Implement chrome.brailleDisplayPrivate API

chrome/browser/extensions/api/braille_display_private/brlapi_connection.cc

+// Copyright (c) 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 "chrome/browser/extensions/api/braille_display_private/brlapi_connection.h"
+
+#include "base/chromeos/chromeos_version.h"
+#include "base/message_loop/message_loop.h"
+
+namespace extensions {
+using base::MessageLoopForIO;
+namespace api {
+namespace braille_display_private {
+
+namespace {
+// Default virtual terminal.  This can be overriden by setting the
+// WINDOWPATH environment variable.  This is only used when not running
+// under Crhome OS (that is in aura for a Linux desktop).
+// TODO(plundblad): Find a way to detect the controlling terminal of the
+// X server.
+static const int kDefaultTtyLinux = 7;
+#if defined(OS_CHROMEOS)
+// The GUI is always running on vt1 in Chrome OS.
+static const int kDefaultTtyChromeOS = 1;
+#endif
+}  // namespace
+
+class BrlapiConnectionImpl : public BrlapiConnection,
+                             MessageLoopForIO::Watcher {
+ public:
+  BrlapiConnectionImpl(LibBrlapiLoader* loader) :
+      libbrlapi_loader_(loader) {}
+
+  virtual ~BrlapiConnectionImpl() {
+    Disconnect();
+  }
+
+  virtual bool Connect(const OnDataReadyCallback& on_data_ready) OVERRIDE;
+  virtual void Disconnect() OVERRIDE;
+  virtual bool Connected() OVERRIDE { return handle_; }
+  virtual brlapi_error_t* BrlapiError() OVERRIDE;
+  virtual std::string BrlapiStrError() OVERRIDE;
+  virtual bool GetDisplaySize(size_t* size) OVERRIDE;
+  virtual bool WriteDots(const unsigned char* cells) OVERRIDE;
+  virtual int ReadKey(brlapi_keyCode_t* keyCode) OVERRIDE;
+
+  // MessageLoopForIO::Watcher
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE {
+    on_data_ready_.Run();
+  }
+
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE {}
+
+ private:
+  bool CheckConnected();
+
+  LibBrlapiLoader* libbrlapi_loader_;
+  scoped_ptr<brlapi_handle_t, base::FreeDeleter> handle_;
+  MessageLoopForIO::FileDescriptorWatcher fd_controller_;
+  OnDataReadyCallback on_data_ready_;
+
+  DISALLOW_COPY_AND_ASSIGN(BrlapiConnectionImpl);
+};
+
+BrlapiConnection::BrlapiConnection() {
+}
+
+BrlapiConnection::~BrlapiConnection() {
+}
+
+scoped_ptr<BrlapiConnection> BrlapiConnection::Create(
+    LibBrlapiLoader* loader) {
+  DCHECK(loader->loaded());
+  return scoped_ptr<BrlapiConnection>(new BrlapiConnectionImpl(loader));
+}
+
+bool BrlapiConnectionImpl::Connect(const OnDataReadyCallback& on_data_ready) {
+  DCHECK(!handle_);
+  handle_.reset((brlapi_handle_t*) malloc(
+      libbrlapi_loader_->brlapi_getHandleSize()));
+  int fd = libbrlapi_loader_->brlapi__openConnection(handle_.get(), NULL, NULL);
+  if (fd < 0) {
+    handle_.reset();
+    LOG(ERROR) << "Error connecting to brlapi: " << BrlapiStrError();
+    return false;
+  }
+  int path[2] = {0, 0};
+  int pathElements = 0;
+#if defined(OS_CHROMEOS)
+  if (base::chromeos::IsRunningOnChromeOS())
+    path[pathElements++] = kDefaultTtyChromeOS;
+#endif
+  if (pathElements == 0 && getenv("WINDOWPATH") == NULL)
+    path[pathElements++] = kDefaultTtyLinux;
+  if (libbrlapi_loader_->brlapi__enterTtyModeWithPath(
+          handle_.get(), path, pathElements, NULL) < 0) {
+    LOG(ERROR) << "brlapi: couldn't enter tty mode: " << BrlapiStrError();
+    Disconnect();
+    return false;
+  }
+
+  const brlapi_keyCode_t extraKeys[] = {
+    BRLAPI_KEY_TYPE_CMD | BRLAPI_KEY_CMD_OFFLINE,
+  };
+  if (libbrlapi_loader_->brlapi__acceptKeys(
+          handle_.get(), brlapi_rangeType_command, extraKeys,
+          arraysize(extraKeys)) < 0) {
+    LOG(ERROR) << "Couldn't acceptKeys: " << BrlapiStrError();
+    Disconnect();
+    return false;
+  }
+
+  if (!MessageLoopForIO::current()->WatchFileDescriptor(
+          fd, true, MessageLoopForIO::WATCH_READ, &fd_controller_, this)) {
+    LOG(ERROR) << "Couldn't watch file descriptor " << fd;
+    Disconnect();
+    return false;
+  }
+
+  on_data_ready_ = on_data_ready;
+
+  return true;
+}
+
+void BrlapiConnectionImpl::Disconnect() {
+  if (!handle_) {
+    return;
+  }
+  fd_controller_.StopWatchingFileDescriptor();
+  libbrlapi_loader_->brlapi__closeConnection(
+      handle_.get());
+  handle_.reset();
+}
+
+brlapi_error_t* BrlapiConnectionImpl::BrlapiError() {
+  return libbrlapi_loader_->brlapi_error_location();
+}
+
+std::string BrlapiConnectionImpl::BrlapiStrError() {
+  return libbrlapi_loader_->brlapi_strerror(BrlapiError());
+}
+
+bool BrlapiConnectionImpl::GetDisplaySize(size_t* size) {
+  if (!CheckConnected()) {
+    return false;
+  }
+  unsigned int columns, rows;
+  if (libbrlapi_loader_->brlapi__getDisplaySize(
+          handle_.get(), &columns, &rows) < 0) {
+    LOG(ERROR) << "Couldn't get braille display size " << BrlapiStrError();
+    return false;
+  }
+  *size = columns * rows;
+  return true;
+}
+
+bool BrlapiConnectionImpl::WriteDots(const unsigned char* cells) {
+  if (!CheckConnected())
+    return false;
+  if (libbrlapi_loader_->brlapi__writeDots(handle_.get(), cells) < 0) {
+    LOG(ERROR) << "Couldn't write to brlapi: " << BrlapiStrError();
+    return false;
+  }
+  return true;
+}
+
+int BrlapiConnectionImpl::ReadKey(brlapi_keyCode_t* key_code) {
+  if (!CheckConnected())
+    return -1;
+  return libbrlapi_loader_->brlapi__readKey(
+      handle_.get(), 0 /*wait*/, key_code);
+}
+
+bool BrlapiConnectionImpl::CheckConnected() {
+  if (!handle_) {
+    BrlapiError()->brlerrno = BRLAPI_ERROR_ILLEGAL_INSTRUCTION;
+    return false;
+  }
+  return true;
+}
+
+}  // braille_display_private
+}  // api
+}  // extensions