chrome.hid : enrich device info with Top-Level collections usages

device/hid/hid_service_linux.cc

Index: device/hid/hid_service_linux.cc
diff --git a/device/hid/hid_service_linux.cc b/device/hid/hid_service_linux.cc
index 04a3c160664468d68db60c74e28f4925e52ec63f..cede20f54d56e3726ea7158dd0382e5ab72969d0 100644
--- a/device/hid/hid_service_linux.cc
+++ b/device/hid/hid_service_linux.cc
@@ -2,12 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <libudev.h>
+#include <linux/hidraw.h>
+#include <sys/ioctl.h>
+
 #include <stdint.h>
 
 #include <string>
-#include <vector>
 
+#include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/platform_file.h"
 #include "base/stl_util.h"
@@ -16,6 +18,7 @@
 #include "base/strings/string_split.h"
 #include "device/hid/hid_connection_linux.h"
 #include "device/hid/hid_device_info.h"
+#include "device/hid/hid_report_descriptor.h"
 #include "device/hid/hid_service_linux.h"
 
 namespace device {
@@ -26,7 +29,7 @@ const char kUdevName[] = "udev";
 const char kUdevActionAdd[] = "add";
 const char kUdevActionRemove[] = "remove";
 const char kHIDSubSystem[] = "hid";
-
+const char kHidrawSubsystem[] = "hidraw";
 const char kHIDID[] = "HID_ID";
 const char kHIDName[] = "HID_NAME";
 const char kHIDUnique[] = "HID_UNIQ";
@@ -84,8 +87,14 @@ scoped_refptr<HidConnection> HidServiceLinux::Connect(
 
   ScopedUdevDevicePtr hid_device(
       udev_device_new_from_syspath(udev_.get(), device_info.device_id.c_str()));
+
   if (hid_device) {
-    return new HidConnectionLinux(device_info, hid_device.Pass());
+    std::string dev_node;
+    if (!FindHidrawDevNode(hid_device.get(), &dev_node)) {
+      LOG(ERROR) << "Cannot open HID device as hidraw device.";
+      return NULL;
+    }
+    return new HidConnectionLinux(device_info, dev_node);
   }
   return NULL;
 }
@@ -183,6 +192,47 @@ void HidServiceLinux::PlatformAddDevice(udev_device* device) {
   if (str_property != NULL)
     device_info.product_name = str_property;
 
+  std::string dev_node;
+  if (!FindHidrawDevNode(device, &dev_node)) {
+    LOG(ERROR) << "Cannot open HID device as hidraw device.";
+    return;
+  }
+
+  int flags = base::File::FLAG_OPEN |
+              base::File::FLAG_READ;
+
+  base::File device_file(base::FilePath(dev_node), flags);
+  if (!device_file.IsValid()) {
+    LOG(ERROR) << device_file.error_details();
+    return;
+  }
+
+  int desc_size = 0;
+  int res = ioctl(device_file.GetPlatformFile(), HIDIOCGRDESCSIZE, &desc_size);
+  if (res < 0)
+  {
+      LOG(ERROR) << "HIDIOCGRDESCSIZE failed.";
+      device_file.Close();
+      return;
+  }
+
+  hidraw_report_descriptor rpt_desc;
+  rpt_desc.size = desc_size;
+
+  res = ioctl(device_file.GetPlatformFile(), HIDIOCGRDESC, &rpt_desc);
+  if (res < 0)
+  {
+      LOG(ERROR) << "HIDIOCGRDESC failed.";
+      device_file.Close();
+      return;
+  }
+
+  device_file.Close();
+
+  HidReportDescriptor report_descriptor(rpt_desc.value, rpt_desc.size);
+
+  device_info.usages = report_descriptor.topLevelCollections();
+
   AddDevice(device_info);
 }
 
@@ -194,4 +244,43 @@ void HidServiceLinux::PlatformRemoveDevice(udev_device* raw_dev) {
   RemoveDevice(device_path);
 }
 
+bool HidServiceLinux::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_subsystem(enumerate.get(), kHidrawSubsystem)) {
+    return false;
+  }
+  if (udev_enumerate_scan_devices(enumerate.get())) {
+    return false;
+  }
+  std::string parent_path(udev_device_get_devpath(parent));
+  if (parent_path.length() == 0 || *parent_path.rbegin() != '/')
+    parent_path += '/';
+  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());
+    std::string device_path = udev_device_get_devpath(hid_dev.get());
+    if (raw_path &&
+        !device_path.compare(0, parent_path.length(), parent_path)) {
+      std::string sub_path = device_path.substr(parent_path.length());
+      if (sub_path.substr(0, sizeof(kHidrawSubsystem)-1) == kHidrawSubsystem) {
+        *result = raw_path;
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
 } // namespace dev