table of contents
DEVFS_CDEVPRIV(9) | Kernel Developer's Manual | DEVFS_CDEVPRIV(9) |
NAME¶
devfs_set_cdevpriv
,
devfs_get_cdevpriv
,
devfs_clear_cdevpriv
—
manage per-open filedescriptor data for devices
SYNOPSIS¶
#include
<sys/param.h>
#include
<sys/conf.h>
typedef void (*cdevpriv_dtr_t)(void *data);
int
devfs_get_cdevpriv
(void
**datap);
int
devfs_set_cdevpriv
(void
*priv,
cdevpriv_dtr_t
dtr);
void
devfs_clear_cdevpriv
(void);
DESCRIPTION¶
Thedevfs_xxx_cdevpriv
() family of functions
allows the cdev driver methods to associate
some driver-specific data with each user process
open(2) of the device special file. Currently,
functioning of these functions is restricted to the context of the
cdevsw switch method calls performed as
devfs(5) operations in response to system calls
that use filedescriptors.
The devfs_set_cdevpriv
() function associates
a data pointed by priv with current calling
context (filedescriptor). The data may be retrieved later, possibly from
another call performed on this filedescriptor, by the
devfs_get_cdevpriv
() function. The
devfs_clear_cdevpriv
() disassociates
previously attached data from context. Immediately after
devfs_clear_cdevpriv
() finished operating,
the dtr callback is called, with private data
supplied data argument. The
devfs_clear_cdevpriv
() function will be
also be called if the open callback function returns an error code.
On the last filedescriptor close, system automatically arranges
devfs_clear_cdevpriv
() call.
If successful, the functions return 0.
The function devfs_set_cdevpriv
() returns the
following values on error:
- [
ENOENT
] - The current call is not associated with some filedescriptor.
- [
EBUSY
] - The private driver data is already associated with current filedescriptor.
devfs_get_cdevpriv
() returns the
following values on error:
- [
EBADF
] - The current call is not associated with some filedescriptor.
- [
ENOENT
] - The private driver data was not associated with current filedescriptor, or
devfs_clear_cdevpriv
() was called.
SEE ALSO¶
open(2), close(2), devfs(5), kern_openat(9)HISTORY¶
Thedevfs_cdevpriv
() family of functions
first appeared in FreeBSD 7.1.August 15, 2012 | Debian |