.\"	$OpenBSD: sigio_init.9,v 1.3 2018/11/12 18:27:31 jmc Exp $
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.\" Copyright (c) 2018 Visa Hankala
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.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" "pid_t pgid"
.Ft pid_t
.Fn "sigio_getown" "struct sigio_ref *sir"
.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.
If
.Fa pgid
is positive, the ID is taken as a process ID.
If
.Fa pgid
is negative, the ID is taken as a process group ID.
The reference
.Fa sir
is cleared if
.Fa pgid
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
returns the ID of the process or process group associated with the reference
.Fa sir .
.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 [EPERM]
.It Bq Er EPERM
The invoking process belongs to another session than the process
or process group
.Fa pgid .
.It Bq Er ESRCH
The process or process group
.Fa pgid
does not exist.
.It Bq Er ESRCH
The process
.Fa pgid
is exiting.
.El
.Pp
The function
.Fn sigio_getown
returns the ID of the process or process group associated with reference
.Fa sir ,
or zero if no signal target has been registered.
.Sh SEE ALSO
.Xr pgsigio 9
.Sh HISTORY
The sigio routines were adapted from
.Fx
and first appeared in
.Ox 6.5 .