static int identify_descriptor()

in manifest.c [98:172]
60 lines of code
11 McCabe index (conditional complexity)

static int identify_descriptor(struct gb_interface *intf,
			       struct greybus_descriptor *desc, size_t size)
{
	struct greybus_descriptor_header *desc_header = &desc->header;
	struct manifest_desc *descriptor;
	size_t desc_size;
	size_t expected_size;

	if (size < sizeof(*desc_header)) {
		dev_err(&intf->dev, "manifest too small (%zu < %zu)\n", size,
			sizeof(*desc_header));
		return -EINVAL;		/* Must at least have header */
	}

	desc_size = le16_to_cpu(desc_header->size);
	if (desc_size > size) {
		dev_err(&intf->dev, "descriptor too big (%zu > %zu)\n",
			desc_size, size);
		return -EINVAL;
	}

	/* Descriptor needs to at least have a header */
	expected_size = sizeof(*desc_header);

	switch (desc_header->type) {
	case GREYBUS_TYPE_STRING:
		expected_size += sizeof(struct greybus_descriptor_string);
		expected_size += desc->string.length;

		/* String descriptors are padded to 4 byte boundaries */
		expected_size = ALIGN(expected_size, 4);
		break;
	case GREYBUS_TYPE_INTERFACE:
		expected_size += sizeof(struct greybus_descriptor_interface);
		break;
	case GREYBUS_TYPE_BUNDLE:
		expected_size += sizeof(struct greybus_descriptor_bundle);
		break;
	case GREYBUS_TYPE_CPORT:
		expected_size += sizeof(struct greybus_descriptor_cport);
		break;
	case GREYBUS_TYPE_INVALID:
	default:
		dev_err(&intf->dev, "invalid descriptor type (%u)\n",
			desc_header->type);
		return -EINVAL;
	}

	if (desc_size < expected_size) {
		dev_err(&intf->dev, "%s descriptor too small (%zu < %zu)\n",
			get_descriptor_type_string(desc_header->type),
			desc_size, expected_size);
		return -EINVAL;
	}

	/* Descriptor bigger than what we expect */
	if (desc_size > expected_size) {
		dev_warn(&intf->dev, "%s descriptor size mismatch (want %zu got %zu)\n",
			 get_descriptor_type_string(desc_header->type),
			 expected_size, desc_size);
	}

	descriptor = kzalloc(sizeof(*descriptor), GFP_KERNEL);
	if (!descriptor)
		return -ENOMEM;

	descriptor->size = desc_size;
	descriptor->data = (char *)desc + sizeof(*desc_header);
	descriptor->type = desc_header->type;
	list_add_tail(&descriptor->links, &intf->manifest_descs);

	/* desc_size is positive and is known to fit in a signed int */

	return desc_size;
}