package mirage-types

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Console input/output

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Console input/output

type error = [

| `Invalid_console of string

]

The type for representing possible errors when attaching a console.

include DEVICE with type error := error

type +'a io

The type for potentially blocking I/O operation

type t

The type representing the internal state of the device

type id

This type is no longer used and will be removed once other * modules stop using it in their type signatures.

val disconnect : t -> unit io

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

include FLOW
  with type error := error
   and type 'a io := 'a io
   and type flow := t

type buffer

The type for memory buffer.

val error_message : error -> string

Convert an error to a human-readable message, suitable for logging.

val read : t -> [ `Ok of buffer | `Eof | `Error of error ] io

read flow will block until it either successfully reads a segment of data from the current flow, receives an Eof signifying that the connection is now closed, or an Error.

val write : t -> buffer -> [ `Ok of unit | `Eof | `Error of error ] io

write flow buffer will block until buffer has been added to the send queue. There is no indication when the buffer has actually been read and, therefore, it must not be reused. The contents may be transmitted in separate packets, depending on the underlying transport. The result `Ok () indicates success, `Eof indicates that the connection is now closed and `Error indicates some other error.

val writev : t -> buffer list -> [ `Ok of unit | `Eof | `Error of error ] io

writev flow buffers will block until the buffers have all been added to the send queue. There is no indication when the buffers have actually been read and, therefore, they must not be reused. The result `Ok () indicates success, `Eof indicates that the connection is now closed and `Error indicates some other error.

val close : t -> unit io

close flow will flush all pending writes and signal the remote endpoint that there will be no future writes. Once the remote endpoint has read all pending data, it is expected that calls to read on the remote will return `Eof.

Note it is still possible for the remote endpoint to write to the flow and for the local endpoint to call read. This state where the local endpoint has called close but the remote endpoint has not called close is similar to that of a half-closed TCP connection or a Unix socket after shutdown(SHUTDOWN_WRITE).

The result unit io will become determined when the remote endpoint finishes calling write and calls close. At this point no data can flow in either direction and resources associated with the flow can be freed.

val log : t -> string -> unit

log str writes as many characters of str that can be written in one write operation to the console t, then writes "\r\n" to it.

val log_s : t -> string -> unit io

log_s str is a thread that writes str ^ "\r\n" in the console t.