[core] is_device_interface_accessible() prototype

* also introduces 3 new driver related error codes

4 files changed, 61 insertions, 0 deletions

diff --git a/libusb/core.c b/libusb/core.c
index 3969fd5..d5aa095 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -1566,6 +1566,35 @@ int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev,
 		return LIBUSB_ERROR_NOT_SUPPORTED;
 }
 
+/** \ingroup dev
+ * Determine if libusb can access a device or interface.
+ *
+ * \param dev a device handle
+ * \param interface_number the interface to check. On Windows, it is acceptable
+ * to pass a negative value as the interface number, for composite devices that
+ * have been split by the OS into multiple ones (MI_##), in which case the
+ * interface associated with the Windows device is assumed.
+ * \returns LIBUSB_SUCCESS if libusb can access the interface
+ * \returns LIBUSB_ERROR_DETACHEABLE_DRIVER_IN_USE if a libusb incompatible
+ * but detacheable driver is preventing access. See libusb_detach_kernel_driver.
+ * \returns LIBUSB_ERROR_NON_DETACHEABLE_DRIVER_IN_USE if a libusb incompatible
+ * and non detacheable driver is preventing access
+ * \returns LIBUSB_ERROR_NO_DRIVER on Windows if no driver has been installed
+ * for this device
+ * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
+ * is not available
+ * \returns another LIBUSB_ERROR code on other failure
+ */
+int LIBUSB_CALL libusb_is_device_interface_accessible(libusb_device_handle *dev,
+	int interface_number)
+{
+	usbi_dbg("interface %d", interface_number);
+	if (usbi_backend->is_device_interface_accessible)
+		return usbi_backend->is_device_interface_accessible(dev, interface_number);
+	else
+		return LIBUSB_ERROR_NOT_SUPPORTED;
+}
+
 /** \ingroup lib
  * Set message verbosity.
  *  - Level 0: no messages ever printed by the library (default)
diff --git a/libusb/libusb.h b/libusb/libusb.h
index e29c9b8..648f776 100644
--- a/libusb/libusb.h
+++ b/libusb/libusb.h
@@ -760,6 +760,16 @@ enum libusb_error {
 	/** Operation not supported or unimplemented on this platform */
 	LIBUSB_ERROR_NOT_SUPPORTED = -12,
 
+	// TODO: libusb_strerror
+	/** A detacheable kernel driver is in use */
+	LIBUSB_ERROR_DETACHEABLE_DRIVER_IN_USE = -13,
+
+	/** A non-detacheable driver is in use */
+	LIBUSB_ERROR_NON_DETACHEABLE_DRIVER_IN_USE = -14,
+
+	/** A driver has not been installed for this device (Windows) */
+	LIBUSB_ERROR_NO_DRIVER = -15,
+
 	/** Other error */
 	LIBUSB_ERROR_OTHER = -99
 
@@ -963,6 +973,9 @@ int LIBUSB_CALL libusb_detach_kernel_driver(libusb_device_handle *dev,
 int LIBUSB_CALL libusb_attach_kernel_driver(libusb_device_handle *dev,
 	int interface_number);
 
+int LIBUSB_CALL libusb_is_device_interface_accessible(libusb_device_handle *dev,
+	int interface_number);
+
 /* async I/O */
 
 /** \ingroup asyncio
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index 9651387..e449a2c 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -774,6 +774,19 @@ struct usbi_os_backend {
 	int (*attach_kernel_driver)(struct libusb_device_handle *handle,
 		int interface_number);
 
+	/* Determine if libusb can access a device or interface.
+	 *
+	 * Return:
+	 * - LIBUSB_SUCCESS if libusb can access the interface
+	 * - LIBUSB_ERROR_DETACHEABLE_DRIVER_IN_USE if a detacheable driver is in use
+	 * - LIBUSB_ERROR_NON_DETACHEABLE_DRIVER_IN_USE if a libusb incompatible
+	 *   and non detacheable driver is in use
+	 * - LIBUSB_ERROR_NO_DRIVER if no driver has been installed (Windows)
+	* - another LIBUSB_ERROR code on other failure
+	 */
+	int (*is_device_interface_accessible)(struct libusb_device_handle *handle,
+		int interface_number);
+
 	/* Destroy a device. Optional.
 	 *
 	 * This function is called when the last reference to a device is
diff --git a/libusb/os/windows_usb.c b/libusb/os/windows_usb.c
index 2922d54..1d51e74 100644
--- a/libusb/os/windows_usb.c
+++ b/libusb/os/windows_usb.c
@@ -1787,6 +1787,11 @@ static int windows_detach_kernel_driver(struct libusb_device_handle *dev_handle,
 	return LIBUSB_ERROR_NOT_SUPPORTED;
 }
 
+static int windows_is_device_interface_accessible(struct libusb_device_handle *handle, int iface)
+{
+	return LIBUSB_ERROR_NOT_SUPPORTED;
+}
+
 static void windows_destroy_device(struct libusb_device *dev)
 {
 	windows_device_priv_release(dev);
@@ -2181,6 +2186,7 @@ const struct usbi_os_backend windows_backend = {
 	windows_kernel_driver_active,
 	windows_detach_kernel_driver,
 	windows_attach_kernel_driver,
+	windows_is_device_interface_accessible,
 
 	windows_destroy_device,