Implement the gamepad API in the IPC proxy

content/browser/gamepad/gamepad_platform_data_fetcher_linux.cc

+// Copyright (c) 2012 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 "content/browser/gamepad/gamepad_platform_data_fetcher_linux.h"
+
+#include <fcntl.h>
+#include <libudev.h>
+#include <linux/joystick.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "base/debug/trace_event.h"
+#include "base/eintr_wrapper.h"
+#include "base/message_loop.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
+#include "base/stringprintf.h"
+#include "base/utf_string_conversions.h"
+#include "content/browser/udev_linux.h"
+
+namespace {
+
+const char kInputSubsystem[] = "input";
+const char kUsbSubsystem[] = "usb";
+const char kUsbDeviceType[] = "usb_device";
+const float kMaxLinuxAxisValue = 32767.0;
+
+void CloseFileDescriptorIfValid(int fd) {
+  if (fd >= 0)
+    close(fd);
+}
+
+bool IsGamepad(udev_device* dev, int* index, std::string* path) {
+  if (!udev_device_get_property_value(dev, "ID_INPUT_JOYSTICK"))
+    return false;
+
+  const char* node_path = udev_device_get_devnode(dev);
+  if (!node_path)
+    return false;
+
+  static const char kJoystickRoot[] = "/dev/input/js";
+  bool is_gamepad = StartsWithASCII(node_path, kJoystickRoot, true);
+  if (!is_gamepad)
+    return false;
+
+  int tmp_idx = -1;
+  const int base_len = sizeof(kJoystickRoot) - 1;
+  base::StringPiece str(&node_path[base_len], strlen(node_path) - base_len);
+  if (!base::StringToInt(str, &tmp_idx))
+    return false;
+  if (tmp_idx < 0 ||
+      tmp_idx >= static_cast<int>(WebKit::WebGamepads::itemsLengthCap)) {
+    return false;
+  }
+  *index = tmp_idx;
+  *path = node_path;
+  return true;
+}
+
+}  // namespace
+
+namespace content {
+
+using WebKit::WebGamepad;
+using WebKit::WebGamepads;
+
+GamepadPlatformDataFetcherLinux::GamepadPlatformDataFetcherLinux() {
+  for (size_t i = 0; i < arraysize(device_fds_); ++i)
+    device_fds_[i] = -1;
+  memset(mappers_, 0, sizeof(mappers_));
+
+  std::vector<UdevLinux::UdevMonitorFilter> filters;
+  filters.push_back(
+      content::UdevLinux::UdevMonitorFilter(kInputSubsystem, NULL));
+  udev_.reset(
+      new UdevLinux(filters,
+                    base::Bind(&GamepadPlatformDataFetcherLinux::RefreshDevice,
+                               base::Unretained(this))));
+
+  EnumerateDevices();
+}
+
+GamepadPlatformDataFetcherLinux::~GamepadPlatformDataFetcherLinux() {
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i)
+    CloseFileDescriptorIfValid(device_fds_[i]);
+}
+
+void GamepadPlatformDataFetcherLinux::GetGamepadData(WebGamepads* pads, bool) {
+  TRACE_EVENT0("GAMEPAD", "GetGamepadData");
+
+  data_.length = WebGamepads::itemsLengthCap;
+
+  // Update our internal state.
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+    if (device_fds_[i] >= 0) {
+      ReadDeviceData(i);
+    }
+  }
+
+  // Copy to the current state to the output buffer, using the mapping
+  // function, if there is one available.
+  pads->length = data_.length;
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+    if (mappers_[i])
+      mappers_[i](data_.items[i], &pads->items[i]);
+    else
+      pads->items[i] = data_.items[i];
+  }
+}
+
+// Used during enumeration, and monitor notifications.
+void GamepadPlatformDataFetcherLinux::RefreshDevice(udev_device* dev) {
+  int index;
+  std::string node_path;
+  if (IsGamepad(dev, &index, &node_path)) {
+    int& device_fd = device_fds_[index];
+    WebGamepad& pad = data_.items[index];
+    GamepadStandardMappingFunction& mapper = mappers_[index];
+
+    CloseFileDescriptorIfValid(device_fd);
+
+    // The device pointed to by dev contains information about the logical
+    // joystick device. In order to get the information about the physical
+    // hardware, get the parent device that is also in the "input" subsystem.
+    // This function should just walk up the tree one level.
+    dev = udev_device_get_parent_with_subsystem_devtype(
+        dev,
+        kInputSubsystem,
+        NULL);
+    if (!dev) {
+      // Unable to get device information, don't use this device.
+      device_fd = -1;
+      pad.connected = false;
+      return;
+    }
+
+    device_fd = HANDLE_EINTR(open(node_path.c_str(), O_RDONLY | O_NONBLOCK));
+    if (device_fd < 0) {
+      // Unable to open device, don't use.
+      pad.connected = false;
+      return;
+    }
+
+    const char* vendor_id = udev_device_get_sysattr_value(dev, "id/vendor");
+    const char* product_id = udev_device_get_sysattr_value(dev, "id/product");
+    mapper = GetGamepadStandardMappingFunction(vendor_id, product_id);
+
+    // Driver returns utf-8 strings here, so combine in utf-8 first and
+    // convert to WebUChar later once we've picked an id string.
+    const char* name = udev_device_get_sysattr_value(dev, "name");
+    std::string name_string = base::StringPrintf("%s", name);
+
+    // In many cases the information the input subsystem contains isn't
+    // as good as the information that the device bus has, walk up further
+    // to the subsystem/device type "usb"/"usb_device" and if this device
+    // has the same vendor/product id, prefer the description from that.
+    struct udev_device *usb_dev = udev_device_get_parent_with_subsystem_devtype(
+        dev,
+        kUsbSubsystem,
+        kUsbDeviceType);
+    if (usb_dev) {
+      const char* usb_vendor_id =
+          udev_device_get_sysattr_value(usb_dev, "idVendor");
+      const char* usb_product_id =
+          udev_device_get_sysattr_value(usb_dev, "idProduct");
+
+      if (strcmp(vendor_id, usb_vendor_id) == 0 &&
+          strcmp(product_id, usb_product_id) == 0) {
+        const char* manufacturer =
+            udev_device_get_sysattr_value(usb_dev, "manufacturer");
+        const char* product = udev_device_get_sysattr_value(usb_dev, "product");
+
+        // Replace the previous name string with one containing the better
+        // information, again driver returns utf-8 strings here so combine
+        // in utf-8 for conversion to WebUChar below.
+        name_string = base::StringPrintf("%s %s", manufacturer, product);
+      }
+    }
+
+    // Append the vendor and product information then convert the utf-8
+    // id string to WebUChar.
+    std::string id = name_string + base::StringPrintf(
+        " (%sVendor: %s Product: %s)",
+        mapper ? "STANDARD GAMEPAD " : "",
+        vendor_id,
+        product_id);
+    TruncateUTF8ToByteSize(id, WebGamepad::idLengthCap - 1, &id);
+    string16 tmp16 = UTF8ToUTF16(id);
+    memset(pad.id, 0, sizeof(pad.id));
+    tmp16.copy(pad.id, arraysize(pad.id) - 1);
+
+    pad.connected = true;
+  }
+}
+
+void GamepadPlatformDataFetcherLinux::EnumerateDevices() {
+  udev_enumerate* enumerate = udev_enumerate_new(udev_->udev_handle());
+  if (!enumerate)
+    return;
+  int ret = udev_enumerate_add_match_subsystem(enumerate, kInputSubsystem);
+  if (ret != 0)
+    return;
+  ret = udev_enumerate_scan_devices(enumerate);
+  if (ret != 0)
+    return;
+
+  udev_list_entry* devices = udev_enumerate_get_list_entry(enumerate);
+  for (udev_list_entry* dev_list_entry = devices;
+       dev_list_entry != NULL;
+       dev_list_entry = udev_list_entry_get_next(dev_list_entry)) {
+    // Get the filename of the /sys entry for the device and create a
+    // udev_device object (dev) representing it
+    const char* path = udev_list_entry_get_name(dev_list_entry);
+    udev_device* dev = udev_device_new_from_syspath(udev_->udev_handle(), path);
+    if (!dev)
+      continue;
+    RefreshDevice(dev);
+    udev_device_unref(dev);
+  }
+  // Free the enumerator object
+  udev_enumerate_unref(enumerate);
+}
+
+void GamepadPlatformDataFetcherLinux::ReadDeviceData(size_t index) {
+  // Linker does not like CHECK_LT(index, WebGamepads::itemsLengthCap). =/
+  if (index >= WebGamepads::itemsLengthCap) {
+    CHECK(false);
+    return;
+  }
+
+  const int& fd = device_fds_[index];
+  WebGamepad& pad = data_.items[index];
+  DCHECK_GE(fd, 0);
+
+  js_event event;
+  while (HANDLE_EINTR(read(fd, &event, sizeof(struct js_event)) > 0)) {
+    size_t item = event.number;
+    if (event.type & JS_EVENT_AXIS) {
+      if (item >= WebGamepad::axesLengthCap)
+        continue;
+      pad.axes[item] = event.value / kMaxLinuxAxisValue;
+      if (item >= pad.axesLength)
+        pad.axesLength = item + 1;
+    } else if (event.type & JS_EVENT_BUTTON) {
+      if (item >= WebGamepad::buttonsLengthCap)
+        continue;
+      pad.buttons[item] = event.value ? 1.0 : 0.0;
+      if (item >= pad.buttonsLength)
+        pad.buttonsLength = item + 1;
+    }
+    pad.timestamp = event.time;
+  }
+}
+
+}  // namespace content