.\"	$OpenBSD: opendisk.3,v 1.9 2015/09/10 15:16:43 schwarze Exp $
.\"	$NetBSD: opendisk.3,v 1.4 1999/07/02 15:49:12 simonb Exp $
.\"
.\" Copyright (c) 1997 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Luke Mewburn.
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.\" modification, are permitted provided that the following conditions
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.Dd $Mdocdate: September 10 2015 $
.Dt OPENDISK 3
.Os
.Sh NAME
.Nm opendisk
.Nd open a disk's raw partition
.Sh SYNOPSIS
.In sys/types.h
.In util.h
.Ft int
.Fo opendisk
.Fa "const char *path"
.Fa "int flags"
.Fa "char *buf"
.Fa "size_t buflen"
.Fa "int iscooked"
.Fc
.Sh DESCRIPTION
.Fn opendisk
opens
.Fa path ,
for reading and/or writing as specified by the argument
.Fa flags
using
.Xr open 2 ,
and the file descriptor is returned to the caller.
.Fa buf
is used to store the resultant filename.
.Fa buflen
is the size, in bytes, of the array referenced by
.Fa buf
(usually
.Dv MAXPATHLEN
bytes).
If
.Fa iscooked
is non zero, the
.Dq cooked
partition (block device) is opened, rather than the
.Dq raw
partition (character device).
.Pp
.Fn opendisk
attempts to open the following variations of
.Fa path ,
in order:
.Bl -tag -width "/dev/rpathX"
.It Fa path
The pathname as given.
.It Fa path Ns Em X
.Fa path
with a suffix of
.Sq Em X ,
where
.Sq Em X
represents the raw partition of the device, as determined by
.Xr getrawpartition 3 ,
usually
.Dq c .
.El
.Pp
If
.Fa iscooked
is zero, then the following two variations are attempted:
.Bl -tag -width "/dev/rpathX"
.It Pa /dev/r Ns Fa path
.Fa path
with a prefix of
.Dq Pa /dev/r .
.It Pa /dev/r Ns Fa path Ns Em X
.Fa path
with a prefix of
.Dq Pa /dev/r
and a suffix of
.Sq Em X
(q.v.).
.El
.Pp
Otherwise (i.e.,
.Fa iscooked
is non-zero), the following variations are attempted:
.Bl -tag -width "/dev/rpathX"
.It Pa /dev/ Ns Fa path
.Fa path
with a prefix of
.Dq Pa /dev/ .
.It Pa /dev/ Ns Fa path Ns Em X
.Fa path
with a prefix of
.Dq Pa /dev/
and a suffix of
.Sq Em X
(q.v.).
.El
.Sh RETURN VALUES
An open file descriptor, or -1 if the
.Xr open 2
failed.
.Sh ERRORS
.Fn opendisk
may set
.Va errno
to one of the following values:
.Bl -tag -width Er
.It Bq Er EINVAL
.Dv O_CREAT
was set in
.Fa flags ,
or
.Xr getrawpartition 3
didn't return a valid partition.
.El
.Pp
The
.Fn opendisk
function
may also set
.Va errno
to any value specified by the
.Xr open 2
function.
.Sh SEE ALSO
.Xr open 2 ,
.Xr getrawpartition 3
.Sh HISTORY
The
.Fn opendisk
function first appeared in
.Nx 1.3 .