nsaccess.c

h内核

	*return_node = ACPI_ENTRY_NOT_FOUND;

	if (!acpi_gbl_root_node) {
		return_ACPI_STATUS (AE_NO_NAMESPACE);
	}

	/*
	 * Get the prefix scope.
	 * A null scope means use the root scope
	 */
	if ((!scope_info) ||
		(!scope_info->scope.node)) {
		ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
			"Null scope prefix, using root node (%p)\n",
			acpi_gbl_root_node));

		prefix_node = acpi_gbl_root_node;
	}
	else {
		prefix_node = scope_info->scope.node;
		if (ACPI_GET_DESCRIPTOR_TYPE (prefix_node) != ACPI_DESC_TYPE_NAMED) {
			ACPI_REPORT_ERROR (("ns_lookup: %p is not a namespace node [%s]\n",
					prefix_node, acpi_ut_get_descriptor_name (prefix_node)));
			return_ACPI_STATUS (AE_AML_INTERNAL);
		}

		/*
		 * This node might not be a actual "scope" node (such as a
		 * Device/Method, etc.)  It could be a Package or other object node.
		 * Backup up the tree to find the containing scope node.
		 */
		while (!acpi_ns_opens_scope (prefix_node->type) &&
				prefix_node->type != ACPI_TYPE_ANY) {
			prefix_node = acpi_ns_get_parent_node (prefix_node);
		}
	}

	/* Save type   TBD: may be no longer necessary */

	type_to_check_for = type;

	/*
	 * Begin examination of the actual pathname
	 */
	if (!pathname) {
		/* A Null name_path is allowed and refers to the root */

		num_segments = 0;
		this_node    = acpi_gbl_root_node;
		path     = "";

		ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
			"Null Pathname (Zero segments), Flags=%X\n", flags));
	}
	else {
		/*
		 * Name pointer is valid (and must be in internal name format)
		 *
		 * Check for scope prefixes:
		 *
		 * As represented in the AML stream, a namepath consists of an
		 * optional scope prefix followed by a name segment part.
		 *
		 * If present, the scope prefix is either a Root Prefix (in
		 * which case the name is fully qualified), or one or more
		 * Parent Prefixes (in which case the name's scope is relative
		 * to the current scope).
		 */
		if (*path == (u8) AML_ROOT_PREFIX) {
			/* Pathname is fully qualified, start from the root */

			this_node = acpi_gbl_root_node;
			search_parent_flag = ACPI_NS_NO_UPSEARCH;

			/* Point to name segment part */

			path++;

			ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
				"Path is absolute from root [%p]\n", this_node));
		}
		else {
			/* Pathname is relative to current scope, start there */

			ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
				"Searching relative to prefix scope [%4.4s] (%p)\n",
				acpi_ut_get_node_name (prefix_node), prefix_node));

			/*
			 * Handle multiple Parent Prefixes (carat) by just getting
			 * the parent node for each prefix instance.
			 */
			this_node = prefix_node;
			num_carats = 0;
			while (*path == (u8) AML_PARENT_PREFIX) {
				/* Name is fully qualified, no search rules apply */

				search_parent_flag = ACPI_NS_NO_UPSEARCH;
				/*
				 * Point past this prefix to the name segment
				 * part or the next Parent Prefix
				 */
				path++;

				/* Backup to the parent node */

				num_carats++;
				this_node = acpi_ns_get_parent_node (this_node);
				if (!this_node) {
					/* Current scope has no parent scope */

					ACPI_REPORT_ERROR (
						("ACPI path has too many parent prefixes (^) - reached beyond root node\n"));
					return_ACPI_STATUS (AE_NOT_FOUND);
				}
			}

			if (search_parent_flag == ACPI_NS_NO_UPSEARCH) {
				ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
					"Search scope is [%4.4s], path has %d carat(s)\n",
					acpi_ut_get_node_name (this_node), num_carats));
			}
		}

		/*
		 * Determine the number of ACPI name segments in this pathname.
		 *
		 * The segment part consists of either:
		 *  - A Null name segment (0)
		 *  - A dual_name_prefix followed by two 4-byte name segments
		 *  - A multi_name_prefix followed by a byte indicating the
		 *      number of segments and the segments themselves.
		 *  - A single 4-byte name segment
		 *
		 * Examine the name prefix opcode, if any, to determine the number of
		 * segments.
		 */
		switch (*path) {
		case 0:
			/*
			 * Null name after a root or parent prefixes. We already
			 * have the correct target node and there are no name segments.
			 */
			num_segments = 0;
			type = this_node->type;

			ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
				"Prefix-only Pathname (Zero name segments), Flags=%X\n",
				flags));
			break;

		case AML_DUAL_NAME_PREFIX:

			/* More than one name_seg, search rules do not apply */

			search_parent_flag = ACPI_NS_NO_UPSEARCH;

			/* Two segments, point to first name segment */

			num_segments = 2;
			path++;

			ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
				"Dual Pathname (2 segments, Flags=%X)\n", flags));
			break;

		case AML_MULTI_NAME_PREFIX_OP:

			/* More than one name_seg, search rules do not apply */

			search_parent_flag = ACPI_NS_NO_UPSEARCH;

			/* Extract segment count, point to first name segment */

			path++;
			num_segments = (u32) (u8) *path;
			path++;

			ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
				"Multi Pathname (%d Segments, Flags=%X) \n",
				num_segments, flags));
			break;

		default:
			/*
			 * Not a Null name, no Dual or Multi prefix, hence there is
			 * only one name segment and Pathname is already pointing to it.
			 */
			num_segments = 1;

			ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
				"Simple Pathname (1 segment, Flags=%X)\n", flags));
			break;
		}

		ACPI_DEBUG_EXEC (acpi_ns_print_pathname (num_segments, path));
	}


	/*
	 * Search namespace for each segment of the name.  Loop through and
	 * verify (or add to the namespace) each name segment.
	 *
	 * The object type is significant only at the last name
	 * segment.  (We don't care about the types along the path, only
	 * the type of the final target object.)
	 */
	this_search_type = ACPI_TYPE_ANY;
	current_node = this_node;
	while (num_segments && current_node) {
		num_segments--;
		if (!num_segments) {
			/*
			 * This is the last segment, enable typechecking
			 */
			this_search_type = type;

			/*
			 * Only allow automatic parent search (search rules) if the caller
			 * requested it AND we have a single, non-fully-qualified name_seg
			 */
			if ((search_parent_flag != ACPI_NS_NO_UPSEARCH) &&
				(flags & ACPI_NS_SEARCH_PARENT)) {
				local_flags |= ACPI_NS_SEARCH_PARENT;
			}

			/* Set error flag according to caller */

			if (flags & ACPI_NS_ERROR_IF_FOUND) {
				local_flags |= ACPI_NS_ERROR_IF_FOUND;
			}
		}

		/* Extract one ACPI name from the front of the pathname */

		ACPI_MOVE_32_TO_32 (&simple_name, path);

		/* Try to find the single (4 character) ACPI name */

		status = acpi_ns_search_and_enter (simple_name, walk_state, current_node,
				 interpreter_mode, this_search_type, local_flags, &this_node);
		if (ACPI_FAILURE (status)) {
			if (status == AE_NOT_FOUND) {
				/* Name not found in ACPI namespace */

				ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
					"Name [%4.4s] not found in scope [%4.4s] %p\n",
					(char *) &simple_name, (char *) &current_node->name,
					current_node));
			}

			*return_node = this_node;
			return_ACPI_STATUS (status);
		}

		/*
		 * Sanity typecheck of the target object:
		 *
		 * If 1) This is the last segment (num_segments == 0)
		 *    2) And we are looking for a specific type
		 *       (Not checking for TYPE_ANY)
		 *    3) Which is not an alias
		 *    4) Which is not a local type (TYPE_SCOPE)
		 *    5) And the type of target object is known (not TYPE_ANY)
		 *    6) And target object does not match what we are looking for
		 *
		 * Then we have a type mismatch.  Just warn and ignore it.
		 */
		if ((num_segments       == 0)                               &&
			(type_to_check_for  != ACPI_TYPE_ANY)                   &&
			(type_to_check_for  != ACPI_TYPE_LOCAL_ALIAS)           &&
			(type_to_check_for  != ACPI_TYPE_LOCAL_METHOD_ALIAS)    &&
			(type_to_check_for  != ACPI_TYPE_LOCAL_SCOPE)           &&
			(this_node->type    != ACPI_TYPE_ANY)                   &&
			(this_node->type    != type_to_check_for)) {
			/* Complain about a type mismatch */

			ACPI_REPORT_WARNING (
				("ns_lookup: Type mismatch on %4.4s (%s), searching for (%s)\n",
				(char *) &simple_name, acpi_ut_get_type_name (this_node->type),
				acpi_ut_get_type_name (type_to_check_for)));
		}

		/*
		 * If this is the last name segment and we are not looking for a
		 * specific type, but the type of found object is known, use that type
		 * to see if it opens a scope.
		 */
		if ((num_segments == 0) && (type == ACPI_TYPE_ANY)) {
			type = this_node->type;
		}

		/* Point to next name segment and make this node current */

		path += ACPI_NAME_SIZE;
		current_node = this_node;
	}

	/*
	 * Always check if we need to open a new scope
	 */
	if (!(flags & ACPI_NS_DONT_OPEN_SCOPE) && (walk_state)) {
		/*
		 * If entry is a type which opens a scope, push the new scope on the
		 * scope stack.
		 */
		if (acpi_ns_opens_scope (type)) {
			status = acpi_ds_scope_stack_push (this_node, type, walk_state);
			if (ACPI_FAILURE (status)) {
				return_ACPI_STATUS (status);
			}
		}
	}

	*return_node = this_node;
	return_ACPI_STATUS (AE_OK);
}