Fd (eio.Eio_unix.Fd)

type t

A wrapper around a Unix.file_descr.

Creation

val of_unix : 
  sw:Eio.Std.Switch.t ->
  ?blocking:bool ->
  ?seekable:bool ->
  close_unix:bool ->
  Unix.file_descr ->
  t

of_unix ~sw ~close_unix fd wraps fd.

parameter sw
Close fd automatically when sw is finished.

parameter blocking
Indicates whether fd is in blocking mode. If not given, fd is probed for its blocking state if needed.

parameter seekable
The value to be returned by is_seekable. Defaults to probing if needed.

parameter close_unix
Whether close also closes fd (this should normally be true).

val of_unix_list : sw:Eio.Std.Switch.t -> Unix.file_descr list -> t list

of_unix_list ~sw fds is like List.map (of_unix ~sw ~close_unix:true) fds, except that if sw is off then it closes all the FDs.

Using FDs

val use : t -> (Unix.file_descr -> 'a) -> if_closed:(unit -> 'a) -> 'a

use t fn ~if_closed calls fn wrapped_fd, ensuring that wrapped_fd will not be closed before fn returns.

If t is already closed, it returns if_closed () instead.

val use_exn : string -> t -> (Unix.file_descr -> 'a) -> 'a

use_exn op t fn calls fn wrapped_fd, ensuring that wrapped_fd will not be closed before fn returns.

If t is already closed, it raises an exception, using op as the name of the failing operation.

val use_exn_list : string -> t list -> (Unix.file_descr list -> 'a) -> 'a

use_exn_list op fds fn calls use_exn on each FD in fds, calling fn wrapped_fds on the results.

val use_exn_opt : string -> t option -> (Unix.file_descr option -> 'a) -> 'a

use_exn_opt op fd fn is like use_exn, but if fd = None then it just calls fn None.

Closing

val close : t -> unit

close t marks t as closed, so that use can no longer be used to start new operations.

The wrapped FD will be closed once all current users of the FD have finished (unless close_unix = false).

Has no effect if t is already closed.

val remove : t -> Unix.file_descr option

remove t marks t as closed, so that use can no longer be used to start new operations.

It then waits for all current users of the wrapped FD to finish using it, and then returns the FD.

This operation suspends the calling fiber and so must run from an Eio fiber. It does not allow itself to be cancelled, since it takes ownership of the FD and that would be leaked if it aborted.

Returns None if t is closed by another fiber first.

val is_open : t -> bool

is_open t returns true until t has been marked as closing, after which it returns false.

This is mostly useful inside the callback of use, to test whether another fiber has started closing t (in which case you may decide to stop early).

Flags

val is_blocking : t -> bool

is_blocking t returns the value of blocking passed to of_unix.

If not known, it first probes for it (and if the FD is already closed, returns false).

val is_seekable : t -> bool

is_seekable t returns the value of seekable passed to of_unix.

If not known, it first probes for it (and if the FD is already closed, returns false).

Standard FDs

val stdin : t

val stdout : t

val stderr : t

Printing

val pp : t Fmt.t

Displays the FD number.