xref: /dflybsd-src/lib/libc/gen/getdevpath.3 (revision 86d7f5d305c6adaa56ff4582ece9859d73106103)

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.Dd July 10, 2009
.Dt GETDEVPATH 3
.Os
.Sh NAME
.Nm getdevpath
.Nd retrieve device path given name or label
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In fstab.h
.Ft char *
.Fn getdevpath "const char *devname" "int flags"
.Sh DESCRIPTION
.Fn getdevpath
takes a device name such as
.Dq Pa da0 ,
a device identifier such as
.Dq Li V21JYQ0G ,
a device path beginning with
.Dq Pa /
or
.Dq Pa \&. ,
or a device label from one of the
.Pa devtab
files, and returns an allocated path which may be used to open the device.
.Pp
Device names prefixed with
.Dq Pa /
or
.Dq Pa \&.
are assumed to be device paths and an exact allocated copy is simply returned.
However, flags may modify the operation.
.Pp
Device names specified with a type prefix, such as
.Dq Li serno:V21JYQ0G
are assumed to be typed device identifiers and are directly translated to
the appropriate path in
.Pa /dev ,
for example
.Dq Pa /dev/serno/V21JYQ0G .
.Pp
Device labels are directly checked against
.Pa /dev
first, using
.Fn lstat ,
and if not found will be searched for in one of the
.Pa devtab
files.
.Pp
The following flags may be passed to
.Fn getdevpath :
.Bl -tag -width ".Dv GETDEVPATH_RAWDEV" -offset indent
.It Dv GETDEVPATH_RAWDEV
Normally,
.Fn getdevpath
returns a high level devfs path which often winds up being a softlink in
devfs.
If this flag is specified and the device path represents a softlink,
.Fn getdevpath
will do a
.Xr readlink 2
and return the actual raw device path instead.
If the device path cannot be
.Fn lstat Ap d
this option will return
.Dv NULL .
.El
.Sh RETURN VALUES
.Fn getdevpath
returns a pointer to a
.Fn malloc Ap d
path on success and
.Dv NULL
on failure.
If a failure occurs
.Va errno
will be set appropriately.
.Pp
Note that a
.Fn malloc Ap d
path may be returned even if it does not exist in the filesystem.
Callers should not assume that the device is accessible
unless they can also open the device.
.Sh SEE ALSO
.Xr devfs 5 ,
.Xr devtab 5 ,
.Xr fstab 5
.Sh HISTORY
The
.Nm
function appeared in
.Dx 2.3 .