Introduce HID_API_MAX_REPORT_DESCRIPTOR_SIZE (signal11#452)

- first step is to use HID_API_MAX_REPORT_DESCRIPTOR_SIZE internally;
- port a few improvements from get-descriptor branch early;

Resolves: signal11#384

Author: Youw

hidapi/hidapi.h

@@ -88,6 +88,14 @@
 */
 #define HID_API_VERSION_STR HID_API_TO_VERSION_STR(HID_API_VERSION_MAJOR, HID_API_VERSION_MINOR, HID_API_VERSION_PATCH)
 
+/** @brief Maximum expected HID Report descriptor size in bytes.
+
+	Since version 0.13.0, @ref HID_API_VERSION >= HID_API_MAKE_VERSION(0, 13, 0)
+
+	@ingroup API
+*/
+#define HID_API_MAX_REPORT_DESCRIPTOR_SIZE 4096
+
 #ifdef __cplusplus
 extern "C" {
 #endif

libusb/hid.c

@@ -564,28 +564,43 @@ int HID_API_EXPORT hid_exit(void)
 	return 0;
 }
 
-/**
- * Requires an opened device with *claimed interface*.
- */
-static void fill_device_info_usage(struct hid_device_info *cur_dev, libusb_device_handle *handle, int interface_num, uint16_t report_descriptor_size)
+static int hid_get_report_descriptor_libusb(libusb_device_handle *handle, int interface_num, uint16_t expected_report_descriptor_size, unsigned char *buf, size_t buf_size)
 {
-	unsigned char data[4096];
-	unsigned short page = 0, usage = 0;
+	unsigned char tmp[HID_API_MAX_REPORT_DESCRIPTOR_SIZE];
 
-	if (report_descriptor_size > 4096)
-		report_descriptor_size = 4096;
+	if (expected_report_descriptor_size > HID_API_MAX_REPORT_DESCRIPTOR_SIZE)
+		expected_report_descriptor_size = HID_API_MAX_REPORT_DESCRIPTOR_SIZE;
 
 	/* Get the HID Report Descriptor.
 	   See USB HID Specificatin, sectin 7.1.1
 	*/
-	int res = libusb_control_transfer(handle, LIBUSB_ENDPOINT_IN|LIBUSB_RECIPIENT_INTERFACE, LIBUSB_REQUEST_GET_DESCRIPTOR, (LIBUSB_DT_REPORT << 8), interface_num, data, report_descriptor_size, 5000);
+	int res = libusb_control_transfer(handle, LIBUSB_ENDPOINT_IN|LIBUSB_RECIPIENT_INTERFACE, LIBUSB_REQUEST_GET_DESCRIPTOR, (LIBUSB_DT_REPORT << 8), interface_num, tmp, expected_report_descriptor_size, 5000);
+	if (res < 0) {
+		LOG("libusb_control_transfer() for getting the HID Report descriptor failed with %d: %s\n", res, libusb_error_name(res));
+		return -1;
+	}
+
+	if (res > (int)buf_size)
+		res = (int)buf_size;
+
+	memcpy(buf, tmp, (size_t)res);
+	return res;
+}
+
+/**
+ * Requires an opened device with *claimed interface*.
+ */
+static void fill_device_info_usage(struct hid_device_info *cur_dev, libusb_device_handle *handle, int interface_num, uint16_t expected_report_descriptor_size)
+{
+	unsigned char hid_report_descriptor[HID_API_MAX_REPORT_DESCRIPTOR_SIZE];
+	unsigned short page = 0, usage = 0;
+
+	int res = hid_get_report_descriptor_libusb(handle, interface_num, expected_report_descriptor_size, hid_report_descriptor, sizeof(hid_report_descriptor));
 	if (res >= 0) {
 		/* Parse the usage and usage page
 		   out of the report descriptor. */
-		get_usage(data, res,  &page, &usage);
+		get_usage(hid_report_descriptor, res,  &page, &usage);
 	}
-	else
-		LOG("libusb_control_transfer() for getting the HID report descriptor failed with %d: %s\n", res, libusb_error_name(res));
 
 	cur_dev->usage_page = page;
 	cur_dev->usage = usage;
@@ -619,7 +634,7 @@ static void invasive_fill_device_info_usage(struct hid_device_info *cur_dev, lib
 			LOG("Can't release the interface.\n");
 	}
 	else
-		LOG("Can't claim interface %d\n", res);
+		LOG("Can't claim interface: (%d) %s\n", res, libusb_error_name(res));
 
 #ifdef DETACH_KERNEL_DRIVER
 	/* Re-attach kernel driver if necessary. */
@@ -675,7 +690,7 @@ static uint16_t get_report_descriptor_size_from_interface_descriptors(const stru
 {
 	int i = 0;
 	int found_hid_report_descriptor = 0;
-	uint16_t result = 4096;
+	uint16_t result = HID_API_MAX_REPORT_DESCRIPTOR_SIZE;
 	const unsigned char *extra = intf_desc->extra;
 	int extra_length = intf_desc->extra_length;
 
@@ -943,7 +958,7 @@ static void read_callback(struct libusb_transfer *transfer)
 	/* Re-submit the transfer object. */
 	res = libusb_submit_transfer(transfer);
 	if (res != 0) {
-		LOG("Unable to submit URB. libusb error code: %d\n", res);
+		LOG("Unable to submit URB: (%d) %s\n", res, libusb_error_name(res));
 		dev->shutdown_thread = 1;
 		dev->transfer_loop_finished = 1;
 	}
@@ -981,7 +996,7 @@ static void *read_thread(void *param)
 		res = libusb_handle_events(usb_context);
 		if (res < 0) {
 			/* There was an error. */
-			LOG("read_thread(): libusb reports error # %d\n", res);
+			LOG("read_thread(): (%d) %s\n", res, libusb_error_name(res));
 
 			/* Break out of this loop only on fatal error.*/
 			if (res != LIBUSB_ERROR_BUSY &&
@@ -1036,7 +1051,7 @@ static int hidapi_initialize_device(hid_device *dev, int config_number, const st
 	if (libusb_kernel_driver_active(dev->device_handle, intf_desc->bInterfaceNumber) == 1) {
 		res = libusb_detach_kernel_driver(dev->device_handle, intf_desc->bInterfaceNumber);
 		if (res < 0) {
-			LOG("Unable to detach Kernel Driver\n");
+			LOG("Unable to detach Kernel Driver: (%d) %s\n", res, libusb_error_name(res));
 			return 0;
 		}
 		else {
@@ -1047,13 +1062,13 @@ static int hidapi_initialize_device(hid_device *dev, int config_number, const st
 #endif
 	res = libusb_claim_interface(dev->device_handle, intf_desc->bInterfaceNumber);
 	if (res < 0) {
-		LOG("can't claim interface %d: %d\n", intf_desc->bInterfaceNumber, res);
+		LOG("can't claim interface %d: (%d) %s\n", intf_desc->bInterfaceNumber, res, libusb_error_name(res));
 
 #ifdef DETACH_KERNEL_DRIVER
 		if (dev->is_driver_detached) {
 			res = libusb_attach_kernel_driver(dev->device_handle, intf_desc->bInterfaceNumber);
 			if (res < 0)
-				LOG("Failed to reattach the driver to kernel.\n");
+				LOG("Failed to reattach the driver to kernel: (%d) %s\n", res, libusb_error_name(res));
 		}
 #endif
 		return 0;

linux/hid.c

@@ -71,7 +71,6 @@
 struct hid_device_ {
 	int device_handle;
 	int blocking;
-	int uses_numbered_reports;
 	wchar_t *last_error_str;
 	struct hid_device_info* device_info;
 };
@@ -88,9 +87,12 @@ static wchar_t *last_global_error_str = NULL;
 static hid_device *new_hid_device(void)
 {
 	hid_device *dev = (hid_device*) calloc(1, sizeof(hid_device));
+	if (dev == NULL) {
+		return NULL;
+	}
+
 	dev->device_handle = -1;
 	dev->blocking = 1;
-	dev->uses_numbered_reports = 0;
 	dev->last_error_str = NULL;
 	dev->device_info = NULL;
 
@@ -242,34 +244,6 @@ static int get_hid_item_size(__u8 *report_descriptor, unsigned int pos, __u32 si
 	return 0;
 }
 
-/* uses_numbered_reports() returns 1 if report_descriptor describes a device
-   which contains numbered reports. */
-static int uses_numbered_reports(__u8 *report_descriptor, __u32 size) {
-	unsigned int i = 0;
-	int data_len, key_size;
-
-	while (i < size) {
-		int key = report_descriptor[i];
-
-		/* Check for the Report ID key */
-		if (key == 0x85/*Report ID*/) {
-			/* This device has a Report ID, which means it uses
-			   numbered reports. */
-			return 1;
-		}
-
-		/* Determine data_len and key_size */
-		if (!get_hid_item_size(report_descriptor, i, size, &data_len, &key_size))
-			return 0; /* malformed report */
-
-		/* Skip over this key and its associated data */
-		i += data_len + key_size;
-	}
-
-	/* Didn't find a Report ID key. Device doesn't use numbered reports. */
-	return 0;
-}
-
 /*
  * Get bytes from a HID Report Descriptor.
  * Only call with a num_bytes of 0, 1, 2, or 4.
@@ -988,32 +962,22 @@ hid_device * HID_API_EXPORT hid_open_path(const char *path)
 	/* register_global_error: global error is reset by hid_init */
 
 	dev = new_hid_device();
+	if (!dev) {
+		register_global_error("Couldn't allocate memory");
+		return NULL;
+	}
 
 	dev->device_handle = open(path, O_RDWR | O_CLOEXEC);
 
-	/* If we have a good handle, return it. */
 	if (dev->device_handle >= 0) {
-		/* Get the report descriptor */
 		int res, desc_size = 0;
-		struct hidraw_report_descriptor rpt_desc;
-
-		memset(&rpt_desc, 0x0, sizeof(rpt_desc));
 
-		/* Get Report Descriptor Size */
+		/* Make sure this is a HIDRAW device - responds to HIDIOCGRDESCSIZE */
 		res = ioctl(dev->device_handle, HIDIOCGRDESCSIZE, &desc_size);
-		if (res < 0)
-			register_device_error_format(dev, "ioctl (GRDESCSIZE): %s", strerror(errno));
-
-		/* Get Report Descriptor */
-		rpt_desc.size = desc_size;
-		res = ioctl(dev->device_handle, HIDIOCGRDESC, &rpt_desc);
 		if (res < 0) {
-			register_device_error_format(dev, "ioctl (GRDESC): %s", strerror(errno));
-		} else {
-			/* Determine if this device uses numbered reports. */
-			dev->uses_numbered_reports =
-				uses_numbered_reports(rpt_desc.value,
-				                      rpt_desc.size);
+			hid_close(dev);
+			register_device_error_format(dev, "ioctl(GRDESCSIZE) error for '%s', not a HIDRAW device?: %s", path, strerror(errno));
+			return NULL;
 		}
 
 		return dev;

mac/hid.c

@@ -124,7 +124,6 @@ struct hid_device_ {
 	IOHIDDeviceRef device_handle;
 	IOOptionBits open_options;
 	int blocking;
-	int uses_numbered_reports;
 	int disconnected;
 	CFStringRef run_loop_mode;
 	CFRunLoopRef run_loop;
@@ -148,7 +147,6 @@ static hid_device *new_hid_device(void)
 	dev->device_handle = NULL;
 	dev->open_options = device_open_options;
 	dev->blocking = 1;
-	dev->uses_numbered_reports = 0;
 	dev->disconnected = 0;
 	dev->run_loop_mode = NULL;
 	dev->run_loop = NULL;