(* Diskimage library for reading disk images.
   (C) Copyright 2007-2008 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.
 *)

open Printf
open ExtList
open Unix

open Int63.Operators

include Diskimage_utils

(* Use as the natural block size for disk images, but really we should
 * use the 'blockdev -getbsz' command to find the real block size.
 *)
let disk_block_size = ~^512

let partition_types = [
  Diskimage_mbr.plugin_id,
    ("MBR", Diskimage_mbr.probe);
]

let filesystem_types = [
  Diskimage_ext2.plugin_id,
    ("Linux ext2/3", Diskimage_ext2.probe);
  Diskimage_linux_swap.plugin_id,
    ("Linux swap", Diskimage_linux_swap.probe);
]

let lvm_types = [
  Diskimage_lvm2.plugin_id,
    ("Linux LVM2", Diskimage_lvm2.probe, Diskimage_lvm2.list);
]

let name_of_parts id =
  let name, _ = List.assoc id partition_types in
  name
let name_of_filesystem id =
  let name, _ = List.assoc id filesystem_types in
  name
let name_of_lvm id =
  let name, _, _ = List.assoc id lvm_types in
  name

(* Probe a device for partitions.  Returns [Some parts] or [None]. *)
let probe_for_partitions dev =
  if !debug then eprintf "probing for partitions on %s ...\n%!" dev#name;
  let rec loop = function
    | [] -> None
    | (parts_plugin_id, (_, probe_fn)) :: rest ->
	try Some (probe_fn dev)
	with Not_found -> loop rest
  in
  let r = loop partition_types in
  if !debug then (
    match r with
    | None -> eprintf "no partitions found on %s\n%!" dev#name
    | Some { parts_plugin_id = name; parts = parts } ->
	eprintf "found %d %s partitions on %s\n"
	  (List.length parts) name dev#name
  );
  r

(* Probe a device for a filesystem.  Returns [Some fs] or [None]. *)
let probe_for_filesystem dev =
  if !debug then eprintf "probing for a filesystem on %s ...\n%!" dev#name;
  let rec loop = function
    | [] -> None
    | (fs_name, (_, probe_fn)) :: rest ->
	try Some (probe_fn dev)
	with Not_found -> loop rest
  in
  let r = loop filesystem_types in
  if !debug then (
    match r with
    | None -> eprintf "no filesystem found on %s\n%!" dev#name
    | Some fs ->
	eprintf "found a filesystem on %s:\n" dev#name;
	eprintf "\t%s\n%!" fs.fs_plugin_id
  );
  r

(* Probe a device for a PV.  Returns [Some lvm_name] or [None]. *)
let probe_for_pv dev =
  if !debug then eprintf "probing if %s is a PV ...\n%!" dev#name;
  let rec loop = function
    | [] -> None
    | (lvm_name, (_, probe_fn, _)) :: rest ->
	try Some (probe_fn lvm_name dev)
	with Not_found -> loop rest
  in
  let r = loop lvm_types in
  if !debug then (
    match r with
    | None -> eprintf "no PV found on %s\n%!" dev#name
    | Some { lvm_plugin_id = name } ->
	eprintf "%s contains a %s PV\n%!" dev#name name
  );
  r

let list_lvs lvm_name devs =
  let _, _, list_lvs_fn = List.assoc lvm_name lvm_types in
  list_lvs_fn devs

(* Create machine description. *)
let open_machine name disks =
  let disks = List.map (
    fun (name, path) ->
      let dev = new block_device path disk_block_size (* XXX *) in
      { d_name = name; d_dev = dev; d_content = `Unknown }
  ) disks in
  { m_name = name; m_disks = disks; m_lv_filesystems = [] }

let close_machine { m_disks = m_disks } =
  (* Only close the disks, assume all other devices are derived from them. *)
  List.iter (fun { d_dev = d_dev } -> d_dev#close ()) m_disks

let scan_machine ({ m_disks = m_disks } as machine) =
  let m_disks = List.map (
    fun ({ d_dev = dev } as disk) ->
      let dev = (dev :> device) in
      (* See if it is partitioned first. *)
      let parts = probe_for_partitions dev in
      match parts with
      | Some parts ->
	  { disk with d_content = `Partitions parts }
      | None ->
	  (* Not partitioned.  Does it contain a filesystem? *)
	  let fs = probe_for_filesystem dev in
	  match fs with
	  | Some fs ->
	      { disk with d_content = `Filesystem fs }
	  | None ->
	      (* Not partitioned, no filesystem, is it a PV? *)
	      let pv = probe_for_pv dev in
	      match pv with
	      | Some lvm_name ->
		  { disk with d_content = `PhysicalVolume lvm_name }
	      | None ->
		  disk (* Spare/unknown. *)
  ) m_disks in

  (* Now we have either detected partitions or a filesystem on each
   * physical device (or perhaps neither).  See what is on those
   * partitions.
   *)
  let m_disks = List.map (
    function
    | ({ d_dev = dev; d_content = `Partitions parts } as disk) ->
	let ps = List.map (
	  fun p ->
	    if p.part_status = Bootable || p.part_status = Nonbootable then (
	      let fs = probe_for_filesystem p.part_dev in
	      match fs with
	      | Some fs ->
		  { p with part_content = `Filesystem fs }
	      | None ->
		  (* Is it a PV? *)
		  let pv = probe_for_pv p.part_dev in
		  match pv with
		  | Some lvm_name ->
		      { p with part_content = `PhysicalVolume lvm_name }
		  | None ->
		      p (* Spare/unknown. *)
	    ) else p
	) parts.parts in
	let parts = { parts with parts = ps } in
	{ disk with d_content = `Partitions parts }
    | disk -> disk
  ) m_disks in

  (* LVM filesystem detection
   *
   * Look for all disks/partitions which have been identified as PVs
   * and pass those back to the respective LVM plugin for LV detection.
   *
   * (Note - a two-stage process because an LV can be spread over
   * several PVs, so we have to detect all PVs belonging to a
   * domain first).
   *
   * XXX To deal with RAID (ie. md devices) we will need to loop
   * around here because RAID is like LVM except that they normally
   * present as block devices which can be used by LVM.
   *)
  (* First: LV detection.
   * Find all physical volumes, can be disks or partitions.
   *)
  let pvs_on_disks = List.filter_map (
    function
    | { d_dev = d_dev;
	d_content = `PhysicalVolume pv } -> Some (pv, (d_dev :> device))
    | _ -> None
  ) m_disks in
  let pvs_on_partitions = List.map (
    function
    | { d_content = `Partitions { parts = parts } } ->
	List.filter_map (
	  function
	  | { part_dev = part_dev;
	      part_content = `PhysicalVolume pv } ->
	      Some (pv, part_dev)
	  | _ -> None
	) parts
    | _ -> []
  ) m_disks in
  let lvs = List.concat (pvs_on_disks :: pvs_on_partitions) in

  (* Second: filesystem on LV detection.
   * Group the LVs by plug-in type.
   *)
  let cmp (a,_) (b,_) = compare a b in
  let lvs = List.sort ~cmp lvs in
  let lvs = group_by lvs in

  let lvs =
    List.map (fun (pv, devs) -> list_lvs pv.lvm_plugin_id devs) lvs in
  let lvs = List.concat lvs in

  (* lvs is a list of potential LV devices.  Now run them through the
   * probes to see if any contain filesystems.
   *)
  let filesystems =
    List.filter_map (
      fun ({ lv_dev = dev } as lv) ->
	match probe_for_filesystem dev with
	| Some fs -> Some (lv, fs)
	| None -> None
    ) lvs in

  { machine with
      m_disks = m_disks;
      m_lv_filesystems = filesystems }