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// Copyright 2013 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 "mojo/public/cpp/bindings/lib/connector.h"
#include "mojo/public/cpp/bindings/error_handler.h"
#include "mojo/public/cpp/environment/logging.h"
namespace mojo {
namespace internal {
// ----------------------------------------------------------------------------
Connector::Connector(ScopedMessagePipeHandle message_pipe,
const MojoAsyncWaiter* waiter)
: error_handler_(nullptr),
waiter_(waiter),
message_pipe_(message_pipe.Pass()),
incoming_receiver_(nullptr),
async_wait_id_(0),
error_(false),
drop_writes_(false),
enforce_errors_from_incoming_receiver_(true),
destroyed_flag_(nullptr) {
// Even though we don't have an incoming receiver, we still want to monitor
// the message pipe to know if is closed or encounters an error.
WaitToReadMore();
}
Connector::~Connector() {
if (destroyed_flag_)
*destroyed_flag_ = true;
CancelWait();
}
void Connector::CloseMessagePipe() {
CancelWait();
Close(message_pipe_.Pass());
}
ScopedMessagePipeHandle Connector::PassMessagePipe() {
CancelWait();
return message_pipe_.Pass();
}
bool Connector::WaitForIncomingMessage() {
if (error_)
return false;
MojoResult rv = Wait(message_pipe_.get(),
MOJO_HANDLE_SIGNAL_READABLE,
MOJO_DEADLINE_INDEFINITE,
nullptr);
if (rv != MOJO_RESULT_OK) {
NotifyError();
return false;
}
mojo_ignore_result(ReadSingleMessage(&rv));
return (rv == MOJO_RESULT_OK);
}
bool Connector::Accept(Message* message) {
MOJO_CHECK(message_pipe_.is_valid());
if (error_)
return false;
if (drop_writes_)
return true;
MojoResult rv =
WriteMessageRaw(message_pipe_.get(),
message->data(),
message->data_num_bytes(),
message->mutable_handles()->empty()
? nullptr
: reinterpret_cast<const MojoHandle*>(
&message->mutable_handles()->front()),
static_cast<uint32_t>(message->mutable_handles()->size()),
MOJO_WRITE_MESSAGE_FLAG_NONE);
switch (rv) {
case MOJO_RESULT_OK:
// The handles were successfully transferred, so we don't need the message
// to track their lifetime any longer.
message->mutable_handles()->clear();
break;
case MOJO_RESULT_FAILED_PRECONDITION:
// There's no point in continuing to write to this pipe since the other
// end is gone. Avoid writing any future messages. Hide write failures
// from the caller since we'd like them to continue consuming any backlog
// of incoming messages before regarding the message pipe as closed.
drop_writes_ = true;
break;
case MOJO_RESULT_BUSY:
// We'd get a "busy" result if one of the message's handles is:
// - |message_pipe_|'s own handle;
// - simultaneously being used on another thread; or
// - in a "busy" state that prohibits it from being transferred (e.g.,
// a data pipe handle in the middle of a two-phase read/write,
// regardless of which thread that two-phase read/write is happening
// on).
// TODO(vtl): I wonder if this should be a |MOJO_DCHECK()|. (But, until
// crbug.com/389666, etc. are resolved, this will make tests fail quickly
// rather than hanging.)
MOJO_CHECK(false) << "Race condition or other bug detected";
return false;
default:
// This particular write was rejected, presumably because of bad input.
// The pipe is not necessarily in a bad state.
return false;
}
return true;
}
// static
void Connector::CallOnHandleReady(void* closure, MojoResult result) {
Connector* self = static_cast<Connector*>(closure);
self->OnHandleReady(result);
}
void Connector::OnHandleReady(MojoResult result) {
MOJO_CHECK(async_wait_id_ != 0);
async_wait_id_ = 0;
if (result != MOJO_RESULT_OK) {
NotifyError();
return;
}
ReadAllAvailableMessages();
// At this point, this object might have been deleted. Return.
}
void Connector::WaitToReadMore() {
MOJO_CHECK(!async_wait_id_);
async_wait_id_ = waiter_->AsyncWait(message_pipe_.get().value(),
MOJO_HANDLE_SIGNAL_READABLE,
MOJO_DEADLINE_INDEFINITE,
&Connector::CallOnHandleReady,
this);
}
bool Connector::ReadSingleMessage(MojoResult* read_result) {
bool receiver_result = false;
// Detect if |this| was destroyed during message dispatch. Allow for the
// possibility of re-entering ReadMore() through message dispatch.
bool was_destroyed_during_dispatch = false;
bool* previous_destroyed_flag = destroyed_flag_;
destroyed_flag_ = &was_destroyed_during_dispatch;
MojoResult rv = ReadAndDispatchMessage(
message_pipe_.get(), incoming_receiver_, &receiver_result);
if (read_result)
*read_result = rv;
if (was_destroyed_during_dispatch) {
if (previous_destroyed_flag)
*previous_destroyed_flag = true; // Propagate flag.
return false;
}
destroyed_flag_ = previous_destroyed_flag;
if (rv == MOJO_RESULT_SHOULD_WAIT)
return true;
if (rv != MOJO_RESULT_OK ||
(enforce_errors_from_incoming_receiver_ && !receiver_result)) {
NotifyError();
return false;
}
return true;
}
void Connector::ReadAllAvailableMessages() {
while (!error_) {
MojoResult rv;
// Return immediately if |this| was destroyed. Do not touch any members!
if (!ReadSingleMessage(&rv))
return;
if (rv == MOJO_RESULT_SHOULD_WAIT) {
WaitToReadMore();
break;
}
}
}
void Connector::CancelWait() {
if (!async_wait_id_)
return;
waiter_->CancelWait(async_wait_id_);
async_wait_id_ = 0;
}
void Connector::NotifyError() {
error_ = true;
CancelWait();
if (error_handler_)
error_handler_->OnConnectionError();
}
} // namespace internal
} // namespace mojo
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