Source file mirage_block_patterns.ml

(*
 * Copyright (C) 2015 David Scott <dave.scott@unikernel.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *)
open Lwt.Infix
open Mirage_block_lwt_s
module B = Mirage_block

module Fill (Block: S) = struct
  let random (b: Block.t) =
    Block.get_info b
    >>= fun info ->
    let buffer = Io_page.(to_cstruct (get 8)) in
    let sectors = Cstruct.len buffer / info.B.sector_size in

    let rec loop next =
      if next >= info.B.size_sectors
      then Lwt.return (Ok ())
      else begin
        let remaining = Int64.sub info.B.size_sectors next in
        let this_time = min sectors (Int64.to_int remaining) in
        let buf = Cstruct.sub buffer 0 (info.B.sector_size * this_time) in
        for i = 0 to Cstruct.len buf - 1 do
          Cstruct.set_uint8 buf i (Random.int 256)
        done;
        Block.write b next [ buf ]
        >>= function
        | Error _ as e -> Lwt.return e
        | Ok () ->
          loop Int64.(add next (of_int this_time))
      end in
    loop 0L

end