mirage-block 1.0.0 · OCaml Package

Operations on sector-addressible block devices, usually used for persistent storage.

type page_aligned_buffer

The type for page-aligned memory buffers.

type error = private [>

| 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 [>

| Mirage_device.error
| `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 +'a io

The type for potentially blocking I/O operation

type t

The type representing the internal state of the device

val disconnect : t -> unit io

Disconnect from the device. While this might take some time to complete, it can never result in an error.

val get_info : t -> info io

Query the characteristics of a specific block device

val read : 
  t ->
  int64 ->
  page_aligned_buffer list ->
  (unit, error) Result.result io

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 ->
  page_aligned_buffer list ->
  (unit, write_error) Result.result io

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.

package mirage-block