1.\" Copyright (c) 2008 Konstantin Belousov 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd August 20, 2015 28.Dt DEVFS_CDEVPRIV 9 29.Os 30.Sh NAME 31.Nm devfs_set_cdevpriv , 32.Nm devfs_get_cdevpriv , 33.Nm devfs_clear_cdevpriv 34.Nd manage per-open filedescriptor data for devices 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/conf.h 38.Bd -literal 39typedef void (*cdevpriv_dtr_t)(void *data); 40.Ed 41.Ft int 42.Fn devfs_get_cdevpriv "void **datap" 43.Ft int 44.Fn devfs_set_cdevpriv "void *priv" "cdevpriv_dtr_t dtr" 45.Ft void 46.Fn devfs_clear_cdevpriv "void" 47.Sh DESCRIPTION 48The 49.Fn devfs_xxx_cdevpriv 50family of functions allows the 51.Fa cdev 52driver methods to associate some driver-specific data with each 53user process 54.Xr open 2 55of the device special file. 56Currently, functioning of these functions is restricted to the context 57of the 58.Fa cdevsw 59switch method calls performed as 60.Xr devfs 5 61operations in response to system calls that use filedescriptors. 62.Pp 63The 64.Fn devfs_set_cdevpriv 65function associates a data pointed by 66.Va priv 67with current calling context (filedescriptor). 68The data may be retrieved later, possibly from another call 69performed on this filedescriptor, by the 70.Fn devfs_get_cdevpriv 71function. 72The 73.Fn devfs_clear_cdevpriv 74disassociates previously attached data from context. 75Immediately after 76.Fn devfs_clear_cdevpriv 77finished operating, the 78.Va dtr 79callback is called, with private data supplied 80.Va data 81argument. 82The 83.Fn devfs_clear_cdevpriv 84function will be also be called if the open callback 85function returns an error code. 86.Pp 87On the last filedescriptor close, system automatically arranges 88.Fn devfs_clear_cdevpriv 89call. 90.Pp 91If successful, the functions return 0. 92.Pp 93The function 94.Fn devfs_set_cdevpriv 95returns the following values on error: 96.Bl -tag -width Er 97.It Bq Er ENOENT 98The current call is not associated with some filedescriptor. 99.It Bq Er EBUSY 100The private driver data is already associated with current 101filedescriptor. 102.El 103.Pp 104The function 105.Fn devfs_get_cdevpriv 106returns the following values on error: 107.Bl -tag -width Er 108.It Bq Er EBADF 109The current call is not associated with some filedescriptor. 110.It Bq Er ENOENT 111The private driver data was not associated with current 112filedescriptor, or 113.Fn devfs_clear_cdevpriv 114was called. 115.El 116.Sh SEE ALSO 117.Xr close 2 , 118.Xr open 2 , 119.Xr devfs 5 120.Sh HISTORY 121The 122.Fn devfs_cdevpriv 123family of functions first appeared in 124.Fx 7.1 . 125