lib/efi_loader/efi_device_path_utilities.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  EFI device path interface
 *
 *  Copyright (c) 2017 Leif Lindholm
 */

#define LOG_CATEGORY LOGC_EFI

#include <efi_loader.h>

const efi_guid_t efi_guid_device_path_utilities_protocol =
		EFI_DEVICE_PATH_UTILITIES_PROTOCOL_GUID;

/*
 * Get size of a device path.
 *
 * This function implements the GetDevicePathSize service of the device path
 * utilities protocol. The device path length includes the end of path tag
 * which may be an instance end.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @device_path		device path
 * Return:		size in bytes
 */
static efi_uintn_t EFIAPI get_device_path_size(
	const struct efi_device_path *device_path)
{
	efi_uintn_t sz = 0;

	EFI_ENTRY("%pD", device_path);
	/* size includes the END node: */
	if (device_path)
		sz = efi_dp_size(device_path) + sizeof(struct efi_device_path);
	return EFI_EXIT(sz);
}

/*
 * Duplicate a device path.
 *
 * This function implements the DuplicateDevicePath service of the device path
 * utilities protocol.
 *
 * The UEFI spec does not indicate what happens to the end tag. We follow the
 * EDK2 logic: In case the device path ends with an end of instance tag, the
 * copy will also end with an end of instance tag.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @device_path		device path
 * Return:		copy of the device path
 */
static struct efi_device_path * EFIAPI duplicate_device_path(
	const struct efi_device_path *device_path)
{
	EFI_ENTRY("%pD", device_path);
	return EFI_EXIT(efi_dp_dup(device_path));
}

/*
 * Append device path.
 *
 * This function implements the AppendDevicePath service of the device path
 * utilities protocol.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @src1		1st device path
 * @src2		2nd device path
 * Return:		concatenated device path
 */
static struct efi_device_path * EFIAPI append_device_path(
	const struct efi_device_path *src1,
	const struct efi_device_path *src2)
{
	EFI_ENTRY("%pD, %pD", src1, src2);
	return EFI_EXIT(efi_dp_concat(src1, src2, 0));
}

/*
 * Append device path node.
 *
 * This function implements the AppendDeviceNode service of the device path
 * utilities protocol.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @device_path		device path
 * @device_node		device node
 * Return:		concatenated device path
 */
static struct efi_device_path * EFIAPI append_device_node(
	const struct efi_device_path *device_path,
	const struct efi_device_path *device_node)
{
	EFI_ENTRY("%pD, %p", device_path, device_node);
	return EFI_EXIT(efi_dp_append_node(device_path, device_node));
}

/*
 * Append device path instance.
 *
 * This function implements the AppendDevicePathInstance service of the device
 * path utilities protocol.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @device_path			1st device path
 * @device_path_instance	2nd device path
 * Return:			concatenated device path
 */
static struct efi_device_path * EFIAPI append_device_path_instance(
	const struct efi_device_path *device_path,
	const struct efi_device_path *device_path_instance)
{
	EFI_ENTRY("%pD, %pD", device_path, device_path_instance);
	return EFI_EXIT(efi_dp_append_instance(device_path,
					       device_path_instance));
}

/*
 * Get next device path instance.
 *
 * This function implements the GetNextDevicePathInstance service of the device
 * path utilities protocol.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @device_path_instance	next device path instance
 * @device_path_instance_size	size of the device path instance
 * Return:			concatenated device path
 */
static struct efi_device_path * EFIAPI get_next_device_path_instance(
	struct efi_device_path **device_path_instance,
	efi_uintn_t *device_path_instance_size)
{
	EFI_ENTRY("%pD, %p", device_path_instance, device_path_instance_size);
	return EFI_EXIT(efi_dp_get_next_instance(device_path_instance,
						 device_path_instance_size));
}

/*
 * Check if a device path contains more than one instance.
 *
 * This function implements the AppendDeviceNode service of the device path
 * utilities protocol.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @device_path		device path
 * @device_node		device node
 * Return:		concatenated device path
 */
static bool EFIAPI is_device_path_multi_instance(
	const struct efi_device_path *device_path)
{
	EFI_ENTRY("%pD", device_path);
	return EFI_EXIT(efi_dp_is_multi_instance(device_path));
}

/*
 * Create device node.
 *
 * This function implements the CreateDeviceNode service of the device path
 * utilities protocol.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification
 * for details.
 *
 * @node_type		node type
 * @node_sub_type	node sub type
 * @node_length		node length
 * Return:		device path node
 */
static struct efi_device_path * EFIAPI create_device_node(
	uint8_t node_type, uint8_t node_sub_type, uint16_t node_length)
{
	EFI_ENTRY("%u, %u, %u", node_type, node_sub_type, node_length);
	return EFI_EXIT(efi_dp_create_device_node(node_type, node_sub_type,
			node_length));
}

const struct efi_device_path_utilities_protocol efi_device_path_utilities = {
	.get_device_path_size = get_device_path_size,
	.duplicate_device_path = duplicate_device_path,
	.append_device_path = append_device_path,
	.append_device_node = append_device_node,
	.append_device_path_instance = append_device_path_instance,
	.get_next_device_path_instance = get_next_device_path_instance,
	.is_device_path_multi_instance = is_device_path_multi_instance,
	.create_device_node = create_device_node,
};