package qcow

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Parameters

Signature

include Qcow_s.RESIZABLE_BLOCK
include Mirage_block.S
type error = private [>
  1. | Mirage_device.error
]

The type for block errors.

val pp_error : error Fmt.t

pp_error is the pretty-printer for errors.

type write_error = private [>
  1. | Mirage_device.error
  2. | `Is_read_only
]

The type for write errors.

val pp_write_error : write_error Fmt.t

pp_write_error is the pretty-printer for write errors.

include Mirage_device.S
type t
val disconnect : t -> unit Lwt.t
val get_info : t -> Mirage_block.info Lwt.t

Query the characteristics of a specific block device

val read : t -> int64 -> Cstruct.t list -> (unit, error) Stdlib.result Lwt.t

read device sector_start buffers reads data starting at sector_start from the block device into buffers. Ok () means the buffers have been filled. Error _ indicates an I/O error has happened and some of the buffers may not be filled. Each of elements in the list buffers must be a whole number of sectors in length. The list of buffers can be of any length.

val write : t -> int64 -> Cstruct.t list -> (unit, write_error) Stdlib.result Lwt.t

write device sector_start buffers writes data from buffers onto the block device starting at sector_start. Ok () means the contents of the buffers have been written. Error _ indicates a partial failure in which some of the writes may not have happened.

Once submitted, it is not possible to cancel a request and there is no timeout.

The operation may fail with:

  • `Unimplemented: the operation has not been implemented, no data has been written.
  • `Is_read_only: the device is read-only, no data has been written.
  • `Disconnected: the device has been disconnected at application request, an unknown amount of data has been written.

Each of buffers must be a whole number of sectors in length. The list of buffers can be of any length.

The data will not be copied, so the supplied buffers must not be re-used until the IO operation completes.

val resize : t -> int64 -> (unit, write_error) Stdlib.result Lwt.t

Resize the file to the given number of sectors.

val flush : t -> (unit, write_error) Stdlib.result Lwt.t

flush t flushes any buffers, if the file has been opened in buffered mode

val connect : ?max_size_bytes:int64 -> B.t -> t Lwt.t

connect ?max_size_bytes b constructs a cache over b with a maximum memory footprint of max_size_bytes. Writes are heavily cached and only written to disk on a flush, disconnect or when out of space.

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