NAME
fsetown,
fgetown,
fownsignal —
file descriptor owner
handling functions
SYNOPSIS
#include <sys/file.h>
int
fsetown(
struct
lwp *l,
pid_t *pgid,
int cmd,
const void *data);
int
fgetown(
struct
lwp *l,
pid_t pgid,
int cmd,
void *data);
void
fownsignal(
pid_t
pgid,
int signo,
int code,
int band,
void *fdescdata);
DESCRIPTION
These functions handle file descriptor owner related ioctls and related signal
delivery. Device drivers and other parts of the kernel call these functions
from ioctl entry functions or I/O notification functions.
fsetown() sets the owner of file.
cmd is
an ioctl command, one of
SIOCSPGRP
,
FIOSETOWN
, and
TIOCSPGRP
.
data is interpreted as a pointer to a signed integer,
the integer being the ID of the owner. The
cmd
determines how exactly
data should be interpreted. If
cmd is
TIOCSPGRP
, the ID needs
to be positive and is interpreted as process group ID. For
SIOCSPGRP
and
FIOSETOWN
, the
passed ID is the process ID if positive, or the process group ID if negative.
fgetown() returns the current owner of the file.
cmd is an ioctl command, one of
SIOCGPGRP
,
FIOGETOWN
, and
TIOCGPGRP
.
data is interpreted
as a pointer to a signed integer, and the value is set according to the passed
cmd. For
TIOCGPGRP
, the returned
data value is positive process group ID if the owner is
the process group, or negative process ID if the owner is a process. For other
ioctls, the returned value is the positive process ID if the owner is a
process, or the negative process group ID if the owner is a process group.
fownsignal() schedules the
signo signal
to be sent to the current file descriptor owner. The signals typically used
with this function are
SIGIO
and
SIGURG
. The
code and
band arguments are sent along with the signal as
additional signal specific information if
SA_SIGINFO
is activated. If the information is not available from the context of the
fownsignal() call, these should be passed as zero.
fdescdata is used to lookup the file descriptor for
SA_SIGINFO
signals. If it is specified, the file
descriptor number is sent along with the signal as additional signal specific
information. If file descriptor data pointer is not available in the context
of the
fownsignal() call,
NULL
should be used instead.
Note that a
fcntl(2)
F_SETOWN request
is translated by the kernel to a
FIOSETOWN
ioctl, and
F_GETOWN
is translated to
FIOGETOWN
. This is done transparently
by generic code, before the device- or subsystem-specific ioctl entry function
is called.
SEE ALSO
fcntl(2),
siginfo(2),
signal(7),
ioctl(9),
signal(9)
HISTORY
These kernel functions appeared in
NetBSD 2.0.