X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=slave.ml;h=01105ef8700c143eadb89f83c684a3ccadb0f8f4;hb=f09bb82de01019f24411cac2916d9567b5e9a235;hp=1017dd89624a0ae1c856441575cc0ee7080bde10;hpb=bbfe03c47f1d7f03c3e6c0cab9e4f500f588c80a;p=guestfs-browser.git

diff --git a/slave.ml b/slave.ml
index 1017dd8..01105ef 100644
--- a/slave.ml
+++ b/slave.ml
@@ -16,8 +16,15 @@
  * 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
@@ -30,8 +37,14 @@ type 'a callback = 'a -> unit
 (* The commands. *)
 type command =
   | Exit_thread
-  | Connect of string option * unit callback
-  | Get_domains of domain list callback
+  | 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;
@@ -39,15 +52,96 @@ and domain = {
   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
@@ -63,90 +157,577 @@ let with_lock m f =
 
 (* 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 cmd =
-  debug "sending message %s to slave thread ..." (string_of_command cmd)
+let send_to_slave ?fail cmd =
+  debug "sending message %s to slave thread ..." (string_of_command cmd);
   with_lock q_lock (
     fun () ->
-      Q.push cmd q;
+      Q.push (fail, cmd) q;
       Cond.signal q_cond
   )
 
-let discard_command_queue () = with_lock q_lock (fun () -> Q.clear q)
+let discard_command_queue () =
+  with_lock q_lock (
+    fun () ->
+      Q.clear q;
+      (* Discard the currently running command. *)
+      q_discard := true
+  )
 
-let connect uri cb = send_to_slave (Connect (uri, cb))
-let get_domains cb = send_to_slave (Get_domains cb)
+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 cmd =
+  let fail, cmd =
     with_lock q_lock (
       fun () ->
-        while Q.is_empty q do
-          Cond.wait q_cond q_lock
-        done;
+        while Q.is_empty q do Cond.wait q_cond q_lock done;
+        q_discard := false;
         Q.pop q
     ) in
 
-  debug "slave thread processing command %s ..." (string_of_command cmd);
+  debug "slave processing command %s ..." (string_of_command cmd);
 
   (try
-     call_callback !busy_hook ();
-     execute_command cmd;
-     call_callback !idle_hook ();
+     GtkThread.async !busy_hook ();
+     execute_command cmd
    with exn ->
-     (* If a command fails, clear the command queue and run the
-      * failure hook in the main thread.
+     (* If the user provided an override ?fail parameter to the
+      * original call, call that, else call the global hook.
       *)
-     call_callback !idle_hook ();
-     discard_command_queue ();
-     call_callback !failure_hook exn
+     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;
-      disconnect_all ()
+      close_all ()
+
+  | Connect (name, cb) ->
+      let printable_name =
+        match name with None -> "default hypervisor" | Some uri -> uri in
+      status "Connecting to %s ..." printable_name;
 
-  | Connect (uri, cb) ->
-      disconnect_all ();
-      conn := Some (C.connect_readonly ?uri ());
-      call_callback cb ()
+      close_all ();
+      conn := Some (C.connect_readonly ?name ());
 
-  | Get_domains cb ->
       let conn = get_conn () in
       let doms = D.get_domains conn [D.ListAll] in
       let doms = List.map (
         fun d ->
-          D.get_id d, D.get_name d, (D.get_info d).D.state
+          { dom_id = D.get_id d;
+            dom_name = D.get_name d;
+            dom_state = (D.get_info d).D.state }
       ) doms in
-      call_callback cb doms
+      let cmp { dom_name = n1 } { dom_name = n2 } = UTF8.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
 
-(* Call a callback function or hook in the main thread. *)
-and call_callback cb arg =
-  GtkThread.async cb arg
+  | 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. *)
-let get_conn () =
+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 disconnect_all () =
+and close_all () =
   (match !conn with Some conn -> C.close conn | None -> ());
-  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 ()
@@ -154,5 +735,5 @@ let slave_thread = Thread.create loop ()
 (* Note the following function is called from the main thread. *)
 let exit_thread () =
   discard_command_queue ();
-  send_to_slave Exit_thread;
+  ignore (send_to_slave Exit_thread);
   Thread.join slave_thread