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content/browser/sensors/provider_impl.cc

+// Copyright (c) 2011 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 "base/file_util.h"
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "base/string_util.h"
+#include "base/stringprintf.h"
+#include "content/browser/sensors/provider_impl.h"
+
+#include <vector>
+
+#include <fcntl.h>
+#include <unistd.h>
+
+// TODO: The thread safety varies from tolerable (normal operation) to
+//       non-existent (delete). Need to fix that.
+
+namespace sensors {
+
+class ConnectionImpl : public Connection {
+ public:
+  ConnectionImpl(ProviderImpl* provider, Listener* listener)
+      : provider_(provider), listener_(listener),
+        listener_proxy_(base::MessageLoopProxy::CreateForCurrentThread()) {
+  }
+
+  virtual void Start(Channel channel, const std::string& data) {
+    provider_->ConnectionStarted(this, channel, data);
+  }
+
+  virtual void Stop(Channel channel) {
+    provider_->ConnectionStopped(this, channel);
+  }
+
+  virtual void Close() {
+    provider_->ConnectionClosed(this);
+    listener_ = NULL;
+  }
+
+  virtual void FireSensorChanged(Channel channel, const std::string& data) {
+    if (!listener_proxy_->BelongsToCurrentThread()) {
+      listener_proxy_->PostTask(FROM_HERE, NewRunnableMethod(
+          this, &ConnectionImpl::FireSensorChanged, channel, data));
+      return;
+    }
+
+    if (listener_)
+      listener_->SensorChanged(channel, data);
+  }
+
+ private:
+  ProviderImpl* provider_;
+  Listener* listener_;
+  scoped_refptr<base::MessageLoopProxy> listener_proxy_;
+};
+
+ProviderImpl* ProviderImpl::GetInstance() {
+  return Singleton<ProviderImpl>::get();
+}
+
+ProviderImpl::ProviderImpl()
+    : device_fd_(-1),
+      device_buf_end_(0) {
+  base::Thread* thread = new base::Thread("sensor provider");
+  thread->Start();
+
+  device_proxy_ = thread->message_loop_proxy();
+
+  device_proxy_->PostTask(FROM_HERE,
+    NewRunnableMethod(this, &ProviderImpl::DeviceStart));
+}
+
+ProviderImpl::~ProviderImpl() {
+  DCHECK(device_fd_ == -1);
+}
+
+Connection* ProviderImpl::Open(Listener* listener) {
+  ConnectionImpl* conn = new ConnectionImpl(this, listener);
+  connections_.AddObserver(conn);
+  return conn;
+}
+
+void ProviderImpl::FireSensorChanged(Channel channel, const std::string& data) {
+  FOR_EACH_OBSERVER(ConnectionImpl, connections_, FireSensorChanged(channel, data));
+}
+
+void ProviderImpl::DeviceStart() {
+  DCHECK(device_proxy_->BelongsToCurrentThread());
+
+  static const char* kDeviceEventPath = "/dev/device0:event0";
+  static const char* kEnableEventPath =
+    "/sys/bus/iio/devices/device0:event0/tilt_change_en";

[Jói, 2011/06/30 19:50:50]

This seems device-dependent, or at least POSIX-specific, yet the file is being
compiled on all platforms including Windows.

+
+  int ret;
+
+  int fd = open(kDeviceEventPath, O_RDONLY, 0);
+  if (fd < 0) {
+    LOG(ERROR) << "Failed to open accelerometer: " << strerror(errno);
+    LOG(ERROR) << "Orientation will be unavailable until Chrome is restarted.";
+    return;
+  }
+
+  ret = file_util::WriteFile(FilePath(kEnableEventPath), "1\n", 2);
+  if (ret < 0) {
+    LOG(ERROR) << "Failed to enable accelerometer: " << strerror(errno);
+    LOG(ERROR) << "Orientation will be unavailable until Chrome is restarted.";
+    return;
+  }
+
+  device_fd_ = fd;
+  device_proxy_->PostDelayedTask(FROM_HERE,
+    NewRunnableMethod(this, &ProviderImpl::DeviceRead), 1000);
+}
+
+struct iio_event {
+  uint32 code;
+  uint32 unused;
+  uint64 time;
+};
+
+void ProviderImpl::DeviceRead() {
+  DCHECK(device_proxy_->BelongsToCurrentThread());
+
+  if (!DoDeviceRead()) {
+    LOG(ERROR) << "Orientation will be unavailable until Chrome is restarted.";
+    return;
+  }
+
+  device_proxy_->PostTask(FROM_HERE,
+    NewRunnableMethod(this, &ProviderImpl::DeviceRead));
+}
+
+bool ProviderImpl::DoDeviceRead() {
+  DCHECK(device_proxy_->BelongsToCurrentThread());
+  DCHECK(device_fd_ != -1);
+
+  ssize_t rv = read(device_fd_, device_buf_ + device_buf_end_,
+                    sizeof(device_buf_) - device_buf_end_);
+  if (rv < 0) {
+    if (errno == EAGAIN || errno == EWOULDBLOCK)
+      return true; // Do not have any data to read
+
+    LOG(ERROR) << "Failed to read accelerometer events: " << strerror(errno);
+    return false;
+  }
+  device_buf_end_ += rv;
+
+  if (device_buf_end_ < kIIOMessageSize)
+    return true;  // Do not have a complete message yet
+
+  device_buf_end_ = 0;
+
+  struct iio_event* event = reinterpret_cast<struct iio_event*>(device_buf_);
+
+  // HACK: These orientations are rearranged from their definitions in the
+  //       accelerometer driver so that the development devices report their
+  //       orientation correctly. This will eventually be configured in the
+  //       sensor manager, and the data received by Chrome will be correct.
+  ScreenOrientationChange change;
+  switch (event->code >> 8) {
+    case 0: change.upward = ScreenOrientationChange::TOP; break;
+    case 1: change.upward = ScreenOrientationChange::BOTTOM; break;
+    case 2: change.upward = ScreenOrientationChange::RIGHT; break;
+    case 3: change.upward = ScreenOrientationChange::LEFT; break;
+    case 4: change.upward = ScreenOrientationChange::FRONT; break;
+    case 5: change.upward = ScreenOrientationChange::BACK; break;
+    default: return true;  // drop unknown orientation
+  }
+
+  std::string data(reinterpret_cast<const char*>(&change), sizeof(change));
+  FireSensorChanged(kScreenOrientationChannel, data);
+  return true;
+}
+
+void ProviderImpl::DeviceStop() {
+  DCHECK(device_proxy_->BelongsToCurrentThread());
+
+  close(device_fd_);
+  device_fd_ = -1;
+}
+
+void ProviderImpl::ConnectionClosed(ConnectionImpl* conn) {
+  connections_.RemoveObserver(conn);
+}
+
+void ProviderImpl::ConnectionStarted(ConnectionImpl* conn,
+                                     Channel channel, const std::string& data) {
+  
+  connections_.AddObserver(conn);
+}
+
+void ProviderImpl::ConnectionStopped(ConnectionImpl* conn, Channel channel) {
+  connections_.RemoveObserver(conn);
+}
+
+}  // namespace sensors