class WireServer

Terminates the connection.

After calling `Close`, the client must not send any other requests.

Servers, after sending the status response, should close the connection

regardless of status and without sending an epitaph.

Closing the client end of the channel should be semantically equivalent

to calling `Close` without knowing when the close has completed or its

status.

Reads up to 'count' bytes at the seek offset.

The seek offset is moved forward by the number of bytes read.

## Invariants

* The returned `data.length` will never be greater than `count`.

* If `data.length` is less than `count`, it means that the seek offset

has reached the end of file as part of this operation.

* If `data.length` is zero while `count` is not, it means that the

seek offset is already at or beyond the end of file, and no data could

be read.

* If `count` is zero, the server should perform all the checks ensuring

read access without actually read anything, and return an empty

`data` vector.

This method requires the [`Rights.READ_BYTES`] right.

Returns `ZX_ERR_OUT_OF_RANGE` if `count` is greater than `MAX_TRANSFER_SIZE`.

Writes data at the seek offset.

The seek offset is moved forward by the number of bytes written.

If the file is in append mode, the seek offset is first set to the end

of the file, followed by the write, in one atomic step.

The file size may grow if the seek offset plus `data.length` is beyond

the current end of file.

+ request `data` the byte buffer to write to the file.

- response `actual_count` the number of bytes written.

## Invariants

* The returned `actual_count` will never be greater than `data.length`.

* If the server is unable to write all the data due to e.g. not enough

space, `actual_count` may be less than `data.length`. If no bytes

could be written, an error is returned.

* If `data.length` is zero, the server should perform all the checks

ensuring write access without mutating the file and return a

successful write of zero bytes. The seek offset is still updated if

in append mode.

This method requires the [`Rights.WRITE_BYTES`] right.

Open a client PTY device with a unique `id`. `client` should be a handle

to one endpoint of a channel that (on success) will become an open

connection to the newly created device. On failure, the channel will be

closed. Closing the channel will close the connection and release the

device. If the provided `id` is 0, then the new client is a controlling

client and has the capability to open additional clients. If the

current device is not a controlling client, `ZX_ERR_ACCESS_DENIED` will be

returned. If `id` is not unique, `ZX_ERR_INVALID_ARGS` will be returned.

Otherwise the status code from `device_add` is passed on.

allowed on Client PTYs

-----------------------------

Clear and/or Set PTY Features

Obtain the window size (in character cells)

allowed on the Controlling PTY

-------------------------------------

Select which Client PTY receives input.

Reads will simply block on non-active PTYs.

Returns pending OOB events, simultaneously clearing them

allowed on the Server PTY

--------------------------------

Sets the window size

|bind_handler| returns a handler that binds incoming connections to this

server implementation.

The returned handler borrows the server instance.

The server must outlive the provided |dispatcher|. Only after

the dispatcher is shutdown will it be safe to destroy the servers.

The server should not be moved.