Initial

1 files changed, 4527 insertions, 0 deletions

diff --git a/src/os/windows_winusb.c b/src/os/windows_winusb.c
new file mode 100644
index 0000000..a03d6a5
--- /dev/null
+++ b/src/os/windows_winusb.c
@@ -0,0 +1,4527 @@
+/*
+ * windows backend for libusb 1.0
+ * Copyright © 2009-2012 Pete Batard <pete@akeo.ie>
+ * Copyright © 2016-2018 Chris Dickens <christopher.a.dickens@gmail.com>
+ * With contributions from Michael Plante, Orin Eman et al.
+ * Parts of this code adapted from libusb-win32-v1 by Stephan Meyer
+ * HID Reports IOCTLs inspired from HIDAPI by Alan Ott, Signal 11 Software
+ * Hash table functions adapted from glibc, by Ulrich Drepper et al.
+ * Major code testing contribution by Xiaofan Chen
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <config.h>
+
+#include <windows.h>
+#include <setupapi.h>
+#include <ctype.h>
+#include <stdio.h>
+
+#include "libusbi.h"
+#include "windows_winusb.h"
+
+#define HANDLE_VALID(h) (((h) != NULL) && ((h) != INVALID_HANDLE_VALUE))
+
+// The below macro is used in conjunction with safe loops.
+#define LOOP_BREAK(err)				\
+	{					\
+		r = err;			\
+		continue;			\
+	}
+
+// WinUSB-like API prototypes
+static bool winusbx_init(struct libusb_context *ctx);
+static void winusbx_exit(void);
+static int winusbx_open(int sub_api, struct libusb_device_handle *dev_handle);
+static void winusbx_close(int sub_api, struct libusb_device_handle *dev_handle);
+static int winusbx_configure_endpoints(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int winusbx_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int winusbx_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int winusbx_submit_control_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int winusbx_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting);
+static int winusbx_submit_iso_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int winusbx_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int winusbx_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint);
+static int winusbx_cancel_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int winusbx_reset_device(int sub_api, struct libusb_device_handle *dev_handle);
+static enum libusb_transfer_status winusbx_copy_transfer_data(int sub_api, struct usbi_transfer *itransfer, DWORD length);
+// HID API prototypes
+static bool hid_init(struct libusb_context *ctx);
+static void hid_exit(void);
+static int hid_open(int sub_api, struct libusb_device_handle *dev_handle);
+static void hid_close(int sub_api, struct libusb_device_handle *dev_handle);
+static int hid_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int hid_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int hid_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting);
+static int hid_submit_control_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int hid_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int hid_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint);
+static int hid_reset_device(int sub_api, struct libusb_device_handle *dev_handle);
+static enum libusb_transfer_status hid_copy_transfer_data(int sub_api, struct usbi_transfer *itransfer, DWORD length);
+// Composite API prototypes
+static int composite_open(int sub_api, struct libusb_device_handle *dev_handle);
+static void composite_close(int sub_api, struct libusb_device_handle *dev_handle);
+static int composite_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int composite_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting);
+static int composite_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface);
+static int composite_submit_control_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int composite_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int composite_submit_iso_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int composite_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint);
+static int composite_cancel_transfer(int sub_api, struct usbi_transfer *itransfer);
+static int composite_reset_device(int sub_api, struct libusb_device_handle *dev_handle);
+static enum libusb_transfer_status composite_copy_transfer_data(int sub_api, struct usbi_transfer *itransfer, DWORD length);
+
+static usbi_mutex_t autoclaim_lock;
+
+// API globals
+static struct winusb_interface WinUSBX[SUB_API_MAX];
+#define CHECK_WINUSBX_AVAILABLE(sub_api)		\
+	do {						\
+		if (sub_api == SUB_API_NOTSET)		\
+			sub_api = priv->sub_api;	\
+		if (WinUSBX[sub_api].hDll == NULL)	\
+			return LIBUSB_ERROR_ACCESS;	\
+	} while (0)
+
+#define CHECK_HID_AVAILABLE				\
+	do {						\
+		if (DLL_HANDLE_NAME(hid) == NULL)	\
+			return LIBUSB_ERROR_ACCESS;	\
+	} while (0)
+
+#if defined(ENABLE_LOGGING)
+static const char *guid_to_string(const GUID *guid, char guid_string[MAX_GUID_STRING_LENGTH])
+{
+	if (guid == NULL) {
+		guid_string[0] = '\0';
+		return guid_string;
+	}
+
+	sprintf(guid_string, "{%08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X}",
+		(unsigned int)guid->Data1, guid->Data2, guid->Data3,
+		guid->Data4[0], guid->Data4[1], guid->Data4[2], guid->Data4[3],
+		guid->Data4[4], guid->Data4[5], guid->Data4[6], guid->Data4[7]);
+
+	return guid_string;
+}
+#endif
+
+static bool string_to_guid(const char guid_string[MAX_GUID_STRING_LENGTH], GUID *guid)
+{
+	unsigned short tmp[4];
+	int num_chars = -1;
+	char extra;
+	int r;
+
+	// Unfortunately MinGW complains that '%hhx' is not a valid format specifier,
+	// even though Visual Studio 2013 and later support it. Rather than complicating
+	// the logic in this function with '#ifdef's, use a temporary array on the stack
+	// to store the conversions.
+	r = sscanf(guid_string, "{%8x-%4hx-%4hx-%4hx-%4hx%4hx%4hx}%n%c",
+		(unsigned int *)&guid->Data1, &guid->Data2, &guid->Data3,
+		&tmp[0], &tmp[1], &tmp[2], &tmp[3], &num_chars, &extra);
+
+	if ((r != 7) || (num_chars != 38))
+		return false;
+
+	// Extract the bytes from the 2-byte shorts
+	guid->Data4[0] = (unsigned char)((tmp[0] >> 8) & 0xFF);
+	guid->Data4[1] = (unsigned char)(tmp[0] & 0xFF);
+	guid->Data4[2] = (unsigned char)((tmp[1] >> 8) & 0xFF);
+	guid->Data4[3] = (unsigned char)(tmp[1] & 0xFF);
+	guid->Data4[4] = (unsigned char)((tmp[2] >> 8) & 0xFF);
+	guid->Data4[5] = (unsigned char)(tmp[2] & 0xFF);
+	guid->Data4[6] = (unsigned char)((tmp[3] >> 8) & 0xFF);
+	guid->Data4[7] = (unsigned char)(tmp[3] & 0xFF);
+
+	return true;
+}
+
+/*
+ * Normalize Microsoft's paths: return a duplicate of the given path
+ * with all characters converted to uppercase
+ */
+static char *normalize_path(const char *path)
+{
+	char *ret_path = _strdup(path);
+	char *p;
+
+	if (ret_path == NULL)
+		return NULL;
+
+	for (p = ret_path; *p != '\0'; p++)
+		*p = (char)toupper((unsigned char)*p);
+
+	return ret_path;
+}
+
+/*
+ * Cfgmgr32, AdvAPI32, OLE32 and SetupAPI DLL functions
+ */
+static bool init_dlls(struct libusb_context *ctx)
+{
+	DLL_GET_HANDLE(ctx, Cfgmgr32);
+	DLL_LOAD_FUNC(Cfgmgr32, CM_Get_Parent, true);
+	DLL_LOAD_FUNC(Cfgmgr32, CM_Get_Child, true);
+
+	// Prefixed to avoid conflict with header files
+	DLL_GET_HANDLE(ctx, AdvAPI32);
+	DLL_LOAD_FUNC_PREFIXED(AdvAPI32, p, RegQueryValueExA, true);
+	DLL_LOAD_FUNC_PREFIXED(AdvAPI32, p, RegCloseKey, true);
+
+	DLL_GET_HANDLE(ctx, SetupAPI);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiGetClassDevsA, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiEnumDeviceInfo, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiEnumDeviceInterfaces, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiGetDeviceInstanceIdA, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiGetDeviceInterfaceDetailA, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiGetDeviceRegistryPropertyA, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiDestroyDeviceInfoList, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiOpenDevRegKey, true);
+	DLL_LOAD_FUNC_PREFIXED(SetupAPI, p, SetupDiOpenDeviceInterfaceRegKey, true);
+
+	return true;
+}
+
+static void exit_dlls(void)
+{
+	DLL_FREE_HANDLE(SetupAPI);
+	DLL_FREE_HANDLE(AdvAPI32);
+	DLL_FREE_HANDLE(Cfgmgr32);
+}
+
+/*
+ * enumerate interfaces for the whole USB class
+ *
+ * Parameters:
+ * dev_info: a pointer to a dev_info list
+ * dev_info_data: a pointer to an SP_DEVINFO_DATA to be filled (or NULL if not needed)
+ * enumerator: the generic USB class for which to retrieve interface details
+ * index: zero based index of the interface in the device info list
+ *
+ * Note: it is the responsibility of the caller to free the DEVICE_INTERFACE_DETAIL_DATA
+ * structure returned and call this function repeatedly using the same guid (with an
+ * incremented index starting at zero) until all interfaces have been returned.
+ */
+static bool get_devinfo_data(struct libusb_context *ctx,
+	HDEVINFO *dev_info, SP_DEVINFO_DATA *dev_info_data, const char *enumerator, unsigned _index)
+{
+	if (_index == 0) {
+		*dev_info = pSetupDiGetClassDevsA(NULL, enumerator, NULL, DIGCF_PRESENT|DIGCF_ALLCLASSES);
+		if (*dev_info == INVALID_HANDLE_VALUE) {
+			usbi_err(ctx, "could not obtain device info set for PnP enumerator '%s': %s",
+				enumerator, windows_error_str(0));
+			return false;
+		}
+	}
+
+	dev_info_data->cbSize = sizeof(SP_DEVINFO_DATA);
+	if (!pSetupDiEnumDeviceInfo(*dev_info, _index, dev_info_data)) {
+		if (GetLastError() != ERROR_NO_MORE_ITEMS)
+			usbi_err(ctx, "could not obtain device info data for PnP enumerator '%s' index %u: %s",
+				enumerator, _index, windows_error_str(0));
+
+		pSetupDiDestroyDeviceInfoList(*dev_info);
+		*dev_info = INVALID_HANDLE_VALUE;
+		return false;
+	}
+	return true;
+}
+
+/*
+ * enumerate interfaces for a specific GUID
+ *
+ * Parameters:
+ * dev_info: a pointer to a dev_info list
+ * dev_info_data: a pointer to an SP_DEVINFO_DATA to be filled (or NULL if not needed)
+ * guid: the GUID for which to retrieve interface details
+ * index: zero based index of the interface in the device info list
+ *
+ * Note: it is the responsibility of the caller to free the DEVICE_INTERFACE_DETAIL_DATA
+ * structure returned and call this function repeatedly using the same guid (with an
+ * incremented index starting at zero) until all interfaces have been returned.
+ */
+static int get_interface_details(struct libusb_context *ctx, HDEVINFO dev_info,
+	PSP_DEVINFO_DATA dev_info_data, LPCGUID guid, DWORD *_index, char **dev_interface_path)
+{
+	SP_DEVICE_INTERFACE_DATA dev_interface_data;
+	PSP_DEVICE_INTERFACE_DETAIL_DATA_A dev_interface_details;
+	char guid_string[MAX_GUID_STRING_LENGTH];
+	DWORD size;
+
+	dev_info_data->cbSize = sizeof(SP_DEVINFO_DATA);
+	dev_interface_data.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
+	for (;;) {
+		if (!pSetupDiEnumDeviceInfo(dev_info, *_index, dev_info_data)) {
+			if (GetLastError() != ERROR_NO_MORE_ITEMS) {
+				usbi_err(ctx, "Could not obtain device info data for %s index %lu: %s",
+					guid_to_string(guid, guid_string), ULONG_CAST(*_index), windows_error_str(0));
+				return LIBUSB_ERROR_OTHER;
+			}
+
+			// No more devices
+			return LIBUSB_SUCCESS;
+		}
+
+		// Always advance the index for the next iteration
+		(*_index)++;
+
+		if (pSetupDiEnumDeviceInterfaces(dev_info, dev_info_data, guid, 0, &dev_interface_data))
+			break;
+
+		if (GetLastError() != ERROR_NO_MORE_ITEMS) {
+			usbi_err(ctx, "Could not obtain interface data for %s devInst %lX: %s",
+				guid_to_string(guid, guid_string), ULONG_CAST(dev_info_data->DevInst), windows_error_str(0));
+			return LIBUSB_ERROR_OTHER;
+		}
+
+		// Device does not have an interface matching this GUID, skip
+	}
+
+	// Read interface data (dummy + actual) to access the device path
+	if (!pSetupDiGetDeviceInterfaceDetailA(dev_info, &dev_interface_data, NULL, 0, &size, NULL)) {
+		// The dummy call should fail with ERROR_INSUFFICIENT_BUFFER
+		if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+			usbi_err(ctx, "could not access interface data (dummy) for %s devInst %lX: %s",
+				guid_to_string(guid, guid_string), ULONG_CAST(dev_info_data->DevInst), windows_error_str(0));
+			return LIBUSB_ERROR_OTHER;
+		}
+	} else {
+		usbi_err(ctx, "program assertion failed - http://msdn.microsoft.com/en-us/library/ms792901.aspx is wrong");
+		return LIBUSB_ERROR_OTHER;
+	}
+
+	dev_interface_details = malloc(size);
+	if (dev_interface_details == NULL) {
+		usbi_err(ctx, "could not allocate interface data for %s devInst %lX",
+			guid_to_string(guid, guid_string), ULONG_CAST(dev_info_data->DevInst));
+		return LIBUSB_ERROR_NO_MEM;
+	}
+
+	dev_interface_details->cbSize = sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA_A);
+	if (!pSetupDiGetDeviceInterfaceDetailA(dev_info, &dev_interface_data,
+		dev_interface_details, size, NULL, NULL)) {
+		usbi_err(ctx, "could not access interface data (actual) for %s devInst %lX: %s",
+			guid_to_string(guid, guid_string), ULONG_CAST(dev_info_data->DevInst), windows_error_str(0));
+		free(dev_interface_details);
+		return LIBUSB_ERROR_OTHER;
+	}
+
+	*dev_interface_path = normalize_path(dev_interface_details->DevicePath);
+	free(dev_interface_details);
+
+	if (*dev_interface_path == NULL) {
+		usbi_err(ctx, "could not allocate interface path for %s devInst %lX",
+			guid_to_string(guid, guid_string), ULONG_CAST(dev_info_data->DevInst));
+		return LIBUSB_ERROR_NO_MEM;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+/* For libusb0 filter */
+static int get_interface_details_filter(struct libusb_context *ctx, HDEVINFO *dev_info,
+	DWORD _index, char *filter_path, char **dev_interface_path)
+{
+	const GUID *libusb0_guid = &GUID_DEVINTERFACE_LIBUSB0_FILTER;
+	SP_DEVICE_INTERFACE_DATA dev_interface_data;
+	PSP_DEVICE_INTERFACE_DETAIL_DATA_A dev_interface_details;
+	HKEY hkey_dev_interface;
+	DWORD size;
+	int err = LIBUSB_ERROR_OTHER;
+
+	if (_index == 0) {
+		*dev_info = pSetupDiGetClassDevsA(libusb0_guid, NULL, NULL, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
+		if (*dev_info == INVALID_HANDLE_VALUE) {
+			usbi_err(ctx, "could not obtain device info set: %s", windows_error_str(0));
+			return LIBUSB_ERROR_OTHER;
+		}
+	}
+
+	dev_interface_data.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
+	if (!pSetupDiEnumDeviceInterfaces(*dev_info, NULL, libusb0_guid, _index, &dev_interface_data)) {
+		if (GetLastError() != ERROR_NO_MORE_ITEMS) {
+			usbi_err(ctx, "Could not obtain interface data for index %lu: %s",
+				ULONG_CAST(_index), windows_error_str(0));
+			goto err_exit;
+		}
+
+		pSetupDiDestroyDeviceInfoList(*dev_info);
+		*dev_info = INVALID_HANDLE_VALUE;
+		return LIBUSB_SUCCESS;
+	}
+
+	// Read interface data (dummy + actual) to access the device path
+	if (!pSetupDiGetDeviceInterfaceDetailA(*dev_info, &dev_interface_data, NULL, 0, &size, NULL)) {
+		// The dummy call should fail with ERROR_INSUFFICIENT_BUFFER
+		if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+			usbi_err(ctx, "could not access interface data (dummy) for index %lu: %s",
+				ULONG_CAST(_index), windows_error_str(0));
+			goto err_exit;
+		}
+	} else {
+		usbi_err(ctx, "program assertion failed - http://msdn.microsoft.com/en-us/library/ms792901.aspx is wrong");
+		goto err_exit;
+	}
+
+	dev_interface_details = malloc(size);
+	if (dev_interface_details == NULL) {
+		usbi_err(ctx, "could not allocate interface data for index %lu", ULONG_CAST(_index));
+		err = LIBUSB_ERROR_NO_MEM;
+		goto err_exit;
+	}
+
+	dev_interface_details->cbSize = sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA_A);
+	if (!pSetupDiGetDeviceInterfaceDetailA(*dev_info, &dev_interface_data, dev_interface_details, size, NULL, NULL)) {
+		usbi_err(ctx, "could not access interface data (actual) for index %lu: %s",
+			ULONG_CAST(_index), windows_error_str(0));
+		free(dev_interface_details);
+		goto err_exit;
+	}
+
+	*dev_interface_path = normalize_path(dev_interface_details->DevicePath);
+	free(dev_interface_details);
+
+	if (*dev_interface_path == NULL) {
+		usbi_err(ctx, "could not allocate interface path for index %lu", ULONG_CAST(_index));
+		err = LIBUSB_ERROR_NO_MEM;
+		goto err_exit;
+	}
+
+	// [trobinso] lookup the libusb0 symbolic index.
+	hkey_dev_interface = pSetupDiOpenDeviceInterfaceRegKey(*dev_info, &dev_interface_data, 0, KEY_READ);
+	if (hkey_dev_interface != INVALID_HANDLE_VALUE) {
+		DWORD libusb0_symboliclink_index = 0;
+		DWORD value_length = sizeof(DWORD);
+		LONG status;
+
+		status = pRegQueryValueExA(hkey_dev_interface, "LUsb0", NULL, NULL,
+			(LPBYTE)&libusb0_symboliclink_index, &value_length);
+		if (status == ERROR_SUCCESS) {
+			if (libusb0_symboliclink_index < 256) {
+				// libusb0.sys is connected to this device instance.
+				// If the the device interface guid is {F9F3FF14-AE21-48A0-8A25-8011A7A931D9} then it's a filter.
+				sprintf(filter_path, "\\\\.\\libusb0-%04u", (unsigned int)libusb0_symboliclink_index);
+				usbi_dbg(ctx, "assigned libusb0 symbolic link %s", filter_path);
+			} else {
+				// libusb0.sys was connected to this device instance at one time; but not anymore.
+			}
+		}
+		pRegCloseKey(hkey_dev_interface);
+	} else {
+		usbi_warn(ctx, "could not open device interface registry key for index %lu: %s",
+			ULONG_CAST(_index), windows_error_str(0));
+		// TODO: should this be an error?
+	}
+
+	return LIBUSB_SUCCESS;
+
+err_exit:
+	pSetupDiDestroyDeviceInfoList(*dev_info);
+	*dev_info = INVALID_HANDLE_VALUE;
+	return err;
+}
+
+/*
+ * Returns the first known ancestor of a device
+ */
+static struct libusb_device *get_ancestor(struct libusb_context *ctx,
+	DEVINST devinst, PDEVINST _parent_devinst)
+{
+	struct libusb_device *dev = NULL;
+	DEVINST parent_devinst;
+
+	while (dev == NULL) {
+		if (CM_Get_Parent(&parent_devinst, devinst, 0) != CR_SUCCESS)
+			break;
+		devinst = parent_devinst;
+		dev = usbi_get_device_by_session_id(ctx, (unsigned long)devinst);
+	}
+
+	if ((dev != NULL) && (_parent_devinst != NULL))
+		*_parent_devinst = devinst;
+
+	return dev;
+}
+
+/*
+ * Determine which interface the given endpoint address belongs to
+ */
+static int get_interface_by_endpoint(struct libusb_config_descriptor *conf_desc, uint8_t ep)
+{
+	const struct libusb_interface *intf;
+	const struct libusb_interface_descriptor *intf_desc;
+	uint8_t i, k;
+	int j;
+
+	for (i = 0; i < conf_desc->bNumInterfaces; i++) {
+		intf = &conf_desc->interface[i];
+		for (j = 0; j < intf->num_altsetting; j++) {
+			intf_desc = &intf->altsetting[j];
+			for (k = 0; k < intf_desc->bNumEndpoints; k++) {
+				if (intf_desc->endpoint[k].bEndpointAddress == ep) {
+					usbi_dbg(NULL, "found endpoint %02X on interface %d", intf_desc->bInterfaceNumber, i);
+					return intf_desc->bInterfaceNumber;
+				}
+			}
+		}
+	}
+
+	usbi_dbg(NULL, "endpoint %02X not found on any interface", ep);
+	return LIBUSB_ERROR_NOT_FOUND;
+}
+
+/*
+ * Open a device and associate the HANDLE with the context's I/O completion port
+ */
+static HANDLE windows_open(struct libusb_device_handle *dev_handle, const char *path, DWORD access)
+{
+	struct libusb_context *ctx = HANDLE_CTX(dev_handle);
+	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
+	HANDLE handle;
+
+	handle = CreateFileA(path, access, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
+	if (handle == INVALID_HANDLE_VALUE)
+		return handle;
+
+	if (CreateIoCompletionPort(handle, priv->completion_port, (ULONG_PTR)dev_handle, 0) == NULL) {
+		usbi_err(ctx, "failed to associate handle to I/O completion port: %s", windows_error_str(0));
+		CloseHandle(handle);
+		return INVALID_HANDLE_VALUE;
+	}
+
+	return handle;
+}
+
+/*
+ * Populate the endpoints addresses of the device_priv interface helper structs
+ */
+static int windows_assign_endpoints(struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	struct libusb_config_descriptor *conf_desc;
+	const struct libusb_interface_descriptor *if_desc;
+	int i, r;
+
+	r = libusb_get_active_config_descriptor(dev_handle->dev, &conf_desc);
+	if (r != LIBUSB_SUCCESS) {
+		usbi_warn(HANDLE_CTX(dev_handle), "could not read config descriptor: error %d", r);
+		return r;
+	}
+
+	if_desc = &conf_desc->interface[iface].altsetting[altsetting];
+	safe_free(priv->usb_interface[iface].endpoint);
+
+	if (if_desc->bNumEndpoints == 0) {
+		usbi_dbg(HANDLE_CTX(dev_handle), "no endpoints found for interface %u", iface);
+	} else {
+		priv->usb_interface[iface].endpoint = malloc(if_desc->bNumEndpoints);
+		if (priv->usb_interface[iface].endpoint == NULL) {
+			libusb_free_config_descriptor(conf_desc);
+			return LIBUSB_ERROR_NO_MEM;
+		}
+		priv->usb_interface[iface].nb_endpoints = if_desc->bNumEndpoints;
+		for (i = 0; i < if_desc->bNumEndpoints; i++) {
+			priv->usb_interface[iface].endpoint[i] = if_desc->endpoint[i].bEndpointAddress;
+			usbi_dbg(HANDLE_CTX(dev_handle), "(re)assigned endpoint %02X to interface %u", priv->usb_interface[iface].endpoint[i], iface);
+		}
+	}
+	libusb_free_config_descriptor(conf_desc);
+
+	// Extra init may be required to configure endpoints
+	if (priv->apib->configure_endpoints)
+		r = priv->apib->configure_endpoints(SUB_API_NOTSET, dev_handle, iface);
+
+	if (r == LIBUSB_SUCCESS)
+		priv->usb_interface[iface].current_altsetting = altsetting;
+
+	return r;
+}
+
+// Lookup for a match in the list of API driver names
+// return -1 if not found, driver match number otherwise
+static int get_sub_api(char *driver, int api)
+{
+	const char sep_str[2] = {LIST_SEPARATOR, 0};
+	char *tok, *tmp_str;
+	size_t len = strlen(driver);
+	int i;
+
+	if (len == 0)
+		return SUB_API_NOTSET;
+
+	tmp_str = _strdup(driver);
+	if (tmp_str == NULL)
+		return SUB_API_NOTSET;
+
+	tok = strtok(tmp_str, sep_str);
+	while (tok != NULL) {
+		for (i = 0; i < usb_api_backend[api].nb_driver_names; i++) {
+			if (_stricmp(tok, usb_api_backend[api].driver_name_list[i]) == 0) {
+				free(tmp_str);
+				return i;
+			}
+		}
+		tok = strtok(NULL, sep_str);
+	}
+
+	free(tmp_str);
+	return SUB_API_NOTSET;
+}
+
+/*
+ * auto-claiming and auto-release helper functions
+ */
+static int auto_claim(struct libusb_transfer *transfer, int *interface_number, int api_type)
+{
+	struct winusb_device_handle_priv *handle_priv =
+		get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int current_interface = *interface_number;
+	int r = LIBUSB_SUCCESS;
+
+	switch (api_type) {
+	case USB_API_WINUSBX:
+	case USB_API_HID:
+		break;
+	default:
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	usbi_mutex_lock(&autoclaim_lock);
+	if (current_interface < 0) { // No serviceable interface was found
+		for (current_interface = 0; current_interface < USB_MAXINTERFACES; current_interface++) {
+			// Must claim an interface of the same API type
+			if ((priv->usb_interface[current_interface].apib->id == api_type)
+					&& (libusb_claim_interface(transfer->dev_handle, current_interface) == LIBUSB_SUCCESS)) {
+				usbi_dbg(TRANSFER_CTX(transfer), "auto-claimed interface %d for control request", current_interface);
+				if (handle_priv->autoclaim_count[current_interface] != 0)
+					usbi_err(TRANSFER_CTX(transfer), "program assertion failed - autoclaim_count was nonzero");
+				handle_priv->autoclaim_count[current_interface]++;
+				break;
+			}
+		}
+		if (current_interface == USB_MAXINTERFACES) {
+			usbi_err(TRANSFER_CTX(transfer), "could not auto-claim any interface");
+			r = LIBUSB_ERROR_NOT_FOUND;
+		}
+	} else {
+		// If we have a valid interface that was autoclaimed, we must increment
+		// its autoclaim count so that we can prevent an early release.
+		if (handle_priv->autoclaim_count[current_interface] != 0)
+			handle_priv->autoclaim_count[current_interface]++;
+	}
+	usbi_mutex_unlock(&autoclaim_lock);
+
+	*interface_number = current_interface;
+	return r;
+}
+
+static void auto_release(struct usbi_transfer *itransfer)
+{
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	libusb_device_handle *dev_handle = transfer->dev_handle;
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	int r;
+
+	usbi_mutex_lock(&autoclaim_lock);
+	if (handle_priv->autoclaim_count[transfer_priv->interface_number] > 0) {
+		handle_priv->autoclaim_count[transfer_priv->interface_number]--;
+		if (handle_priv->autoclaim_count[transfer_priv->interface_number] == 0) {
+			r = libusb_release_interface(dev_handle, transfer_priv->interface_number);
+			if (r == LIBUSB_SUCCESS)
+				usbi_dbg(ITRANSFER_CTX(itransfer), "auto-released interface %d", transfer_priv->interface_number);
+			else
+				usbi_dbg(ITRANSFER_CTX(itransfer), "failed to auto-release interface %d (%s)",
+					transfer_priv->interface_number, libusb_error_name((enum libusb_error)r));
+		}
+	}
+	usbi_mutex_unlock(&autoclaim_lock);
+}
+
+/*
+ * init: libusb backend init function
+ */
+static int winusb_init(struct libusb_context *ctx)
+{
+	int i;
+
+	// Load DLL imports
+	if (!init_dlls(ctx)) {
+		usbi_err(ctx, "could not resolve DLL functions");
+		return LIBUSB_ERROR_OTHER;
+	}
+
+	// Initialize the low level APIs (we don't care about errors at this stage)
+	for (i = 0; i < USB_API_MAX; i++) {
+		if (usb_api_backend[i].init && !usb_api_backend[i].init(ctx))
+			usbi_warn(ctx, "error initializing %s backend",
+				usb_api_backend[i].designation);
+	}
+
+	// We need a lock for proper auto-release
+	usbi_mutex_init(&autoclaim_lock);
+
+	return LIBUSB_SUCCESS;
+}
+
+/*
+* exit: libusb backend deinitialization function
+*/
+static void winusb_exit(struct libusb_context *ctx)
+{
+	int i;
+
+	UNUSED(ctx);
+
+	usbi_mutex_destroy(&autoclaim_lock);
+
+	for (i = 0; i < USB_API_MAX; i++) {
+		if (usb_api_backend[i].exit)
+			usb_api_backend[i].exit();
+	}
+
+	exit_dlls();
+}
+
+/*
+ * fetch and cache all the config descriptors through I/O
+ */
+static void cache_config_descriptors(struct libusb_device *dev, HANDLE hub_handle)
+{
+	struct libusb_context *ctx = DEVICE_CTX(dev);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	DWORD size, ret_size;
+	uint8_t i, num_configurations;
+
+	USB_CONFIGURATION_DESCRIPTOR_SHORT cd_buf_short; // dummy request
+	PUSB_DESCRIPTOR_REQUEST cd_buf_actual = NULL;    // actual request
+	PUSB_CONFIGURATION_DESCRIPTOR cd_data;
+
+	num_configurations = dev->device_descriptor.bNumConfigurations;
+	if (num_configurations == 0)
+		return;
+
+	assert(sizeof(USB_DESCRIPTOR_REQUEST) == USB_DESCRIPTOR_REQUEST_SIZE);
+
+	priv->config_descriptor = calloc(num_configurations, sizeof(PUSB_CONFIGURATION_DESCRIPTOR));
+	if (priv->config_descriptor == NULL) {
+		usbi_err(ctx, "could not allocate configuration descriptor array for '%s'", priv->dev_id);
+		return;
+	}
+
+	for (i = 0; i <= num_configurations; i++) {
+		safe_free(cd_buf_actual);
+
+		if (i == num_configurations)
+			break;
+
+		size = sizeof(cd_buf_short);
+		memset(&cd_buf_short.desc, 0, sizeof(cd_buf_short.desc));
+
+		cd_buf_short.req.ConnectionIndex = (ULONG)dev->port_number;
+		cd_buf_short.req.SetupPacket.bmRequest = LIBUSB_ENDPOINT_IN;
+		cd_buf_short.req.SetupPacket.bRequest = LIBUSB_REQUEST_GET_DESCRIPTOR;
+		cd_buf_short.req.SetupPacket.wValue = (LIBUSB_DT_CONFIG << 8) | i;
+		cd_buf_short.req.SetupPacket.wIndex = 0;
+		cd_buf_short.req.SetupPacket.wLength = (USHORT)sizeof(USB_CONFIGURATION_DESCRIPTOR);
+
+		// Dummy call to get the required data size. Initial failures are reported as info rather
+		// than error as they can occur for non-penalizing situations, such as with some hubs.
+		// coverity[tainted_data_argument]
+		if (!DeviceIoControl(hub_handle, IOCTL_USB_GET_DESCRIPTOR_FROM_NODE_CONNECTION, &cd_buf_short, size,
+			&cd_buf_short, size, &ret_size, NULL)) {
+			usbi_info(ctx, "could not access configuration descriptor %u (dummy) for '%s': %s", i, priv->dev_id, windows_error_str(0));
+			continue;
+		}
+
+		if ((ret_size != size) || (cd_buf_short.desc.wTotalLength < sizeof(USB_CONFIGURATION_DESCRIPTOR))) {
+			usbi_info(ctx, "unexpected configuration descriptor %u size (dummy) for '%s'", i, priv->dev_id);
+			continue;
+		}
+
+		size = sizeof(USB_DESCRIPTOR_REQUEST) + cd_buf_short.desc.wTotalLength;
+		cd_buf_actual = malloc(size);
+		if (cd_buf_actual == NULL) {
+			usbi_err(ctx, "could not allocate configuration descriptor %u buffer for '%s'", i, priv->dev_id);
+			continue;
+		}
+
+		// Actual call
+		cd_buf_actual->ConnectionIndex = (ULONG)dev->port_number;
+		cd_buf_actual->SetupPacket.bmRequest = LIBUSB_ENDPOINT_IN;
+		cd_buf_actual->SetupPacket.bRequest = LIBUSB_REQUEST_GET_DESCRIPTOR;
+		cd_buf_actual->SetupPacket.wValue = (LIBUSB_DT_CONFIG << 8) | i;
+		cd_buf_actual->SetupPacket.wIndex = 0;
+		cd_buf_actual->SetupPacket.wLength = cd_buf_short.desc.wTotalLength;
+
+		if (!DeviceIoControl(hub_handle, IOCTL_USB_GET_DESCRIPTOR_FROM_NODE_CONNECTION, cd_buf_actual, size,
+			cd_buf_actual, size, &ret_size, NULL)) {
+			usbi_err(ctx, "could not access configuration descriptor %u (actual) for '%s': %s", i, priv->dev_id, windows_error_str(0));
+			continue;
+		}
+
+		cd_data = (PUSB_CONFIGURATION_DESCRIPTOR)((UCHAR *)cd_buf_actual + USB_DESCRIPTOR_REQUEST_SIZE);
+
+		if ((size != ret_size) || (cd_data->wTotalLength != cd_buf_short.desc.wTotalLength)) {
+			usbi_err(ctx, "unexpected configuration descriptor %u size (actual) for '%s'", i, priv->dev_id);
+			continue;
+		}
+
+		if (cd_data->bDescriptorType != LIBUSB_DT_CONFIG) {
+			usbi_err(ctx, "descriptor %u not a configuration descriptor for '%s'", i, priv->dev_id);
+			continue;
+		}
+
+		usbi_dbg(ctx, "cached config descriptor %u (bConfigurationValue=%u, %u bytes)",
+			i, cd_data->bConfigurationValue, cd_data->wTotalLength);
+
+		// Cache the descriptor
+		priv->config_descriptor[i] = cd_data;
+		cd_buf_actual = NULL;
+	}
+}
+
+#define ROOT_HUB_FS_CONFIG_DESC_LENGTH		0x19
+#define ROOT_HUB_HS_CONFIG_DESC_LENGTH		0x19
+#define ROOT_HUB_SS_CONFIG_DESC_LENGTH		0x1f
+#define CONFIG_DESC_WTOTAL_LENGTH_OFFSET	0x02
+#define CONFIG_DESC_EP_MAX_PACKET_OFFSET	0x16
+#define CONFIG_DESC_EP_BINTERVAL_OFFSET		0x18
+
+static const uint8_t root_hub_config_descriptor_template[] = {
+	// Configuration Descriptor
+	LIBUSB_DT_CONFIG_SIZE,		// bLength
+	LIBUSB_DT_CONFIG,		// bDescriptorType
+	0x00, 0x00,			// wTotalLength (filled in)
+	0x01,				// bNumInterfaces
+	0x01,				// bConfigurationValue
+	0x00,				// iConfiguration
+	0xc0,				// bmAttributes (reserved + self-powered)
+	0x00,				// bMaxPower
+	// Interface Descriptor
+	LIBUSB_DT_INTERFACE_SIZE,	// bLength
+	LIBUSB_DT_INTERFACE,		// bDescriptorType
+	0x00,				// bInterfaceNumber
+	0x00,				// bAlternateSetting
+	0x01,				// bNumEndpoints
+	LIBUSB_CLASS_HUB,		// bInterfaceClass
+	0x00,				// bInterfaceSubClass
+	0x00,				// bInterfaceProtocol
+	0x00,				// iInterface
+	// Endpoint Descriptor
+	LIBUSB_DT_ENDPOINT_SIZE,	// bLength
+	LIBUSB_DT_ENDPOINT,		// bDescriptorType
+	0x81,				// bEndpointAddress
+	0x03,				// bmAttributes (Interrupt)
+	0x00, 0x00,			// wMaxPacketSize (filled in)
+	0x00,				// bInterval (filled in)
+	// SuperSpeed Endpoint Companion Descriptor
+	LIBUSB_DT_SS_ENDPOINT_COMPANION_SIZE,	// bLength
+	LIBUSB_DT_SS_ENDPOINT_COMPANION,	// bDescriptorType
+	0x00,					// bMaxBurst
+	0x00,					// bmAttributes
+	0x02, 0x00				// wBytesPerInterval
+};
+
+static int alloc_root_hub_config_desc(struct libusb_device *dev, ULONG num_ports,
+	uint8_t config_desc_length, uint8_t ep_interval)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	uint8_t *ptr;
+
+	priv->config_descriptor = malloc(sizeof(*priv->config_descriptor));
+	if (priv->config_descriptor == NULL)
+		return LIBUSB_ERROR_NO_MEM;
+
+	// Most config descriptors come from cache_config_descriptors() which obtains the
+	// descriptors from the hub using an allocated USB_DESCRIPTOR_REQUEST structure.
+	// To avoid an extra malloc + memcpy we just hold on to the USB_DESCRIPTOR_REQUEST
+	// structure we already have and back up the pointer in windows_device_priv_release()
+	// when freeing the descriptors. To keep a single execution path, we need to offset
+	// the pointer here by the same amount.
+	ptr = malloc(USB_DESCRIPTOR_REQUEST_SIZE + config_desc_length);
+	if (ptr == NULL)
+		return LIBUSB_ERROR_NO_MEM;
+
+	ptr += USB_DESCRIPTOR_REQUEST_SIZE;
+
+	memcpy(ptr, root_hub_config_descriptor_template, config_desc_length);
+	ptr[CONFIG_DESC_WTOTAL_LENGTH_OFFSET] = config_desc_length;
+	ptr[CONFIG_DESC_EP_MAX_PACKET_OFFSET] = (uint8_t)((num_ports + 7) / 8);
+	ptr[CONFIG_DESC_EP_BINTERVAL_OFFSET] = ep_interval;
+
+	priv->config_descriptor[0] = (PUSB_CONFIGURATION_DESCRIPTOR)ptr;
+	priv->active_config = 1;
+
+	return 0;
+}
+
+static int init_root_hub(struct libusb_device *dev)
+{
+	struct libusb_context *ctx = DEVICE_CTX(dev);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	USB_NODE_CONNECTION_INFORMATION_EX conn_info;
+	USB_NODE_CONNECTION_INFORMATION_EX_V2 conn_info_v2;
+	USB_NODE_INFORMATION hub_info;
+	enum libusb_speed speed = LIBUSB_SPEED_UNKNOWN;
+	uint8_t config_desc_length;
+	uint8_t ep_interval;
+	HANDLE handle;
+	ULONG port_number, num_ports;
+	DWORD size;
+	int r;
+
+	// Determining the speed of a root hub is painful. Microsoft does not directly report the speed
+	// capabilities of the root hub itself, only its ports and/or connected devices. Therefore we
+	// are forced to query each individual port of the root hub to try and infer the root hub's
+	// speed. Note that we have to query all ports because the presence of a device on that port
+	// changes if/how Windows returns any useful speed information.
+	handle = CreateFileA(priv->path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
+	if (handle == INVALID_HANDLE_VALUE) {
+		usbi_err(ctx, "could not open root hub %s: %s", priv->path, windows_error_str(0));
+		return LIBUSB_ERROR_ACCESS;
+	}
+
+	if (!DeviceIoControl(handle, IOCTL_USB_GET_NODE_INFORMATION, NULL, 0, &hub_info, sizeof(hub_info), &size, NULL)) {
+		usbi_warn(ctx, "could not get root hub info for '%s': %s", priv->dev_id, windows_error_str(0));
+		CloseHandle(handle);
+		return LIBUSB_ERROR_ACCESS;
+	}
+
+	num_ports = hub_info.u.HubInformation.HubDescriptor.bNumberOfPorts;
+	usbi_dbg(ctx, "root hub '%s' reports %lu ports", priv->dev_id, ULONG_CAST(num_ports));
+
+	if (windows_version >= WINDOWS_8) {
+		// Windows 8 and later is better at reporting the speed capabilities of the root hub,
+		// but it is not perfect. If no device is attached to the port being queried, the
+		// returned information will only indicate whether that port supports USB 3.0 signalling.
+		// That is not enough information to distinguish between SuperSpeed and SuperSpeed Plus.
+		for (port_number = 1; port_number <= num_ports; port_number++) {
+			conn_info_v2.ConnectionIndex = port_number;
+			conn_info_v2.Length = sizeof(conn_info_v2);
+			conn_info_v2.SupportedUsbProtocols.Usb300 = 1;
+			if (!DeviceIoControl(handle, IOCTL_USB_GET_NODE_CONNECTION_INFORMATION_EX_V2,
+				&conn_info_v2, sizeof(conn_info_v2), &conn_info_v2, sizeof(conn_info_v2), &size, NULL)) {
+				usbi_warn(ctx, "could not get node connection information (V2) for root hub '%s' port %lu: %s",
+					priv->dev_id, ULONG_CAST(port_number), windows_error_str(0));
+				break;
+			}
+
+			if (conn_info_v2.Flags.DeviceIsSuperSpeedPlusCapableOrHigher)
+				speed = MAX(speed, LIBUSB_SPEED_SUPER_PLUS);
+			else if (conn_info_v2.Flags.DeviceIsSuperSpeedCapableOrHigher || conn_info_v2.SupportedUsbProtocols.Usb300)
+				speed = MAX(speed, LIBUSB_SPEED_SUPER);
+			else if (conn_info_v2.SupportedUsbProtocols.Usb200)
+				speed = MAX(speed, LIBUSB_SPEED_HIGH);
+			else
+				speed = MAX(speed, LIBUSB_SPEED_FULL);
+		}
+
+		if (speed != LIBUSB_SPEED_UNKNOWN)
+			goto make_descriptors;
+	}
+
+	// At this point the speed is still not known, most likely because we are executing on
+	// Windows 7 or earlier. The following hackery peeks into the root hub's Device ID and
+	// tries to extract speed information from it, based on observed naming conventions.
+	// If this does not work, we will query individual ports of the root hub.
+	if (strstr(priv->dev_id, "ROOT_HUB31") != NULL)
+		speed = LIBUSB_SPEED_SUPER_PLUS;
+	else if (strstr(priv->dev_id, "ROOT_HUB30") != NULL)
+		speed = LIBUSB_SPEED_SUPER;
+	else if (strstr(priv->dev_id, "ROOT_HUB20") != NULL)
+		speed = LIBUSB_SPEED_HIGH;
+
+	if (speed != LIBUSB_SPEED_UNKNOWN)
+		goto make_descriptors;
+
+	// Windows only reports speed information about a connected device. This means that a root
+	// hub with no connected devices or devices that are all operating at a speed less than the
+	// highest speed that the root hub supports will not give us the correct speed.
+	for (port_number = 1; port_number <= num_ports; port_number++) {
+		conn_info.ConnectionIndex = port_number;
+		if (!DeviceIoControl(handle, IOCTL_USB_GET_NODE_CONNECTION_INFORMATION_EX, &conn_info, sizeof(conn_info),
+			&conn_info, sizeof(conn_info), &size, NULL)) {
+			usbi_warn(ctx, "could not get node connection information for root hub '%s' port %lu: %s",
+				priv->dev_id, ULONG_CAST(port_number), windows_error_str(0));
+			continue;
+		}
+
+		if (conn_info.ConnectionStatus != DeviceConnected)
+			continue;
+
+		if (conn_info.Speed == UsbHighSpeed) {
+			speed = LIBUSB_SPEED_HIGH;
+			break;
+		}
+	}
+
+make_descriptors:
+	CloseHandle(handle);
+
+	dev->device_descriptor.bLength = LIBUSB_DT_DEVICE_SIZE;
+	dev->device_descriptor.bDescriptorType = LIBUSB_DT_DEVICE;
+	dev->device_descriptor.bDeviceClass = LIBUSB_CLASS_HUB;
+	if ((dev->device_descriptor.idVendor == 0) && (dev->device_descriptor.idProduct == 0)) {
+		dev->device_descriptor.idVendor = 0x1d6b;	// Linux Foundation
+		dev->device_descriptor.idProduct = (uint16_t)speed;
+	}
+	dev->device_descriptor.bcdDevice = 0x0100;
+	dev->device_descriptor.bNumConfigurations = 1;
+
+	switch (speed) {
+	case LIBUSB_SPEED_SUPER_PLUS:
+		dev->device_descriptor.bcdUSB = 0x0310;
+		config_desc_length = ROOT_HUB_SS_CONFIG_DESC_LENGTH;
+		ep_interval = 0x0c;	// 256ms
+		break;
+	case LIBUSB_SPEED_SUPER:
+		dev->device_descriptor.bcdUSB = 0x0300;
+		config_desc_length = ROOT_HUB_SS_CONFIG_DESC_LENGTH;
+		ep_interval = 0x0c;	// 256ms
+		break;
+	case LIBUSB_SPEED_HIGH:
+		dev->device_descriptor.bcdUSB = 0x0200;
+		config_desc_length = ROOT_HUB_HS_CONFIG_DESC_LENGTH;
+		ep_interval = 0x0c;	// 256ms
+		break;
+	case LIBUSB_SPEED_LOW:		// Not used, but keeps compiler happy
+	case LIBUSB_SPEED_UNKNOWN:
+		// This case means absolutely no information about this root hub was determined.
+		// There is not much choice than to be pessimistic and label this as a
+		// full-speed device.
+		speed = LIBUSB_SPEED_FULL;
+		// fallthrough
+	case LIBUSB_SPEED_FULL:
+		dev->device_descriptor.bcdUSB = 0x0110;
+		config_desc_length = ROOT_HUB_FS_CONFIG_DESC_LENGTH;
+		ep_interval = 0xff;	// 255ms
+		break;
+	default:			// Impossible, buts keeps compiler happy
+		usbi_err(ctx, "program assertion failed - unknown root hub speed");
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	if (speed >= LIBUSB_SPEED_SUPER) {
+		dev->device_descriptor.bDeviceProtocol = 0x03;	// USB 3.0 Hub
+		dev->device_descriptor.bMaxPacketSize0 = 0x09;	// 2^9 bytes
+	} else {
+		dev->device_descriptor.bMaxPacketSize0 = 0x40;	// 64 bytes
+	}
+
+	dev->speed = speed;
+
+	r = alloc_root_hub_config_desc(dev, num_ports, config_desc_length, ep_interval);
+	if (r)
+		usbi_err(ctx, "could not allocate config descriptor for root hub '%s'", priv->dev_id);
+
+	return r;
+}
+
+/*
+ * Populate a libusb device structure
+ */
+static int init_device(struct libusb_device *dev, struct libusb_device *parent_dev,
+	uint8_t port_number, DEVINST devinst)
+{
+	struct libusb_context *ctx = NULL;
+	struct libusb_device *tmp_dev;
+	struct winusb_device_priv *priv, *parent_priv, *tmp_priv;
+	USB_NODE_CONNECTION_INFORMATION_EX conn_info;
+	USB_NODE_CONNECTION_INFORMATION_EX_V2 conn_info_v2;
+	HANDLE hub_handle;
+	DWORD size;
+	uint8_t bus_number, depth;
+	int r;
+	int ginfotimeout;
+
+	priv = usbi_get_device_priv(dev);
+
+	// If the device is already initialized, we can stop here
+	if (priv->initialized)
+		return LIBUSB_SUCCESS;
+
+	if (parent_dev != NULL) { // Not a HCD root hub
+		ctx = DEVICE_CTX(dev);
+		parent_priv = usbi_get_device_priv(parent_dev);
+		if (parent_priv->apib->id != USB_API_HUB) {
+			usbi_warn(ctx, "parent for device '%s' is not a hub", priv->dev_id);
+			return LIBUSB_ERROR_NOT_FOUND;
+		}
+
+		// Calculate depth and fetch bus number
+		bus_number = parent_dev->bus_number;
+		if (bus_number == 0) {
+			tmp_dev = get_ancestor(ctx, devinst, &devinst);
+			if (tmp_dev != parent_dev) {
+				usbi_err(ctx, "program assertion failed - first ancestor is not parent");
+				return LIBUSB_ERROR_NOT_FOUND;
+			}
+			libusb_unref_device(tmp_dev);
+
+			for (depth = 1; bus_number == 0; depth++) {
+				tmp_dev = get_ancestor(ctx, devinst, &devinst);
+				if (tmp_dev == NULL) {
+					usbi_warn(ctx, "ancestor for device '%s' not found at depth %u", priv->dev_id, depth);
+					return LIBUSB_ERROR_NO_DEVICE;
+				}
+				if (tmp_dev->bus_number != 0) {
+					bus_number = tmp_dev->bus_number;
+					tmp_priv = usbi_get_device_priv(tmp_dev);
+					depth += tmp_priv->depth;
+				}
+				libusb_unref_device(tmp_dev);
+			}
+		} else {
+			depth = parent_priv->depth + 1;
+		}
+
+		if (bus_number == 0) {
+			usbi_err(ctx, "program assertion failed - bus number not found for '%s'", priv->dev_id);
+			return LIBUSB_ERROR_NOT_FOUND;
+		}
+
+		dev->bus_number = bus_number;
+		dev->port_number = port_number;
+		dev->parent_dev = parent_dev;
+		priv->depth = depth;
+
+		hub_handle = CreateFileA(parent_priv->path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
+		if (hub_handle == INVALID_HANDLE_VALUE) {
+			usbi_warn(ctx, "could not open hub %s: %s", parent_priv->path, windows_error_str(0));
+			return LIBUSB_ERROR_ACCESS;
+		}
+
+		conn_info.ConnectionIndex = (ULONG)port_number;
+		// coverity[tainted_data_argument]
+		ginfotimeout = 20;
+		do {
+			if (!DeviceIoControl(hub_handle, IOCTL_USB_GET_NODE_CONNECTION_INFORMATION_EX, &conn_info, sizeof(conn_info),
+				&conn_info, sizeof(conn_info), &size, NULL)) {
+				usbi_warn(ctx, "could not get node connection information for device '%s': %s",
+					priv->dev_id, windows_error_str(0));
+				CloseHandle(hub_handle);
+				return LIBUSB_ERROR_NO_DEVICE;
+			}
+
+			if (conn_info.ConnectionStatus == NoDeviceConnected) {
+				usbi_err(ctx, "device '%s' is no longer connected!", priv->dev_id);
+				CloseHandle(hub_handle);
+				return LIBUSB_ERROR_NO_DEVICE;
+			}
+
+			if ((conn_info.DeviceDescriptor.bLength != LIBUSB_DT_DEVICE_SIZE)
+				 || (conn_info.DeviceDescriptor.bDescriptorType != LIBUSB_DT_DEVICE)) {
+				SleepEx(50, TRUE);
+				continue;
+			}
+
+			static_assert(sizeof(dev->device_descriptor) == sizeof(conn_info.DeviceDescriptor),
+				      "mismatch between libusb and OS device descriptor sizes");
+			memcpy(&dev->device_descriptor, &conn_info.DeviceDescriptor, LIBUSB_DT_DEVICE_SIZE);
+			usbi_localize_device_descriptor(&dev->device_descriptor);
+
+			priv->active_config = conn_info.CurrentConfigurationValue;
+			if (priv->active_config == 0) {
+				usbi_dbg(ctx, "0x%x:0x%x found %u configurations (not configured)",
+					dev->device_descriptor.idVendor,
+					dev->device_descriptor.idProduct,
+					dev->device_descriptor.bNumConfigurations);
+				SleepEx(50, TRUE);
+			}
+		} while (priv->active_config == 0 && --ginfotimeout >= 0);
+
+		if ((conn_info.DeviceDescriptor.bLength != LIBUSB_DT_DEVICE_SIZE)
+			 || (conn_info.DeviceDescriptor.bDescriptorType != LIBUSB_DT_DEVICE)) {
+			usbi_err(ctx, "device '%s' has invalid descriptor!", priv->dev_id);
+			CloseHandle(hub_handle);
+			return LIBUSB_ERROR_OTHER;
+		}
+
+		if (priv->active_config == 0) {
+			usbi_info(ctx, "0x%x:0x%x found %u configurations but device isn't configured, "
+				"forcing current configuration to 1",
+				dev->device_descriptor.idVendor,
+				dev->device_descriptor.idProduct,
+				dev->device_descriptor.bNumConfigurations);
+			priv->active_config = 1;
+		} else {
+			usbi_dbg(ctx, "found %u configurations (current config: %u)", dev->device_descriptor.bNumConfigurations, priv->active_config);
+		}
+
+		// Cache as many config descriptors as we can
+		cache_config_descriptors(dev, hub_handle);
+
+		// In their great wisdom, Microsoft decided to BREAK the USB speed report between Windows 7 and Windows 8
+		if (windows_version >= WINDOWS_8) {
+			conn_info_v2.ConnectionIndex = (ULONG)port_number;
+			conn_info_v2.Length = sizeof(USB_NODE_CONNECTION_INFORMATION_EX_V2);
+			conn_info_v2.SupportedUsbProtocols.Usb300 = 1;
+			if (!DeviceIoControl(hub_handle, IOCTL_USB_GET_NODE_CONNECTION_INFORMATION_EX_V2,
+				&conn_info_v2, sizeof(conn_info_v2), &conn_info_v2, sizeof(conn_info_v2), &size, NULL)) {
+				usbi_warn(ctx, "could not get node connection information (V2) for device '%s': %s",
+					priv->dev_id,  windows_error_str(0));
+			} else if (conn_info_v2.Flags.DeviceIsOperatingAtSuperSpeedPlusOrHigher) {
+				conn_info.Speed = UsbSuperSpeedPlus;
+			} else if (conn_info_v2.Flags.DeviceIsOperatingAtSuperSpeedOrHigher) {
+				conn_info.Speed = UsbSuperSpeed;
+			}
+		}
+
+		CloseHandle(hub_handle);
+
+		if (conn_info.DeviceAddress > UINT8_MAX)
+			usbi_err(ctx, "program assertion failed - device address overflow");
+
+		dev->device_address = (uint8_t)conn_info.DeviceAddress;
+
+		switch (conn_info.Speed) {
+		case UsbLowSpeed: dev->speed = LIBUSB_SPEED_LOW; break;
+		case UsbFullSpeed: dev->speed = LIBUSB_SPEED_FULL; break;
+		case UsbHighSpeed: dev->speed = LIBUSB_SPEED_HIGH; break;
+		case UsbSuperSpeed: dev->speed = LIBUSB_SPEED_SUPER; break;
+		case UsbSuperSpeedPlus: dev->speed = LIBUSB_SPEED_SUPER_PLUS; break;
+		default:
+			usbi_warn(ctx, "unknown device speed %u", conn_info.Speed);
+			break;
+		}
+	} else {
+		r = init_root_hub(dev);
+		if (r)
+			return r;
+	}
+
+	r = usbi_sanitize_device(dev);
+	if (r)
+		return r;
+
+	priv->initialized = true;
+
+	usbi_dbg(ctx, "(bus: %u, addr: %u, depth: %u, port: %u): '%s'",
+		dev->bus_number, dev->device_address, priv->depth, dev->port_number, priv->dev_id);
+
+	return LIBUSB_SUCCESS;
+}
+
+static bool get_dev_port_number(HDEVINFO dev_info, SP_DEVINFO_DATA *dev_info_data, DWORD *port_nr)
+{
+	char buffer[MAX_KEY_LENGTH];
+	DWORD size;
+
+	// First try SPDRP_LOCATION_INFORMATION, which returns a REG_SZ. The string *may* have a format
+	// similar to "Port_#0002.Hub_#000D", in which case we can extract the port number. However, we
+	// cannot extract the port if the returned string does not follow this format.
+	if (pSetupDiGetDeviceRegistryPropertyA(dev_info, dev_info_data, SPDRP_LOCATION_INFORMATION,
+			NULL, (PBYTE)buffer, sizeof(buffer), NULL)) {
+		// Check for the required format.
+		if (strncmp(buffer, "Port_#", 6) == 0) {
+			*port_nr = atoi(buffer + 6);
+			return true;
+		}
+	}
+
+	// Next try SPDRP_LOCATION_PATHS, which returns a REG_MULTI_SZ (but we only examine the first
+	// string in it). Each path has a format similar to,
+	// "PCIROOT(B2)#PCI(0300)#PCI(0000)#USBROOT(0)#USB(1)#USB(2)#USBMI(3)", and the port number is
+	// the number within the last "USB(x)" token.
+	if (pSetupDiGetDeviceRegistryPropertyA(dev_info, dev_info_data, SPDRP_LOCATION_PATHS,
+			NULL, (PBYTE)buffer, sizeof(buffer), NULL)) {
+		// Find the last "#USB(x)" substring
+		for (char *token = strrchr(buffer, '#'); token != NULL; token = strrchr(buffer, '#')) {
+			if (strncmp(token, "#USB(", 5) == 0) {
+				*port_nr = atoi(token + 5);
+				return true;
+			}
+			// Shorten the string and try again.
+			*token = '\0';
+		}
+	}
+
+	// Lastly, try SPDRP_ADDRESS, which returns a REG_DWORD. The address *may* be the port number,
+	// which is true for the Microsoft driver but may not be true for other drivers. However, we
+	// have no other options here but to accept what it returns.
+	return pSetupDiGetDeviceRegistryPropertyA(dev_info, dev_info_data, SPDRP_ADDRESS,
+			NULL, (PBYTE)port_nr, sizeof(*port_nr), &size) && (size == sizeof(*port_nr));
+}
+
+static int enumerate_hcd_root_hub(struct libusb_context *ctx, const char *dev_id,
+	uint8_t bus_number, DEVINST devinst)
+{
+	struct libusb_device *dev;
+	struct winusb_device_priv *priv;
+	unsigned long session_id;
+	DEVINST child_devinst;
+
+	if (CM_Get_Child(&child_devinst, devinst, 0) != CR_SUCCESS) {
+		usbi_warn(ctx, "could not get child devinst for '%s'", dev_id);
+		return LIBUSB_SUCCESS;
+	}
+
+	session_id = (unsigned long)child_devinst;
+	dev = usbi_get_device_by_session_id(ctx, session_id);
+	if (dev == NULL) {
+		usbi_err(ctx, "program assertion failed - HCD '%s' child not found", dev_id);
+		return LIBUSB_SUCCESS;
+	}
+
+	if (dev->bus_number == 0) {
+		// Only do this once
+		usbi_dbg(ctx, "assigning HCD '%s' bus number %u", dev_id, bus_number);
+		dev->bus_number = bus_number;
+
+		if (sscanf(dev_id, "PCI\\VEN_%04hx&DEV_%04hx%*s", &dev->device_descriptor.idVendor, &dev->device_descriptor.idProduct) != 2)
+			usbi_warn(ctx, "could not infer VID/PID of HCD root hub from '%s'", dev_id);
+
+		priv = usbi_get_device_priv(dev);
+		priv->root_hub = true;
+	}
+
+	libusb_unref_device(dev);
+	return LIBUSB_SUCCESS;
+}
+
+// Returns the api type, or 0 if not found/unsupported
+static void get_api_type(HDEVINFO *dev_info, SP_DEVINFO_DATA *dev_info_data,
+	int *api, int *sub_api)
+{
+	// Precedence for filter drivers vs driver is in the order of this array
+	struct driver_lookup lookup[3] = {
+		{"\0\0", SPDRP_SERVICE, "driver"},
+		{"\0\0", SPDRP_UPPERFILTERS, "upper filter driver"},
+		{"\0\0", SPDRP_LOWERFILTERS, "lower filter driver"}
+	};
+	DWORD size, reg_type;
+	unsigned k, l;
+	int i, j;
+
+	// Check the service & filter names to know the API we should use
+	for (k = 0; k < 3; k++) {
+		if (pSetupDiGetDeviceRegistryPropertyA(*dev_info, dev_info_data, lookup[k].reg_prop,
+			&reg_type, (PBYTE)lookup[k].list, MAX_KEY_LENGTH, &size)) {
+			// Turn the REG_SZ SPDRP_SERVICE into REG_MULTI_SZ
+			if (lookup[k].reg_prop == SPDRP_SERVICE)
+				// our buffers are MAX_KEY_LENGTH + 1 so we can overflow if needed
+				lookup[k].list[strlen(lookup[k].list) + 1] = 0;
+
+			// MULTI_SZ is a pain to work with. Turn it into something much more manageable
+			// NB: none of the driver names we check against contain LIST_SEPARATOR,
+			// (currently ';'), so even if an unsupported one does, it's not an issue
+			for (l = 0; (lookup[k].list[l] != 0) || (lookup[k].list[l + 1] != 0); l++) {
+				if (lookup[k].list[l] == 0)
+					lookup[k].list[l] = LIST_SEPARATOR;
+			}
+			usbi_dbg(NULL, "%s(s): %s", lookup[k].designation, lookup[k].list);
+		} else {
+			if (GetLastError() != ERROR_INVALID_DATA)
+				usbi_dbg(NULL, "could not access %s: %s", lookup[k].designation, windows_error_str(0));
+			lookup[k].list[0] = 0;
+		}
+	}
+
+	for (i = 2; i < USB_API_MAX; i++) {
+		for (k = 0; k < 3; k++) {
+			j = get_sub_api(lookup[k].list, i);
+			if (j >= 0) {
+				usbi_dbg(NULL, "matched %s name against %s", lookup[k].designation,
+					(i != USB_API_WINUSBX) ? usb_api_backend[i].designation : usb_api_backend[i].driver_name_list[j]);
+				*api = i;
+				*sub_api = j;
+				return;
+			}
+		}
+	}
+}
+
+static int set_composite_interface(struct libusb_context *ctx, struct libusb_device *dev,
+	char *dev_interface_path, char *device_id, int api, int sub_api)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	int interface_number;
+	const char *mi_str;
+
+	// Because MI_## are not necessarily in sequential order (some composite
+	// devices will have only MI_00 & MI_03 for instance), we retrieve the actual
+	// interface number from the path's MI value
+	mi_str = strstr(device_id, "MI_");
+	if ((mi_str != NULL) && isdigit((unsigned char)mi_str[3]) && isdigit((unsigned char)mi_str[4])) {
+		interface_number = ((mi_str[3] - '0') * 10) + (mi_str[4] - '0');
+	} else {
+		usbi_warn(ctx, "failure to read interface number for %s, using default value", device_id);
+		interface_number = 0;
+	}
+
+	if (interface_number >= USB_MAXINTERFACES) {
+		usbi_warn(ctx, "interface %d too large - ignoring interface path %s", interface_number, dev_interface_path);
+		return LIBUSB_ERROR_ACCESS;
+	}
+
+	if (priv->usb_interface[interface_number].path != NULL) {
+		if (api == USB_API_HID) {
+			// HID devices can have multiple collections (COL##) for each MI_## interface
+			usbi_dbg(ctx, "interface[%d] already set - ignoring HID collection: %s",
+				interface_number, device_id);
+			return LIBUSB_ERROR_ACCESS;
+		}
+		// In other cases, just use the latest data
+		safe_free(priv->usb_interface[interface_number].path);
+	}
+
+	usbi_dbg(ctx, "interface[%d] = %s", interface_number, dev_interface_path);
+	priv->usb_interface[interface_number].path = dev_interface_path;
+	priv->usb_interface[interface_number].apib = &usb_api_backend[api];
+	priv->usb_interface[interface_number].sub_api = sub_api;
+	if ((api == USB_API_HID) && (priv->hid == NULL)) {
+		priv->hid = calloc(1, sizeof(struct hid_device_priv));
+		if (priv->hid == NULL)
+			return LIBUSB_ERROR_NO_MEM;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int set_hid_interface(struct libusb_context *ctx, struct libusb_device *dev,
+	char *dev_interface_path)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	uint8_t i;
+
+	if (priv->hid == NULL) {
+		usbi_err(ctx, "program assertion failed - parent is not HID");
+		return LIBUSB_ERROR_NO_DEVICE;
+	} else if (priv->hid->nb_interfaces == USB_MAXINTERFACES) {
+		usbi_err(ctx, "program assertion failed - max USB interfaces reached for HID device");
+		return LIBUSB_ERROR_NO_DEVICE;
+	}
+
+	for (i = 0; i < priv->hid->nb_interfaces; i++) {
+		if ((priv->usb_interface[i].path != NULL) && strcmp(priv->usb_interface[i].path, dev_interface_path) == 0) {
+			usbi_dbg(ctx, "interface[%u] already set to %s", i, dev_interface_path);
+			return LIBUSB_ERROR_ACCESS;
+		}
+	}
+
+	priv->usb_interface[priv->hid->nb_interfaces].path = dev_interface_path;
+	priv->usb_interface[priv->hid->nb_interfaces].apib = &usb_api_backend[USB_API_HID];
+	usbi_dbg(ctx, "interface[%u] = %s", priv->hid->nb_interfaces, dev_interface_path);
+	priv->hid->nb_interfaces++;
+	return LIBUSB_SUCCESS;
+}
+
+/*
+ * get_device_list: libusb backend device enumeration function
+ */
+static int winusb_get_device_list(struct libusb_context *ctx, struct discovered_devs **_discdevs)
+{
+	struct discovered_devs *discdevs;
+	HDEVINFO *dev_info, dev_info_intf, dev_info_enum;
+	SP_DEVINFO_DATA dev_info_data;
+	DWORD _index = 0;
+	GUID hid_guid;
+	int r = LIBUSB_SUCCESS;
+	int api, sub_api;
+	unsigned int pass, i, j;
+	char enumerator[16];
+	char dev_id[MAX_PATH_LENGTH];
+	struct libusb_device *dev, *parent_dev;
+	struct winusb_device_priv *priv, *parent_priv;
+	char *dev_interface_path = NULL;
+	unsigned long session_id;
+	DWORD size, port_nr, reg_type, install_state;
+	HKEY key;
+	char guid_string[MAX_GUID_STRING_LENGTH];
+	GUID *if_guid;
+	LONG s;
+#define HUB_PASS 0
+#define DEV_PASS 1
+#define HCD_PASS 2
+#define GEN_PASS 3
+#define HID_PASS 4
+#define EXT_PASS 5
+	// Keep a list of guids that will be enumerated
+#define GUID_SIZE_STEP 8
+	const GUID **guid_list, **new_guid_list;
+	unsigned int guid_size = GUID_SIZE_STEP;
+	unsigned int nb_guids;
+	// Keep a list of PnP enumerator strings that are found
+	const char *usb_enumerator[8] = { "USB" };
+	unsigned int nb_usb_enumerators = 1;
+	unsigned int usb_enum_index = 0;
+	// Keep a list of newly allocated devs to unref
+#define UNREF_SIZE_STEP 16
+	libusb_device **unref_list, **new_unref_list;
+	unsigned int unref_size = UNREF_SIZE_STEP;
+	unsigned int unref_cur = 0;
+
+	// PASS 1 : (re)enumerate HCDs (allows for HCD hotplug)
+	// PASS 2 : (re)enumerate HUBS
+	// PASS 3 : (re)enumerate generic USB devices (including driverless)
+	//           and list additional USB device interface GUIDs to explore
+	// PASS 4 : (re)enumerate master USB devices that have a device interface
+	// PASS 5+: (re)enumerate device interfaced GUIDs (including HID) and
+	//           set the device interfaces.
+
+	// Init the GUID table
+	guid_list = malloc(guid_size * sizeof(void *));
+	if (guid_list == NULL) {
+		usbi_err(ctx, "failed to alloc guid list");
+		return LIBUSB_ERROR_NO_MEM;
+	}
+
+	guid_list[HUB_PASS] = &GUID_DEVINTERFACE_USB_HUB;
+	guid_list[DEV_PASS] = &GUID_DEVINTERFACE_USB_DEVICE;
+	guid_list[HCD_PASS] = &GUID_DEVINTERFACE_USB_HOST_CONTROLLER;
+	guid_list[GEN_PASS] = NULL;
+	if (HidD_GetHidGuid != NULL) {
+		HidD_GetHidGuid(&hid_guid);
+		guid_list[HID_PASS] = &hid_guid;
+	} else {
+		guid_list[HID_PASS] = NULL;
+	}
+	nb_guids = EXT_PASS;
+
+	unref_list = malloc(unref_size * sizeof(void *));
+	if (unref_list == NULL) {
+		usbi_err(ctx, "failed to alloc unref list");
+		free((void *)guid_list);
+		return LIBUSB_ERROR_NO_MEM;
+	}
+
+	dev_info_intf = pSetupDiGetClassDevsA(NULL, NULL, NULL, DIGCF_ALLCLASSES | DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
+	if (dev_info_intf == INVALID_HANDLE_VALUE) {
+		usbi_err(ctx, "failed to obtain device info list: %s", windows_error_str(0));
+		free(unref_list);
+		free((void *)guid_list);
+		return LIBUSB_ERROR_OTHER;
+	}
+
+	for (pass = 0; ((pass < nb_guids) && (r == LIBUSB_SUCCESS)); pass++) {
+//#define ENUM_DEBUG
+#if defined(ENABLE_LOGGING) && defined(ENUM_DEBUG)
+		const char * const passname[] = {"HUB", "DEV", "HCD", "GEN", "HID", "EXT"};
+		usbi_dbg(ctx, "#### PROCESSING %ss %s", passname[MIN(pass, EXT_PASS)], guid_to_string(guid_list[pass], guid_string));
+#endif
+		if ((pass == HID_PASS) && (guid_list[HID_PASS] == NULL))
+			continue;
+
+		dev_info = (pass != GEN_PASS) ? &dev_info_intf : &dev_info_enum;
+
+		for (i = 0; ; i++) {
+			// safe loop: free up any (unprotected) dynamic resource
+			// NB: this is always executed before breaking the loop
+			safe_free(dev_interface_path);
+			priv = parent_priv = NULL;
+			dev = parent_dev = NULL;
+
+			// Safe loop: end of loop conditions
+			if (r != LIBUSB_SUCCESS)
+				break;
+
+			if ((pass == HCD_PASS) && (i == UINT8_MAX)) {
+				usbi_warn(ctx, "program assertion failed - found more than %u buses, skipping the rest", UINT8_MAX);
+				break;
+			}
+
+			if (pass != GEN_PASS) {
+				// Except for GEN, all passes deal with device interfaces
+				r = get_interface_details(ctx, *dev_info, &dev_info_data, guid_list[pass], &_index, &dev_interface_path);
+				if ((r != LIBUSB_SUCCESS) || (dev_interface_path == NULL)) {
+					_index = 0;
+					break;
+				}
+			} else {
+				// Workaround for a Nec/Renesas USB 3.0 driver bug where root hubs are
+				// being listed under the "NUSB3" PnP Symbolic Name rather than "USB".
+				// The Intel USB 3.0 driver behaves similar, but uses "IUSB3"
+				// The Intel Alpine Ridge USB 3.1 driver uses "IARUSB3"
+				for (; usb_enum_index < nb_usb_enumerators; usb_enum_index++) {
+					if (get_devinfo_data(ctx, dev_info, &dev_info_data, usb_enumerator[usb_enum_index], i))
+						break;
+					i = 0;
+				}
+				if (usb_enum_index == nb_usb_enumerators)
+					break;
+			}
+
+			// Read the Device ID path
+			if (!pSetupDiGetDeviceInstanceIdA(*dev_info, &dev_info_data, dev_id, sizeof(dev_id), NULL)) {
+				usbi_warn(ctx, "could not read the device instance ID for devInst %lX, skipping",
+					  ULONG_CAST(dev_info_data.DevInst));
+				continue;
+			}
+
+#ifdef ENUM_DEBUG
+			usbi_dbg(ctx, "PRO: %s", dev_id);
+#endif
+
+			// Set API to use or get additional data from generic pass
+			api = USB_API_UNSUPPORTED;
+			sub_api = SUB_API_NOTSET;
+			switch (pass) {
+			case HCD_PASS:
+				break;
+			case HUB_PASS:
+				api = USB_API_HUB;
+				// Fetch the PnP enumerator class for this hub
+				// This will allow us to enumerate all classes during the GEN pass
+				if (!pSetupDiGetDeviceRegistryPropertyA(*dev_info, &dev_info_data, SPDRP_ENUMERATOR_NAME,
+					NULL, (PBYTE)enumerator, sizeof(enumerator), NULL)) {
+					usbi_err(ctx, "could not read enumerator string for device '%s': %s", dev_id, windows_error_str(0));
+					LOOP_BREAK(LIBUSB_ERROR_OTHER);
+				}
+				for (j = 0; j < nb_usb_enumerators; j++) {
+					if (strcmp(usb_enumerator[j], enumerator) == 0)
+						break;
+				}
+				if (j == nb_usb_enumerators) {
+					usbi_dbg(ctx, "found new PnP enumerator string '%s'", enumerator);
+					if (nb_usb_enumerators < ARRAYSIZE(usb_enumerator)) {
+						usb_enumerator[nb_usb_enumerators] = _strdup(enumerator);
+						if (usb_enumerator[nb_usb_enumerators] != NULL) {
+							nb_usb_enumerators++;
+						} else {
+							usbi_err(ctx, "could not allocate enumerator string '%s'", enumerator);
+							LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+						}
+					} else {
+						usbi_warn(ctx, "too many enumerator strings, some devices may not be accessible");
+					}
+				}
+				break;
+			case GEN_PASS:
+				// We use the GEN pass to detect driverless devices...
+				if (!pSetupDiGetDeviceRegistryPropertyA(*dev_info, &dev_info_data, SPDRP_DRIVER,
+					NULL, NULL, 0, NULL) && (GetLastError() != ERROR_INSUFFICIENT_BUFFER)) {
+					usbi_info(ctx, "The following device has no driver: '%s'", dev_id);
+					usbi_info(ctx, "libusb will not be able to access it");
+				}
+				// ...and to add the additional device interface GUIDs
+				key = pSetupDiOpenDevRegKey(*dev_info, &dev_info_data, DICS_FLAG_GLOBAL, 0, DIREG_DEV, KEY_READ);
+				if (key == INVALID_HANDLE_VALUE)
+					break;
+				// Look for both DeviceInterfaceGUIDs *and* DeviceInterfaceGUID, in that order
+				// If multiple GUIDs just process the first and ignore the others
+				size = sizeof(guid_string);
+				s = pRegQueryValueExA(key, "DeviceInterfaceGUIDs", NULL, &reg_type,
+					(LPBYTE)guid_string, &size);
+				if (s == ERROR_FILE_NOT_FOUND)
+					s = pRegQueryValueExA(key, "DeviceInterfaceGUID", NULL, &reg_type,
+						(LPBYTE)guid_string, &size);
+				pRegCloseKey(key);
+				if (s == ERROR_FILE_NOT_FOUND) {
+					break; /* no DeviceInterfaceGUID registered */
+				} else if (s != ERROR_SUCCESS && s != ERROR_MORE_DATA) {
+					usbi_warn(ctx, "unexpected error from pRegQueryValueExA for '%s'", dev_id);
+					break;
+				}
+				// https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regqueryvalueexa#remarks
+				// - "string may not have been stored with the proper terminating null characters"
+				// - "Note that REG_MULTI_SZ strings could have two terminating null characters"
+			        if ((reg_type == REG_SZ && size >= sizeof(guid_string) - sizeof(char))
+				    || (reg_type == REG_MULTI_SZ && size >= sizeof(guid_string) - 2 * sizeof(char))) {
+					if (nb_guids == guid_size) {
+						new_guid_list = realloc((void *)guid_list, (guid_size + GUID_SIZE_STEP) * sizeof(void *));
+						if (new_guid_list == NULL) {
+							usbi_err(ctx, "failed to realloc guid list");
+							LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+						}
+						guid_list = new_guid_list;
+						guid_size += GUID_SIZE_STEP;
+					}
+					if_guid = malloc(sizeof(*if_guid));
+					if (if_guid == NULL) {
+						usbi_err(ctx, "failed to alloc if_guid");
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+					}
+					if (!string_to_guid(guid_string, if_guid)) {
+						usbi_warn(ctx, "device '%s' has malformed DeviceInterfaceGUID string '%s', skipping", dev_id, guid_string);
+						free(if_guid);
+					} else {
+						// Check if we've already seen this GUID
+						for (j = EXT_PASS; j < nb_guids; j++) {
+							if (memcmp(guid_list[j], if_guid, sizeof(*if_guid)) == 0)
+								break;
+						}
+						if (j == nb_guids) {
+							usbi_dbg(ctx, "extra GUID: %s", guid_string);
+							guid_list[nb_guids++] = if_guid;
+						} else {
+							// Duplicate, ignore
+							free(if_guid);
+						}
+					}
+				} else {
+					usbi_warn(ctx, "unexpected type/size of DeviceInterfaceGUID for '%s'", dev_id);
+				}
+				break;
+			case HID_PASS:
+				api = USB_API_HID;
+				break;
+			default:
+				// Get the API type (after checking that the driver installation is OK)
+				if ((!pSetupDiGetDeviceRegistryPropertyA(*dev_info, &dev_info_data, SPDRP_INSTALL_STATE,
+					NULL, (PBYTE)&install_state, sizeof(install_state), &size)) || (size != sizeof(install_state))) {
+					usbi_warn(ctx, "could not detect installation state of driver for '%s': %s",
+						dev_id, windows_error_str(0));
+				} else if (install_state != 0) {
+					usbi_warn(ctx, "driver for device '%s' is reporting an issue (code: %lu) - skipping",
+						dev_id, ULONG_CAST(install_state));
+					continue;
+				}
+				get_api_type(dev_info, &dev_info_data, &api, &sub_api);
+				break;
+			}
+
+			// Find parent device (for the passes that need it)
+			if (pass >= GEN_PASS) {
+				parent_dev = get_ancestor(ctx, dev_info_data.DevInst, NULL);
+				if (parent_dev == NULL) {
+					// Root hubs will not have a parent
+					dev = usbi_get_device_by_session_id(ctx, (unsigned long)dev_info_data.DevInst);
+					if (dev != NULL) {
+						priv = usbi_get_device_priv(dev);
+						if (priv->root_hub)
+							goto track_unref;
+						libusb_unref_device(dev);
+					}
+
+					usbi_dbg(ctx, "unlisted ancestor for '%s' (non USB HID, newly connected, etc.) - ignoring", dev_id);
+					continue;
+				}
+
+				parent_priv = usbi_get_device_priv(parent_dev);
+				// virtual USB devices are also listed during GEN - don't process these yet
+				if ((pass == GEN_PASS) && (parent_priv->apib->id != USB_API_HUB)) {
+					libusb_unref_device(parent_dev);
+					continue;
+				}
+			}
+
+			// Create new or match existing device, using the devInst as session id
+			if ((pass <= GEN_PASS) && (pass != HCD_PASS)) {	// For subsequent passes, we'll lookup the parent
+				// These are the passes that create "new" devices
+				session_id = (unsigned long)dev_info_data.DevInst;
+				dev = usbi_get_device_by_session_id(ctx, session_id);
+				if (dev == NULL) {
+				alloc_device:
+					usbi_dbg(ctx, "allocating new device for session [%lX]", session_id);
+					dev = usbi_alloc_device(ctx, session_id);
+					if (dev == NULL)
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+
+					priv = winusb_device_priv_init(dev);
+					priv->dev_id = _strdup(dev_id);
+					priv->class_guid = dev_info_data.ClassGuid;
+					if (priv->dev_id == NULL) {
+						libusb_unref_device(dev);
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+					}
+				} else {
+					usbi_dbg(ctx, "found existing device for session [%lX]", session_id);
+
+					priv = usbi_get_device_priv(dev);
+					if (strcmp(priv->dev_id, dev_id) != 0) {
+						usbi_dbg(ctx, "device instance ID for session [%lX] changed", session_id);
+						usbi_disconnect_device(dev);
+						libusb_unref_device(dev);
+						goto alloc_device;
+					}
+					if (!IsEqualGUID(&priv->class_guid, &dev_info_data.ClassGuid)) {
+						usbi_dbg(ctx, "device class GUID for session [%lX] changed", session_id);
+						usbi_disconnect_device(dev);
+						libusb_unref_device(dev);
+						goto alloc_device;
+					}
+				}
+
+			track_unref:
+				// Keep track of devices that need unref
+				if (unref_cur == unref_size) {
+					new_unref_list = realloc(unref_list, (unref_size + UNREF_SIZE_STEP) * sizeof(void *));
+					if (new_unref_list == NULL) {
+						usbi_err(ctx, "could not realloc list for unref - aborting");
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+					}
+					unref_list = new_unref_list;
+					unref_size += UNREF_SIZE_STEP;
+				}
+				unref_list[unref_cur++] = dev;
+			}
+
+			// Setup device
+			switch (pass) {
+			case HUB_PASS:
+			case DEV_PASS:
+				// If the device has already been setup, don't do it again
+				if (priv->path != NULL)
+					break;
+				// Take care of API initialization
+				priv->path = dev_interface_path;
+				dev_interface_path = NULL;
+				priv->apib = &usb_api_backend[api];
+				priv->sub_api = sub_api;
+				switch (api) {
+				case USB_API_COMPOSITE:
+				case USB_API_HUB:
+					break;
+				case USB_API_HID:
+					priv->hid = calloc(1, sizeof(struct hid_device_priv));
+					if (priv->hid == NULL)
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+					break;
+				default:
+					// For other devices, the first interface is the same as the device
+					priv->usb_interface[0].path = _strdup(priv->path);
+					if (priv->usb_interface[0].path == NULL)
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+					// The following is needed if we want API calls to work for both simple
+					// and composite devices.
+					for (j = 0; j < USB_MAXINTERFACES; j++)
+						priv->usb_interface[j].apib = &usb_api_backend[api];
+					break;
+				}
+				break;
+			case HCD_PASS:
+				r = enumerate_hcd_root_hub(ctx, dev_id, (uint8_t)(i + 1), dev_info_data.DevInst);
+				break;
+			case GEN_PASS:
+				port_nr = 0;
+				if (!get_dev_port_number(*dev_info, &dev_info_data, &port_nr))
+					usbi_warn(ctx, "could not retrieve port number for device '%s': %s", dev_id, windows_error_str(0));
+				r = init_device(dev, parent_dev, (uint8_t)port_nr, dev_info_data.DevInst);
+				if (r == LIBUSB_SUCCESS) {
+					// Append device to the list of discovered devices
+					discdevs = discovered_devs_append(*_discdevs, dev);
+					if (!discdevs)
+						LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
+
+					*_discdevs = discdevs;
+				} else {
+					// Failed to initialize a single device doesn't stop us from enumerating all other devices,
+					// but we skip it (don't add to list of discovered devices)
+					usbi_warn(ctx, "failed to initialize device '%s'", priv->dev_id);
+					r = LIBUSB_SUCCESS;
+				}
+				break;
+			default: // HID_PASS and later
+				if (parent_priv->apib->id == USB_API_HID || parent_priv->apib->id == USB_API_COMPOSITE) {
+					if (parent_priv->apib->id == USB_API_HID) {
+						usbi_dbg(ctx, "setting HID interface for [%lX]:", parent_dev->session_data);
+						r = set_hid_interface(ctx, parent_dev, dev_interface_path);
+					} else {
+						usbi_dbg(ctx, "setting composite interface for [%lX]:", parent_dev->session_data);
+						r = set_composite_interface(ctx, parent_dev, dev_interface_path, dev_id, api, sub_api);
+					}
+					switch (r) {
+					case LIBUSB_SUCCESS:
+						dev_interface_path = NULL;
+						break;
+					case LIBUSB_ERROR_ACCESS:
+						// interface has already been set => make sure dev_interface_path is freed then
+						r = LIBUSB_SUCCESS;
+						break;
+					default:
+						LOOP_BREAK(r);
+						break;
+					}
+				}
+				libusb_unref_device(parent_dev);
+				break;
+			}
+		}
+	}
+
+	pSetupDiDestroyDeviceInfoList(dev_info_intf);
+
+	// Free any additional GUIDs
+	for (pass = EXT_PASS; pass < nb_guids; pass++)
+		free((void *)guid_list[pass]);
+	free((void *)guid_list);
+
+	// Free any PnP enumerator strings
+	for (i = 1; i < nb_usb_enumerators; i++)
+		free((void *)usb_enumerator[i]);
+
+	// Unref newly allocated devs
+	for (i = 0; i < unref_cur; i++)
+		libusb_unref_device(unref_list[i]);
+	free(unref_list);
+
+	return r;
+}
+
+static int winusb_get_config_descriptor(struct libusb_device *dev, uint8_t config_index, void *buffer, size_t len)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	PUSB_CONFIGURATION_DESCRIPTOR config_header;
+
+	if ((priv->config_descriptor == NULL) || (priv->config_descriptor[config_index] == NULL))
+		return LIBUSB_ERROR_NOT_FOUND;
+
+	config_header = priv->config_descriptor[config_index];
+
+	len = MIN(len, config_header->wTotalLength);
+	memcpy(buffer, config_header, len);
+	return (int)len;
+}
+
+static int winusb_get_config_descriptor_by_value(struct libusb_device *dev, uint8_t bConfigurationValue,
+	void **buffer)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	PUSB_CONFIGURATION_DESCRIPTOR config_header;
+	uint8_t index;
+
+	if (priv->config_descriptor == NULL)
+		return LIBUSB_ERROR_NOT_FOUND;
+
+	for (index = 0; index < dev->device_descriptor.bNumConfigurations; index++) {
+		config_header = priv->config_descriptor[index];
+		if (config_header == NULL)
+			continue;
+		if (config_header->bConfigurationValue == bConfigurationValue) {
+			*buffer = config_header;
+			return (int)config_header->wTotalLength;
+		}
+	}
+
+	return LIBUSB_ERROR_NOT_FOUND;
+}
+
+/*
+ * return the cached copy of the active config descriptor
+ */
+static int winusb_get_active_config_descriptor(struct libusb_device *dev, void *buffer, size_t len)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	void *config_desc;
+	int r;
+
+	if (priv->active_config == 0)
+		return LIBUSB_ERROR_NOT_FOUND;
+
+	r = winusb_get_config_descriptor_by_value(dev, priv->active_config, &config_desc);
+	if (r < 0)
+		return r;
+
+	len = MIN(len, (size_t)r);
+	memcpy(buffer, config_desc, len);
+	return (int)len;
+}
+
+static int winusb_open(struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	CHECK_SUPPORTED_API(priv->apib, open);
+
+	return priv->apib->open(SUB_API_NOTSET, dev_handle);
+}
+
+static void winusb_close(struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	if (priv->apib->close)
+		priv->apib->close(SUB_API_NOTSET, dev_handle);
+}
+
+static int winusb_get_configuration(struct libusb_device_handle *dev_handle, uint8_t *config)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	*config = priv->active_config;
+	return LIBUSB_SUCCESS;
+}
+
+/*
+ * from http://msdn.microsoft.com/en-us/library/ms793522.aspx: "The port driver
+ * does not currently expose a service that allows higher-level drivers to set
+ * the configuration."
+ */
+static int winusb_set_configuration(struct libusb_device_handle *dev_handle, uint8_t config)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int r = LIBUSB_SUCCESS;
+
+	r = libusb_control_transfer(dev_handle, LIBUSB_ENDPOINT_OUT |
+		LIBUSB_REQUEST_TYPE_STANDARD | LIBUSB_RECIPIENT_DEVICE,
+		LIBUSB_REQUEST_SET_CONFIGURATION, config,
+		0, NULL, 0, 1000);
+
+	if (r == LIBUSB_SUCCESS)
+		priv->active_config = config;
+
+	return r;
+}
+
+static int winusb_claim_interface(struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int r;
+
+	CHECK_SUPPORTED_API(priv->apib, claim_interface);
+
+	safe_free(priv->usb_interface[iface].endpoint);
+	priv->usb_interface[iface].nb_endpoints = 0;
+
+	r = priv->apib->claim_interface(SUB_API_NOTSET, dev_handle, iface);
+
+	if (r == LIBUSB_SUCCESS)
+		r = windows_assign_endpoints(dev_handle, iface, 0);
+
+	return r;
+}
+
+static int winusb_set_interface_altsetting(struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int r;
+
+	CHECK_SUPPORTED_API(priv->apib, set_interface_altsetting);
+
+	safe_free(priv->usb_interface[iface].endpoint);
+	priv->usb_interface[iface].nb_endpoints = 0;
+
+	r = priv->apib->set_interface_altsetting(SUB_API_NOTSET, dev_handle, iface, altsetting);
+
+	if (r == LIBUSB_SUCCESS)
+		r = windows_assign_endpoints(dev_handle, iface, altsetting);
+
+	return r;
+}
+
+static int winusb_release_interface(struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	CHECK_SUPPORTED_API(priv->apib, release_interface);
+
+	return priv->apib->release_interface(SUB_API_NOTSET, dev_handle, iface);
+}
+
+static int winusb_clear_halt(struct libusb_device_handle *dev_handle, unsigned char endpoint)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	CHECK_SUPPORTED_API(priv->apib, clear_halt);
+
+	return priv->apib->clear_halt(SUB_API_NOTSET, dev_handle, endpoint);
+}
+
+static int winusb_reset_device(struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	CHECK_SUPPORTED_API(priv->apib, reset_device);
+
+	return priv->apib->reset_device(SUB_API_NOTSET, dev_handle);
+}
+
+static void winusb_destroy_device(struct libusb_device *dev)
+{
+	winusb_device_priv_release(dev);
+}
+
+static void winusb_clear_transfer_priv(struct usbi_transfer *itransfer)
+{
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int sub_api = priv->sub_api;
+
+	safe_free(transfer_priv->hid_buffer);
+
+	if (transfer->type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS && sub_api == SUB_API_WINUSB) {
+		if (transfer_priv->isoch_buffer_handle != NULL) {
+			if (WinUSBX[sub_api].UnregisterIsochBuffer(transfer_priv->isoch_buffer_handle)) {
+				transfer_priv->isoch_buffer_handle = NULL;
+			} else {
+				usbi_warn(TRANSFER_CTX(transfer), "failed to unregister WinUSB isoch buffer: %s", windows_error_str(0));
+			}
+		}
+	}
+
+	safe_free(transfer_priv->iso_context);
+
+	// When auto claim is in use, attempt to release the auto-claimed interface
+	auto_release(itransfer);
+}
+
+static int winusb_submit_transfer(struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int (*transfer_fn)(int, struct usbi_transfer *);
+
+	switch (transfer->type) {
+	case LIBUSB_TRANSFER_TYPE_CONTROL:
+		transfer_fn = priv->apib->submit_control_transfer;
+		break;
+	case LIBUSB_TRANSFER_TYPE_BULK:
+	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
+		transfer_fn = priv->apib->submit_bulk_transfer;
+		break;
+	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
+		transfer_fn = priv->apib->submit_iso_transfer;
+		break;
+	default:
+		// Should not get here since windows_submit_transfer() validates
+		// the transfer->type field
+		usbi_err(TRANSFER_CTX(transfer), "unknown endpoint type %d", transfer->type);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	if (transfer_fn == NULL) {
+		usbi_warn(TRANSFER_CTX(transfer),
+			"unsupported transfer type %d (unrecognized device driver)",
+			transfer->type);
+		return LIBUSB_ERROR_NOT_SUPPORTED;
+	}
+
+	return transfer_fn(SUB_API_NOTSET, itransfer);
+}
+
+static int winusb_cancel_transfer(struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+
+	CHECK_SUPPORTED_API(priv->apib, cancel_transfer);
+
+	return priv->apib->cancel_transfer(SUB_API_NOTSET, itransfer);
+}
+
+static enum libusb_transfer_status winusb_copy_transfer_data(struct usbi_transfer *itransfer, DWORD length)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+
+	if (priv->apib->copy_transfer_data == NULL) {
+		usbi_err(TRANSFER_CTX(transfer), "program assertion failed - no function to copy transfer data");
+		return LIBUSB_TRANSFER_ERROR;
+	}
+
+	return priv->apib->copy_transfer_data(SUB_API_NOTSET, itransfer, length);
+}
+
+// NB: MSVC6 does not support named initializers.
+const struct windows_backend winusb_backend = {
+	winusb_init,
+	winusb_exit,
+	winusb_get_device_list,
+	winusb_open,
+	winusb_close,
+	winusb_get_active_config_descriptor,
+	winusb_get_config_descriptor,
+	winusb_get_config_descriptor_by_value,
+	winusb_get_configuration,
+	winusb_set_configuration,
+	winusb_claim_interface,
+	winusb_release_interface,
+	winusb_set_interface_altsetting,
+	winusb_clear_halt,
+	winusb_reset_device,
+	winusb_destroy_device,
+	winusb_submit_transfer,
+	winusb_cancel_transfer,
+	winusb_clear_transfer_priv,
+	winusb_copy_transfer_data,
+};
+
+/*
+ * USB API backends
+ */
+
+static const char * const composite_driver_names[] = {"USBCCGP"};
+static const char * const winusbx_driver_names[] = {"libusbK", "libusb0", "WinUSB"};
+static const char * const hid_driver_names[] = {"HIDUSB", "MOUHID", "KBDHID"};
+const struct windows_usb_api_backend usb_api_backend[USB_API_MAX] = {
+	{
+		USB_API_UNSUPPORTED,
+		"Unsupported API",
+		NULL,	/* driver_name_list */
+		0,	/* nb_driver_names */
+		NULL,	/* init */
+		NULL,	/* exit */
+		NULL,	/* open */
+		NULL,	/* close */
+		NULL,	/* configure_endpoints */
+		NULL,	/* claim_interface */
+		NULL,	/* set_interface_altsetting */
+		NULL,	/* release_interface */
+		NULL,	/* clear_halt */
+		NULL,	/* reset_device */
+		NULL,	/* submit_bulk_transfer */
+		NULL,	/* submit_iso_transfer */
+		NULL,	/* submit_control_transfer */
+		NULL,	/* cancel_transfer */
+		NULL,	/* copy_transfer_data */
+	},
+	{
+		USB_API_HUB,
+		"HUB API",
+		NULL,	/* driver_name_list */
+		0,	/* nb_driver_names */
+		NULL,	/* init */
+		NULL,	/* exit */
+		NULL,	/* open */
+		NULL,	/* close */
+		NULL,	/* configure_endpoints */
+		NULL,	/* claim_interface */
+		NULL,	/* set_interface_altsetting */
+		NULL,	/* release_interface */
+		NULL,	/* clear_halt */
+		NULL,	/* reset_device */
+		NULL,	/* submit_bulk_transfer */
+		NULL,	/* submit_iso_transfer */
+		NULL,	/* submit_control_transfer */
+		NULL,	/* cancel_transfer */
+		NULL,	/* copy_transfer_data */
+	},
+	{
+		USB_API_COMPOSITE,
+		"Composite API",
+		composite_driver_names,
+		ARRAYSIZE(composite_driver_names),
+		NULL,	/* init */
+		NULL,	/* exit */
+		composite_open,
+		composite_close,
+		NULL,	/* configure_endpoints */
+		composite_claim_interface,
+		composite_set_interface_altsetting,
+		composite_release_interface,
+		composite_clear_halt,
+		composite_reset_device,
+		composite_submit_bulk_transfer,
+		composite_submit_iso_transfer,
+		composite_submit_control_transfer,
+		composite_cancel_transfer,
+		composite_copy_transfer_data,
+	},
+	{
+		USB_API_WINUSBX,
+		"WinUSB-like APIs",
+		winusbx_driver_names,
+		ARRAYSIZE(winusbx_driver_names),
+		winusbx_init,
+		winusbx_exit,
+		winusbx_open,
+		winusbx_close,
+		winusbx_configure_endpoints,
+		winusbx_claim_interface,
+		winusbx_set_interface_altsetting,
+		winusbx_release_interface,
+		winusbx_clear_halt,
+		winusbx_reset_device,
+		winusbx_submit_bulk_transfer,
+		winusbx_submit_iso_transfer,
+		winusbx_submit_control_transfer,
+		winusbx_cancel_transfer,
+		winusbx_copy_transfer_data,
+	},
+	{
+		USB_API_HID,
+		"HID API",
+		hid_driver_names,
+		ARRAYSIZE(hid_driver_names),
+		hid_init,
+		hid_exit,
+		hid_open,
+		hid_close,
+		NULL,	/* configure_endpoints */
+		hid_claim_interface,
+		hid_set_interface_altsetting,
+		hid_release_interface,
+		hid_clear_halt,
+		hid_reset_device,
+		hid_submit_bulk_transfer,
+		NULL,	/* submit_iso_transfer */
+		hid_submit_control_transfer,
+		NULL,	/* cancel_transfer */
+		hid_copy_transfer_data,
+	},
+};
+
+
+/*
+ * WinUSB-like (WinUSB, libusb0/libusbK through libusbk DLL) API functions
+ */
+#define WinUSB_Set(h, fn, required)										\
+	do {											\
+		WinUSBX[SUB_API_WINUSB].fn = (WinUsb_##fn##_t)GetProcAddress(h, "WinUsb_" #fn);	\
+		if (required && (WinUSBX[SUB_API_WINUSB].fn == NULL)) {				\
+			usbi_err(ctx, "GetProcAddress() failed for WinUsb_%s", #fn);		\
+			goto cleanup_winusb;							\
+		}										\
+	} while (0)
+
+#define libusbK_Set(sub_api, fn, required)								\
+	do {											\
+		pLibK_GetProcAddress((PVOID *)&WinUSBX[sub_api].fn, sub_api, KUSB_FNID_##fn);	\
+		if (required && (WinUSBX[sub_api].fn == NULL)) {				\
+			usbi_err(ctx, "LibK_GetProcAddress() failed for LibK_%s", #fn);		\
+			goto cleanup_libusbk;							\
+		}										\
+	} while (0)
+
+static bool winusbx_init(struct libusb_context *ctx)
+{
+	HMODULE hWinUSB, hlibusbK;
+
+	hWinUSB = load_system_library(ctx, "WinUSB");
+	if (hWinUSB != NULL) {
+		WinUSB_Set(hWinUSB, AbortPipe, true);
+		WinUSB_Set(hWinUSB, ControlTransfer, true);
+		WinUSB_Set(hWinUSB, FlushPipe, true);
+		WinUSB_Set(hWinUSB, Free, true);
+		WinUSB_Set(hWinUSB, GetAssociatedInterface, true);
+		WinUSB_Set(hWinUSB, Initialize, true);
+		WinUSB_Set(hWinUSB, ReadPipe, true);
+		WinUSB_Set(hWinUSB, ResetPipe, true);
+		WinUSB_Set(hWinUSB, SetCurrentAlternateSetting, true);
+		WinUSB_Set(hWinUSB, SetPipePolicy, true);
+		WinUSB_Set(hWinUSB, WritePipe, true);
+
+		// Check for isochronous transfers support (available starting with Windows 8.1)
+		WinUSB_Set(hWinUSB, ReadIsochPipeAsap, false);
+		if (WinUSBX[SUB_API_WINUSB].ReadIsochPipeAsap != NULL) {
+			WinUSB_Set(hWinUSB, QueryPipeEx, true);
+			WinUSB_Set(hWinUSB, RegisterIsochBuffer, true);
+			WinUSB_Set(hWinUSB, UnregisterIsochBuffer, true);
+			WinUSB_Set(hWinUSB, WriteIsochPipeAsap, true);
+		}
+
+		WinUSBX[SUB_API_WINUSB].hDll = hWinUSB;
+
+		usbi_info(ctx, "WinUSB DLL available (%s isoch support)",
+			(WinUSBX[SUB_API_WINUSB].ReadIsochPipeAsap != NULL) ? "with" : "without");
+
+cleanup_winusb:
+		if (WinUSBX[SUB_API_WINUSB].hDll == NULL) {
+			usbi_err(ctx, "failed to initialize WinUSB");
+			memset(&WinUSBX[SUB_API_WINUSB], 0, sizeof(WinUSBX[SUB_API_WINUSB]));
+			FreeLibrary(hWinUSB);
+			hWinUSB = NULL;
+		}
+	} else {
+		usbi_info(ctx, "WinUSB DLL is not available");
+	}
+
+	hlibusbK = load_system_library(ctx, "libusbK");
+	if (hlibusbK != NULL) {
+		LibK_GetVersion_t pLibK_GetVersion;
+		LibK_GetProcAddress_t pLibK_GetProcAddress;
+		int sub_api = 0;
+
+		pLibK_GetVersion = (LibK_GetVersion_t)GetProcAddress(hlibusbK, "LibK_GetVersion");
+		if (pLibK_GetVersion != NULL) {
+			KLIB_VERSION LibK_Version;
+
+			pLibK_GetVersion(&LibK_Version);
+			usbi_dbg(ctx, "libusbK DLL found, version: %d.%d.%d.%d", LibK_Version.Major, LibK_Version.Minor,
+				LibK_Version.Micro, LibK_Version.Nano);
+		} else {
+			usbi_dbg(ctx, "libusbK DLL found, version unknown");
+		}
+
+		pLibK_GetProcAddress = (LibK_GetProcAddress_t)GetProcAddress(hlibusbK, "LibK_GetProcAddress");
+		if (pLibK_GetProcAddress == NULL) {
+			usbi_err(ctx, "LibK_GetProcAddress() not found in libusbK DLL");
+			goto cleanup_libusbk;
+		}
+
+		// NB: The below for loop works because the sub_api value for WinUSB
+		// is a higher value than that of libusbK and libusb0
+		for (; sub_api < SUB_API_WINUSB; sub_api++) {
+			libusbK_Set(sub_api, AbortPipe, true);
+			libusbK_Set(sub_api, ControlTransfer, true);
+			libusbK_Set(sub_api, FlushPipe, true);
+			libusbK_Set(sub_api, Free, true);
+			libusbK_Set(sub_api, GetAssociatedInterface, true);
+			libusbK_Set(sub_api, Initialize, true);
+			libusbK_Set(sub_api, ReadPipe, true);
+			libusbK_Set(sub_api, ResetPipe, true);
+			libusbK_Set(sub_api, SetCurrentAlternateSetting, true);
+			libusbK_Set(sub_api, SetPipePolicy, true);
+			libusbK_Set(sub_api, WritePipe, true);
+
+			// Optional isochronous support
+			libusbK_Set(sub_api, IsoReadPipe, false);
+			if (WinUSBX[sub_api].IsoReadPipe != NULL)
+				libusbK_Set(sub_api, IsoWritePipe, true);
+
+			// Optional device reset support
+			libusbK_Set(sub_api, ResetDevice, false);
+
+			WinUSBX[sub_api].hDll = hlibusbK;
+		}
+
+cleanup_libusbk:
+		if (sub_api < SUB_API_WINUSB) {
+			usbi_err(ctx, "failed to initialize libusbK");
+			while (sub_api >= 0) {
+				memset(&WinUSBX[sub_api], 0, sizeof(WinUSBX[sub_api]));
+				sub_api--;
+			}
+			FreeLibrary(hlibusbK);
+			hlibusbK = NULL;
+		}
+	} else {
+		usbi_info(ctx, "libusbK DLL is not available");
+	}
+
+	if ((hWinUSB == NULL) && (hlibusbK == NULL)) {
+		usbi_warn(ctx, "neither WinUSB nor libusbK DLLs were found, "
+			"you will not be able to access devices outside of enumeration");
+		return false;
+	}
+
+	return true;
+}
+
+static void winusbx_exit(void)
+{
+	bool loaded = false;
+	HMODULE hDll;
+
+	hDll = WinUSBX[SUB_API_LIBUSBK].hDll;
+	if (hDll != NULL) {
+		FreeLibrary(hDll);
+		loaded = true;
+	}
+
+	hDll = WinUSBX[SUB_API_WINUSB].hDll;
+	if (hDll != NULL) {
+		FreeLibrary(hDll);
+		loaded = true;
+	}
+
+	// Reset the WinUSBX API structures if something was loaded
+	if (loaded)
+		memset(&WinUSBX, 0, sizeof(WinUSBX));
+}
+
+// NB: open and close must ensure that they only handle interface of
+// the right API type, as these functions can be called wholesale from
+// composite_open(), with interfaces belonging to different APIs
+static int winusbx_open(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	HANDLE file_handle;
+	int i;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	// WinUSB requires a separate handle for each interface
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		if ((priv->usb_interface[i].path != NULL)
+				&& (priv->usb_interface[i].apib->id == USB_API_WINUSBX)) {
+			file_handle = windows_open(dev_handle, priv->usb_interface[i].path, GENERIC_READ | GENERIC_WRITE);
+			if (file_handle == INVALID_HANDLE_VALUE) {
+				usbi_err(HANDLE_CTX(dev_handle), "could not open device %s (interface %d): %s", priv->usb_interface[i].path, i, windows_error_str(0));
+				switch (GetLastError()) {
+				case ERROR_FILE_NOT_FOUND: // The device was disconnected
+					return LIBUSB_ERROR_NO_DEVICE;
+				case ERROR_ACCESS_DENIED:
+					return LIBUSB_ERROR_ACCESS;
+				default:
+					return LIBUSB_ERROR_IO;
+				}
+			}
+
+			handle_priv->interface_handle[i].dev_handle = file_handle;
+		}
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static void winusbx_close(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE handle;
+	int i;
+
+	if (sub_api == SUB_API_NOTSET)
+		sub_api = priv->sub_api;
+
+	if (WinUSBX[sub_api].hDll == NULL)
+		return;
+
+	if (priv->apib->id == USB_API_COMPOSITE) {
+		// If this is a composite device, just free and close all WinUSB-like
+		// interfaces directly (each is independent and not associated with another)
+		for (i = 0; i < USB_MAXINTERFACES; i++) {
+			if (priv->usb_interface[i].apib->id == USB_API_WINUSBX) {
+				handle = handle_priv->interface_handle[i].api_handle;
+				if (HANDLE_VALID(handle))
+					WinUSBX[sub_api].Free(handle);
+
+				handle = handle_priv->interface_handle[i].dev_handle;
+				if (HANDLE_VALID(handle))
+					CloseHandle(handle);
+			}
+		}
+	} else {
+		// If this is a WinUSB device, free all interfaces above interface 0,
+		// then free and close interface 0 last
+		for (i = 1; i < USB_MAXINTERFACES; i++) {
+			handle = handle_priv->interface_handle[i].api_handle;
+			if (HANDLE_VALID(handle))
+				WinUSBX[sub_api].Free(handle);
+		}
+		handle = handle_priv->interface_handle[0].api_handle;
+		if (HANDLE_VALID(handle))
+			WinUSBX[sub_api].Free(handle);
+
+		handle = handle_priv->interface_handle[0].dev_handle;
+		if (HANDLE_VALID(handle))
+			CloseHandle(handle);
+	}
+}
+
+static int winusbx_configure_endpoints(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE winusb_handle = handle_priv->interface_handle[iface].api_handle;
+	UCHAR policy;
+	ULONG timeout = 0;
+	uint8_t endpoint_address;
+	int i;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	// With handle and endpoints set (in parent), we can setup the default pipe properties
+	// see http://download.microsoft.com/download/D/1/D/D1DD7745-426B-4CC3-A269-ABBBE427C0EF/DVC-T705_DDC08.pptx
+	for (i = -1; i < priv->usb_interface[iface].nb_endpoints; i++) {
+		endpoint_address = (i == -1) ? 0 : priv->usb_interface[iface].endpoint[i];
+		if (!WinUSBX[sub_api].SetPipePolicy(winusb_handle, endpoint_address,
+			PIPE_TRANSFER_TIMEOUT, sizeof(ULONG), &timeout))
+			usbi_dbg(HANDLE_CTX(dev_handle), "failed to set PIPE_TRANSFER_TIMEOUT for control endpoint %02X", endpoint_address);
+
+		if ((i == -1) || (sub_api == SUB_API_LIBUSB0))
+			continue; // Other policies don't apply to control endpoint or libusb0
+
+		policy = false;
+		handle_priv->interface_handle[iface].zlp[endpoint_address] = WINUSB_ZLP_UNSET;
+		if (!WinUSBX[sub_api].SetPipePolicy(winusb_handle, endpoint_address,
+			SHORT_PACKET_TERMINATE, sizeof(UCHAR), &policy))
+			usbi_dbg(HANDLE_CTX(dev_handle), "failed to disable SHORT_PACKET_TERMINATE for endpoint %02X", endpoint_address);
+
+		if (!WinUSBX[sub_api].SetPipePolicy(winusb_handle, endpoint_address,
+			IGNORE_SHORT_PACKETS, sizeof(UCHAR), &policy))
+			usbi_dbg(HANDLE_CTX(dev_handle), "failed to disable IGNORE_SHORT_PACKETS for endpoint %02X", endpoint_address);
+
+		policy = true;
+		/* ALLOW_PARTIAL_READS must be enabled due to likely libusbK bug. See:
+		   https://sourceforge.net/mailarchive/message.php?msg_id=29736015 */
+		if (!WinUSBX[sub_api].SetPipePolicy(winusb_handle, endpoint_address,
+			ALLOW_PARTIAL_READS, sizeof(UCHAR), &policy))
+			usbi_dbg(HANDLE_CTX(dev_handle), "failed to enable ALLOW_PARTIAL_READS for endpoint %02X", endpoint_address);
+
+		if (!WinUSBX[sub_api].SetPipePolicy(winusb_handle, endpoint_address,
+			AUTO_CLEAR_STALL, sizeof(UCHAR), &policy))
+			usbi_dbg(HANDLE_CTX(dev_handle), "failed to enable AUTO_CLEAR_STALL for endpoint %02X", endpoint_address);
+
+		if (sub_api == SUB_API_LIBUSBK) {
+			if (!WinUSBX[sub_api].SetPipePolicy(winusb_handle, endpoint_address,
+				ISO_ALWAYS_START_ASAP, sizeof(UCHAR), &policy))
+				usbi_dbg(HANDLE_CTX(dev_handle), "failed to enable ISO_ALWAYS_START_ASAP for endpoint %02X", endpoint_address);
+		}
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int winusbx_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct libusb_context *ctx = HANDLE_CTX(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	bool is_using_usbccgp = (priv->apib->id == USB_API_COMPOSITE);
+	HDEVINFO dev_info;
+	char *dev_interface_path = NULL;
+	char *dev_interface_path_guid_start;
+	char filter_path[] = "\\\\.\\libusb0-0000";
+	bool found_filter = false;
+	HANDLE file_handle, winusb_handle;
+	DWORD err, _index;
+	int r;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	// If the device is composite, but using the default Windows composite parent driver (usbccgp)
+	// or if it's the first WinUSB-like interface, we get a handle through Initialize().
+	if ((is_using_usbccgp) || (iface == 0)) {
+		// composite device (independent interfaces) or interface 0
+		file_handle = handle_priv->interface_handle[iface].dev_handle;
+		if (!HANDLE_VALID(file_handle))
+			return LIBUSB_ERROR_NOT_FOUND;
+
+		if (!WinUSBX[sub_api].Initialize(file_handle, &winusb_handle)) {
+			handle_priv->interface_handle[iface].api_handle = INVALID_HANDLE_VALUE;
+			err = GetLastError();
+			switch (err) {
+			case ERROR_BAD_COMMAND:
+				// The device was disconnected
+				usbi_err(ctx, "could not access interface %u: %s", iface, windows_error_str(0));
+				return LIBUSB_ERROR_NO_DEVICE;
+			default:
+				// it may be that we're using the libusb0 filter driver.
+				// TODO: can we move this whole business into the K/0 DLL?
+				r = LIBUSB_SUCCESS;
+				for (_index = 0; ; _index++) {
+					safe_free(dev_interface_path);
+
+					if (found_filter)
+						break;
+
+					r = get_interface_details_filter(ctx, &dev_info, _index, filter_path, &dev_interface_path);
+					if ((r != LIBUSB_SUCCESS) || (dev_interface_path == NULL))
+						break;
+
+					// ignore GUID part
+					dev_interface_path_guid_start = strchr(dev_interface_path, '{');
+					if (dev_interface_path_guid_start == NULL)
+						continue;
+					*dev_interface_path_guid_start = '\0';
+
+					if (strncmp(dev_interface_path, priv->usb_interface[iface].path, strlen(dev_interface_path)) == 0) {
+						file_handle = windows_open(dev_handle, filter_path, GENERIC_READ | GENERIC_WRITE);
+						if (file_handle != INVALID_HANDLE_VALUE) {
+							if (WinUSBX[sub_api].Initialize(file_handle, &winusb_handle)) {
+								// Replace the existing file handle with the working one
+								CloseHandle(handle_priv->interface_handle[iface].dev_handle);
+								handle_priv->interface_handle[iface].dev_handle = file_handle;
+								found_filter = true;
+							} else {
+								usbi_err(ctx, "could not initialize filter driver for %s", filter_path);
+								CloseHandle(file_handle);
+							}
+						} else {
+							usbi_err(ctx, "could not open device %s: %s", filter_path, windows_error_str(0));
+						}
+					}
+				}
+				if (r != LIBUSB_SUCCESS)
+					return r;
+				if (!found_filter) {
+					usbi_err(ctx, "could not access interface %u: %s", iface, windows_error_str(err));
+					return LIBUSB_ERROR_ACCESS;
+				}
+			}
+		}
+		handle_priv->interface_handle[iface].api_handle = winusb_handle;
+	} else {
+		// For all other interfaces, use GetAssociatedInterface()
+		winusb_handle = handle_priv->interface_handle[0].api_handle;
+		// It is a requirement for multiple interface devices on Windows that, to you
+		// must first claim the first interface before you claim the others
+		if (!HANDLE_VALID(winusb_handle)) {
+			file_handle = handle_priv->interface_handle[0].dev_handle;
+			if (WinUSBX[sub_api].Initialize(file_handle, &winusb_handle)) {
+				handle_priv->interface_handle[0].api_handle = winusb_handle;
+				usbi_warn(ctx, "auto-claimed interface 0 (required to claim %u with WinUSB)", iface);
+			} else {
+				usbi_warn(ctx, "failed to auto-claim interface 0 (required to claim %u with WinUSB): %s", iface, windows_error_str(0));
+				return LIBUSB_ERROR_ACCESS;
+			}
+		}
+		if (!WinUSBX[sub_api].GetAssociatedInterface(winusb_handle, (UCHAR)(iface - 1),
+			&handle_priv->interface_handle[iface].api_handle)) {
+			handle_priv->interface_handle[iface].api_handle = INVALID_HANDLE_VALUE;
+			switch (GetLastError()) {
+			case ERROR_NO_MORE_ITEMS:   // invalid iface
+				return LIBUSB_ERROR_NOT_FOUND;
+			case ERROR_BAD_COMMAND:     // The device was disconnected
+				return LIBUSB_ERROR_NO_DEVICE;
+			case ERROR_ALREADY_EXISTS:  // already claimed
+				return LIBUSB_ERROR_BUSY;
+			default:
+				usbi_err(ctx, "could not claim interface %u: %s", iface, windows_error_str(0));
+				return LIBUSB_ERROR_ACCESS;
+			}
+		}
+		handle_priv->interface_handle[iface].dev_handle = handle_priv->interface_handle[0].dev_handle;
+	}
+	usbi_dbg(ctx, "claimed interface %u", iface);
+	handle_priv->active_interface = iface;
+
+	return LIBUSB_SUCCESS;
+}
+
+static int winusbx_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE winusb_handle;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	winusb_handle = handle_priv->interface_handle[iface].api_handle;
+	if (!HANDLE_VALID(winusb_handle))
+		return LIBUSB_ERROR_NOT_FOUND;
+
+	WinUSBX[sub_api].Free(winusb_handle);
+	handle_priv->interface_handle[iface].api_handle = INVALID_HANDLE_VALUE;
+
+	return LIBUSB_SUCCESS;
+}
+
+/*
+ * Return the first valid interface (of the same API type), for control transfers
+ */
+static int get_valid_interface(struct libusb_device_handle *dev_handle, int api_id)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int i;
+
+	if ((api_id < USB_API_WINUSBX) || (api_id > USB_API_HID)) {
+		usbi_dbg(HANDLE_CTX(dev_handle), "unsupported API ID");
+		return -1;
+	}
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+	if (HANDLE_VALID(handle_priv->interface_handle[i].dev_handle)
+			&& HANDLE_VALID(handle_priv->interface_handle[i].api_handle)
+			&& (priv->usb_interface[i].apib->id == api_id))
+		return i;
+	}
+
+	return -1;
+}
+
+/*
+* Check a specific interface is valid (of the same API type), for control transfers
+*/
+static int check_valid_interface(struct libusb_device_handle *dev_handle, unsigned short interface, int api_id)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	if (interface >= USB_MAXINTERFACES)
+		return -1;
+
+	if ((api_id < USB_API_WINUSBX) || (api_id > USB_API_HID)) {
+		usbi_dbg(HANDLE_CTX(dev_handle), "unsupported API ID");
+		return -1;
+	}
+
+	// try the requested interface
+	if (HANDLE_VALID(handle_priv->interface_handle[interface].dev_handle)
+		&& HANDLE_VALID(handle_priv->interface_handle[interface].api_handle)
+		&& (priv->usb_interface[interface].apib->id == api_id))
+		return interface;
+
+	return -1;
+}
+
+/*
+ * Lookup interface by endpoint address. -1 if not found
+ */
+static int interface_by_endpoint(struct winusb_device_priv *priv,
+	struct winusb_device_handle_priv *handle_priv, uint8_t endpoint_address)
+{
+	int i, j;
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		if (!HANDLE_VALID(handle_priv->interface_handle[i].api_handle))
+			continue;
+		if (priv->usb_interface[i].endpoint == NULL)
+			continue;
+		for (j = 0; j < priv->usb_interface[i].nb_endpoints; j++) {
+			if (priv->usb_interface[i].endpoint[j] == endpoint_address)
+				return i;
+		}
+	}
+
+	return -1;
+}
+
+static int winusbx_submit_control_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	PWINUSB_SETUP_PACKET setup = (PWINUSB_SETUP_PACKET)transfer->buffer;
+	ULONG size, transferred;
+	HANDLE winusb_handle;
+	OVERLAPPED *overlapped;
+	int current_interface;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	size = transfer->length - LIBUSB_CONTROL_SETUP_SIZE;
+
+	// Windows places upper limits on the control transfer size
+	// See: https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/usb-bandwidth-allocation#maximum-transfer-size
+	if (size > MAX_CTRL_BUFFER_LENGTH)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
+	if ((setup->RequestType & 0x1F) == LIBUSB_RECIPIENT_INTERFACE)
+		current_interface = check_valid_interface(transfer->dev_handle, setup->Index & 0xff, USB_API_WINUSBX);
+	else
+		current_interface = get_valid_interface(transfer->dev_handle, USB_API_WINUSBX);
+	if (current_interface < 0) {
+		if (auto_claim(transfer, &current_interface, USB_API_WINUSBX) != LIBUSB_SUCCESS)
+			return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(ITRANSFER_CTX(itransfer), "will use interface %d", current_interface);
+
+	transfer_priv->interface_number = (uint8_t)current_interface;
+	winusb_handle = handle_priv->interface_handle[current_interface].api_handle;
+	set_transfer_priv_handle(itransfer, handle_priv->interface_handle[current_interface].dev_handle);
+	overlapped = get_transfer_priv_overlapped(itransfer);
+
+	// Sending of set configuration control requests from WinUSB creates issues, except when using libusb0.sys
+	if (sub_api != SUB_API_LIBUSB0
+			&& (LIBUSB_REQ_TYPE(setup->RequestType) == LIBUSB_REQUEST_TYPE_STANDARD)
+			&& (setup->Request == LIBUSB_REQUEST_SET_CONFIGURATION)) {
+		if (setup->Value != priv->active_config) {
+			usbi_warn(TRANSFER_CTX(transfer), "cannot set configuration other than the default one");
+			return LIBUSB_ERROR_NOT_SUPPORTED;
+		}
+		windows_force_sync_completion(itransfer, 0);
+	} else {
+		if (!WinUSBX[sub_api].ControlTransfer(winusb_handle, *setup, transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE, size, &transferred, overlapped)) {
+			if (GetLastError() != ERROR_IO_PENDING) {
+				usbi_warn(TRANSFER_CTX(transfer), "ControlTransfer failed: %s", windows_error_str(0));
+				return LIBUSB_ERROR_IO;
+			}
+		} else {
+			windows_force_sync_completion(itransfer, transferred);
+		}
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int winusbx_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE winusb_handle;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	winusb_handle = handle_priv->interface_handle[iface].api_handle;
+	if (!HANDLE_VALID(winusb_handle)) {
+		usbi_err(HANDLE_CTX(dev_handle), "interface must be claimed first");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	if (!WinUSBX[sub_api].SetCurrentAlternateSetting(winusb_handle, altsetting)) {
+		usbi_err(HANDLE_CTX(dev_handle), "SetCurrentAlternateSetting failed: %s", windows_error_str(0));
+		return LIBUSB_ERROR_IO;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+
+static void WINAPI winusbx_native_iso_transfer_continue_stream_callback(struct libusb_transfer *transfer)
+{
+	// If this callback is invoked, this means that we attempted to set ContinueStream
+	// to TRUE when calling Read/WriteIsochPipeAsap in winusbx_do_iso_transfer.
+	// The role of this callback is to fallback to ContinueStream = FALSE if the transfer
+	// did not succeed.
+
+	struct winusb_transfer_priv *transfer_priv =
+		get_winusb_transfer_priv(LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer));
+	bool fallback = (transfer->status != LIBUSB_TRANSFER_COMPLETED);
+	int idx;
+
+	// Restore the user callback
+	transfer->callback = transfer_priv->iso_user_callback;
+
+	for (idx = 0; idx < transfer->num_iso_packets && !fallback; idx++) {
+		if (transfer->iso_packet_desc[idx].status != LIBUSB_TRANSFER_COMPLETED)
+			fallback = true;
+	}
+
+	if (!fallback) {
+		// If the transfer was successful, we restore the user callback and call it.
+		if (transfer->callback)
+			transfer->callback(transfer);
+	} else {
+		// If the transfer wasn't successful we reschedule the transfer while forcing it
+		// not to continue the stream. This might results in a 5-ms delay.
+		transfer_priv->iso_break_stream = TRUE;
+		libusb_submit_transfer(transfer);
+	}
+}
+static int winusbx_submit_iso_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	HANDLE winusb_handle;
+	OVERLAPPED *overlapped;
+	BOOL ret;
+	int current_interface;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, transfer->endpoint);
+	if (current_interface < 0) {
+		usbi_err(TRANSFER_CTX(transfer), "unable to match endpoint to an open interface - cancelling transfer");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(TRANSFER_CTX(transfer), "matched endpoint %02X with interface %d", transfer->endpoint, current_interface);
+
+	transfer_priv->interface_number = (uint8_t)current_interface;
+	winusb_handle = handle_priv->interface_handle[current_interface].api_handle;
+	set_transfer_priv_handle(itransfer, handle_priv->interface_handle[current_interface].dev_handle);
+	overlapped = get_transfer_priv_overlapped(itransfer);
+
+	if ((sub_api == SUB_API_LIBUSBK) || (sub_api == SUB_API_LIBUSB0)) {
+		int i;
+		UINT offset;
+		size_t iso_ctx_size;
+		PKISO_CONTEXT iso_context;
+
+		if (WinUSBX[sub_api].IsoReadPipe == NULL) {
+			usbi_warn(TRANSFER_CTX(transfer), "libusbK DLL does not support isoch transfers");
+			return LIBUSB_ERROR_NOT_SUPPORTED;
+		}
+
+		iso_ctx_size = sizeof(KISO_CONTEXT) + (transfer->num_iso_packets * sizeof(KISO_PACKET));
+		transfer_priv->iso_context = iso_context = calloc(1, iso_ctx_size);
+		if (transfer_priv->iso_context == NULL)
+			return LIBUSB_ERROR_NO_MEM;
+
+		// start ASAP
+		iso_context->StartFrame = 0;
+		iso_context->NumberOfPackets = (SHORT)transfer->num_iso_packets;
+
+		// convert the transfer packet lengths to iso_packet offsets
+		offset = 0;
+		for (i = 0; i < transfer->num_iso_packets; i++) {
+			iso_context->IsoPackets[i].offset = offset;
+			offset += transfer->iso_packet_desc[i].length;
+		}
+
+		if (IS_XFERIN(transfer)) {
+			usbi_dbg(TRANSFER_CTX(transfer), "reading %d iso packets", transfer->num_iso_packets);
+			ret = WinUSBX[sub_api].IsoReadPipe(winusb_handle, transfer->endpoint, transfer->buffer, transfer->length, overlapped, iso_context);
+		} else {
+			usbi_dbg(TRANSFER_CTX(transfer), "writing %d iso packets", transfer->num_iso_packets);
+			ret = WinUSBX[sub_api].IsoWritePipe(winusb_handle, transfer->endpoint, transfer->buffer, transfer->length, overlapped, iso_context);
+		}
+
+		if (!ret && GetLastError() != ERROR_IO_PENDING) {
+			usbi_err(TRANSFER_CTX(transfer), "IsoReadPipe/IsoWritePipe failed: %s", windows_error_str(0));
+			return LIBUSB_ERROR_IO;
+		}
+
+		return LIBUSB_SUCCESS;
+	} else if (sub_api == SUB_API_WINUSB) {
+		WINUSB_PIPE_INFORMATION_EX pipe_info_ex = { 0 };
+		WINUSB_ISOCH_BUFFER_HANDLE buffer_handle;
+		ULONG iso_transfer_size_multiple;
+		int out_transfer_length = 0;
+		int idx;
+
+		// Depending on the version of Microsoft WinUSB, isochronous transfers may not be supported.
+		if (WinUSBX[sub_api].ReadIsochPipeAsap == NULL) {
+			usbi_warn(TRANSFER_CTX(transfer), "WinUSB DLL does not support isoch transfers");
+			return LIBUSB_ERROR_NOT_SUPPORTED;
+		}
+
+		if (sizeof(struct libusb_iso_packet_descriptor) != sizeof(USBD_ISO_PACKET_DESCRIPTOR)) {
+			usbi_err(TRANSFER_CTX(transfer), "size of WinUsb and libusb isoch packet descriptors don't match");
+			return LIBUSB_ERROR_NOT_SUPPORTED;
+		}
+
+		// Query the pipe extended information to find the pipe index corresponding to the endpoint.
+		for (idx = 0; idx < priv->usb_interface[current_interface].nb_endpoints; ++idx) {
+			ret = WinUSBX[sub_api].QueryPipeEx(winusb_handle, (UINT8)priv->usb_interface[current_interface].current_altsetting, (UCHAR)idx, &pipe_info_ex);
+			if (!ret) {
+				usbi_err(TRANSFER_CTX(transfer), "couldn't query interface settings for USB pipe with index %d. Error: %s", idx, windows_error_str(0));
+				return LIBUSB_ERROR_NOT_FOUND;
+			}
+
+			if (pipe_info_ex.PipeId == transfer->endpoint && pipe_info_ex.PipeType == UsbdPipeTypeIsochronous)
+				break;
+		}
+
+		// Make sure we found the index.
+		if (idx == priv->usb_interface[current_interface].nb_endpoints) {
+			usbi_err(TRANSFER_CTX(transfer), "couldn't find isoch endpoint 0x%02x", transfer->endpoint);
+			return LIBUSB_ERROR_NOT_FOUND;
+		}
+
+		if (IS_XFERIN(transfer)) {
+			int interval = pipe_info_ex.Interval;
+
+			// For high-speed and SuperSpeed device, the interval is 2**(bInterval-1).
+			if (transfer->dev_handle->dev->speed >= LIBUSB_SPEED_HIGH)
+				interval = (1 << (pipe_info_ex.Interval - 1));
+
+			// WinUSB only supports isoch transfers spanning a full USB frames. Later, we might be smarter about this
+			// and allocate a temporary buffer. However, this is harder than it seems as its destruction would depend on overlapped
+			// IO...
+			iso_transfer_size_multiple = (pipe_info_ex.MaximumBytesPerInterval * 8) / interval;
+			if (transfer->length % iso_transfer_size_multiple != 0) {
+				usbi_err(TRANSFER_CTX(transfer), "length of isoch buffer must be a multiple of the MaximumBytesPerInterval * 8 / Interval");
+				return LIBUSB_ERROR_INVALID_PARAM;
+			}
+		} else {
+			// If this is an OUT transfer, we make sure the isoch packets are contiguous as this isn't supported otherwise.
+			bool size_should_be_zero = false;
+
+			for (idx = 0; idx < transfer->num_iso_packets; ++idx) {
+				if ((size_should_be_zero && transfer->iso_packet_desc[idx].length != 0) ||
+					(transfer->iso_packet_desc[idx].length != pipe_info_ex.MaximumBytesPerInterval && idx + 1 < transfer->num_iso_packets && transfer->iso_packet_desc[idx + 1].length > 0)) {
+					usbi_err(TRANSFER_CTX(transfer), "isoch packets for OUT transfer with WinUSB must be contiguous in memory");
+					return LIBUSB_ERROR_INVALID_PARAM;
+				}
+
+				size_should_be_zero = (transfer->iso_packet_desc[idx].length == 0);
+				out_transfer_length += transfer->iso_packet_desc[idx].length;
+			}
+		}
+
+		if (transfer_priv->isoch_buffer_handle != NULL) {
+			if (WinUSBX[sub_api].UnregisterIsochBuffer(transfer_priv->isoch_buffer_handle)) {
+				transfer_priv->isoch_buffer_handle = NULL;
+			} else {
+				usbi_err(TRANSFER_CTX(transfer), "failed to unregister WinUSB isoch buffer: %s", windows_error_str(0));
+				return LIBUSB_ERROR_OTHER;
+			}
+		}
+
+		// Register the isoch buffer to the operating system.
+		ret = WinUSBX[sub_api].RegisterIsochBuffer(winusb_handle, transfer->endpoint, transfer->buffer, transfer->length, &buffer_handle);
+		if (!ret) {
+			usbi_err(TRANSFER_CTX(transfer), "failed to register WinUSB isoch buffer: %s", windows_error_str(0));
+			return LIBUSB_ERROR_NO_MEM;
+		}
+
+		// Important note: the WinUSB_Read/WriteIsochPipeAsap API requires a ContinueStream parameter that tells whether the isochronous
+		// stream must be continued or if the WinUSB driver can schedule the transfer at its convenience. Profiling subsequent transfers
+		// with ContinueStream = FALSE showed that 5 frames, i.e. about 5 milliseconds, were left empty between each transfer. This
+		// is critical as this greatly diminish the achievable isochronous bandwidth. We solved the problem using the following strategy:
+		// - Transfers are first scheduled with ContinueStream = TRUE and with winusbx_iso_transfer_continue_stream_callback as user callback.
+		// - If the transfer succeeds, winusbx_iso_transfer_continue_stream_callback restore the user callback and calls its.
+		// - If the transfer fails, winusbx_iso_transfer_continue_stream_callback reschedule the transfer and force ContinueStream = FALSE.
+		if (!transfer_priv->iso_break_stream) {
+			transfer_priv->iso_user_callback = transfer->callback;
+			transfer->callback = winusbx_native_iso_transfer_continue_stream_callback;
+		}
+
+		// Initiate the transfers.
+		if (IS_XFERIN(transfer))
+			ret = WinUSBX[sub_api].ReadIsochPipeAsap(buffer_handle, 0, transfer->length, !transfer_priv->iso_break_stream, transfer->num_iso_packets, (PUSBD_ISO_PACKET_DESCRIPTOR)transfer->iso_packet_desc, overlapped);
+		else
+			ret = WinUSBX[sub_api].WriteIsochPipeAsap(buffer_handle, 0, out_transfer_length, !transfer_priv->iso_break_stream, overlapped);
+
+		if (!ret && GetLastError() != ERROR_IO_PENDING) {
+			usbi_err(TRANSFER_CTX(transfer), "ReadIsochPipeAsap/WriteIsochPipeAsap failed: %s", windows_error_str(0));
+			if (!WinUSBX[sub_api].UnregisterIsochBuffer(buffer_handle))
+				usbi_warn(TRANSFER_CTX(transfer), "failed to unregister WinUSB isoch buffer: %s", windows_error_str(0));
+			return LIBUSB_ERROR_IO;
+		}
+
+		// Restore the ContinueStream parameter to TRUE.
+		transfer_priv->iso_break_stream = FALSE;
+
+		transfer_priv->isoch_buffer_handle = buffer_handle;
+
+		return LIBUSB_SUCCESS;
+	} else {
+		PRINT_UNSUPPORTED_API(winusbx_submit_iso_transfer);
+		return LIBUSB_ERROR_NOT_SUPPORTED;
+	}
+}
+
+static int winusbx_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	HANDLE winusb_handle;
+	OVERLAPPED *overlapped;
+	BOOL ret;
+	int current_interface;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, transfer->endpoint);
+	if (current_interface < 0) {
+		usbi_err(TRANSFER_CTX(transfer), "unable to match endpoint to an open interface - cancelling transfer");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(TRANSFER_CTX(transfer), "matched endpoint %02X with interface %d", transfer->endpoint, current_interface);
+
+	transfer_priv->interface_number = (uint8_t)current_interface;
+	winusb_handle = handle_priv->interface_handle[current_interface].api_handle;
+	set_transfer_priv_handle(itransfer, handle_priv->interface_handle[current_interface].dev_handle);
+	overlapped = get_transfer_priv_overlapped(itransfer);
+
+	if (IS_XFERIN(transfer)) {
+		usbi_dbg(TRANSFER_CTX(transfer), "reading %d bytes", transfer->length);
+		ret = WinUSBX[sub_api].ReadPipe(winusb_handle, transfer->endpoint, transfer->buffer, transfer->length, NULL, overlapped);
+	} else {
+		// Set SHORT_PACKET_TERMINATE if ZLP requested.
+		// Changing this can be a problem with packets in flight, so only allow on the first transfer.
+		UCHAR policy = (transfer->flags & LIBUSB_TRANSFER_ADD_ZERO_PACKET) != 0;
+		uint8_t* current_zlp = &handle_priv->interface_handle[current_interface].zlp[transfer->endpoint];
+		if (*current_zlp == WINUSB_ZLP_UNSET) {
+			if (policy &&
+				!WinUSBX[sub_api].SetPipePolicy(winusb_handle, transfer->endpoint,
+				SHORT_PACKET_TERMINATE, sizeof(UCHAR), &policy)) {
+				usbi_err(TRANSFER_CTX(transfer), "failed to set SHORT_PACKET_TERMINATE for endpoint %02X", transfer->endpoint);
+				return LIBUSB_ERROR_NOT_SUPPORTED;
+			}
+			*current_zlp = policy ? WINUSB_ZLP_ON : WINUSB_ZLP_OFF;
+		} else if (policy != (*current_zlp == WINUSB_ZLP_ON)) {
+			usbi_err(TRANSFER_CTX(transfer), "cannot change ZERO_PACKET for endpoint %02X on Windows", transfer->endpoint);
+			return LIBUSB_ERROR_NOT_SUPPORTED;
+		}
+
+		usbi_dbg(TRANSFER_CTX(transfer), "writing %d bytes", transfer->length);
+		ret = WinUSBX[sub_api].WritePipe(winusb_handle, transfer->endpoint, transfer->buffer, transfer->length, NULL, overlapped);
+	}
+
+	if (!ret && GetLastError() != ERROR_IO_PENDING) {
+		usbi_err(TRANSFER_CTX(transfer), "ReadPipe/WritePipe failed: %s", windows_error_str(0));
+		return LIBUSB_ERROR_IO;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int winusbx_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE winusb_handle;
+	int current_interface;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, endpoint);
+	if (current_interface < 0) {
+		usbi_err(HANDLE_CTX(dev_handle), "unable to match endpoint to an open interface - cannot clear");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(HANDLE_CTX(dev_handle), "matched endpoint %02X with interface %d", endpoint, current_interface);
+	winusb_handle = handle_priv->interface_handle[current_interface].api_handle;
+
+	if (!WinUSBX[sub_api].ResetPipe(winusb_handle, endpoint)) {
+		usbi_err(HANDLE_CTX(dev_handle), "ResetPipe failed: %s", windows_error_str(0));
+		return LIBUSB_ERROR_NO_DEVICE;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int winusbx_cancel_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int current_interface = transfer_priv->interface_number;
+	HANDLE handle;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	usbi_dbg(TRANSFER_CTX(transfer), "will use interface %d", current_interface);
+
+	handle = handle_priv->interface_handle[current_interface].api_handle;
+	if (!WinUSBX[sub_api].AbortPipe(handle, transfer->endpoint)) {
+		usbi_err(TRANSFER_CTX(transfer), "AbortPipe failed: %s", windows_error_str(0));
+		return LIBUSB_ERROR_NO_DEVICE;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+/*
+ * from the "How to Use WinUSB to Communicate with a USB Device" Microsoft white paper
+ * (http://www.microsoft.com/whdc/connect/usb/winusb_howto.mspx):
+ * "WinUSB does not support host-initiated reset port and cycle port operations" and
+ * IOCTL_INTERNAL_USB_CYCLE_PORT is only available in kernel mode and the
+ * IOCTL_USB_HUB_CYCLE_PORT ioctl was removed from Vista => the best we can do is
+ * cycle the pipes (and even then, the control pipe can not be reset using WinUSB)
+ */
+// TODO: (post hotplug): see if we can force eject the device and redetect it (reuse hotplug?)
+static int winusbx_reset_device(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE winusb_handle;
+	int i, j;
+
+	CHECK_WINUSBX_AVAILABLE(sub_api);
+
+	// Reset any available pipe (except control)
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		winusb_handle = handle_priv->interface_handle[i].api_handle;
+		if (HANDLE_VALID(winusb_handle)) {
+			for (j = 0; j < priv->usb_interface[i].nb_endpoints; j++) {
+				usbi_dbg(HANDLE_CTX(dev_handle), "resetting ep %02X", priv->usb_interface[i].endpoint[j]);
+				if (!WinUSBX[sub_api].AbortPipe(winusb_handle, priv->usb_interface[i].endpoint[j]))
+					usbi_err(HANDLE_CTX(dev_handle), "AbortPipe (pipe address %02X) failed: %s",
+						priv->usb_interface[i].endpoint[j], windows_error_str(0));
+
+				// FlushPipe seems to fail on OUT pipes
+				if (IS_EPIN(priv->usb_interface[i].endpoint[j])
+						&& (!WinUSBX[sub_api].FlushPipe(winusb_handle, priv->usb_interface[i].endpoint[j])))
+					usbi_err(HANDLE_CTX(dev_handle), "FlushPipe (pipe address %02X) failed: %s",
+						priv->usb_interface[i].endpoint[j], windows_error_str(0));
+
+				if (!WinUSBX[sub_api].ResetPipe(winusb_handle, priv->usb_interface[i].endpoint[j]))
+					usbi_err(HANDLE_CTX(dev_handle), "ResetPipe (pipe address %02X) failed: %s",
+						priv->usb_interface[i].endpoint[j], windows_error_str(0));
+			}
+		}
+	}
+
+	// libusbK & libusb0 have the ability to issue an actual device reset
+	if ((sub_api != SUB_API_WINUSB) && (WinUSBX[sub_api].ResetDevice != NULL)) {
+		winusb_handle = handle_priv->interface_handle[0].api_handle;
+		if (HANDLE_VALID(winusb_handle))
+			WinUSBX[sub_api].ResetDevice(winusb_handle);
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static enum libusb_transfer_status winusbx_copy_transfer_data(int sub_api, struct usbi_transfer *itransfer, DWORD length)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	int i;
+
+	if (transfer->type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS) {
+		// for isochronous, need to copy the individual iso packet actual_lengths and statuses
+		if ((sub_api == SUB_API_LIBUSBK) || (sub_api == SUB_API_LIBUSB0)) {
+			// iso only supported on libusbk-based backends for now
+			PKISO_CONTEXT iso_context = transfer_priv->iso_context;
+			for (i = 0; i < transfer->num_iso_packets; i++) {
+				transfer->iso_packet_desc[i].actual_length = iso_context->IsoPackets[i].actual_length;
+				// TODO translate USDB_STATUS codes http://msdn.microsoft.com/en-us/library/ff539136(VS.85).aspx to libusb_transfer_status
+				//transfer->iso_packet_desc[i].status = transfer_priv->iso_context->IsoPackets[i].status;
+			}
+		} else if (sub_api == SUB_API_WINUSB) {
+			if (IS_XFERIN(transfer)) {
+				/* Convert isochronous packet descriptor between Windows and libusb representation.
+				 * Both representation are guaranteed to have the same length in bytes.*/
+				PUSBD_ISO_PACKET_DESCRIPTOR usbd_iso_packet_desc = (PUSBD_ISO_PACKET_DESCRIPTOR)transfer->iso_packet_desc;
+				for (i = 0; i < transfer->num_iso_packets; i++) {
+					unsigned int packet_length = (i < transfer->num_iso_packets - 1) ? (usbd_iso_packet_desc[i + 1].Offset - usbd_iso_packet_desc[i].Offset) : usbd_iso_packet_desc[i].Length;
+					unsigned int actual_length = usbd_iso_packet_desc[i].Length;
+					USBD_STATUS status = usbd_iso_packet_desc[i].Status;
+
+					transfer->iso_packet_desc[i].length = packet_length;
+					transfer->iso_packet_desc[i].actual_length = actual_length;
+					transfer->iso_packet_desc[i].status = usbd_status_to_libusb_transfer_status(status);
+				}
+			} else {
+				for (i = 0; i < transfer->num_iso_packets; i++) {
+					transfer->iso_packet_desc[i].status = LIBUSB_TRANSFER_COMPLETED;
+				}
+			}
+		} else {
+			// This should only occur if backend is not set correctly or other backend isoc is partially implemented
+			PRINT_UNSUPPORTED_API(copy_transfer_data);
+			return LIBUSB_TRANSFER_ERROR;
+		}
+	}
+
+	itransfer->transferred += (int)length;
+	return LIBUSB_TRANSFER_COMPLETED;
+}
+
+/*
+ * Internal HID Support functions (from libusb-win32)
+ * Note that functions that complete data transfer synchronously must return
+ * LIBUSB_COMPLETED instead of LIBUSB_SUCCESS
+ */
+static int _hid_get_hid_descriptor(struct hid_device_priv *dev, void *data, size_t *size);
+static int _hid_get_report_descriptor(struct hid_device_priv *dev, void *data, size_t *size);
+
+static int _hid_wcslen(WCHAR *str)
+{
+	int i = 0;
+
+	while (str[i] && (str[i] != 0x409))
+		i++;
+
+	return i;
+}
+
+static int _hid_get_device_descriptor(struct hid_device_priv *hid_priv, void *data, size_t *size)
+{
+	struct libusb_device_descriptor d;
+
+	d.bLength = LIBUSB_DT_DEVICE_SIZE;
+	d.bDescriptorType = LIBUSB_DT_DEVICE;
+	d.bcdUSB = 0x0200; /* 2.00 */
+	d.bDeviceClass = 0;
+	d.bDeviceSubClass = 0;
+	d.bDeviceProtocol = 0;
+	d.bMaxPacketSize0 = 64; /* fix this! */
+	d.idVendor = (uint16_t)hid_priv->vid;
+	d.idProduct = (uint16_t)hid_priv->pid;
+	d.bcdDevice = 0x0100;
+	d.iManufacturer = hid_priv->string_index[0];
+	d.iProduct = hid_priv->string_index[1];
+	d.iSerialNumber = hid_priv->string_index[2];
+	d.bNumConfigurations = 1;
+
+	if (*size > LIBUSB_DT_DEVICE_SIZE)
+		*size = LIBUSB_DT_DEVICE_SIZE;
+	memcpy(data, &d, *size);
+
+	return LIBUSB_COMPLETED;
+}
+
+static int _hid_get_config_descriptor(struct hid_device_priv *hid_priv, void *data, size_t *size)
+{
+	char num_endpoints = 0;
+	size_t config_total_len = 0;
+	char tmp[HID_MAX_CONFIG_DESC_SIZE];
+	struct libusb_config_descriptor *cd;
+	struct libusb_interface_descriptor *id;
+	struct libusb_hid_descriptor *hd;
+	struct libusb_endpoint_descriptor *ed;
+	size_t tmp_size;
+
+	if (hid_priv->input_report_size)
+		num_endpoints++;
+	if (hid_priv->output_report_size)
+		num_endpoints++;
+
+	config_total_len = LIBUSB_DT_CONFIG_SIZE + LIBUSB_DT_INTERFACE_SIZE
+		+ LIBUSB_DT_HID_SIZE + num_endpoints * LIBUSB_DT_ENDPOINT_SIZE;
+
+	cd = (struct libusb_config_descriptor *)tmp;
+	id = (struct libusb_interface_descriptor *)(tmp + LIBUSB_DT_CONFIG_SIZE);
+	hd = (struct libusb_hid_descriptor *)(tmp + LIBUSB_DT_CONFIG_SIZE
+		+ LIBUSB_DT_INTERFACE_SIZE);
+	ed = (struct libusb_endpoint_descriptor *)(tmp + LIBUSB_DT_CONFIG_SIZE
+		+ LIBUSB_DT_INTERFACE_SIZE
+		+ LIBUSB_DT_HID_SIZE);
+
+	cd->bLength = LIBUSB_DT_CONFIG_SIZE;
+	cd->bDescriptorType = LIBUSB_DT_CONFIG;
+	cd->wTotalLength = (uint16_t)config_total_len;
+	cd->bNumInterfaces = 1;
+	cd->bConfigurationValue = 1;
+	cd->iConfiguration = 0;
+	cd->bmAttributes = 1 << 7; /* bus powered */
+	cd->MaxPower = 50;
+
+	id->bLength = LIBUSB_DT_INTERFACE_SIZE;
+	id->bDescriptorType = LIBUSB_DT_INTERFACE;
+	id->bInterfaceNumber = 0;
+	id->bAlternateSetting = 0;
+	id->bNumEndpoints = num_endpoints;
+	id->bInterfaceClass = 3;
+	id->bInterfaceSubClass = 0;
+	id->bInterfaceProtocol = 0;
+	id->iInterface = 0;
+
+	tmp_size = LIBUSB_DT_HID_SIZE;
+	_hid_get_hid_descriptor(hid_priv, hd, &tmp_size);
+
+	if (hid_priv->input_report_size) {
+		ed->bLength = LIBUSB_DT_ENDPOINT_SIZE;
+		ed->bDescriptorType = LIBUSB_DT_ENDPOINT;
+		ed->bEndpointAddress = HID_IN_EP;
+		ed->bmAttributes = 3;
+		ed->wMaxPacketSize = hid_priv->input_report_size - 1;
+		ed->bInterval = 10;
+		ed = (struct libusb_endpoint_descriptor *)((char *)ed + LIBUSB_DT_ENDPOINT_SIZE);
+	}
+
+	if (hid_priv->output_report_size) {
+		ed->bLength = LIBUSB_DT_ENDPOINT_SIZE;
+		ed->bDescriptorType = LIBUSB_DT_ENDPOINT;
+		ed->bEndpointAddress = HID_OUT_EP;
+		ed->bmAttributes = 3;
+		ed->wMaxPacketSize = hid_priv->output_report_size - 1;
+		ed->bInterval = 10;
+	}
+
+	if (*size > config_total_len)
+		*size = config_total_len;
+	memcpy(data, tmp, *size);
+
+	return LIBUSB_COMPLETED;
+}
+
+static int _hid_get_string_descriptor(struct hid_device_priv *hid_priv, int _index,
+	void *data, size_t *size, HANDLE hid_handle)
+{
+	void *tmp = NULL;
+	WCHAR string[MAX_USB_STRING_LENGTH];
+	size_t tmp_size = 0;
+	int i;
+
+	/* language ID, EN-US */
+	char string_langid[] = {0x09, 0x04};
+
+	if (_index == 0) {
+		tmp = string_langid;
+		tmp_size = sizeof(string_langid) + 2;
+	} else {
+		for (i = 0; i < 3; i++) {
+			if (_index == (hid_priv->string_index[i])) {
+				tmp = hid_priv->string[i];
+				tmp_size = (_hid_wcslen(hid_priv->string[i]) + 1) * sizeof(WCHAR);
+				break;
+			}
+		}
+
+		if (i == 3) {
+			if (!HidD_GetIndexedString(hid_handle, _index, string, sizeof(string)))
+				return LIBUSB_ERROR_INVALID_PARAM;
+			tmp = string;
+			tmp_size = (_hid_wcslen(string) + 1) * sizeof(WCHAR);
+		}
+	}
+
+	if (!tmp_size)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
+	if (tmp_size < *size)
+		*size = tmp_size;
+
+	// 2 byte header
+	((uint8_t *)data)[0] = (uint8_t)*size;
+	((uint8_t *)data)[1] = LIBUSB_DT_STRING;
+	memcpy((uint8_t *)data + 2, tmp, *size - 2);
+
+	return LIBUSB_COMPLETED;
+}
+
+static int _hid_get_hid_descriptor(struct hid_device_priv *hid_priv, void *data, size_t *size)
+{
+	struct libusb_hid_descriptor d;
+	uint8_t tmp[MAX_HID_DESCRIPTOR_SIZE];
+	size_t report_len = MAX_HID_DESCRIPTOR_SIZE;
+
+	_hid_get_report_descriptor(hid_priv, tmp, &report_len);
+
+	d.bLength = LIBUSB_DT_HID_SIZE;
+	d.bDescriptorType = LIBUSB_DT_HID;
+	d.bcdHID = 0x0110; /* 1.10 */
+	d.bCountryCode = 0;
+	d.bNumDescriptors = 1;
+	d.bClassDescriptorType = LIBUSB_DT_REPORT;
+	d.wClassDescriptorLength = (uint16_t)report_len;
+
+	if (*size > LIBUSB_DT_HID_SIZE)
+		*size = LIBUSB_DT_HID_SIZE;
+	memcpy(data, &d, *size);
+
+	return LIBUSB_COMPLETED;
+}
+
+static int _hid_get_report_descriptor(struct hid_device_priv *hid_priv, void *data, size_t *size)
+{
+	uint8_t d[MAX_HID_DESCRIPTOR_SIZE];
+	size_t i = 0;
+
+	/* usage page */
+	d[i++] = 0x06; d[i++] = hid_priv->usagePage & 0xFF; d[i++] = hid_priv->usagePage >> 8;
+	/* usage */
+	d[i++] = 0x09; d[i++] = (uint8_t)hid_priv->usage;
+	/* start collection (application) */
+	d[i++] = 0xA1; d[i++] = 0x01;
+	/* input report */
+	if (hid_priv->input_report_size) {
+		/* usage (vendor defined) */
+		d[i++] = 0x09; d[i++] = 0x01;
+		/* logical minimum (0) */
+		d[i++] = 0x15; d[i++] = 0x00;
+		/* logical maximum (255) */
+		d[i++] = 0x25; d[i++] = 0xFF;
+		/* report size (8 bits) */
+		d[i++] = 0x75; d[i++] = 0x08;
+		/* report count */
+		d[i++] = 0x95; d[i++] = (uint8_t)hid_priv->input_report_size - 1;
+		/* input (data, variable, absolute) */
+		d[i++] = 0x81; d[i++] = 0x00;
+	}
+	/* output report */
+	if (hid_priv->output_report_size) {
+		/* usage (vendor defined) */
+		d[i++] = 0x09; d[i++] = 0x02;
+		/* logical minimum (0) */
+		d[i++] = 0x15; d[i++] = 0x00;
+		/* logical maximum (255) */
+		d[i++] = 0x25; d[i++] = 0xFF;
+		/* report size (8 bits) */
+		d[i++] = 0x75; d[i++] = 0x08;
+		/* report count */
+		d[i++] = 0x95; d[i++] = (uint8_t)hid_priv->output_report_size - 1;
+		/* output (data, variable, absolute) */
+		d[i++] = 0x91; d[i++] = 0x00;
+	}
+	/* feature report */
+	if (hid_priv->feature_report_size) {
+		/* usage (vendor defined) */
+		d[i++] = 0x09; d[i++] = 0x03;
+		/* logical minimum (0) */
+		d[i++] = 0x15; d[i++] = 0x00;
+		/* logical maximum (255) */
+		d[i++] = 0x25; d[i++] = 0xFF;
+		/* report size (8 bits) */
+		d[i++] = 0x75; d[i++] = 0x08;
+		/* report count */
+		d[i++] = 0x95; d[i++] = (uint8_t)hid_priv->feature_report_size - 1;
+		/* feature (data, variable, absolute) */
+		d[i++] = 0xb2; d[i++] = 0x02; d[i++] = 0x01;
+	}
+
+	/* end collection */
+	d[i++] = 0xC0;
+
+	if (*size > i)
+		*size = i;
+	memcpy(data, d, *size);
+
+	return LIBUSB_COMPLETED;
+}
+
+static int _hid_get_descriptor(struct libusb_device *dev, HANDLE hid_handle, int recipient,
+	int type, int _index, void *data, size_t *size)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	UNUSED(recipient);
+
+	switch (type) {
+	case LIBUSB_DT_DEVICE:
+		usbi_dbg(DEVICE_CTX(dev), "LIBUSB_DT_DEVICE");
+		return _hid_get_device_descriptor(priv->hid, data, size);
+	case LIBUSB_DT_CONFIG:
+		usbi_dbg(DEVICE_CTX(dev), "LIBUSB_DT_CONFIG");
+		if (!_index)
+			return _hid_get_config_descriptor(priv->hid, data, size);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	case LIBUSB_DT_STRING:
+		usbi_dbg(DEVICE_CTX(dev), "LIBUSB_DT_STRING");
+		return _hid_get_string_descriptor(priv->hid, _index, data, size, hid_handle);
+	case LIBUSB_DT_HID:
+		usbi_dbg(DEVICE_CTX(dev), "LIBUSB_DT_HID");
+		if (!_index)
+			return _hid_get_hid_descriptor(priv->hid, data, size);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	case LIBUSB_DT_REPORT:
+		usbi_dbg(DEVICE_CTX(dev), "LIBUSB_DT_REPORT");
+		if (!_index)
+			return _hid_get_report_descriptor(priv->hid, data, size);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	case LIBUSB_DT_PHYSICAL:
+		usbi_dbg(DEVICE_CTX(dev), "LIBUSB_DT_PHYSICAL");
+		if (HidD_GetPhysicalDescriptor(hid_handle, data, (ULONG)*size))
+			return LIBUSB_COMPLETED;
+		return LIBUSB_ERROR_OTHER;
+	}
+
+	usbi_warn(DEVICE_CTX(dev), "unsupported");
+	return LIBUSB_ERROR_NOT_SUPPORTED;
+}
+
+static int _hid_get_report(struct libusb_device *dev, HANDLE hid_handle, int id, void *data,
+	struct winusb_transfer_priv *tp, size_t size, OVERLAPPED *overlapped, int report_type)
+{
+	DWORD ioctl_code, expected_size = (DWORD)size;
+	uint8_t *buf;
+
+	if (tp->hid_buffer != NULL)
+		usbi_err(DEVICE_CTX(dev), "program assertion failed - hid_buffer is not NULL");
+
+	if ((size == 0) || (size > MAX_HID_REPORT_SIZE)) {
+		usbi_warn(DEVICE_CTX(dev), "invalid size (%"PRIuPTR")", (uintptr_t)size);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	switch (report_type) {
+	case HID_REPORT_TYPE_INPUT:
+		ioctl_code = IOCTL_HID_GET_INPUT_REPORT;
+		break;
+	case HID_REPORT_TYPE_FEATURE:
+		ioctl_code = IOCTL_HID_GET_FEATURE;
+		break;
+	default:
+		usbi_warn(DEVICE_CTX(dev), "unknown HID report type %d", report_type);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	// Add a trailing byte to detect overflows
+	buf = calloc(1, expected_size + 1);
+	if (buf == NULL)
+		return LIBUSB_ERROR_NO_MEM;
+
+	buf[0] = (uint8_t)id; // Must be set always
+	usbi_dbg(DEVICE_CTX(dev), "report ID: 0x%02X", buf[0]);
+
+	// NB: The size returned by DeviceIoControl doesn't include report IDs when not in use (0)
+	if (!DeviceIoControl(hid_handle, ioctl_code, buf, expected_size + 1,
+		buf, expected_size + 1, NULL, overlapped)) {
+		if (GetLastError() != ERROR_IO_PENDING) {
+			usbi_err(DEVICE_CTX(dev), "failed to read HID Report: %s", windows_error_str(0));
+			free(buf);
+			return LIBUSB_ERROR_IO;
+		}
+	}
+
+	// Asynchronous wait
+	tp->hid_buffer = buf;
+	tp->hid_dest = data; // copy dest, as not necessarily the start of the transfer buffer
+	tp->hid_expected_size = expected_size;
+
+	return LIBUSB_SUCCESS;
+}
+
+static int _hid_set_report(struct libusb_device *dev, HANDLE hid_handle, int id, void *data,
+	struct winusb_transfer_priv *tp, size_t size, OVERLAPPED *overlapped, int report_type)
+{
+	DWORD ioctl_code, write_size = (DWORD)size;
+	// If an id is reported, we must allow MAX_HID_REPORT_SIZE + 1
+	size_t max_report_size = MAX_HID_REPORT_SIZE + (id ? 1 : 0);
+	uint8_t *buf;
+
+	if (tp->hid_buffer != NULL)
+		usbi_err(DEVICE_CTX(dev), "program assertion failed - hid_buffer is not NULL");
+
+	if ((size == 0) || (size > max_report_size)) {
+		usbi_warn(DEVICE_CTX(dev), "invalid size (%"PRIuPTR")", (uintptr_t)size);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	switch (report_type) {
+	case HID_REPORT_TYPE_OUTPUT:
+		ioctl_code = IOCTL_HID_SET_OUTPUT_REPORT;
+		break;
+	case HID_REPORT_TYPE_FEATURE:
+		ioctl_code = IOCTL_HID_SET_FEATURE;
+		break;
+	default:
+		usbi_warn(DEVICE_CTX(dev), "unknown HID report type %d", report_type);
+		return LIBUSB_ERROR_INVALID_PARAM;
+	}
+
+	usbi_dbg(DEVICE_CTX(dev), "report ID: 0x%02X", id);
+	// When report IDs are not used (i.e. when id == 0), we must add
+	// a null report ID. Otherwise, we just use original data buffer
+	if (id == 0)
+		write_size++;
+
+	buf = malloc(write_size);
+	if (buf == NULL)
+		return LIBUSB_ERROR_NO_MEM;
+
+	if (id == 0) {
+		buf[0] = 0;
+		memcpy(buf + 1, data, size);
+	} else {
+		// This seems like a waste, but if we don't duplicate the
+		// data, we'll get issues when freeing hid_buffer
+		memcpy(buf, data, size);
+		if (buf[0] != id)
+			usbi_warn(DEVICE_CTX(dev), "mismatched report ID (data is %02X, parameter is %02X)", buf[0], id);
+	}
+
+	// NB: The size returned by DeviceIoControl doesn't include report IDs when not in use (0)
+	if (!DeviceIoControl(hid_handle, ioctl_code, buf, write_size,
+		buf, write_size, NULL, overlapped)) {
+		if (GetLastError() != ERROR_IO_PENDING) {
+			usbi_err(DEVICE_CTX(dev), "failed to write HID Output Report: %s", windows_error_str(0));
+			free(buf);
+			return LIBUSB_ERROR_IO;
+		}
+	}
+
+	tp->hid_buffer = buf;
+	tp->hid_dest = NULL;
+	return LIBUSB_SUCCESS;
+}
+
+static int _hid_class_request(struct libusb_device *dev, HANDLE hid_handle, int request_type,
+	int request, int value, int _index, void *data, struct winusb_transfer_priv *tp,
+	size_t size, OVERLAPPED *overlapped)
+{
+	int report_type = (value >> 8) & 0xFF;
+	int report_id = value & 0xFF;
+
+	UNUSED(_index);
+
+	if ((LIBUSB_REQ_RECIPIENT(request_type) != LIBUSB_RECIPIENT_INTERFACE)
+			&& (LIBUSB_REQ_RECIPIENT(request_type) != LIBUSB_RECIPIENT_DEVICE))
+		return LIBUSB_ERROR_INVALID_PARAM;
+
+	if (LIBUSB_REQ_OUT(request_type) && request == HID_REQ_SET_REPORT)
+		return _hid_set_report(dev, hid_handle, report_id, data, tp, size, overlapped, report_type);
+
+	if (LIBUSB_REQ_IN(request_type) && request == HID_REQ_GET_REPORT)
+		return _hid_get_report(dev, hid_handle, report_id, data, tp, size, overlapped, report_type);
+
+	return LIBUSB_ERROR_INVALID_PARAM;
+}
+
+/*
+ * HID API functions
+ */
+static bool hid_init(struct libusb_context *ctx)
+{
+	DLL_GET_HANDLE(ctx, hid);
+
+	DLL_LOAD_FUNC(hid, HidD_GetAttributes, true);
+	DLL_LOAD_FUNC(hid, HidD_GetHidGuid, true);
+	DLL_LOAD_FUNC(hid, HidD_GetPreparsedData, true);
+	DLL_LOAD_FUNC(hid, HidD_FreePreparsedData, true);
+	DLL_LOAD_FUNC(hid, HidD_GetManufacturerString, true);
+	DLL_LOAD_FUNC(hid, HidD_GetProductString, true);
+	DLL_LOAD_FUNC(hid, HidD_GetSerialNumberString, true);
+	DLL_LOAD_FUNC(hid, HidD_GetIndexedString, true);
+	DLL_LOAD_FUNC(hid, HidP_GetCaps, true);
+	DLL_LOAD_FUNC(hid, HidD_SetNumInputBuffers, true);
+	DLL_LOAD_FUNC(hid, HidD_GetPhysicalDescriptor, true);
+	DLL_LOAD_FUNC(hid, HidD_FlushQueue, true);
+	DLL_LOAD_FUNC(hid, HidP_GetValueCaps, true);
+
+	return true;
+}
+
+static void hid_exit(void)
+{
+	DLL_FREE_HANDLE(hid);
+}
+
+// NB: open and close must ensure that they only handle interface of
+// the right API type, as these functions can be called wholesale from
+// composite_open(), with interfaces belonging to different APIs
+static int hid_open(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct libusb_device *dev = dev_handle->dev;
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	HIDD_ATTRIBUTES hid_attributes;
+	PHIDP_PREPARSED_DATA preparsed_data = NULL;
+	HIDP_CAPS capabilities;
+	HIDP_VALUE_CAPS *value_caps;
+	HANDLE hid_handle = INVALID_HANDLE_VALUE;
+	int i, j;
+	// report IDs handling
+	ULONG size[3];
+	int nb_ids[2]; // zero and nonzero report IDs
+#if defined(ENABLE_LOGGING)
+	const char * const type[3] = {"input", "output", "feature"};
+#endif
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	if (priv->hid == NULL) {
+		usbi_err(HANDLE_CTX(dev_handle), "program assertion failed - private HID structure is uninitialized");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		if ((priv->usb_interface[i].path != NULL)
+				&& (priv->usb_interface[i].apib->id == USB_API_HID)) {
+			hid_handle = windows_open(dev_handle, priv->usb_interface[i].path, GENERIC_READ | GENERIC_WRITE);
+			/*
+			 * http://www.lvr.com/hidfaq.htm: Why do I receive "Access denied" when attempting to access my HID?
+			 * "Windows 2000 and later have exclusive read/write access to HIDs that are configured as a system
+			 * keyboards or mice. An application can obtain a handle to a system keyboard or mouse by not
+			 * requesting READ or WRITE access with CreateFile. Applications can then use HidD_SetFeature and
+			 * HidD_GetFeature (if the device supports Feature reports)."
+			 */
+			if (hid_handle == INVALID_HANDLE_VALUE) {
+				usbi_warn(HANDLE_CTX(dev_handle), "could not open HID device in R/W mode (keyboard or mouse?) - trying without");
+				hid_handle = windows_open(dev_handle, priv->usb_interface[i].path, 0);
+				if (hid_handle == INVALID_HANDLE_VALUE) {
+					usbi_err(HANDLE_CTX(dev_handle), "could not open device %s (interface %d): %s", priv->path, i, windows_error_str(0));
+					switch (GetLastError()) {
+					case ERROR_FILE_NOT_FOUND: // The device was disconnected
+						return LIBUSB_ERROR_NO_DEVICE;
+					case ERROR_ACCESS_DENIED:
+						return LIBUSB_ERROR_ACCESS;
+					default:
+						return LIBUSB_ERROR_IO;
+					}
+				}
+				priv->usb_interface[i].restricted_functionality = true;
+			}
+			handle_priv->interface_handle[i].api_handle = hid_handle;
+		}
+	}
+
+	hid_attributes.Size = sizeof(hid_attributes);
+	do {
+		if (!HidD_GetAttributes(hid_handle, &hid_attributes)) {
+			usbi_err(HANDLE_CTX(dev_handle), "could not gain access to HID top collection (HidD_GetAttributes)");
+			break;
+		}
+
+		priv->hid->vid = hid_attributes.VendorID;
+		priv->hid->pid = hid_attributes.ProductID;
+
+		// Set the maximum available input buffer size
+		for (i = 32; HidD_SetNumInputBuffers(hid_handle, i); i *= 2);
+		usbi_dbg(HANDLE_CTX(dev_handle), "set maximum input buffer size to %d", i / 2);
+
+		// Get the maximum input and output report size
+		if (!HidD_GetPreparsedData(hid_handle, &preparsed_data) || !preparsed_data) {
+			usbi_err(HANDLE_CTX(dev_handle), "could not read HID preparsed data (HidD_GetPreparsedData)");
+			break;
+		}
+		if (HidP_GetCaps(preparsed_data, &capabilities) != HIDP_STATUS_SUCCESS) {
+			usbi_err(HANDLE_CTX(dev_handle), "could not parse HID capabilities (HidP_GetCaps)");
+			break;
+		}
+
+		// Find out if interrupt will need report IDs
+		size[0] = capabilities.NumberInputValueCaps;
+		size[1] = capabilities.NumberOutputValueCaps;
+		size[2] = capabilities.NumberFeatureValueCaps;
+		for (j = HidP_Input; j <= HidP_Feature; j++) {
+			usbi_dbg(HANDLE_CTX(dev_handle), "%lu HID %s report value(s) found", ULONG_CAST(size[j]), type[j]);
+			priv->hid->uses_report_ids[j] = false;
+			if (size[j] > 0) {
+				value_caps = calloc(size[j], sizeof(HIDP_VALUE_CAPS));
+				if ((value_caps != NULL)
+						&& (HidP_GetValueCaps((HIDP_REPORT_TYPE)j, value_caps, &size[j], preparsed_data) == HIDP_STATUS_SUCCESS)
+						&& (size[j] >= 1)) {
+					nb_ids[0] = 0;
+					nb_ids[1] = 0;
+					for (i = 0; i < (int)size[j]; i++) {
+						usbi_dbg(HANDLE_CTX(dev_handle), "  Report ID: 0x%02X", value_caps[i].ReportID);
+						if (value_caps[i].ReportID != 0)
+							nb_ids[1]++;
+						else
+							nb_ids[0]++;
+					}
+					if (nb_ids[1] != 0) {
+						if (nb_ids[0] != 0)
+							usbi_warn(HANDLE_CTX(dev_handle), "program assertion failed - zero and nonzero report IDs used for %s",
+								type[j]);
+						priv->hid->uses_report_ids[j] = true;
+					}
+				} else {
+					usbi_warn(HANDLE_CTX(dev_handle), "  could not process %s report IDs", type[j]);
+				}
+				free(value_caps);
+			}
+		}
+
+		// Set the report sizes
+		priv->hid->input_report_size = capabilities.InputReportByteLength;
+		priv->hid->output_report_size = capabilities.OutputReportByteLength;
+		priv->hid->feature_report_size = capabilities.FeatureReportByteLength;
+
+		// Store usage and usagePage values
+		priv->hid->usage = capabilities.Usage;
+		priv->hid->usagePage = capabilities.UsagePage;
+
+		// Fetch string descriptors
+		priv->hid->string_index[0] = dev->device_descriptor.iManufacturer;
+		if (priv->hid->string_index[0] != 0)
+			HidD_GetManufacturerString(hid_handle, priv->hid->string[0], sizeof(priv->hid->string[0]));
+		else
+			priv->hid->string[0][0] = 0;
+
+		priv->hid->string_index[1] = dev->device_descriptor.iProduct;
+		if (priv->hid->string_index[1] != 0)
+			HidD_GetProductString(hid_handle, priv->hid->string[1], sizeof(priv->hid->string[1]));
+		else
+			priv->hid->string[1][0] = 0;
+
+		priv->hid->string_index[2] = dev->device_descriptor.iSerialNumber;
+		if (priv->hid->string_index[2] != 0)
+			HidD_GetSerialNumberString(hid_handle, priv->hid->string[2], sizeof(priv->hid->string[2]));
+		else
+			priv->hid->string[2][0] = 0;
+	} while (0);
+
+	if (preparsed_data)
+		HidD_FreePreparsedData(preparsed_data);
+
+	return LIBUSB_SUCCESS;
+}
+
+static void hid_close(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	HANDLE file_handle;
+	int i;
+
+	UNUSED(sub_api);
+
+	if (DLL_HANDLE_NAME(hid) == NULL)
+		return;
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		if (priv->usb_interface[i].apib->id == USB_API_HID) {
+			file_handle = handle_priv->interface_handle[i].api_handle;
+			if (HANDLE_VALID(file_handle))
+				CloseHandle(file_handle);
+		}
+	}
+}
+
+static int hid_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	// NB: Disconnection detection is not possible in this function
+	if (priv->usb_interface[iface].path == NULL)
+		return LIBUSB_ERROR_NOT_FOUND; // invalid iface
+
+	// We use dev_handle as a flag for interface claimed
+	if (handle_priv->interface_handle[iface].dev_handle == INTERFACE_CLAIMED)
+		return LIBUSB_ERROR_BUSY; // already claimed
+
+	handle_priv->interface_handle[iface].dev_handle = INTERFACE_CLAIMED;
+
+	usbi_dbg(HANDLE_CTX(dev_handle), "claimed interface %u", iface);
+	handle_priv->active_interface = iface;
+
+	return LIBUSB_SUCCESS;
+}
+
+static int hid_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	if (priv->usb_interface[iface].path == NULL)
+		return LIBUSB_ERROR_NOT_FOUND; // invalid iface
+
+	if (handle_priv->interface_handle[iface].dev_handle != INTERFACE_CLAIMED)
+		return LIBUSB_ERROR_NOT_FOUND; // invalid iface
+
+	handle_priv->interface_handle[iface].dev_handle = INVALID_HANDLE_VALUE;
+
+	return LIBUSB_SUCCESS;
+}
+
+static int hid_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
+{
+	UNUSED(sub_api);
+	UNUSED(iface);
+
+	CHECK_HID_AVAILABLE;
+
+	if (altsetting != 0) {
+		usbi_err(HANDLE_CTX(dev_handle), "set interface altsetting not supported for altsetting >0");
+		return LIBUSB_ERROR_NOT_SUPPORTED;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int hid_submit_control_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct libusb_device_handle *dev_handle = transfer->dev_handle;
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	WINUSB_SETUP_PACKET *setup = (WINUSB_SETUP_PACKET *)transfer->buffer;
+	HANDLE hid_handle;
+	OVERLAPPED *overlapped;
+	int current_interface;
+	uint8_t config;
+	size_t size;
+	int r;
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	safe_free(transfer_priv->hid_buffer);
+	transfer_priv->hid_dest = NULL;
+	size = transfer->length - LIBUSB_CONTROL_SETUP_SIZE;
+
+	if (size > MAX_CTRL_BUFFER_LENGTH)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
+	current_interface = get_valid_interface(dev_handle, USB_API_HID);
+	if (current_interface < 0) {
+		if (auto_claim(transfer, &current_interface, USB_API_HID) != LIBUSB_SUCCESS)
+			return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(ITRANSFER_CTX(itransfer), "will use interface %d", current_interface);
+
+	transfer_priv->interface_number = (uint8_t)current_interface;
+	hid_handle = handle_priv->interface_handle[current_interface].api_handle;
+	set_transfer_priv_handle(itransfer, hid_handle);
+	overlapped = get_transfer_priv_overlapped(itransfer);
+
+	switch (LIBUSB_REQ_TYPE(setup->RequestType)) {
+	case LIBUSB_REQUEST_TYPE_STANDARD:
+		switch (setup->Request) {
+		case LIBUSB_REQUEST_GET_DESCRIPTOR:
+			r = _hid_get_descriptor(dev_handle->dev, hid_handle, LIBUSB_REQ_RECIPIENT(setup->RequestType),
+				(setup->Value >> 8) & 0xFF, setup->Value & 0xFF, transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE, &size);
+			break;
+		case LIBUSB_REQUEST_GET_CONFIGURATION:
+			r = winusb_get_configuration(dev_handle, &config);
+			if (r == LIBUSB_SUCCESS) {
+				size = 1;
+				((uint8_t *)transfer->buffer)[LIBUSB_CONTROL_SETUP_SIZE] = config;
+				r = LIBUSB_COMPLETED;
+			}
+			break;
+		case LIBUSB_REQUEST_SET_CONFIGURATION:
+			if (setup->Value == priv->active_config) {
+				r = LIBUSB_COMPLETED;
+			} else {
+				usbi_warn(TRANSFER_CTX(transfer), "cannot set configuration other than the default one");
+				r = LIBUSB_ERROR_NOT_SUPPORTED;
+			}
+			break;
+		case LIBUSB_REQUEST_GET_INTERFACE:
+			size = 1;
+			((uint8_t *)transfer->buffer)[LIBUSB_CONTROL_SETUP_SIZE] = 0;
+			r = LIBUSB_COMPLETED;
+			break;
+		case LIBUSB_REQUEST_SET_INTERFACE:
+			r = hid_set_interface_altsetting(0, dev_handle, (uint8_t)setup->Index, (uint8_t)setup->Value);
+			if (r == LIBUSB_SUCCESS)
+				r = LIBUSB_COMPLETED;
+			break;
+		default:
+			usbi_warn(TRANSFER_CTX(transfer), "unsupported HID control request");
+			return LIBUSB_ERROR_NOT_SUPPORTED;
+		}
+		break;
+	case LIBUSB_REQUEST_TYPE_CLASS:
+		r = _hid_class_request(dev_handle->dev, hid_handle, setup->RequestType, setup->Request, setup->Value,
+			setup->Index, transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE, transfer_priv,
+			size, overlapped);
+		break;
+	default:
+		usbi_warn(TRANSFER_CTX(transfer), "unsupported HID control request");
+		return LIBUSB_ERROR_NOT_SUPPORTED;
+	}
+
+	if (r < 0)
+		return r;
+
+	if (r == LIBUSB_COMPLETED) {
+		// Force request to be completed synchronously. Transferred size has been set by previous call
+		windows_force_sync_completion(itransfer, (ULONG)size);
+		r = LIBUSB_SUCCESS;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int hid_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	HANDLE hid_handle;
+	OVERLAPPED *overlapped;
+	bool direction_in;
+	BOOL ret;
+	int current_interface, length;
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	if (IS_XFEROUT(transfer) && (transfer->flags & LIBUSB_TRANSFER_ADD_ZERO_PACKET))
+		return LIBUSB_ERROR_NOT_SUPPORTED;
+
+	transfer_priv->hid_dest = NULL;
+	safe_free(transfer_priv->hid_buffer);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, transfer->endpoint);
+	if (current_interface < 0) {
+		usbi_err(TRANSFER_CTX(transfer), "unable to match endpoint to an open interface - cancelling transfer");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(TRANSFER_CTX(transfer), "matched endpoint %02X with interface %d", transfer->endpoint, current_interface);
+
+	transfer_priv->interface_number = (uint8_t)current_interface;
+	hid_handle = handle_priv->interface_handle[current_interface].api_handle;
+	set_transfer_priv_handle(itransfer, hid_handle);
+	overlapped = get_transfer_priv_overlapped(itransfer);
+	direction_in = IS_XFERIN(transfer);
+
+	// If report IDs are not in use, an extra prefix byte must be added
+	if (((direction_in) && (!priv->hid->uses_report_ids[0]))
+			|| ((!direction_in) && (!priv->hid->uses_report_ids[1])))
+		length = transfer->length + 1;
+	else
+		length = transfer->length;
+
+	// Add a trailing byte to detect overflows on input
+	transfer_priv->hid_buffer = calloc(1, length + 1);
+	if (transfer_priv->hid_buffer == NULL)
+		return LIBUSB_ERROR_NO_MEM;
+
+	transfer_priv->hid_expected_size = length;
+
+	if (direction_in) {
+		transfer_priv->hid_dest = transfer->buffer;
+		usbi_dbg(TRANSFER_CTX(transfer), "reading %d bytes (report ID: 0x00)", length);
+		ret = ReadFile(hid_handle, transfer_priv->hid_buffer, length + 1, NULL, overlapped);
+	} else {
+		if (!priv->hid->uses_report_ids[1])
+			memcpy(transfer_priv->hid_buffer + 1, transfer->buffer, transfer->length);
+		else
+			// We could actually do without the calloc and memcpy in this case
+			memcpy(transfer_priv->hid_buffer, transfer->buffer, transfer->length);
+
+		usbi_dbg(TRANSFER_CTX(transfer), "writing %d bytes (report ID: 0x%02X)", length, transfer_priv->hid_buffer[0]);
+		ret = WriteFile(hid_handle, transfer_priv->hid_buffer, length, NULL, overlapped);
+	}
+
+	if (!ret && GetLastError() != ERROR_IO_PENDING) {
+		usbi_err(TRANSFER_CTX(transfer), "HID transfer failed: %s", windows_error_str(0));
+		safe_free(transfer_priv->hid_buffer);
+		return LIBUSB_ERROR_IO;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int hid_reset_device(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	HANDLE hid_handle;
+	int current_interface;
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	// Flushing the queues on all interfaces is the best we can achieve
+	for (current_interface = 0; current_interface < USB_MAXINTERFACES; current_interface++) {
+		hid_handle = handle_priv->interface_handle[current_interface].api_handle;
+		if (HANDLE_VALID(hid_handle))
+			HidD_FlushQueue(hid_handle);
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static int hid_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	HANDLE hid_handle;
+	int current_interface;
+
+	UNUSED(sub_api);
+	CHECK_HID_AVAILABLE;
+
+	current_interface = interface_by_endpoint(priv, handle_priv, endpoint);
+	if (current_interface < 0) {
+		usbi_err(HANDLE_CTX(dev_handle), "unable to match endpoint to an open interface - cannot clear");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	usbi_dbg(HANDLE_CTX(dev_handle), "matched endpoint %02X with interface %d", endpoint, current_interface);
+	hid_handle = handle_priv->interface_handle[current_interface].api_handle;
+
+	// No endpoint selection with Microsoft's implementation, so we try to flush the
+	// whole interface. Should be OK for most case scenarios
+	if (!HidD_FlushQueue(hid_handle)) {
+		usbi_err(HANDLE_CTX(dev_handle), "Flushing of HID queue failed: %s", windows_error_str(0));
+		// Device was probably disconnected
+		return LIBUSB_ERROR_NO_DEVICE;
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+// This extra function is only needed for HID
+static enum libusb_transfer_status hid_copy_transfer_data(int sub_api, struct usbi_transfer *itransfer, DWORD length)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	enum libusb_transfer_status r = LIBUSB_TRANSFER_COMPLETED;
+
+	UNUSED(sub_api);
+
+	if (transfer_priv->hid_buffer != NULL) {
+		// If we have a valid hid_buffer, it means the transfer was async
+		if (transfer_priv->hid_dest != NULL) { // Data readout
+			if (length > 0) {
+				// First, check for overflow
+				if ((size_t)length > transfer_priv->hid_expected_size) {
+					usbi_err(TRANSFER_CTX(transfer), "OVERFLOW!");
+					length = (DWORD)transfer_priv->hid_expected_size;
+					r = LIBUSB_TRANSFER_OVERFLOW;
+				}
+
+				if (transfer_priv->hid_buffer[0] == 0) {
+					memcpy(transfer_priv->hid_dest, transfer_priv->hid_buffer + 1, length);
+				} else {
+					memcpy(transfer_priv->hid_dest, transfer_priv->hid_buffer, length);
+				}
+			}
+			transfer_priv->hid_dest = NULL;
+		}
+		// For write, we just need to free the hid buffer
+		safe_free(transfer_priv->hid_buffer);
+	}
+
+	itransfer->transferred += (int)length;
+	return r;
+}
+
+
+/*
+ * Composite API functions
+ */
+static int composite_open(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int i, r = LIBUSB_ERROR_NOT_FOUND;
+	// SUB_API_MAX + 1 as the SUB_API_MAX pos is used to indicate availability of HID
+	bool available[SUB_API_MAX + 1];
+
+	UNUSED(sub_api);
+
+	for (i = 0; i < SUB_API_MAX + 1; i++)
+		available[i] = false;
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		switch (priv->usb_interface[i].apib->id) {
+		case USB_API_WINUSBX:
+			if (priv->usb_interface[i].sub_api != SUB_API_NOTSET)
+				available[priv->usb_interface[i].sub_api] = true;
+			break;
+		case USB_API_HID:
+			available[SUB_API_MAX] = true;
+			break;
+		default:
+			break;
+		}
+	}
+
+	for (i = 0; i < SUB_API_MAX; i++) { // WinUSB-like drivers
+		if (available[i]) {
+			r = usb_api_backend[USB_API_WINUSBX].open(i, dev_handle);
+			if (r != LIBUSB_SUCCESS)
+				return r;
+		}
+	}
+
+	if (available[SUB_API_MAX]) { // HID driver
+		r = hid_open(SUB_API_NOTSET, dev_handle);
+
+		// On Windows 10 version 1903 (OS Build 18362) and later Windows blocks attempts to
+		// open HID devices with a U2F usage unless running as administrator. We ignore this
+		// failure and proceed without the HID device opened.
+		if (r == LIBUSB_ERROR_ACCESS) {
+			usbi_dbg(HANDLE_CTX(dev_handle), "ignoring access denied error while opening HID interface of composite device");
+			r = LIBUSB_SUCCESS;
+		}
+	}
+
+	return r;
+}
+
+static void composite_close(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int i;
+	// SUB_API_MAX + 1 as the SUB_API_MAX pos is used to indicate availability of HID
+	bool available[SUB_API_MAX + 1];
+
+	UNUSED(sub_api);
+
+	for (i = 0; i < SUB_API_MAX + 1; i++)
+		available[i] = false;
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		switch (priv->usb_interface[i].apib->id) {
+		case USB_API_WINUSBX:
+			if (priv->usb_interface[i].sub_api != SUB_API_NOTSET)
+				available[priv->usb_interface[i].sub_api] = true;
+			break;
+		case USB_API_HID:
+			available[SUB_API_MAX] = true;
+			break;
+		default:
+			break;
+		}
+	}
+
+	for (i = 0; i < SUB_API_MAX; i++) { // WinUSB-like drivers
+		if (available[i])
+			usb_api_backend[USB_API_WINUSBX].close(i, dev_handle);
+	}
+
+	if (available[SUB_API_MAX]) // HID driver
+		hid_close(SUB_API_NOTSET, dev_handle);
+}
+
+static int composite_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	UNUSED(sub_api);
+	CHECK_SUPPORTED_API(priv->usb_interface[iface].apib, claim_interface);
+
+	return priv->usb_interface[iface].apib->
+		claim_interface(priv->usb_interface[iface].sub_api, dev_handle, iface);
+}
+
+static int composite_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	UNUSED(sub_api);
+	CHECK_SUPPORTED_API(priv->usb_interface[iface].apib, set_interface_altsetting);
+
+	return priv->usb_interface[iface].apib->
+		set_interface_altsetting(priv->usb_interface[iface].sub_api, dev_handle, iface, altsetting);
+}
+
+static int composite_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+
+	UNUSED(sub_api);
+	CHECK_SUPPORTED_API(priv->usb_interface[iface].apib, release_interface);
+
+	return priv->usb_interface[iface].apib->
+		release_interface(priv->usb_interface[iface].sub_api, dev_handle, iface);
+}
+
+static int composite_submit_control_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	struct libusb_config_descriptor *conf_desc;
+	WINUSB_SETUP_PACKET *setup = (WINUSB_SETUP_PACKET *)transfer->buffer;
+	int iface, pass, r;
+
+	UNUSED(sub_api);
+
+	// Interface shouldn't matter for control, but it does in practice, with Windows'
+	// restrictions with regards to accessing HID keyboards and mice. Try to target
+	// a specific interface first, if possible.
+	switch (LIBUSB_REQ_RECIPIENT(setup->RequestType)) {
+	case LIBUSB_RECIPIENT_INTERFACE:
+		iface = setup->Index & 0xFF;
+		break;
+	case LIBUSB_RECIPIENT_ENDPOINT:
+		r = libusb_get_active_config_descriptor(transfer->dev_handle->dev, &conf_desc);
+		if (r == LIBUSB_SUCCESS) {
+			iface = get_interface_by_endpoint(conf_desc, (setup->Index & 0xFF));
+			libusb_free_config_descriptor(conf_desc);
+			break;
+		}
+		// No break if not able to determine interface
+		// Fall through
+	default:
+		iface = -1;
+		break;
+	}
+
+	// Try and target a specific interface if the control setup indicates such
+	if ((iface >= 0) && (iface < USB_MAXINTERFACES)) {
+		usbi_dbg(TRANSFER_CTX(transfer), "attempting control transfer targeted to interface %d", iface);
+		if ((priv->usb_interface[iface].path != NULL)
+				&& (priv->usb_interface[iface].apib->submit_control_transfer != NULL)) {
+			r = priv->usb_interface[iface].apib->submit_control_transfer(priv->usb_interface[iface].sub_api, itransfer);
+			if (r == LIBUSB_SUCCESS)
+				return r;
+		}
+	}
+
+	// Either not targeted to a specific interface or no luck in doing so.
+	// Try a 2 pass approach with all interfaces.
+	for (pass = 0; pass < 2; pass++) {
+		for (iface = 0; iface < USB_MAXINTERFACES; iface++) {
+			if ((priv->usb_interface[iface].path != NULL)
+					&& (priv->usb_interface[iface].apib->submit_control_transfer != NULL)) {
+				if ((pass == 0) && (priv->usb_interface[iface].restricted_functionality)) {
+					usbi_dbg(TRANSFER_CTX(transfer), "trying to skip restricted interface #%d (HID keyboard or mouse?)", iface);
+					continue;
+				}
+				usbi_dbg(TRANSFER_CTX(transfer), "using interface %d", iface);
+				r = priv->usb_interface[iface].apib->submit_control_transfer(priv->usb_interface[iface].sub_api, itransfer);
+				// If not supported on this API, it may be supported on another, so don't give up yet!!
+				if (r == LIBUSB_ERROR_NOT_SUPPORTED)
+					continue;
+				return r;
+			}
+		}
+	}
+
+	usbi_err(TRANSFER_CTX(transfer), "no libusb supported interfaces to complete request");
+	return LIBUSB_ERROR_NOT_FOUND;
+}
+
+static int composite_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int current_interface;
+
+	UNUSED(sub_api);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, transfer->endpoint);
+	if (current_interface < 0) {
+		usbi_err(TRANSFER_CTX(transfer), "unable to match endpoint to an open interface - cancelling transfer");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	CHECK_SUPPORTED_API(priv->usb_interface[current_interface].apib, submit_bulk_transfer);
+
+	return priv->usb_interface[current_interface].apib->
+		submit_bulk_transfer(priv->usb_interface[current_interface].sub_api, itransfer);
+}
+
+static int composite_submit_iso_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int current_interface;
+
+	UNUSED(sub_api);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, transfer->endpoint);
+	if (current_interface < 0) {
+		usbi_err(TRANSFER_CTX(transfer), "unable to match endpoint to an open interface - cancelling transfer");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	CHECK_SUPPORTED_API(priv->usb_interface[current_interface].apib, submit_iso_transfer);
+
+	return priv->usb_interface[current_interface].apib->
+		submit_iso_transfer(priv->usb_interface[current_interface].sub_api, itransfer);
+}
+
+static int composite_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint)
+{
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int current_interface;
+
+	UNUSED(sub_api);
+
+	current_interface = interface_by_endpoint(priv, handle_priv, endpoint);
+	if (current_interface < 0) {
+		usbi_err(HANDLE_CTX(dev_handle), "unable to match endpoint to an open interface - cannot clear");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	CHECK_SUPPORTED_API(priv->usb_interface[current_interface].apib, clear_halt);
+
+	return priv->usb_interface[current_interface].apib->
+		clear_halt(priv->usb_interface[current_interface].sub_api, dev_handle, endpoint);
+}
+
+static int composite_cancel_transfer(int sub_api, struct usbi_transfer *itransfer)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int current_interface = transfer_priv->interface_number;
+
+	UNUSED(sub_api);
+
+	if ((current_interface < 0) || (current_interface >= USB_MAXINTERFACES)) {
+		usbi_err(TRANSFER_CTX(transfer), "program assertion failed - invalid interface_number");
+		return LIBUSB_ERROR_NOT_FOUND;
+	}
+
+	CHECK_SUPPORTED_API(priv->usb_interface[current_interface].apib, cancel_transfer);
+
+	return priv->usb_interface[current_interface].apib->
+		cancel_transfer(priv->usb_interface[current_interface].sub_api, itransfer);
+}
+
+static int composite_reset_device(int sub_api, struct libusb_device_handle *dev_handle)
+{
+	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
+	int i, r;
+	bool available[SUB_API_MAX];
+
+	UNUSED(sub_api);
+
+	for (i = 0; i < SUB_API_MAX; i++)
+		available[i] = false;
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		if ((priv->usb_interface[i].apib->id == USB_API_WINUSBX)
+				&& (priv->usb_interface[i].sub_api != SUB_API_NOTSET))
+			available[priv->usb_interface[i].sub_api] = true;
+	}
+
+	for (i = 0; i < SUB_API_MAX; i++) {
+		if (available[i]) {
+			r = usb_api_backend[USB_API_WINUSBX].reset_device(i, dev_handle);
+			if (r != LIBUSB_SUCCESS)
+				return r;
+		}
+	}
+
+	return LIBUSB_SUCCESS;
+}
+
+static enum libusb_transfer_status composite_copy_transfer_data(int sub_api, struct usbi_transfer *itransfer, DWORD length)
+{
+	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
+	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
+	int current_interface = transfer_priv->interface_number;
+
+	UNUSED(sub_api);
+	if (priv->usb_interface[current_interface].apib->copy_transfer_data == NULL) {
+		usbi_err(TRANSFER_CTX(transfer), "program assertion failed - no function to copy transfer data");
+		return LIBUSB_TRANSFER_ERROR;
+	}
+
+	return priv->usb_interface[current_interface].apib->
+		copy_transfer_data(priv->usb_interface[current_interface].sub_api, itransfer, length);
+}