libusb_udevman.c

 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
 
#include <winpr/crt.h>
#include <winpr/cmdline.h>
#include <winpr/collections.h>
 
#include <freerdp/addin.h>
 
#include "urbdrc_types.h"
#include "urbdrc_main.h"
 
#include "libusb_udevice.h"
 
#include <libusb.h>
 
#if !defined(LIBUSB_HOTPLUG_NO_FLAGS)
#define LIBUSB_HOTPLUG_NO_FLAGS 0
#endif
 
#define BASIC_STATE_FUNC_DEFINED(_arg, _type)                   \
  static _type udevman_get_##_arg(IUDEVMAN* idevman)          \
  {                                                           \
    UDEVMAN* udevman = (UDEVMAN*)idevman;                   \
    return udevman->_arg;                                   \
  }                                                           \
  static void udevman_set_##_arg(IUDEVMAN* idevman, _type _t) \
  {                                                           \
    UDEVMAN* udevman = (UDEVMAN*)idevman;                   \
    udevman->_arg = _t;                                     \
  }
 
#define BASIC_STATE_FUNC_REGISTER(_arg, _man)    \
  _man->iface.get_##_arg = udevman_get_##_arg; \
  (_man)->iface.set_##_arg = udevman_set_##_arg
 
typedef struct
{
  UINT16 vid;
  UINT16 pid;
} VID_PID_PAIR;
 
typedef struct
{
  IUDEVMAN iface;
 
  IUDEVICE* idev; /* iterator device */
  IUDEVICE* head; /* head device in linked list */
  IUDEVICE* tail; /* tail device in linked list */
 
  LPCSTR devices_vid_pid;
  LPCSTR devices_addr;
  wArrayList* hotplug_vid_pids;
  UINT16 flags;
  UINT32 device_num;
  UINT32 next_device_id;
  UINT32 channel_id;
 
  HANDLE devman_loading;
  libusb_context* context;
  HANDLE thread;
  BOOL running;
} UDEVMAN;
typedef UDEVMAN* PUDEVMAN;
 
static BOOL poll_libusb_events(UDEVMAN* udevman);
 
static void udevman_rewind(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  udevman->idev = udevman->head;
}
 
static BOOL udevman_has_next(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
 
  return !(!udevman || !udevman->idev);
}
 
static IUDEVICE* udevman_get_next(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  IUDEVICE* pdev = nullptr;
  pdev = udevman->idev;
  udevman->idev = (IUDEVICE*)((UDEVICE*)udevman->idev)->next;
  return pdev;
}
 
static IUDEVICE* udevman_get_udevice_by_addr(IUDEVMAN* idevman, BYTE bus_number, BYTE dev_number)
{
  IUDEVICE* dev = nullptr;
 
  if (!idevman)
    return nullptr;
 
  idevman->loading_lock(idevman);
  idevman->rewind(idevman);
 
  while (idevman->has_next(idevman))
  {
    IUDEVICE* pdev = idevman->get_next(idevman);
 
    if ((pdev->get_bus_number(pdev) == bus_number) &&
        (pdev->get_dev_number(pdev) == dev_number))
    {
      dev = pdev;
      break;
    }
  }
 
  idevman->loading_unlock(idevman);
  return dev;
}
 
static size_t udevman_register_udevice(IUDEVMAN* idevman, BYTE bus_number, BYTE dev_number,
                                       UINT16 idVendor, UINT16 idProduct, UINT32 flag)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  IUDEVICE* pdev = nullptr;
  IUDEVICE** devArray = nullptr;
  URBDRC_PLUGIN* urbdrc = nullptr;
  size_t num = 0;
  size_t addnum = 0;
 
  if (!idevman || !idevman->plugin)
    return 0;
 
  urbdrc = (URBDRC_PLUGIN*)idevman->plugin;
  pdev = udevman_get_udevice_by_addr(idevman, bus_number, dev_number);
 
  if (pdev != nullptr)
    return 0;
 
  if (flag & UDEVMAN_FLAG_ADD_BY_ADDR)
  {
    UINT32 id = 0;
    IUDEVICE* tdev = udev_new_by_addr(urbdrc, udevman->context, bus_number, dev_number);
 
    if (tdev == nullptr)
      return 0;
 
    id = idevman->get_next_device_id(idevman);
    tdev->set_UsbDevice(tdev, id);
    idevman->loading_lock(idevman);
 
    if (udevman->head == nullptr)
    {
      /* linked list is empty */
      udevman->head = tdev;
      udevman->tail = tdev;
    }
    else
    {
      /* append device to the end of the linked list */
      udevman->tail->set_p_next(udevman->tail, tdev);
      tdev->set_p_prev(tdev, udevman->tail);
      udevman->tail = tdev;
    }
 
    udevman->device_num += 1;
    idevman->loading_unlock(idevman);
  }
  else if (flag & UDEVMAN_FLAG_ADD_BY_VID_PID)
  {
    addnum = 0;
    /* register all device that match pid vid */
    num = udev_new_by_id(urbdrc, udevman->context, idVendor, idProduct, &devArray);
 
    if (num == 0)
    {
      WLog_Print(urbdrc->log, WLOG_WARN,
                 "Could not find or redirect any usb devices by id %04x:%04x", idVendor,
                 idProduct);
    }
 
    for (size_t i = 0; i < num; i++)
    {
      UINT32 id = 0;
      IUDEVICE* tdev = devArray[i];
 
      if (udevman_get_udevice_by_addr(idevman, tdev->get_bus_number(tdev),
                                      tdev->get_dev_number(tdev)) != nullptr)
      {
        tdev->free(tdev);
        devArray[i] = nullptr;
        continue;
      }
 
      id = idevman->get_next_device_id(idevman);
      tdev->set_UsbDevice(tdev, id);
      idevman->loading_lock(idevman);
 
      if (udevman->head == nullptr)
      {
        /* linked list is empty */
        udevman->head = tdev;
        udevman->tail = tdev;
      }
      else
      {
        /* append device to the end of the linked list */
        udevman->tail->set_p_next(udevman->tail, tdev);
        tdev->set_p_prev(tdev, udevman->tail);
        udevman->tail = tdev;
      }
 
      udevman->device_num += 1;
      idevman->loading_unlock(idevman);
      addnum++;
    }
 
    free((void*)devArray);
    return addnum;
  }
  else
  {
    WLog_Print(urbdrc->log, WLOG_ERROR, "udevman_register_udevice: Invalid flag=%08" PRIx32,
               flag);
    return 0;
  }
 
  return 1;
}
 
static BOOL udevman_unregister_udevice(IUDEVMAN* idevman, BYTE bus_number, BYTE dev_number)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  UDEVICE* pdev = nullptr;
  UDEVICE* dev = (UDEVICE*)udevman_get_udevice_by_addr(idevman, bus_number, dev_number);
 
  if (!dev || !idevman)
    return FALSE;
 
  idevman->loading_lock(idevman);
  idevman->rewind(idevman);
 
  while (idevman->has_next(idevman))
  {
    pdev = (UDEVICE*)idevman->get_next(idevman);
 
    if (pdev == dev) /* device exists */
    {
      /* set previous device to point to next device */
      if (dev->prev != nullptr)
      {
        /* unregistered device is not the head */
        pdev = dev->prev;
        pdev->next = dev->next;
      }
      else
      {
        /* unregistered device is the head, update head */
        udevman->head = (IUDEVICE*)dev->next;
      }
 
      /* set next device to point to previous device */
 
      if (dev->next != nullptr)
      {
        /* unregistered device is not the tail */
        pdev = (UDEVICE*)dev->next;
        pdev->prev = dev->prev;
      }
      else
      {
        /* unregistered device is the tail, update tail */
        udevman->tail = (IUDEVICE*)dev->prev;
      }
 
      udevman->device_num--;
      break;
    }
  }
 
  idevman->loading_unlock(idevman);
 
  if (dev)
  {
    dev->iface.free(&dev->iface);
    return TRUE; /* unregistration successful */
  }
 
  /* if we reach this point, the device wasn't found */
  return FALSE;
}
 
static BOOL udevman_unregister_all_udevices(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
 
  if (!idevman)
    return FALSE;
 
  if (!udevman->head)
    return TRUE;
 
  idevman->loading_lock(idevman);
  idevman->rewind(idevman);
 
  while (idevman->has_next(idevman))
  {
    UDEVICE* dev = (UDEVICE*)idevman->get_next(idevman);
 
    if (!dev)
      continue;
 
    /* set previous device to point to next device */
    if (dev->prev != nullptr)
    {
      /* unregistered device is not the head */
      UDEVICE* pdev = dev->prev;
      pdev->next = dev->next;
    }
    else
    {
      /* unregistered device is the head, update head */
      udevman->head = (IUDEVICE*)dev->next;
    }
 
    /* set next device to point to previous device */
 
    if (dev->next != nullptr)
    {
      /* unregistered device is not the tail */
      UDEVICE* pdev = (UDEVICE*)dev->next;
      pdev->prev = dev->prev;
    }
    else
    {
      /* unregistered device is the tail, update tail */
      udevman->tail = (IUDEVICE*)dev->prev;
    }
 
    dev->iface.free(&dev->iface);
    udevman->device_num--;
  }
 
  idevman->loading_unlock(idevman);
 
  return TRUE;
}
 
static int udevman_is_auto_add(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  return (udevman->flags & UDEVMAN_FLAG_ADD_BY_AUTO) ? 1 : 0;
}
 
static IUDEVICE* udevman_get_udevice_by_UsbDevice(IUDEVMAN* idevman, UINT32 UsbDevice)
{
  UDEVICE* pdev = nullptr;
  URBDRC_PLUGIN* urbdrc = nullptr;
 
  if (!idevman || !idevman->plugin)
    return nullptr;
 
  /* Mask highest 2 bits, must be ignored */
  UsbDevice = UsbDevice & INTERFACE_ID_MASK;
  urbdrc = (URBDRC_PLUGIN*)idevman->plugin;
  idevman->loading_lock(idevman);
  idevman->rewind(idevman);
 
  while (idevman->has_next(idevman))
  {
    pdev = (UDEVICE*)idevman->get_next(idevman);
 
    if (pdev->UsbDevice == UsbDevice)
    {
      idevman->loading_unlock(idevman);
      return (IUDEVICE*)pdev;
    }
  }
 
  idevman->loading_unlock(idevman);
  WLog_Print(urbdrc->log, WLOG_WARN, "Failed to find a USB device mapped to deviceId=%08" PRIx32,
             UsbDevice);
  return nullptr;
}
 
static IUDEVICE* udevman_get_udevice_by_ChannelID(IUDEVMAN* idevman, UINT32 channelID)
{
  UDEVICE* pdev = nullptr;
  URBDRC_PLUGIN* urbdrc = nullptr;
 
  if (!idevman || !idevman->plugin)
    return nullptr;
 
  /* Mask highest 2 bits, must be ignored */
  urbdrc = (URBDRC_PLUGIN*)idevman->plugin;
  idevman->loading_lock(idevman);
  idevman->rewind(idevman);
 
  while (idevman->has_next(idevman))
  {
    pdev = (UDEVICE*)idevman->get_next(idevman);
 
    if (pdev->channelID == channelID)
    {
      idevman->loading_unlock(idevman);
      return (IUDEVICE*)pdev;
    }
  }
 
  idevman->loading_unlock(idevman);
  WLog_Print(urbdrc->log, WLOG_WARN, "Failed to find a USB device mapped to channelID=%08" PRIx32,
             channelID);
  return nullptr;
}
 
static void udevman_loading_lock(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  (void)WaitForSingleObject(udevman->devman_loading, INFINITE);
}
 
static void udevman_loading_unlock(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  (void)ReleaseMutex(udevman->devman_loading);
}
 
BASIC_STATE_FUNC_DEFINED(device_num, UINT32)
 
static UINT32 udevman_get_next_device_id(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  return udevman->next_device_id++;
}
 
static void udevman_set_next_device_id(IUDEVMAN* idevman, UINT32 _t)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
  udevman->next_device_id = _t;
}
 
static void udevman_free(IUDEVMAN* idevman)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
 
  if (!udevman)
    return;
 
  udevman->running = FALSE;
  if (udevman->thread)
  {
    (void)WaitForSingleObject(udevman->thread, INFINITE);
    (void)CloseHandle(udevman->thread);
  }
 
  udevman_unregister_all_udevices(idevman);
 
  if (udevman->devman_loading)
    (void)CloseHandle(udevman->devman_loading);
 
  libusb_exit(udevman->context);
 
  ArrayList_Free(udevman->hotplug_vid_pids);
  free(udevman);
}
 
static BOOL filter_by_class(uint8_t bDeviceClass, uint8_t bDeviceSubClass)
{
  switch (bDeviceClass)
  {
    case LIBUSB_CLASS_AUDIO:
    case LIBUSB_CLASS_HID:
    case LIBUSB_CLASS_MASS_STORAGE:
    case LIBUSB_CLASS_HUB:
    case LIBUSB_CLASS_SMART_CARD:
      return TRUE;
    default:
      break;
  }
 
  switch (bDeviceSubClass)
  {
    default:
      break;
  }
 
  return FALSE;
}
 
static BOOL append(char* dst, size_t length, const char* src)
{
  return winpr_str_append(src, dst, length, nullptr);
}
 
static BOOL device_is_filtered(struct libusb_device* dev,
                               const struct libusb_device_descriptor* desc,
                               libusb_hotplug_event event)
{
  char buffer[8192] = WINPR_C_ARRAY_INIT;
  char* what = nullptr;
  BOOL filtered = FALSE;
  append(buffer, sizeof(buffer), usb_interface_class_to_string(desc->bDeviceClass));
  if (filter_by_class(desc->bDeviceClass, desc->bDeviceSubClass))
    filtered = TRUE;
 
  switch (desc->bDeviceClass)
  {
    case LIBUSB_CLASS_PER_INTERFACE:
    {
      struct libusb_config_descriptor* config = nullptr;
      int rc = libusb_get_active_config_descriptor(dev, &config);
      if (rc == LIBUSB_SUCCESS)
      {
        for (uint8_t x = 0; x < config->bNumInterfaces; x++)
        {
          const struct libusb_interface* ifc = &config->interface[x];
          for (int y = 0; y < ifc->num_altsetting; y++)
          {
            const struct libusb_interface_descriptor* const alt = &ifc->altsetting[y];
            if (filter_by_class(alt->bInterfaceClass, alt->bInterfaceSubClass))
              filtered = TRUE;
 
            append(buffer, sizeof(buffer), "|");
            append(buffer, sizeof(buffer),
                   usb_interface_class_to_string(alt->bInterfaceClass));
          }
        }
      }
      libusb_free_config_descriptor(config);
    }
    break;
    default:
      break;
  }
 
  if (filtered)
    what = "Filtered";
  else
  {
    switch (event)
    {
      case LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT:
        what = "Hotplug remove";
        break;
      case LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED:
        what = "Hotplug add";
        break;
      default:
        what = "Hotplug unknown";
        break;
    }
  }
 
  WLog_DBG(TAG, "%s device VID=0x%04X,PID=0x%04X class %s", what, desc->idVendor, desc->idProduct,
           buffer);
  return filtered;
}
 
static int LIBUSB_CALL hotplug_callback(struct libusb_context* ctx, struct libusb_device* dev,
                                        libusb_hotplug_event event, void* user_data)
{
  VID_PID_PAIR pair;
  struct libusb_device_descriptor desc;
  UDEVMAN* udevman = (UDEVMAN*)user_data;
  const uint8_t bus = libusb_get_bus_number(dev);
  const uint8_t addr = libusb_get_device_address(dev);
  int rc = libusb_get_device_descriptor(dev, &desc);
 
  WINPR_UNUSED(ctx);
 
  if (rc != LIBUSB_SUCCESS)
    return rc;
 
  switch (event)
  {
    case LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED:
      pair.vid = desc.idVendor;
      pair.pid = desc.idProduct;
      if ((ArrayList_Contains(udevman->hotplug_vid_pids, &pair)) ||
          (udevman->iface.isAutoAdd(&udevman->iface) &&
           !device_is_filtered(dev, &desc, event)))
      {
        add_device(&udevman->iface, DEVICE_ADD_FLAG_ALL, bus, addr, desc.idVendor,
                   desc.idProduct);
      }
      break;
 
    case LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT:
      del_device(&udevman->iface, DEVICE_ADD_FLAG_ALL, bus, addr, desc.idVendor,
                 desc.idProduct);
      break;
 
    default:
      break;
  }
 
  return 0;
}
 
static BOOL udevman_initialize(IUDEVMAN* idevman, UINT32 channelId)
{
  UDEVMAN* udevman = (UDEVMAN*)idevman;
 
  if (!udevman)
    return FALSE;
 
  idevman->status &= (uint32_t)~URBDRC_DEVICE_CHANNEL_CLOSED;
  idevman->controlChannelId = channelId;
  return TRUE;
}
 
static BOOL udevman_vid_pid_pair_equals(const void* objA, const void* objB)
{
  const VID_PID_PAIR* a = objA;
  const VID_PID_PAIR* b = objB;
 
  return (a->vid == b->vid) && (a->pid == b->pid);
}
 
static BOOL udevman_parse_device_id_addr(const char** str, UINT16* id1, UINT16* id2, UINT16 max,
                                         char split_sign, char delimiter)
{
  char* mid = nullptr;
  char* end = nullptr;
  unsigned long rc = 0;
 
  rc = strtoul(*str, &mid, 16);
 
  if ((mid == *str) || (*mid != split_sign) || (rc > max))
    return FALSE;
 
  *id1 = (UINT16)rc;
  rc = strtoul(++mid, &end, 16);
 
  if ((end == mid) || (rc > max))
    return FALSE;
 
  *id2 = (UINT16)rc;
 
  *str += end - *str;
  if (*end == '\0')
    return TRUE;
  if (*end == delimiter)
  {
    (*str)++;
    return TRUE;
  }
 
  return FALSE;
}
 
static UINT urbdrc_udevman_register_devices(UDEVMAN* udevman, const char* devices, BOOL add_by_addr)
{
  const char* pos = devices;
 
  while (*pos != '\0')
  {
    UINT16 id1 = 0;
    UINT16 id2 = 0;
    if (!udevman_parse_device_id_addr(&pos, &id1, &id2, (add_by_addr) ? UINT8_MAX : UINT16_MAX,
                                      ':', '#'))
    {
      WLog_ERR(TAG, "Invalid device argument: \"%s\"", devices);
      return CHANNEL_RC_INITIALIZATION_ERROR;
    }
 
    if (add_by_addr)
    {
      if (!add_device(&udevman->iface, DEVICE_ADD_FLAG_BUS | DEVICE_ADD_FLAG_DEV, (UINT8)id1,
                      (UINT8)id2, 0, 0))
        return CHANNEL_RC_INITIALIZATION_ERROR;
    }
    else
    {
      VID_PID_PAIR* idpair = calloc(1, sizeof(VID_PID_PAIR));
      if (!idpair)
        return CHANNEL_RC_NO_MEMORY;
      idpair->vid = id1;
      idpair->pid = id2;
      if (!ArrayList_Append(udevman->hotplug_vid_pids, idpair))
      {
        free(idpair);
        return CHANNEL_RC_NO_MEMORY;
      }
 
      // NOLINTNEXTLINE(clang-analyzer-unix.Malloc): ArrayList_Append owns idpair
      if (!add_device(&udevman->iface, DEVICE_ADD_FLAG_VENDOR | DEVICE_ADD_FLAG_PRODUCT, 0, 0,
                      id1, id2))
      {
        // NOLINTNEXTLINE(clang-analyzer-unix.Malloc): ArrayList_Append owns idpair
        return CHANNEL_RC_INITIALIZATION_ERROR;
      }
    }
  }
 
  // NOLINTNEXTLINE(clang-analyzer-unix.Malloc): ArrayList_Append owns idpair
  return CHANNEL_RC_OK;
}
 
static UINT urbdrc_udevman_parse_addin_args(UDEVMAN* udevman, const ADDIN_ARGV* args)
{
  LPCSTR devices = nullptr;
 
  for (int x = 0; x < args->argc; x++)
  {
    const char* arg = args->argv[x];
    if (strcmp(arg, "dbg") == 0)
    {
      WLog_SetLogLevel(WLog_Get(TAG), WLOG_TRACE);
    }
    else if (_strnicmp(arg, "device:", 7) == 0)
    {
      /* Redirect all local devices */
      const char* val = &arg[7];
      const size_t len = strlen(val);
      if (strcmp(val, "*") == 0)
      {
        udevman->flags |= UDEVMAN_FLAG_ADD_BY_AUTO;
      }
      else if (_strnicmp(arg, "USBInstanceID:", 14) == 0)
      {
        // TODO: Usb instance ID
      }
      else if ((val[0] == '{') && (val[len - 1] == '}'))
      {
        // TODO: Usb device class
      }
    }
    else if (_strnicmp(arg, "dev:", 4) == 0)
    {
      devices = &arg[4];
    }
    else if (_strnicmp(arg, "id", 2) == 0)
    {
      const char* p = strchr(arg, ':');
      if (p)
        udevman->devices_vid_pid = p + 1;
      else
        udevman->flags = UDEVMAN_FLAG_ADD_BY_VID_PID;
    }
    else if (_strnicmp(arg, "addr", 4) == 0)
    {
      const char* p = strchr(arg, ':');
      if (p)
        udevman->devices_addr = p + 1;
      else
        udevman->flags = UDEVMAN_FLAG_ADD_BY_ADDR;
    }
    else if (strcmp(arg, "auto") == 0)
    {
      udevman->flags |= UDEVMAN_FLAG_ADD_BY_AUTO;
    }
    else
    {
      const size_t len = strlen(arg);
      if ((arg[0] == '{') && (arg[len - 1] == '}'))
      {
        // TODO: Check for  {Device Setup Class GUID}:
      }
    }
  }
  if (devices)
  {
    if (udevman->flags & UDEVMAN_FLAG_ADD_BY_VID_PID)
      udevman->devices_vid_pid = devices;
    else if (udevman->flags & UDEVMAN_FLAG_ADD_BY_ADDR)
      udevman->devices_addr = devices;
  }
 
  return CHANNEL_RC_OK;
}
 
static UINT udevman_listener_created_callback(IUDEVMAN* iudevman)
{
  UDEVMAN* udevman = (UDEVMAN*)iudevman;
  WINPR_ASSERT(udevman);
 
  if (udevman->devices_vid_pid)
    return urbdrc_udevman_register_devices(udevman, udevman->devices_vid_pid, FALSE);
 
  if (udevman->devices_addr)
    return urbdrc_udevman_register_devices(udevman, udevman->devices_addr, TRUE);
 
  return CHANNEL_RC_OK;
}
 
static void udevman_load_interface(UDEVMAN* udevman)
{
  /* standard */
  udevman->iface.free = udevman_free;
  /* manage devices */
  udevman->iface.rewind = udevman_rewind;
  udevman->iface.get_next = udevman_get_next;
  udevman->iface.has_next = udevman_has_next;
  udevman->iface.register_udevice = udevman_register_udevice;
  udevman->iface.unregister_udevice = udevman_unregister_udevice;
  udevman->iface.get_udevice_by_UsbDevice = udevman_get_udevice_by_UsbDevice;
  udevman->iface.get_udevice_by_ChannelID = udevman_get_udevice_by_ChannelID;
  /* Extension */
  udevman->iface.isAutoAdd = udevman_is_auto_add;
  /* Basic state */
  BASIC_STATE_FUNC_REGISTER(device_num, udevman);
  BASIC_STATE_FUNC_REGISTER(next_device_id, udevman);
 
  /* control semaphore or mutex lock */
  udevman->iface.loading_lock = udevman_loading_lock;
  udevman->iface.loading_unlock = udevman_loading_unlock;
  udevman->iface.initialize = udevman_initialize;
  udevman->iface.listener_created_callback = udevman_listener_created_callback;
}
 
static BOOL poll_libusb_events(UDEVMAN* udevman)
{
  int rc = LIBUSB_SUCCESS;
  struct timeval tv = { 0, 500 };
  if (libusb_try_lock_events(udevman->context) == 0)
  {
    if (libusb_event_handling_ok(udevman->context))
    {
      rc = libusb_handle_events_locked(udevman->context, &tv);
      if (rc != LIBUSB_SUCCESS)
        WLog_WARN(TAG, "libusb_handle_events_locked %d", rc);
    }
    libusb_unlock_events(udevman->context);
  }
  else
  {
    libusb_lock_event_waiters(udevman->context);
    if (libusb_event_handler_active(udevman->context))
    {
      rc = libusb_wait_for_event(udevman->context, &tv);
      if (rc < LIBUSB_SUCCESS)
        WLog_WARN(TAG, "libusb_wait_for_event %d", rc);
    }
    libusb_unlock_event_waiters(udevman->context);
  }
 
  return rc > 0;
}
 
static DWORD WINAPI poll_thread(LPVOID lpThreadParameter)
{
  libusb_hotplug_callback_handle handle = 0;
  UDEVMAN* udevman = (UDEVMAN*)lpThreadParameter;
  BOOL hasHotplug = libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG);
 
  if (hasHotplug)
  {
    int rc = libusb_hotplug_register_callback(
        udevman->context,
        LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED | LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT,
        LIBUSB_HOTPLUG_NO_FLAGS, LIBUSB_HOTPLUG_MATCH_ANY, LIBUSB_HOTPLUG_MATCH_ANY,
        LIBUSB_HOTPLUG_MATCH_ANY, hotplug_callback, udevman, &handle);
 
    if (rc != LIBUSB_SUCCESS)
      udevman->running = FALSE;
  }
  else
    WLog_WARN(TAG, "Platform does not support libusb hotplug. USB devices plugged in later "
                   "will not be detected.");
 
  while (udevman->running)
  {
    poll_libusb_events(udevman);
  }
 
  if (hasHotplug)
    libusb_hotplug_deregister_callback(udevman->context, handle);
 
  /* Process remaining usb events */
  while (poll_libusb_events(udevman))
    ;
 
  ExitThread(0);
  return 0;
}
 
FREERDP_ENTRY_POINT(UINT VCAPITYPE libusb_freerdp_urbdrc_client_subsystem_entry(
    PFREERDP_URBDRC_SERVICE_ENTRY_POINTS pEntryPoints))
{
  wObject* obj = nullptr;
  UINT status = 0;
  UDEVMAN* udevman = nullptr;
  const ADDIN_ARGV* args = pEntryPoints->args;
  udevman = (PUDEVMAN)calloc(1, sizeof(UDEVMAN));
 
  if (!udevman)
    goto fail;
 
  udevman->hotplug_vid_pids = ArrayList_New(TRUE);
  if (!udevman->hotplug_vid_pids)
    goto fail;
  obj = ArrayList_Object(udevman->hotplug_vid_pids);
  obj->fnObjectFree = free;
  obj->fnObjectEquals = udevman_vid_pid_pair_equals;
 
  udevman->next_device_id = BASE_USBDEVICE_NUM;
  udevman->iface.plugin = pEntryPoints->plugin;
 
  {
    const int res = libusb_init(&udevman->context);
    if (res != LIBUSB_SUCCESS)
      goto fail;
  }
 
#ifdef _WIN32
#if LIBUSB_API_VERSION >= 0x01000106
  /* Prefer usbDK backend on windows. Not supported on other platforms. */
  const int rc = libusb_set_option(udevman->context, LIBUSB_OPTION_USE_USBDK);
  switch (rc)
  {
    case LIBUSB_SUCCESS:
      break;
    case LIBUSB_ERROR_NOT_FOUND:
    case LIBUSB_ERROR_NOT_SUPPORTED:
      WLog_WARN(TAG, "LIBUSB_OPTION_USE_USBDK %s [%d]", libusb_strerror(rc), rc);
      break;
    default:
      WLog_ERR(TAG, "LIBUSB_OPTION_USE_USBDK %s [%d]", libusb_strerror(rc), rc);
      goto fail;
  }
#endif
#endif
 
  udevman->flags = UDEVMAN_FLAG_ADD_BY_VID_PID;
  udevman->devman_loading = CreateMutexA(nullptr, FALSE, "devman_loading");
 
  if (!udevman->devman_loading)
    goto fail;
 
  /* load usb device service management */
  udevman_load_interface(udevman);
  status = urbdrc_udevman_parse_addin_args(udevman, args);
 
  if (status != CHANNEL_RC_OK)
    goto fail;
 
  udevman->running = TRUE;
  udevman->thread = CreateThread(nullptr, 0, poll_thread, udevman, 0, nullptr);
 
  if (!udevman->thread)
    goto fail;
 
  if (!pEntryPoints->pRegisterUDEVMAN(pEntryPoints->plugin, (IUDEVMAN*)udevman))
    goto fail;
 
  WLog_DBG(TAG, "UDEVMAN device registered.");
  return 0;
fail:
  udevman_free(&udevman->iface);
  return ERROR_INTERNAL_ERROR;
}