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
HISTORY
These kernel functions appeared in NetBSD 2.0.