Detect duplicate USB device notifications from udev.

device/usb/usb_service_linux.cc

 // Copyright 2016 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/usb/usb_service_linux.h"
 
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/files/file.h"
@@ skipping 199 matching lines @@
 }
 
 void UsbServiceLinux::OnDeviceAdded(const std::string& device_path,
                                     const UsbDeviceDescriptor& descriptor,
                                     const std::string& manufacturer,
                                     const std::string& product,
                                     const std::string& serial_number,
                                     uint8_t active_configuration) {
   DCHECK(CalledOnValidThread());
 
+  if (ContainsKey(devices_by_path_, device_path)) {
+    USB_LOG(ERROR) << "Got duplicate add event for path: " << device_path;
+    return;
+  }
+
   // Devices that appear during initial enumeration are gathered into the first
   // result returned by GetDevices() and prevent device add/remove notifications
   // from being sent.
   if (!enumeration_ready())
     ++first_enumeration_countdown_;
 
   scoped_refptr<UsbDeviceLinux> device(new UsbDeviceLinux(
       device_path, descriptor, manufacturer, product, serial_number,
       active_configuration, blocking_task_runner()));
   devices_by_path_[device->device_path()] = device;
@@ skipping 13 matching lines @@
   bool enumeration_became_ready = false;
   if (!enumeration_ready()) {
     DCHECK_GT(first_enumeration_countdown_, 0u);
     if (--first_enumeration_countdown_ == 0)
       enumeration_became_ready = true;
   }
 
   // If |device| was disconnected while descriptors were being read then it
   // will have been removed from |devices_by_path_|.
   auto it = devices_by_path_.find(device->device_path());
-  if (it != devices_by_path_.end()) {
-    if (success) {
-      DCHECK(!ContainsKey(devices(), device->guid()));
-      devices()[device->guid()] = device;
+  if (it == devices_by_path_.end()) {
+    success = false;
+  } else if (success) {
+    DCHECK(!ContainsKey(devices(), device->guid()));
+    devices()[device->guid()] = device;
 
-      USB_LOG(USER) << "USB device added: path=" << device->device_path()
-                    << " vendor=" << device->vendor_id() << " \""
-                    << device->manufacturer_string()
-                    << "\", product=" << device->product_id() << " \""
-                    << device->product_string() << "\", serial=\""
-                    << device->serial_number() << "\", guid=" << device->guid();
-    } else {
-      devices_by_path_.erase(it);
-    }
+    USB_LOG(USER) << "USB device added: path=" << device->device_path()
+                  << " vendor=" << device->vendor_id() << " \""
+                  << device->manufacturer_string()
+                  << "\", product=" << device->product_id() << " \""
+                  << device->product_string() << "\", serial=\""
+                  << device->serial_number() << "\", guid=" << device->guid();
+  } else {
+    devices_by_path_.erase(it);
   }
 
   if (enumeration_became_ready) {
     std::vector<scoped_refptr<UsbDevice>> result;
     result.reserve(devices().size());
     for (const auto& map_entry : devices())
       result.push_back(map_entry.second);
     for (const auto& callback : enumeration_callbacks_)
       callback.Run(result);
     enumeration_callbacks_.clear();
@@ skipping 30 matching lines @@
     result.reserve(devices().size());
     for (const auto& map_entry : devices())
       result.push_back(map_entry.second);
     for (const auto& callback : enumeration_callbacks_)
       callback.Run(result);
     enumeration_callbacks_.clear();
   }
 }
 
 }  // namespace device