(* 'df' command for virtual domains.

   (C) Copyright 2007 Richard W.M. Jones, Red Hat Inc.
   http://libvirt.org/

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

   Support for LVM2 PVs.
*)

open Printf
open Virt_df_gettext.Gettext
open Virt_df

let plugin_name = "LVM2"

let sector_size = 512
let sector_size64 = 512L

(* Probe to see if it's an LVM2 PV.  Look for the "LABELONE" label. *)
let rec probe_pv lvm_plugin_id dev =
  try
    let uuid, metadata_offset, metadata_length = read_pv_label dev in
    if debug then
      eprintf "LVM2 detected UUID %s md offset 0x%lx len %ld\n%!"
	uuid metadata_offset metadata_length;
    { lvm_plugin_id = lvm_plugin_id; pv_uuid = uuid }
  with _ -> raise Not_found

and read_pv_label dev =
  (* Load the first 8 sectors.  I found by experimentation that
   * the second sector contains the header ("LABELONE" etc) and
   * the nineth sector contains some additional information about
   * the location of the current metadata.
   *)
  let bits = dev#read_bitstring 0L (9 * sector_size) in

  Bitmatch.hexdump_bitstring stdout bits;

  bitmatch bits with
  | sector0 : sector_size*8 : bitstring; (* sector 0 *)
    labelone : 8*8 : bitstring;		(* "LABELONE" *)
    padding : 16*8 : bitstring;		(* Seems to contain something. *)
    lvm2_ver : 8*8 : bitstring;		(* "LVM2 001" *)
    uuid : 32*8 : bitstring;		(* UUID *)
    padding2 : (sector_size-64)*8 : bitstring; (* to end of second sector *)
    sector234567 : sector_size*8 * 6 : bitstring; (* sectors 2-6 *)
    padding3 : 0x28*8 : bitstring;      (* start of sector 8 *)
    metadata_offset : 32 : littleendian;(* metadata offset *)
    padding4 : 4*8 : bitstring;
    metadata_length : 32 : littleendian	(* length of metadata (bytes) *)
      when Bitmatch.string_of_bitstring labelone = "LABELONE" &&
	   Bitmatch.string_of_bitstring lvm2_ver = "LVM2 001" ->
    let metadata_offset = metadata_offset +* 0x1000_l in

    (* Check the metadata offset & length look reasonable for this
     * device.  Otherwise maybe it's a newer or older header which
     * we don't really understand properly.
     *)
    let () =
      let size =
	if dev#size <= Int64.of_int32 Int32.max_int then Int64.to_int32 dev#size
	else Int32.max_int in
      if metadata_offset < 0x1200_l || metadata_offset >= size
	|| metadata_length < 0_l || metadata_offset+*metadata_length >= size
      then
	invalid_arg "read_pv_label: bad metadata offset or length" in

    Bitmatch.string_of_bitstring uuid, metadata_offset, metadata_length


  | _ ->
    invalid_arg (sprintf "read_pv_label: %s: not an LVM2 physical volume"
		   dev#name)

(* We are passed a list of devices which we previously identified
 * as PVs belonging to us.  From these produce a list of all LVs
 * (as devices) and return them.  Note that we don't try to detect
 * what is on these LVs - that will be done in the main code.
 *)
let list_lvs devs =
  []

(* Register with main code. *)
let () =
  lvm_type_register plugin_name probe_pv list_lvs