src/syscall/zx/fidl/message.go

// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build fuchsia

package fidl

import (
	"sync"

	"syscall/zx"
)

// messageBytesPool is a pool of buffers that can fit the data part of any
// FIDL message.
var messageBytesPool = sync.Pool{
	New: func() interface{} {
		return make([]byte, zx.ChannelMaxMessageBytes)
	},
}

// messageHandlesPool is a pool of buffers that can fit the handles part of
// any FIDL message.
var messageHandlesPool = sync.Pool{
	New: func() interface{} {
		return make([]zx.Handle, zx.ChannelMaxMessageHandles)
	},
}

// MessageHeader represents a transactional message header.
type MessageHeader struct {
	_        struct{} `fidl2:"s,16,4"`
	Txid     uint32
	Reserved uint32
	Flags    uint32
	Ordinal  uint32
}

var mMessageHeader = MustCreateMarshaler(MessageHeader{})

func (msg *MessageHeader) Marshaler() Marshaler {
	return mMessageHeader
}

func marshalHeaderThenMessage(header *MessageHeader, msg Message, data []byte, handles []zx.Handle) (int, int, error) {
	if _, _, err := MarshalNew(header, data[:MessageHeaderSize], nil); err != nil {
		return 0, 0, err
	}
	if msg == nil {
		return MessageHeaderSize, 0, nil
	}
	nb, nh, err := MarshalNew(msg, data[MessageHeaderSize:], handles[:])
	if err != nil {
		return 0, 0, err
	}
	return nb + MessageHeaderSize, nh, nil
}

func unmarshalHeaderThenMessage(data []byte, handles []zx.Handle, header *MessageHeader, msg Message) error {
	if _, _, err := UnmarshalNew(data[:MessageHeaderSize], nil, header); err != nil {
		return err
	}
	if msg == nil {
		return nil
	}
	if _, _, err := UnmarshalNew(data[MessageHeaderSize:], handles[:], msg); err != nil {
		return err
	}
	return nil
}