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: releng/10.2/share/man/man9/devfs_set_cdevpriv.9 239303 2012-08-15 16:19:39Z hselasky $
.Dd August 15, 2012 .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 n sys/param.h n sys/conf.h d -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.
p 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.
p On the last filedescriptor close, system automatically arranges .Fn devfs_clear_cdevpriv call.
p If successful, the functions return 0.
p The function .Fn devfs_set_cdevpriv returns the following values on error: l -tag -width Er t Bq Er ENOENT The current call is not associated with some filedescriptor. t Bq Er EBUSY The private driver data is already associated with current filedescriptor. .El
p The function .Fn devfs_get_cdevpriv returns the following values on error: l -tag -width Er t Bq Er EBADF The current call is not associated with some filedescriptor. t 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 open 2 , .Xr close 2 , .Xr devfs 5 , .Xr kern_openat 9 .Sh HISTORY The .Fn devfs_cdevpriv family of functions first appeared in .Fx 7.1 .