xref: /openbsd/share/man/man9/sigio_init.9 (revision 36b1b8b4)

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.Dd $Mdocdate: January 8 2020 $
.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 .