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deps/hidapi/linux/hid.c  view on Meta::CPAN

/* USB HID device property names */
const char *device_string_names[] = {
	"manufacturer",
	"product",
	"serial",
};

/* Symbolic names for the properties above */
enum device_string_id {
	DEVICE_STRING_MANUFACTURER,
	DEVICE_STRING_PRODUCT,
	DEVICE_STRING_SERIAL,

	DEVICE_STRING_COUNT,
};

struct hid_device_ {
	int device_handle;
	int blocking;
	int uses_numbered_reports;
	wchar_t *last_error_str;
};

/* Global error message that is not specific to a device, e.g. for
   hid_open(). It is thread-local like errno. */
__thread wchar_t *last_global_error_str = NULL;

static hid_device *new_hid_device(void)
{
	hid_device *dev = (hid_device*) calloc(1, sizeof(hid_device));
	dev->device_handle = -1;
	dev->blocking = 1;
	dev->uses_numbered_reports = 0;
	dev->last_error_str = NULL;

	return dev;
}


/* The caller must free the returned string with free(). */
static wchar_t *utf8_to_wchar_t(const char *utf8)
{
	wchar_t *ret = NULL;

	if (utf8) {
		size_t wlen = mbstowcs(NULL, utf8, 0);
		if ((size_t) -1 == wlen) {
			return wcsdup(L"");
		}
		ret = (wchar_t*) calloc(wlen+1, sizeof(wchar_t));
		mbstowcs(ret, utf8, wlen+1);
		ret[wlen] = 0x0000;
	}

	return ret;
}


/* Set the last global error to be reported by hid_error(NULL).
 * The given error message will be copied (and decoded according to the
 * currently locale, so do not pass in string constants).
 * The last stored global error message is freed.
 * Use register_global_error(NULL) to indicate "no error". */
static void register_global_error(const char *msg)
{
	if (last_global_error_str)
		free(last_global_error_str);

	last_global_error_str = utf8_to_wchar_t(msg);
}


/* Set the last error for a device to be reported by hid_error(device).
 * The given error message will be copied (and decoded according to the
 * currently locale, so do not pass in string constants).
 * The last stored global error message is freed.
 * Use register_device_error(device, NULL) to indicate "no error". */
static void register_device_error(hid_device *dev, const char *msg)
{
	if (dev->last_error_str)
		free(dev->last_error_str);

	dev->last_error_str = utf8_to_wchar_t(msg);
}

/* See register_device_error, but you can pass a format string into this function. */
static void register_device_error_format(hid_device *dev, const char *format, ...)
{
	va_list args;
	va_start(args, format);

	char msg[100];
	vsnprintf(msg, sizeof(msg), format, args);

	va_end(args);

	register_device_error(dev, msg);
}

/* Get an attribute value from a udev_device and return it as a whar_t
   string. The returned string must be freed with free() when done.*/
static wchar_t *copy_udev_string(struct udev_device *dev, const char *udev_name)
{
	return utf8_to_wchar_t(udev_device_get_sysattr_value(dev, udev_name));
}

/* 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 size_code;
	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;
		}

		//printf("key: %02hhx\n", key);

		if ((key & 0xf0) == 0xf0) {
			/* This is a Long Item. The next byte contains the
			   length of the data section (value) for this key.
			   See the HID specification, version 1.11, section
			   6.2.2.3, titled "Long Items." */
			if (i+1 < size)
				data_len = report_descriptor[i+1];
			else
				data_len = 0; /* malformed report */