
.Xr devfs 5
|
|
.Sh HISTORY
|
|
The
|
|
.Fn devfs_cdevpriv
|
|
family of functions first appeared in
|
|
.Fx 7.1 .
|