.\"	$OpenBSD: sigio_init.9,v 1.4 2020/01/08 16:27:40 visa Exp $
.\"
.\" Copyright (c) 2018 Visa Hankala
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: November 12 2018 $
.Dt SIGIO_INIT 9
.Os
.Sh NAME
.Nm sigio_init ,
.Nm sigio_free ,
.Nm sigio_copy ,
.Nm sigio_setown ,
.Nm sigio_getown
.Nd asynchronous IO signal API
.Sh SYNOPSIS
.In sys/sigio.h
.Ft void
.Fn "sigio_init" "struct sigio_ref *sir"
.Ft void
.Fn "sigio_free" "struct sigio_ref *sir"
.Ft void
.Fn "sigio_copy" "struct sigio_ref *dst" "struct sigio_ref *src"
.Ft int
.Fn "sigio_setown" "struct sigio_ref *sir" "u_long cmd" "caddr_t data"
.Ft pid_t
.Fn "sigio_getown" "struct sigio_ref *sir" "u_long cmd" "caddr_t data"
.Sh DESCRIPTION
The asynchronous IO signal API provides a means to manage signal registrations.
It associates a process or process group with a signal source.
The association is revoked automatically when the process or process group
is deleted.
.Pp
.Fn sigio_init
initializes the sigio reference
.Fa sir .
.Pp
.Fn sigio_free
clears any process or process group associated with reference
.Fa sir .
.Pp
.Fn sigio_copy
copies registration from reference
.Fa src
to reference
.Fa dst .
.Pp
.Fn sigio_setown
associates the reference
.Fa sir
with a process or process group.
.Fa cmd
is one of ioctl commands
.Dv FIOSETOWN ,
.Dv SIOCSPGRP
and
.Dv TIOCSPGRP .
.Fa data
is a pointer to a signed integer that represents the ID of the owner
of the registration.
For
.Dv FIOSETOWN
and
.Dv SIOCSPGRP ,
a positive ID is taken as a process ID,
and a negative ID is taken as a process group ID.
If
.Fa cmd
is
.Dv TIOCSPGRP ,
a positive ID is taken as a process group ID,
and negative ID values are not allowed.
For all values of
.Fa cmd ,
the reference
.Fa sir
is cleared if the ID is zero.
.Pp
When
.Fn sigio_setown
is called, the invoking process' credentials are stored in the reference.
These credentials are checked when the reference is used with
.Xr pgsigio 9 .
.Pp
.Fn sigio_getown
stores the ID of the process or process group associated with the reference
.Fa sir
to the signed integer pointed by
.Fa data .
.Fa cmd
is one of ioctl commands
.Dv FIOGETOWN ,
.Dv SIOCGPGRP
and
.Dv TIOCGPGRP .
For
.Dv FIOGETOWN
and
.Dv SIOCGPGRP ,
a process ID is stored as a positive ID,
and a process group ID is stored as a negative ID.
For
.Dv TIOCGPGRP ,
a process ID is stored as a negative ID,
and a process group ID is stored as a positive ID.
If there is no registered owner, a zero is stored in the integer.
.Sh CONTEXT
.Fn sigio_init ,
.Fn sigio_free ,
.Fn sigio_copy ,
.Fn sigio_setown
and
.Fn sigio_getown
can be called during autoconf, or from process context.
.Sh RETURN VALUES
.Fn sigio_setown
returns 0 on success.
Otherwise, the following error values are returned:
.Bl -tag -width [EINVAL]
.It Bq Er EINVAL
The process group ID is invalid.
.It Bq Er EPERM
The invoking process belongs to another session than the process
or process group.
.It Bq Er ESRCH
The process or process group does not exist.
.It Bq Er ESRCH
The process is exiting.
.El
.Sh SEE ALSO
.Xr pgsigio 9
.Sh HISTORY
The sigio routines were adapted from
.Fx
and first appeared in
.Ox 6.5 .