HID backend

device/hid/hid_connection_linux.cc

+// Copyright (c) 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/hid/hid_connection_linux.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <libudev.h>
+#include <linux/hidraw.h>
+#include <string>
+
+#include "base/threading/thread_restrictions.h"
+#include "device/hid/hid_service.h"
+#include "device/hid/hid_service_linux.h"
+
+
+namespace device {
+
+namespace {
+
+const char* kHidrawSubsystem = "hidraw";
+
+}  // namespace
+
+HidConnectionLinux::HidConnectionLinux(HidDeviceInfo device_info,
+                                       ScopedUdevDevicePtr udev_raw_device)
+    : HidConnection(device_info),
+      initialized_(false) {
+  udev_device* dev = udev_raw_device.get();
+  std::string dev_node;
+  if (!FindHidrawDevNode(dev, &dev_node)) {
+    LOG(ERROR) << "Cannot open HID device as hidraw device.";
+    return;
+  }
+
+  base::PlatformFileError error;
+
+  int flags = base::PLATFORM_FILE_OPEN |
+              base::PLATFORM_FILE_READ |
+              base::PLATFORM_FILE_WRITE |
+              base::PLATFORM_FILE_EXCLUSIVE_READ |
+              base::PLATFORM_FILE_EXCLUSIVE_WRITE;
+
+  base::PlatformFile device_file = base::CreatePlatformFile(
+      base::FilePath(dev_node),
+      flags,
+      NULL,
+      &error);
+  if (error || device_file <= 0) {
+    LOG(ERROR) << error;
+    if (device_file)
+      base::ClosePlatformFile(device_file);
+    return;
+  }
+  if (fcntl(device_file, F_SETFL, fcntl(device_file, F_GETFL) | O_NONBLOCK)) {
+    PLOG(ERROR) << "Failed to set non-blocking flag to device file.";
+    return;
+  }
+  device_file_ = device_file;
+
+  if (!base::MessageLoopForIO::current()->WatchFileDescriptor(
+      device_file_,
+      true,
+      base::MessageLoopForIO::WATCH_READ_WRITE,
+      &device_file_watcher_,
+      this)) {
+    LOG(ERROR) << "Cannot start watching file descriptor.";
+    return;
+  }
+
+  initialized_ = true;
+}
+
+HidConnectionLinux::~HidConnectionLinux() {
+  Disconnect();
+}
+
+void HidConnectionLinux::OnFileCanReadWithoutBlocking(int fd) {
+  DCHECK_EQ(fd, device_file_);
+  DCHECK(initialized_);
+
+  uint8 buffer[1024] = {0};
+  int bytes = read(device_file_, buffer, 1024);
+  if (bytes < 0) {
+    if (errno == EAGAIN) {
+      return;
+    }
+    Disconnect();
+    return;
+  }
+  scoped_refptr<net::IOBuffer> io_buffer(new net::IOBuffer(bytes));
+  memcpy(io_buffer->data(), buffer, bytes);
+  input_reports_.push(std::make_pair(io_buffer, bytes));
+
+  ProcessReadQueue();
+}
+
+void HidConnectionLinux::OnFileCanWriteWithoutBlocking(int fd) {
+  DCHECK_EQ(fd, device_file_);
+  DCHECK(initialized_);
+
+  if (!write_queue_.empty()) {
+    Tuple3<scoped_refptr<net::IOBuffer>, size_t, HidIOCallback> head
+        = write_queue_.front();
+    write_queue_.pop();
+    int bytes = write(device_file_, head.a->data(), head.b);
+    if (bytes < 0) {
+      if (errno == EAGAIN) {
+        return;
+      }
+      Disconnect();
+      return;
+    }
+    head.c.Run(true, NULL, bytes);
+  }
+}
+
+void HidConnectionLinux::Disconnect() {
+  if (!initialized_)
+    return;
+  initialized_ = false;
+  device_file_watcher_.StopWatchingFileDescriptor();
+  close(device_file_);
+  while (!read_queue_.empty()) {
+    HidIOCallback callback = read_queue_.front();
+    read_queue_.pop();
+    callback.Run(false, NULL, 0);
+  }
+  while (!write_queue_.empty()) {
+    Tuple3<scoped_refptr<net::IOBuffer>, size_t, HidIOCallback> head
+        = write_queue_.front();
+    write_queue_.pop();
+    head.c.Run(false, NULL, 0);
+  }
+}
+
+void HidConnectionLinux::Read(const HidIOCallback& callback) {
+  if (!initialized_) {
+    DCHECK(read_queue_.empty());
+    // There might be unread reports.
+    if (!input_reports_.empty()){
+      std::pair<scoped_refptr<net::IOBuffer>, size_t> head =
+          input_reports_.front();
+      input_reports_.pop();
+      callback.Run(true, head.first, head.second);
+      return;
+    }
+    callback.Run(false, NULL, 0);
+    return;
+  } else {
+    read_queue_.push(callback);
+    ProcessReadQueue();
+  }
+}
+
+void HidConnectionLinux::Write(scoped_refptr<net::IOBuffer> buffer,
+                               size_t size,
+                               const HidIOCallback& callback) {
+  if (!initialized_) {
+    callback.Run(false, NULL, 0);
+    return;
+  } else {
+    write_queue_.push(MakeTuple(buffer, size, callback));
+  }
+}
+
+void HidConnectionLinux::GetFeatureReport(const HidIOCallback& callback) {
+  if (!initialized_) {
+    callback.Run(false, NULL, 0);
+    return;
+  }
+  NOTIMPLEMENTED();
+}
+
+void HidConnectionLinux::SendFeatureReport(scoped_refptr<net::IOBuffer> buffer,
+                                           size_t size,
+                                           const HidIOCallback& callback) {
+  if (!initialized_) {
+    callback.Run(false, NULL, 0);
+    return;
+  }
+  NOTIMPLEMENTED();
+}
+
+void HidConnectionLinux::ProcessReadQueue() {
+  while(read_queue_.size() && input_reports_.size()) {
+    HidIOCallback callback = read_queue_.front();
+    read_queue_.pop();
+    std::pair<scoped_refptr<net::IOBuffer>, size_t> report =
+        input_reports_.front();
+    input_reports_.pop();
+    callback.Run(true, report.first, report.second);
+  }
+}
+
+bool HidConnectionLinux::FindHidrawDevNode(udev_device* parent,
+                                           std::string* result) {
+  udev* udev = udev_device_get_udev(parent);
+  if (!udev)
+      return false;
+
+  ScopedUdevEnumeratePtr enumerate(udev_enumerate_new(udev));
+  if (!enumerate)
+    return false;
+
+  if (udev_enumerate_add_match_parent(enumerate.get(), parent)) {
+    return false;
+  }
+
+  if (udev_enumerate_add_match_subsystem(enumerate.get(), kHidrawSubsystem)) {
+    return false;
+  }
+  if (udev_enumerate_scan_devices(enumerate.get())) {
+    return false;
+  }
+
+  udev_list_entry* devices = udev_enumerate_get_list_entry(enumerate.get());
+  for (udev_list_entry* i = devices; i != NULL;
+      i = udev_list_entry_get_next(i)) {
+    ScopedUdevDevicePtr hid_dev(
+        udev_device_new_from_syspath(udev, udev_list_entry_get_name(i)));
+    const char* raw_path = udev_device_get_devnode(hid_dev.get());
+    if (raw_path) {
+      *result = raw_path;
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace device