Add data pipe wrappers to be used to implement serial receive.

device/serial/data_receiver.cc

+// Copyright 2014 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 "device/serial/data_receiver.h"
+
+#include <limits>
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "device/serial/async_waiter.h"
+
+namespace device {
+
+// Represents a receive that is not yet fulfilled.
+class DataReceiver::PendingReceive {
+ public:
+  PendingReceive(DataReceiver* receiver,
+                 const ReceiveDataCallback& callback,
+                 const ReceiveErrorCallback& error_callback,
+                 int32_t fatal_error_value);
+
+  // Dispatches |data| to |receive_callback_|.
+  void DispatchData(const void* data, uint32_t num_bytes);
+
+  // Reports |error| to |receive_error_callback_| if it is an appropriate time.
+  // Returns whether it dispatched |error|.
+  bool DispatchError(DataReceiver::PendingError* error,
+                     uint32_t bytes_received);
+
+  // Reports |fatal_error_value_| to |receive_error_callback_|.
+  void DispatchFatalError();
+
+ private:
+  class Buffer;
+
+  // Invoked when the user is finished with the ReadOnlyBuffer provided to
+  // |receive_callback_|.
+  void Done(uint32_t num_bytes);
+
+  // The DataReceiver that owns this.
+  DataReceiver* receiver_;
+
+  // The callback to dispatch data.
+  ReceiveDataCallback receive_callback_;
+
+  // The callback to report errors.
+  ReceiveErrorCallback receive_error_callback_;
+
+  // The error value to report when DispatchFatalError() is called.
+  const int32_t fatal_error_value_;
+
+  // True if the user owns a buffer passed to |receive_callback_| as part of
+  // DispatchData().
+  bool buffer_in_use_;
+};
+
+// A ReadOnlyBuffer implementation that provides a view of a data pipe owned by
+// a DataReceiver.
+class DataReceiver::PendingReceive::Buffer : public ReadOnlyBuffer {
+ public:
+  Buffer(scoped_refptr<DataReceiver> pipe,
+         PendingReceive* receive,
+         const char* buffer,
+         uint32_t buffer_size);
+  virtual ~Buffer();
+
+  // ReadOnlyBuffer overrides.
+  virtual const char* GetData() OVERRIDE;
+  virtual uint32_t GetSize() OVERRIDE;
+  virtual void Done(uint32_t bytes_consumed) OVERRIDE;
+  virtual void DoneWithError(uint32_t bytes_consumed, int32_t error) OVERRIDE;
+
+ private:
+  // The DataReceiver whose data pipe we are providing a view.
+  scoped_refptr<DataReceiver> receiver_;
+
+  // The PendingReceive to which this buffer has been created in response.
+  PendingReceive* pending_receive_;
+
+  const char* buffer_;
+  uint32_t buffer_size_;
+};
+
+// Represents an error received from the DataSource.
+struct DataReceiver::PendingError {
+  PendingError(uint32_t offset, int32_t error)
+      : offset(offset), error(error), dispatched(false) {}
+
+  // The location within the data stream where the error occurred.
+  const uint32_t offset;
+
+  // The value of the error that occurred.
+  const int32_t error;
+
+  // Whether the error has been dispatched to the user.
+  bool dispatched;
+};
+
+DataReceiver::DataReceiver(mojo::InterfacePtr<serial::DataSource> source,
+                           uint32_t buffer_size,
+                           int32_t fatal_error_value)
+    : source_(source.Pass()),
+      fatal_error_value_(fatal_error_value),
+      bytes_received_(0),
+      shut_down_(false),
+      weak_factory_(this) {
+  MojoCreateDataPipeOptions options = {
+      sizeof(options), MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE, 1, buffer_size,
+  };
+  mojo::ScopedDataPipeProducerHandle remote_handle;
+  MojoResult result = mojo::CreateDataPipe(&options, &remote_handle, &handle_);
+  DCHECK_EQ(MOJO_RESULT_OK, result);
+  source_->Init(remote_handle.Pass());
+  source_.set_client(this);
+}
+
+bool DataReceiver::Receive(const ReceiveDataCallback& callback,
+                           const ReceiveErrorCallback& error_callback) {
+  DCHECK(!callback.is_null() && !error_callback.is_null());
+  if (pending_receive_ || shut_down_)
+    return false;
+  // When the DataSource encounters an error, it pauses transmission. When the
+  // user starts a new receive following notification of the error (via
+  // |error_callback| of the previous Receive call) of the error we can tell the
+  // DataSource to resume transmission of data.
+  if (pending_error_ && pending_error_->dispatched) {
+    source_->Resume();
+    pending_error_.reset();
+  }
+
+  pending_receive_.reset(
+      new PendingReceive(this, callback, error_callback, fatal_error_value_));
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(&DataReceiver::ReceiveInternal, weak_factory_.GetWeakPtr()));
+  return true;
+}
+
+DataReceiver::~DataReceiver() {
+  ShutDown();
+}
+
+void DataReceiver::OnError(uint32_t offset, int32_t error) {
+  if (shut_down_)
+    return;
+
+  if (pending_error_) {
+    // When OnError is called by the DataSource, transmission of data is
+    // suspended. Thus we shouldn't receive another call to OnError until we
+    // have fully dealt with the error and called Resume to resume transmission
+    // (see Receive()). Under normal operation we should never get here, but if
+    // we do (e.g. in the case of a hijacked service process) just shut down.
+    ShutDown();
+    return;
+  }
+  pending_error_.reset(new PendingError(offset, error));
+  if (pending_receive_ &&
+      pending_receive_->DispatchError(pending_error_.get(), bytes_received_)) {
+    pending_receive_.reset();
+    waiter_.reset();
+  }
+}
+
+void DataReceiver::OnConnectionError() {
+  ShutDown();
+}
+
+void DataReceiver::Done(uint32_t bytes_consumed) {
+  if (shut_down_)
+    return;
+
+  DCHECK(pending_receive_);
+  MojoResult result = mojo::EndReadDataRaw(handle_.get(), bytes_consumed);
+  DCHECK_EQ(MOJO_RESULT_OK, result);
+  pending_receive_.reset();
+  bytes_received_ += bytes_consumed;
+}
+
+void DataReceiver::OnDoneWaiting(MojoResult result) {
+  DCHECK(pending_receive_ && !shut_down_ && waiter_);
+  waiter_.reset();
+  if (result != MOJO_RESULT_OK) {
+    ShutDown();
+    return;
+  }
+  ReceiveInternal();
+}
+
+void DataReceiver::ReceiveInternal() {
+  if (shut_down_)
+    return;
+  DCHECK(pending_receive_);
+  if (pending_error_ &&
+      pending_receive_->DispatchError(pending_error_.get(), bytes_received_)) {
+    pending_receive_.reset();
+    waiter_.reset();
+    return;
+  }
+
+  const void* data;
+  uint32_t num_bytes = std::numeric_limits<uint32_t>::max();
+  MojoResult result = mojo::BeginReadDataRaw(
+      handle_.get(), &data, &num_bytes, MOJO_READ_DATA_FLAG_NONE);
+  if (result == MOJO_RESULT_OK) {
+    if (!CheckErrorNotInReadRange(num_bytes)) {
+      ShutDown();
+      return;
+    }
+
+    pending_receive_->DispatchData(data, num_bytes);
+    return;
+  }
+  if (result == MOJO_RESULT_SHOULD_WAIT) {
+    waiter_.reset(new AsyncWaiter(
+        handle_.get(),
+        MOJO_HANDLE_SIGNAL_READABLE,
+        base::Bind(&DataReceiver::OnDoneWaiting, weak_factory_.GetWeakPtr())));
+    return;
+  }
+  ShutDown();
+}
+
+bool DataReceiver::CheckErrorNotInReadRange(uint32_t num_bytes) {
+  DCHECK(pending_receive_);
+  if (!pending_error_)
+    return true;
+
+  DCHECK_NE(bytes_received_, pending_error_->offset);
+  DCHECK_NE(num_bytes, 0u);
+  uint32_t potential_bytes_received = bytes_received_ + num_bytes;
+  // bytes_received_ can overflow so we must consider two cases:
+  //   1. Both |bytes_received_| and |pending_error_->offset| have overflowed an
+  //      equal number of times. In this case, |potential_bytes_received| must
+  //      be in the range (|bytes_received|, |pending_error_->offset|]. Below
+  //      this range can only occur if |bytes_received_| overflows before
+  //      |pending_error_->offset|. Above can only occur if |bytes_received_|
+  //      overtakes |pending_error_->offset|.
+  //   2. |pending_error_->offset| has overflowed once more than
+  //      |bytes_received_|. In this case, |potential_bytes_received| must not
+  //      be in the range (|pending_error_->offset|, |bytes_received_|].
+  if ((bytes_received_ < pending_error_->offset &&
+       (potential_bytes_received > pending_error_->offset ||
+        potential_bytes_received <= bytes_received_)) ||
+      (bytes_received_ > pending_error_->offset &&
+       potential_bytes_received > pending_error_->offset &&
+       potential_bytes_received <= bytes_received_)) {
+    return false;
+  }
+  return true;
+}
+
+void DataReceiver::ShutDown() {
+  shut_down_ = true;
+  if (pending_receive_)
+    pending_receive_->DispatchFatalError();
+  pending_error_.reset();
+  waiter_.reset();
+}
+
+DataReceiver::PendingReceive::PendingReceive(
+    DataReceiver* receiver,
+    const ReceiveDataCallback& callback,
+    const ReceiveErrorCallback& error_callback,
+    int32_t fatal_error_value)
+    : receiver_(receiver),
+      receive_callback_(callback),
+      receive_error_callback_(error_callback),
+      fatal_error_value_(fatal_error_value),
+      buffer_in_use_(false) {
+}
+
+void DataReceiver::PendingReceive::DispatchData(const void* data,
+                                                uint32_t num_bytes) {
+  DCHECK(!buffer_in_use_);
+  buffer_in_use_ = true;
+  receive_callback_.Run(scoped_ptr<ReadOnlyBuffer>(
+      new Buffer(receiver_, this, static_cast<const char*>(data), num_bytes)));
+}
+
+bool DataReceiver::PendingReceive::DispatchError(PendingError* error,
+                                                 uint32_t bytes_received) {
+  DCHECK(!error->dispatched);
+  if (buffer_in_use_ || bytes_received != error->offset)
+    return false;
+
+  error->dispatched = true;
+  receive_error_callback_.Run(error->error);
+  return true;
+}
+
+void DataReceiver::PendingReceive::DispatchFatalError() {
+  receive_error_callback_.Run(fatal_error_value_);
+}
+
+void DataReceiver::PendingReceive::Done(uint32_t bytes_consumed) {
+  DCHECK(buffer_in_use_);
+  buffer_in_use_ = false;
+  receiver_->Done(bytes_consumed);
+}
+
+DataReceiver::PendingReceive::Buffer::Buffer(
+    scoped_refptr<DataReceiver> receiver,
+    PendingReceive* receive,
+    const char* buffer,
+    uint32_t buffer_size)
+    : receiver_(receiver),
+      pending_receive_(receive),
+      buffer_(buffer),
+      buffer_size_(buffer_size) {
+}
+
+DataReceiver::PendingReceive::Buffer::~Buffer() {
+  if (pending_receive_)
+    pending_receive_->Done(0);
+}
+
+const char* DataReceiver::PendingReceive::Buffer::GetData() {
+  return buffer_;
+}
+
+uint32_t DataReceiver::PendingReceive::Buffer::GetSize() {
+  return buffer_size_;
+}
+
+void DataReceiver::PendingReceive::Buffer::Done(uint32_t bytes_consumed) {
+  pending_receive_->Done(bytes_consumed);
+  pending_receive_ = NULL;
+  receiver_ = NULL;
+  buffer_ = NULL;
+  buffer_size_ = 0;
+}
+
+void DataReceiver::PendingReceive::Buffer::DoneWithError(
+    uint32_t bytes_consumed,
+    int32_t error) {
+  Done(bytes_consumed);
+}
+
+}  // namespace device