components/usb_service/usb_service_impl.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/usb_service/usb_service.h"
   6
   7 #include <map>
   8 #include <set>
   9
  10 #include "base/lazy_instance.h"
  11 #include "base/message_loop/message_loop.h"
  12 #include "base/stl_util.h"
  13 #include "components/usb_service/usb_context.h"
  14 #include "components/usb_service/usb_device_impl.h"
  15 #include "components/usb_service/usb_error.h"
  16 #include "content/public/browser/browser_thread.h"
  17 #include "third_party/libusb/src/libusb/libusb.h"
  18
  19 namespace usb_service {
  20
  21 namespace {
  22
  23 base::LazyInstance<scoped_ptr<UsbService> >::Leaky g_usb_service_instance =
  24     LAZY_INSTANCE_INITIALIZER;
  25
  26 }  // namespace
  27
  28 typedef struct libusb_device* PlatformUsbDevice;
  29 typedef struct libusb_context* PlatformUsbContext;
  30
  31 class UsbServiceImpl
  32     : public UsbService,
  33       private base::MessageLoop::DestructionObserver {
  34  public:
  35   explicit UsbServiceImpl(PlatformUsbContext context);
  36   virtual ~UsbServiceImpl();
  37
  38  private:
  39   // usb_service::UsbService implementation
  40   virtual scoped_refptr<UsbDevice> GetDeviceById(uint32 unique_id) OVERRIDE;
  41   virtual void GetDevices(
  42       std::vector<scoped_refptr<UsbDevice> >* devices) OVERRIDE;
  43
  44   // base::MessageLoop::DestructionObserver implementation.
  45   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
  46
  47   // Enumerate USB devices from OS and Update devices_ map.
  48   void RefreshDevices();
  49
  50   scoped_refptr<UsbContext> context_;
  51
  52   // TODO(ikarienator): Figure out a better solution.
  53   uint32 next_unique_id_;
  54
  55   // The map from PlatformUsbDevices to UsbDevices.
  56   typedef std::map<PlatformUsbDevice, scoped_refptr<UsbDeviceImpl> > DeviceMap;
  57   DeviceMap devices_;
  58
  59   DISALLOW_COPY_AND_ASSIGN(UsbServiceImpl);
  60 };
  61
  62 scoped_refptr<UsbDevice> UsbServiceImpl::GetDeviceById(uint32 unique_id) {
  63   DCHECK(CalledOnValidThread());
  64   RefreshDevices();
  65   for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
  66     if (it->second->unique_id() == unique_id)
  67       return it->second;
  68   }
  69   return NULL;
  70 }
  71
  72 void UsbServiceImpl::GetDevices(
  73     std::vector<scoped_refptr<UsbDevice> >* devices) {
  74   DCHECK(CalledOnValidThread());
  75   STLClearObject(devices);
  76   RefreshDevices();
  77
  78   for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
  79     devices->push_back(it->second);
  80   }
  81 }
  82
  83 void UsbServiceImpl::WillDestroyCurrentMessageLoop() {
  84   DCHECK(CalledOnValidThread());
  85   g_usb_service_instance.Get().reset(NULL);
  86 }
  87
  88 UsbServiceImpl::UsbServiceImpl(PlatformUsbContext context)
  89     : context_(new UsbContext(context)), next_unique_id_(0) {
  90   base::MessageLoop::current()->AddDestructionObserver(this);
  91 }
  92
  93 UsbServiceImpl::~UsbServiceImpl() {
  94   base::MessageLoop::current()->RemoveDestructionObserver(this);
  95   for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
  96     it->second->OnDisconnect();
  97   }
  98 }
  99
 100 void UsbServiceImpl::RefreshDevices() {
 101   DCHECK(CalledOnValidThread());
 102
 103   libusb_device** platform_devices = NULL;
 104   const ssize_t device_count =
 105       libusb_get_device_list(context_->context(), &platform_devices);
 106   if (device_count < 0) {
 107     VLOG(1) << "Failed to get device list: "
 108             << ConvertErrorToString(device_count);
 109   }
 110
 111   std::set<UsbDevice*> connected_devices;
 112   std::vector<PlatformUsbDevice> disconnected_devices;
 113
 114   // Populates new devices.
 115   for (ssize_t i = 0; i < device_count; ++i) {
 116     if (!ContainsKey(devices_, platform_devices[i])) {
 117       libusb_device_descriptor descriptor;
 118       const int rv =
 119           libusb_get_device_descriptor(platform_devices[i], &descriptor);
 120       // This test is needed. A valid vendor/produce pair is required.
 121       if (rv != LIBUSB_SUCCESS) {
 122         VLOG(1) << "Failed to get device descriptor: "
 123                 << ConvertErrorToString(rv);
 124         continue;
 125       }
 126       UsbDeviceImpl* new_device = new UsbDeviceImpl(context_,
 127                                                     platform_devices[i],
 128                                                     descriptor.idVendor,
 129                                                     descriptor.idProduct,
 130                                                     ++next_unique_id_);
 131       devices_[platform_devices[i]] = new_device;
 132       connected_devices.insert(new_device);
 133     } else {
 134       connected_devices.insert(devices_[platform_devices[i]].get());
 135     }
 136   }
 137
 138   // Find disconnected devices.
 139   for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
 140     if (!ContainsKey(connected_devices, it->second)) {
 141       disconnected_devices.push_back(it->first);
 142     }
 143   }
 144
 145   // Remove disconnected devices from devices_.
 146   for (size_t i = 0; i < disconnected_devices.size(); ++i) {
 147     // UsbDevice will be destroyed after this. The corresponding
 148     // PlatformUsbDevice will be unref'ed during this process.
 149     devices_.erase(disconnected_devices[i]);
 150   }
 151
 152   libusb_free_device_list(platform_devices, true);
 153 }
 154
 155 // static
 156 UsbService* UsbService::GetInstance() {
 157   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
 158   UsbService* instance = g_usb_service_instance.Get().get();
 159   if (!instance) {
 160     PlatformUsbContext context = NULL;
 161
 162     const int rv = libusb_init(&context);
 163     if (rv != LIBUSB_SUCCESS) {
 164       VLOG(1) << "Failed to initialize libusb: " << ConvertErrorToString(rv);
 165       return NULL;
 166     }
 167     if (!context)
 168       return NULL;
 169
 170     instance = new UsbServiceImpl(context);
 171     g_usb_service_instance.Get().reset(instance);
 172   }
 173   return instance;
 174 }
 175
 176 // static
 177 void UsbService::SetInstanceForTest(UsbService* instance) {
 178   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
 179   g_usb_service_instance.Get().reset(instance);
 180 }
 181
 182 }  // namespace usb_service