(* Guestfs Browser.
 * Copyright (C) 2010 Red Hat Inc.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *)

open ExtList
open ExtString
open CamomileLibrary
open Default.Camomile

open Utils

open Printf

module C = Libvirt.Connect
module Cond = Condition
module D = Libvirt.Domain
module G = Guestfs
module M = Mutex
module Q = Queue

type 'a callback = 'a -> unit

(* The commands. *)
type command =
  | Exit_thread
  | Connect of string option * domain list callback
  | Disk_usage of source * string * int64 callback
  | Download_dir_find0 of source * string * string * unit callback
  | Download_dir_tarball of source * string * download_dir_tarball_format * string * unit callback
  | Download_file of source * string * string * unit callback
  | Open_domain of string * inspection_data callback
  | Open_images of (string * string option) list * inspection_data callback
  | Read_directory of source * string * direntry list callback

and domain = {
  dom_id : int;
  dom_name : string;
  dom_state : D.state;
}

and inspection_data = {
  insp_all_filesystems : (string * string) list;
  insp_oses : inspection_os list;
}

and inspection_os = {
  insp_root : string;
  insp_arch : string;
  insp_distro : string;
  insp_filesystems : string array;
  insp_hostname : string;
  insp_major_version : int;
  insp_minor_version : int;
  insp_mountpoints : (string * string) list;
  insp_package_format : string;
  insp_package_management : string;
  insp_product_name : string;
  insp_type : string;
  insp_windows_systemroot : string option;
  insp_winreg_DEFAULT : string option;
  insp_winreg_SAM : string option;
  insp_winreg_SECURITY : string option;
  insp_winreg_SOFTWARE : string option;
  insp_winreg_SYSTEM : string option;
}

and source = OS of inspection_os | Volume of string

and direntry = {
  dent_name : string;
  dent_stat : G.stat;
  dent_link : string;
}

and download_dir_tarball_format = Tar | TGZ | TXZ

let rec string_of_command = function
  | Exit_thread -> "Exit_thread"
  | Connect (Some name, _) -> sprintf "Connect %s" name
  | Connect (None, _) -> "Connect NULL"
  | Disk_usage (src, remotedir, _) ->
      sprintf "Disk_usage (%s, %s)" (string_of_source src) remotedir
  | Download_dir_find0 (src, remotedir, localfile, _) ->
      sprintf "Download_dir_find0 (%s, %s, %s)"
        (string_of_source src) remotedir localfile
  | Download_dir_tarball (src, remotedir, format, localfile, _) ->
      sprintf "Download_dir_tarball (%s, %s, %s, %s)"
        (string_of_source src) remotedir
        (string_of_download_dir_tarball_format format) localfile
  | Download_file (src, remotefile, localfile, _) ->
      sprintf "Download_file (%s, %s, %s)"
        (string_of_source src) remotefile localfile
  | Open_domain (name, _) -> sprintf "Open_domain %s" name
  | Open_images (images, _) ->
      sprintf "Open_images %s" (string_of_images images)
  | Read_directory (src, dir, _) ->
      sprintf "Read_directory (%s, %s)" (string_of_source src) dir

and string_of_images images =
  "[" ^
    String.concat "; "
    (List.map (function
               | fn, None -> fn
               | fn, Some format -> sprintf "%s (%s)" fn format)
       images) ^ "]"

and string_of_source = function
  | OS { insp_root = root } ->
      sprintf "OS %s" root
  | Volume dev ->
      sprintf "Volume %s" dev

and string_of_download_dir_tarball_format = function
  | Tar -> "Tar"
  | TGZ -> "TGZ"
  | TXZ -> "TXZ"

let no_callback _ = ()

let failure_hook = ref (fun _ -> ())
let busy_hook = ref (fun _ -> ())
let idle_hook = ref (fun _ -> ())
let status_hook = ref (fun _ -> ())
let progress_hook = ref (fun _ -> ())

let set_failure_hook cb = failure_hook := cb
let set_busy_hook cb = busy_hook := cb
let set_idle_hook cb = idle_hook := cb
let set_status_hook cb = status_hook := cb
let set_progress_hook cb = progress_hook := cb

(* Execute a function, while holding a mutex.  If the function
 * fails, ensure we release the mutex before rethrowing the
 * exception.
 *)
let with_lock m f =
  M.lock m;
  let r = try Left (f ()) with exn -> Right exn in
  M.unlock m;
  match r with
  | Left r -> r
  | Right exn -> raise exn

(* The queue of commands, and a lock and condition to protect it. *)
let q = Q.create ()
let q_discard = ref false
let q_lock = M.create ()
let q_cond = Cond.create ()

(* Send a command message to the slave thread. *)
let send_to_slave ?fail cmd =
  debug "sending message %s to slave thread ..." (string_of_command cmd);
  with_lock q_lock (
    fun () ->
      Q.push (fail, cmd) q;
      Cond.signal q_cond
  )

let discard_command_queue () =
  with_lock q_lock (
    fun () ->
      Q.clear q;
      (* Discard the currently running command. *)
      q_discard := true
  )

let connect ?fail uri cb = send_to_slave ?fail (Connect (uri, cb))
let disk_usage ?fail src remotedir cb =
  send_to_slave ?fail (Disk_usage (src, remotedir, cb))
let download_dir_find0 ?fail src remotedir localfile cb =
  send_to_slave ?fail (Download_dir_find0 (src, remotedir, localfile, cb))
let download_dir_tarball ?fail src remotedir format localfile cb =
  send_to_slave ?fail
    (Download_dir_tarball (src, remotedir, format, localfile, cb))
let download_file ?fail src remotefile localfile cb =
  send_to_slave ?fail (Download_file (src, remotefile, localfile, cb))
let open_domain ?fail name cb = send_to_slave ?fail (Open_domain (name, cb))
let open_images ?fail images cb = send_to_slave ?fail (Open_images (images, cb))
let read_directory ?fail src path cb =
  send_to_slave ?fail (Read_directory (src, path, cb))

(*----- Slave thread starts here -----*)

(* Set this to true to exit the thread. *)
let quit = ref false

(* Handles.  These are not protected by locks because only the slave
 * thread has access to them.
 *)
let conn = ref None
let g = ref None

(* Run the callback unless someone set the q_discard flag while
 * we were running the command.
 *)
let callback_if_not_discarded (cb : 'a callback) (arg : 'a) =
  let discard = with_lock q_lock (fun () -> !q_discard) in
  if not discard then
    GtkThread.async cb arg

(* Call 'f ()' with source mounted read-only.  Ensure that everything
 * is unmounted even if an exception is thrown.
 *)
let with_mount_ro g src (f : unit -> 'a) : 'a =
  Std.finally (fun () -> g#umount_all ()) (
    fun () ->
      (* Do the mount - could be OS or single volume. *)
      (match src with
      | Volume dev -> g#mount_ro dev "/";
      | OS { insp_mountpoints = mps } ->
          (* Sort the mountpoint keys by length, shortest first. *)
          let cmp (a,_) (b,_) = compare (String.length a) (String.length b) in
          let mps = List.sort ~cmp mps in
          (* Mount the filesystems. *)
          List.iter (
            fun (mp, dev) -> g#mount_ro dev mp
          ) mps
      );
      f ()
  ) ()

(* Update the status bar. *)
let status fs =
  let f str = GtkThread.async !status_hook str in
  ksprintf f fs

let rec loop () =
  debug "top of slave loop";

  (* Get the next command. *)
  let fail, cmd =
    with_lock q_lock (
      fun () ->
        while Q.is_empty q do Cond.wait q_cond q_lock done;
        q_discard := false;
        Q.pop q
    ) in

  debug "slave processing command %s ..." (string_of_command cmd);

  (try
     GtkThread.async !busy_hook ();
     execute_command cmd
   with exn ->
     (* If the user provided an override ?fail parameter to the
      * original call, call that, else call the global hook.
      *)
     match fail with
     | Some cb -> GtkThread.async cb exn
     | None -> GtkThread.async !failure_hook exn
  );

  (* If there are no more commands in the queue, run the idle hook. *)
  let empty = with_lock q_lock (fun () -> Q.is_empty q) in
  if empty then GtkThread.async !idle_hook ();

  if !quit then Thread.exit ();
  loop ()

and execute_command = function
  | Exit_thread ->
      quit := true;
      close_all ()

  | Connect (name, cb) ->
      let printable_name =
        match name with None -> "default hypervisor" | Some uri -> uri in
      status "Connecting to %s ..." printable_name;

      close_all ();
      conn := Some (C.connect_readonly ?name ());

      let conn = get_conn () in
      let doms = D.get_domains conn [D.ListAll] in
      let doms = List.map (
        fun d ->
          { dom_id = D.get_id d;
            dom_name = D.get_name d;
            dom_state = (D.get_info d).D.state }
      ) doms in
      let cmp { dom_name = n1 } { dom_name = n2 } = compare n1 n2 in
      let doms = List.sort ~cmp doms in

      status "Connected to %s" printable_name;
      callback_if_not_discarded cb doms

  | Disk_usage (src, remotedir, cb) ->
      status "Calculating disk usage of %s ..." remotedir;

      let g = get_g () in
      let r =
        with_mount_ro g src (
          fun () ->
            g#du remotedir
        ) in

      status "Finished calculating disk usage of %s" remotedir;
      callback_if_not_discarded cb r

  | Download_dir_find0 (src, remotedir, localfile, cb) ->
      status "Downloading %s filenames to %s ..." remotedir localfile;

      let g = get_g () in
      with_mount_ro g src (
        fun () ->
          g#find0 remotedir localfile
      );

      status "Finished downloading %s" localfile;
      callback_if_not_discarded cb ()

  | Download_dir_tarball (src, remotedir, format, localfile, cb) ->
      status "Downloading %s to %s ..." remotedir localfile;

      let g = get_g () in
      let f = match format with
        | Tar -> g#tar_out
        | TGZ -> g#tgz_out
        | TXZ -> g#txz_out
      in
      with_mount_ro g src (
        fun () ->
          f remotedir localfile
      );

      status "Finished downloading %s" localfile;
      callback_if_not_discarded cb ()

  | Download_file (src, remotefile, localfile, cb) ->
      status "Downloading %s to %s ..." remotefile localfile;

      let g = get_g () in
      with_mount_ro g src (
        fun () ->
          g#download remotefile localfile
      );

      status "Finished downloading %s" localfile;
      callback_if_not_discarded cb ()

  | Open_domain (name, cb) ->
      status "Opening %s ..." name;

      let conn = get_conn () in
      let dom = D.lookup_by_name conn name in
      let xml = D.get_xml_desc dom in
      let images = get_disk_images_from_xml xml in
      open_disk_images images cb

  | Open_images (images, cb) ->
      status "Opening disk images ...";

      open_disk_images images cb

  | Read_directory (src, dir, cb) ->
      status "Reading directory %s ..." dir;

      let g = get_g () in
      let names, stats, links =
        with_mount_ro g src (
          fun () ->
            let names = g#ls dir in (* sorted and without . and .. *)
            let names = Array.to_list names in
            let stats = lstatlist_wrapper g dir names in
            let links = readlink_wrapper g dir names stats in
            names, stats, links
        ) in
      assert (
        let n = List.length names in
        n = List.length stats && n = List.length links
      );
      let entries = List.combine (List.combine names stats) links in
      let entries = List.map (
        fun ((name, stat), link) ->
          { dent_name = name; dent_stat = stat; dent_link = link }
      ) entries in

      status "Finished reading directory %s" dir;
      callback_if_not_discarded cb entries

(* Expect to be connected, and return the current libvirt connection. *)
and get_conn () =
  match !conn with
  | Some conn -> conn
  | None -> failwith "not connected to libvirt"

and get_g () =
  match !g with
  | Some g -> g
  | None -> failwith "no domain or disk image is open"

(* Close all libvirt and libguestfs handles. *)
and close_all () =
  (match !conn with Some conn -> C.close conn | None -> ());
  conn := None;
  close_g ()

and close_g () =
  (match !g with Some g -> g#close () | None -> ());
  g := None

and get_disk_images_from_xml xml =
  let xml = Xml.parse_string xml in

  (* Return the device nodes. *)
  let devices =
    match xml with
    | Xml.Element ("domain", _, children) ->
        let devices =
          List.filter_map (
            function
            | Xml.Element ("devices", _, devices) -> Some devices
            | _ -> None
          ) children in
        List.concat devices
    | _ ->
        failwith "get_xml_desc didn't return <domain/>" in

  (* Look for <source attr_name=attr_val/> and return attr_val. *)
  let rec source_of attr_name = function
    | [] -> None
    | Xml.Element ("source", attrs, _) :: rest ->
        (try Some (List.assoc attr_name attrs)
         with Not_found -> source_of attr_name rest)
    | _ :: rest -> source_of attr_name rest
  in

  (* Look for <driver type=attr_val/> and return attr_val. *)
  let rec format_of = function
    | [] -> None
    | Xml.Element ("driver", attrs, _) :: rest ->
        (try Some (List.assoc "type" attrs)
         with Not_found -> format_of rest)
    | _ :: rest -> format_of rest
  in

  (* Look for <disk> nodes and return the sources (block devices) of those. *)
  let blkdevs =
    List.filter_map (
      function
      | Xml.Element ("disk", attrs, disks) ->
          let filename =
            try
              let typ = List.assoc "type" attrs in
              if typ = "file" then source_of "file" disks
              else if typ = "block" then source_of "dev" disks
              else None
            with
              Not_found -> None in
          (match filename with
           | None -> None
           | Some filename ->
               let format = format_of disks in
               Some (filename, format)
          );
      | _ -> None
    ) devices in
  blkdevs

(* The common code for Open_domain and Open_images which opens the
 * libguestfs handle, adds the disks, and launches the appliance.
 *)
and open_disk_images images cb =
  debug "opening disk image %s" (string_of_images images);

  close_g ();
  let g' = new G.guestfs () in
  g := Some g';
  let g = g' in

  g#set_trace (trace ());

  (* Uncomment the next line to pass the verbose flag from the command
   * line through to libguestfs.  This is not generally necessary since
   * we are not so interested in debugging libguestfs problems at this
   * level, and the user can always set LIBGUESTFS_DEBUG=1 if they need
   * to.
   *)
  (* g#set_verbose (verbose ());*)

  (* Attach progress bar callback. *)
  g#set_progress_callback (
    fun proc_nr serial position total ->
      debug "progress callback proc_nr=%d serial=%d posn=%Ld total=%Ld"
        proc_nr serial position total;
      GtkThread.async !progress_hook (position, total)
  );

  List.iter (
    function
    | filename, None ->
        g#add_drive_opts ~readonly:true filename
    | filename, Some format ->
        g#add_drive_opts ~readonly:true ~format filename
  ) images;

  g#launch ();

  status "Listing filesystems ...";

  (* Get list of filesystems. *)
  let fses = g#list_filesystems () in

  status "Looking for operating systems ...";

  (* Perform inspection.  This can fail, ignore errors. *)
  let roots =
    try Array.to_list (g#inspect_os ())
    with
      G.Error msg ->
        debug "inspection failed (error ignored): %s" msg;
        [] in

  let oses = List.map (
    fun root ->
      let typ = g#inspect_get_type root in
      let windows_systemroot =
        if typ <> "windows" then None
        else (
          try Some (g#inspect_get_windows_systemroot root)
          with G.Error _ -> None
        ) in

      (* Create most of the OS object that we're going to return.  We
       * have to pass this to with_mount_ro below which is why we need
       * to partially create it here.
       *)
      let os = {
        insp_root = root;
        insp_arch = g#inspect_get_arch root;
        insp_distro = g#inspect_get_distro root;
        insp_filesystems = g#inspect_get_filesystems root;
        insp_hostname = g#inspect_get_hostname root;
        insp_major_version = g#inspect_get_major_version root;
        insp_minor_version = g#inspect_get_minor_version root;
        insp_mountpoints = g#inspect_get_mountpoints root;
        insp_package_format = g#inspect_get_package_format root;
        insp_package_management = g#inspect_get_package_management root;
        insp_product_name = g#inspect_get_product_name root;
        insp_type = typ;
        insp_windows_systemroot = windows_systemroot;
        insp_winreg_DEFAULT = None; (* incomplete, see below *)
        insp_winreg_SAM = None;
        insp_winreg_SECURITY = None;
        insp_winreg_SOFTWARE = None;
        insp_winreg_SYSTEM = None;
      } in

      (* We need to mount the root in order to look for Registry hives. *)
      let winreg_DEFAULT, winreg_SAM, winreg_SECURITY, winreg_SOFTWARE,
        winreg_SYSTEM =
        match windows_systemroot with
        | None -> None, None, None, None, None
        | Some sysroot ->
            with_mount_ro g (OS os) (
              fun () ->
                let check_for_hive filename =
                  let path =
                    sprintf "%s/system32/config/%s" sysroot filename in
                  try Some (g#case_sensitive_path path)
                  with G.Error _ -> None
                in
                check_for_hive "default",
                check_for_hive "sam",
                check_for_hive "security",
                check_for_hive "software",
                check_for_hive "system"
            ) in

      (* Fill in the remaining struct fields. *)
      let os = { os with
                   insp_winreg_DEFAULT = winreg_DEFAULT;
                   insp_winreg_SAM = winreg_SAM;
                   insp_winreg_SECURITY = winreg_SECURITY;
                   insp_winreg_SOFTWARE = winreg_SOFTWARE;
                   insp_winreg_SYSTEM = winreg_SYSTEM
               } in
      os
  ) roots in

  let data = {
    insp_all_filesystems = fses;
    insp_oses = oses;
  } in

  status "Finished opening disk";
  callback_if_not_discarded cb data

(* guestfs_lstatlist has a "hidden" limit of the protocol message size.
 * Call this function, but split the list of names into chunks.
 *)
and lstatlist_wrapper g dir = function
  | [] -> []
  | names ->
      let names', names = List.take 1000 names, List.drop 1000 names in
      let xs = g#lstatlist dir (Array.of_list names') in
      let xs = Array.to_list xs in
      xs @ lstatlist_wrapper g dir names

(* For each entry which is a symlink, read the destination of the
 * symlink.  This is non-trivial because on Windows we cannot use
 * readlink but need to instead parse the reparse data from NTFS.
 *)
and readlink_wrapper g dir names stats =
  (* Is the directory on an NTFS filesystem? *)
  let dev = get_mounted_device g dir in
  if g#vfs_type dev <> "ntfs" then (
    (* Not NTFS, use the fast g#readlinklist method. *)
    let rec readlinklist_wrapper g dir = function
      | [] -> []
      | names ->
          let names', names = List.take 1000 names, List.drop 1000 names in
          let xs = g#readlinklist dir (Array.of_list names') in
          let xs = Array.to_list xs in
          xs @ readlinklist_wrapper g dir names
    in
    readlinklist_wrapper g dir names
  )
  else (
    (* NTFS: look up each symlink individually. *)
    List.map (
      fun (name, stat) ->
        if not (is_symlink stat.G.mode) then ""
        else
          let path = if dir = "/" then dir ^ name else dir ^ "/" ^ name in
          try
            let _, display = get_ntfs_reparse_data g path in
            display
          with exn ->
            debug "get_ntfs_reparse_data: %s: failed: %s"
              path (Printexc.to_string exn);
            "?"
    ) (List.combine names stats)
  )

(* See:
 * https://bugzilla.redhat.com/show_bug.cgi?id=663407
 * http://git.annexia.org/?p=libguestfs.git;a=commit;h=3a3836b933b80c4f9f2c767fda4f8b459f998db2
 * http://www.tuxera.com/community/ntfs-3g-advanced/junction-points-and-symbolic-links/
 * http://www.tuxera.com/community/ntfs-3g-advanced/extended-attributes/
 * http://www.codeproject.com/KB/winsdk/junctionpoints.aspx
 *)
and get_ntfs_reparse_data g path =
  let data = g#lgetxattr path "system.ntfs_reparse_data" in
  let link, display =
    bitmatch Bitstring.bitstring_of_string data with
    (* IO_REPARSE_TAG_MOUNT_POINT *)
    | { 0xa0000003_l : 32 : littleendian;
        _ : 16 : littleendian; (* data length - ignore it *)
        _ : 16 : littleendian; (* reserved *)
        link_offset : 16 : littleendian;
        link_len : 16 : littleendian;
        display_offset : 16 : littleendian;
        display_len : 16 : littleendian;
        link : link_len * 8 :
          string, offset (8 * (link_offset + 0x10));
        display : display_len * 8 :
          string, offset (8 * (display_offset + 0x10)) } ->
          (* These strings should always be valid UTF16LE, but the caller
           * is prepared to catch any exception if this fails.
           *)
          let link = windows_string_to_utf8 link in
          let display = windows_string_to_utf8 display in
          link, display
    | { 0xa0000003_l : 32 : littleendian } ->
          invalid_arg (
            sprintf "%s: could not parse IO_REPARSE_TAG_MOUNT_POINT data" path
          )

    (* IO_REPARSE_TAG_SYMLINK *)
    | { 0xa000000c_l : 32 : littleendian;
        _ : 16 : littleendian; (* data length - ignore it *)
        _ : 16 : littleendian; (* reserved *)
        link_offset : 16 : littleendian;
        link_len : 16 : littleendian;
        display_offset : 16 : littleendian;
        display_len : 16 : littleendian;
        link : link_len * 8 :
          string, offset (8 * (link_offset + 0x14));
        display : display_len * 8 :
          string, offset (8 * (display_offset + 0x14)) } ->
          let link = windows_string_to_utf8 link in
          let display = windows_string_to_utf8 display in
          link, display
    | { 0xa000000c_l : 32 : littleendian } ->
          invalid_arg (
            sprintf "%s: could not parse IO_REPARSE_TAG_SYMLINK data" path
          )

    | { i : 32 : littleendian } ->
          invalid_arg (
            sprintf "%s: reparse data of type 0x%lx is not supported" path i
          )
    | { _ } ->
          invalid_arg (sprintf "%s: reparse data is too short" path) in

  link, display

(* Given a path which is located somewhere on a mountpoint, return the
 * device name.  This works by using g#mountpoints and then looking for
 * the mount path with the longest match.
 *)
and get_mounted_device g path =
  let mps = g#mountpoints () in
  let mps = List.map (
    fun (dev, mp) ->
      if String.starts_with path mp then dev, String.length mp else dev, 0
  ) mps in
  let cmp (_,n1) (_,n2) = compare n2 n1 in
  let mps = List.sort ~cmp mps in
  match mps with
  | [] ->
      invalid_arg (sprintf "%s: not mounted" path)
  | (_,0) :: _ ->
      invalid_arg (sprintf "%s: not found on any filesystem" path)
  | (dev,_) :: _ -> dev

(* Start up one slave thread. *)
let slave_thread = Thread.create loop ()

(* Note the following function is called from the main thread. *)
let exit_thread () =
  discard_command_queue ();
  ignore (send_to_slave Exit_thread);
  Thread.join slave_thread