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.Dd December 2, 2015 26.Dt DEVFS_CDEVPRIV 9 27.Os 28.Sh NAME 29.Nm devfs_set_cdevpriv , 30.Nm devfs_get_cdevpriv , 31.Nm devfs_clear_cdevpriv 32.Nd manage per-open filedescriptor data for devices 33.Sh SYNOPSIS 34.In sys/param.h 35.In sys/conf.h 36.Bd -literal 37typedef void d_priv_dtor_t(void *data); 38.Ed 39.Ft int 40.Fn devfs_get_cdevpriv "void **datap" 41.Ft int 42.Fn devfs_set_cdevpriv "void *priv" "d_priv_dtor_t *dtr" 43.Ft void 44.Fn devfs_clear_cdevpriv "void" 45.Sh DESCRIPTION 46The 47.Fn devfs_xxx_cdevpriv 48family of functions allows the 49.Fa cdev 50driver methods to associate some driver-specific data with each 51user process 52.Xr open 2 53of the device special file. 54Currently, functioning of these functions is restricted to the context 55of the 56.Fa cdevsw 57switch method calls performed as 58.Xr devfs 5 59operations in response to system calls that use filedescriptors. 60.Pp 61The 62.Fn devfs_set_cdevpriv 63function associates a data pointed by 64.Va priv 65with current calling context (filedescriptor). 66The data may be retrieved later, possibly from another call 67performed on this filedescriptor, by the 68.Fn devfs_get_cdevpriv 69function. 70The 71.Fn devfs_clear_cdevpriv 72disassociates previously attached data from context. 73Immediately after 74.Fn devfs_clear_cdevpriv 75finished operating, the 76.Va dtr 77callback is called, with private data supplied 78.Va data 79argument. 80The 81.Fn devfs_clear_cdevpriv 82function will be also be called if the open callback 83function returns an error code. 84.Pp 85On the last filedescriptor close, system automatically arranges 86.Fn devfs_clear_cdevpriv 87call. 88.Pp 89If successful, the functions return 0. 90.Pp 91The function 92.Fn devfs_set_cdevpriv 93returns the following values on error: 94.Bl -tag -width Er 95.It Bq Er ENOENT 96The current call is not associated with some filedescriptor. 97.It Bq Er EBUSY 98The private driver data is already associated with current 99filedescriptor. 100.El 101.Pp 102The function 103.Fn devfs_get_cdevpriv 104returns the following values on error: 105.Bl -tag -width Er 106.It Bq Er EBADF 107The current call is not associated with some filedescriptor. 108.It Bq Er ENOENT 109The private driver data was not associated with current 110filedescriptor, or 111.Fn devfs_clear_cdevpriv 112was called. 113.El 114.Sh SEE ALSO 115.Xr close 2 , 116.Xr open 2 , 117.Xr devfs 5 118.Sh HISTORY 119The 120.Fn devfs_cdevpriv 121family of functions first appeared in 122.Fx 7.1 . 123