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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ipc/ipc_sync_message.h"
#include <stdint.h>
#include <stack>
#include "base/atomic_sequence_num.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/synchronization/waitable_event.h"
#include "build/build_config.h"
namespace {
struct WaitableEventLazyInstanceTraits
: public base::DefaultLazyInstanceTraits<base::WaitableEvent> {
static base::WaitableEvent* New(void* instance) {
// Use placement new to initialize our instance in our preallocated space.
return new (instance) base::WaitableEvent(true, true);
}
};
base::LazyInstance<base::WaitableEvent, WaitableEventLazyInstanceTraits>
dummy_event = LAZY_INSTANCE_INITIALIZER;
base::StaticAtomicSequenceNumber g_next_id;
} // namespace
namespace IPC {
#define kSyncMessageHeaderSize 4
SyncMessage::SyncMessage(int32_t routing_id,
uint32_t type,
PriorityValue priority,
MessageReplyDeserializer* deserializer)
: Message(routing_id, type, priority),
deserializer_(deserializer),
pump_messages_event_(NULL) {
set_sync();
set_unblock(true);
// Add synchronous message data before the message payload.
SyncHeader header;
header.message_id = g_next_id.GetNext();
WriteSyncHeader(this, header);
}
SyncMessage::~SyncMessage() {
}
MessageReplyDeserializer* SyncMessage::GetReplyDeserializer() {
DCHECK(deserializer_.get());
return deserializer_.release();
}
void SyncMessage::EnableMessagePumping() {
DCHECK(!pump_messages_event_);
set_pump_messages_event(dummy_event.Pointer());
}
bool SyncMessage::IsMessageReplyTo(const Message& msg, int request_id) {
if (!msg.is_reply())
return false;
return GetMessageId(msg) == request_id;
}
base::PickleIterator SyncMessage::GetDataIterator(const Message* msg) {
base::PickleIterator iter(*msg);
if (!iter.SkipBytes(kSyncMessageHeaderSize))
return base::PickleIterator();
else
return iter;
}
int SyncMessage::GetMessageId(const Message& msg) {
if (!msg.is_sync() && !msg.is_reply())
return 0;
SyncHeader header;
if (!ReadSyncHeader(msg, &header))
return 0;
return header.message_id;
}
Message* SyncMessage::GenerateReply(const Message* msg) {
DCHECK(msg->is_sync());
Message* reply = new Message(msg->routing_id(), IPC_REPLY_ID,
msg->priority());
reply->set_reply();
SyncHeader header;
// use the same message id, but this time reply bit is set
header.message_id = GetMessageId(*msg);
WriteSyncHeader(reply, header);
return reply;
}
bool SyncMessage::ReadSyncHeader(const Message& msg, SyncHeader* header) {
DCHECK(msg.is_sync() || msg.is_reply());
base::PickleIterator iter(msg);
bool result = iter.ReadInt(&header->message_id);
if (!result) {
NOTREACHED();
return false;
}
return true;
}
bool SyncMessage::WriteSyncHeader(Message* msg, const SyncHeader& header) {
DCHECK(msg->is_sync() || msg->is_reply());
DCHECK(msg->payload_size() == 0);
bool result = msg->WriteInt(header.message_id);
if (!result) {
NOTREACHED();
return false;
}
// Note: if you add anything here, you need to update kSyncMessageHeaderSize.
DCHECK(kSyncMessageHeaderSize == msg->payload_size());
return true;
}
bool MessageReplyDeserializer::SerializeOutputParameters(const Message& msg) {
return SerializeOutputParameters(msg, SyncMessage::GetDataIterator(&msg));
}
} // namespace IPC
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