.\"	$OpenBSD: opendev.3,v 1.24 2022/08/26 21:47:16 kn Exp $
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.\" Copyright (c) 1996, Jason Downs.  All rights reserved.
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.Dd $Mdocdate: August 26 2022 $
.Dt OPENDEV 3
.Os
.Sh NAME
.Nm opendev
.Nd short form device open routine
.Sh SYNOPSIS
.In util.h
.Ft int
.Fn opendev "const char *path" "int oflags" "int dflags" "char **realpath"
.Sh DESCRIPTION
The
.Fn opendev
function opens a device using a
.Dq short form
name or
.Xr disklabel 8
UID
.Pq DUID .
For instance
.Dq sd0
or
.Dq sd0c
will be expanded to
.Pa /dev/rsd0c
on most architectures.
.Pp
Device name lookup is done by first checking
.Fa path
for a
.Sq /
and if one is found attempting to open that file.
If not,
.Fa path
is checked to see if it is a valid DUID.
If it is, the corresponding device is obtained via
.Xr diskmap 4 .
If
.Fa path
has no
.Sq /
and is not a DUID,
.Fa /dev
is searched for a matching device.
.Pp
The
.Fa oflags
are the same as the
.Fa flags
passed to
.Xr open 2 .
.Pp
The
.Fa dflags
are specified by OR'ing the following values:
.Bd -literal -offset indent
OPENDEV_PART	attempt to open the raw partition during expansion
OPENDEV_BLCK	open the block device (default is character device)
.Ed
.Pp
If
.Fa realpath
is not
.Dv NULL ,
it is modified to point at the fully expanded device name.
.Sh RETURN VALUES
The
.Fn opendev
return value and errors are the same as the return value and errors of
.Xr open 2 .
.Sh SEE ALSO
.Xr open 2 ,
.Xr getrawpartition 3 ,
.Xr diskmap 4 ,
.Xr disklabel 8
.Sh HISTORY
The
.Fn opendev
function first appeared in
.Ox 1.2 .
.Sh CAVEATS
If
.Fa realpath
is not
.Dv NULL ,
on return it will point to internal
static storage space that will be overwritten by subsequent calls.