fsetown(9) [netbsd man page]

FSETOWN(9)						   BSD Kernel Developer's Manual						FSETOWN(9)

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 posi-
     tive, 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 addi-
     tional 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.

BSD
								 December 20, 2005							       BSD

FCNTL(2)							System Calls Manual							  FCNTL(2)

NAME

       fcntl - file control

SYNOPSIS

       #include <fcntl.h>

       res = fcntl(fd, cmd, arg)
       int res;
       int fd, cmd, arg;

DESCRIPTION

       Fcntl provides for control over descriptors.  The argument fd is a descriptor to be operated on by cmd as follows:

       F_DUPFD	      Return a new descriptor as follows:

		      Lowest numbered available descriptor greater than or equal to arg.

		      Same object references as the original descriptor.

		      New descriptor shares the same file pointer if the object was a file.

		      Same access mode (read, write or read/write).

		      Same file status flags (i.e., both file descriptors share the same file status flags).

		      The close-on-exec flag associated with the new file descriptor is set to remain open across execv(2) system calls.

       F_GETFD	      Get  the	close-on-exec  flag  associated with the file descriptor fd.  If the low-order bit is 0, the file will remain open
		      across exec, otherwise the file will be closed upon execution of exec.

       F_SETFD	      Set the close-on-exec flag associated with fd to the low order bit of arg (0 or 1 as above).

       F_GETFL	      Get descriptor status flags, as described below.

       F_SETFL	      Set descriptor status flags.

       F_GETOWN       Get the process ID or process group currently receiving SIGIO and SIGURG signals; process groups are  returned  as  negative
		      values.

       F_SETOWN       Set the process or process group to receive SIGIO and SIGURG signals; process groups are specified by supplying arg as nega-
		      tive, otherwise arg is interpreted as a process ID.

       The flags for the F_GETFL and F_SETFL flags are as follows:

       O_NONBLOCK     Non-blocking I/O; if no data is available to a read call, or if a write operation would block, the call returns -1 with  the
		      error EWOULDBLOCK.

       O_APPEND       Force each write to append at the end of file; corresponds to the O_APPEND flag of open(2).

       O_ASYNC	      Enable the SIGIO signal to be sent to the process group when I/O is possible, e.g., upon availability of data to be read.

RETURN VALUE

       Upon successful completion, the value returned depends on cmd as follows:
	 F_DUPFD   A new file descriptor.
	 F_GETFD   Value of flag (only the low-order bit is defined).
	 F_GETFL   Value of flags.
	 F_GETOWN  Value of file descriptor owner.
	 other	   Value other than -1.
       Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

       Fcntl will fail if one or more of the following are true:

       [EBADF]	      Fildes is not a valid open file descriptor.

       [EMFILE]       Cmd is F_DUPFD and the maximum allowed number of file descriptors are currently open.

       [EINVAL]       Cmd is F_DUPFD and arg is negative or greater than the maximum allowable number (see getdtablesize(2)).

       [ESRCH]	      Cmd is F_SETOWN and the process ID given as argument is not in use.

SEE ALSO

       close(2), execve(2), getdtablesize(2), open(2), sigvec(2)

BUGS

       The asynchronous I/O facilities of O_NONBLOCK and O_ASYNC are currently available only for tty and socket operations.

4.2 Berkeley Distribution					   Nov 30, 1994 							  FCNTL(2)