drivers/acpi/namespace/nssearch.c

/*******************************************************************************
 *
 * Module Name: nssearch - Namespace search
 *
 ******************************************************************************/

/*
 * Copyright (C) 2000 - 2006, R. Byron Moore
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <acpi/acpi.h>
#include <acpi/acnamesp.h>

#define _COMPONENT          ACPI_NAMESPACE
ACPI_MODULE_NAME("nssearch")

/* Local prototypes */
static acpi_status
acpi_ns_search_parent_tree(u32 target_name,
			   struct acpi_namespace_node *node,
			   acpi_object_type type,
			   struct acpi_namespace_node **return_node);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_search_node
 *
 * PARAMETERS:  target_name     - Ascii ACPI name to search for
 *              Node            - Starting node where search will begin
 *              Type            - Object type to match
 *              return_node     - Where the matched Named obj is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Search a single level of the namespace.  Performs a
 *              simple search of the specified level, and does not add
 *              entries or search parents.
 *
 *
 *      Named object lists are built (and subsequently dumped) in the
 *      order in which the names are encountered during the namespace load;
 *
 *      All namespace searching is linear in this implementation, but
 *      could be easily modified to support any improved search
 *      algorithm.  However, the linear search was chosen for simplicity
 *      and because the trees are small and the other interpreter
 *      execution overhead is relatively high.
 *
 ******************************************************************************/

acpi_status
acpi_ns_search_node(u32 target_name,
		    struct acpi_namespace_node *node,
		    acpi_object_type type,
		    struct acpi_namespace_node **return_node)
{
	struct acpi_namespace_node *next_node;

	ACPI_FUNCTION_TRACE("ns_search_node");

#ifdef ACPI_DEBUG_OUTPUT
	if (ACPI_LV_NAMES & acpi_dbg_level) {
		char *scope_name;

		scope_name = acpi_ns_get_external_pathname(node);
		if (scope_name) {
			ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
					  "Searching %s (%p) For [%4.4s] (%s)\n",
					  scope_name, node, ACPI_CAST_PTR(char,
									  &target_name),
					  acpi_ut_get_type_name(type)));

			ACPI_FREE(scope_name);
		}
	}
#endif

	/*
	 * Search for name at this namespace level, which is to say that we
	 * must search for the name among the children of this object
	 */
	next_node = node->child;
	while (next_node) {

		/* Check for match against the name */

		if (next_node->name.integer == target_name) {

			/* Resolve a control method alias if any */

			if (acpi_ns_get_type(next_node) ==
			    ACPI_TYPE_LOCAL_METHOD_ALIAS) {
				next_node =
				    ACPI_CAST_PTR(struct acpi_namespace_node,
						  next_node->object);
			}

			/*
			 * Found matching entry.
			 */
			ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
					  "Name [%4.4s] (%s) %p found in scope [%4.4s] %p\n",
					  ACPI_CAST_PTR(char, &target_name),
					  acpi_ut_get_type_name(next_node->
								type),
					  next_node,
					  acpi_ut_get_node_name(node), node));

			*return_node = next_node;
			return_ACPI_STATUS(AE_OK);
		}

		/*
		 * The last entry in the list points back to the parent,
		 * so a flag is used to indicate the end-of-list
		 */
		if (next_node->flags & ANOBJ_END_OF_PEER_LIST) {

			/* Searched entire list, we are done */

			break;
		}

		/* Didn't match name, move on to the next peer object */

		next_node = next_node->peer;
	}

	/* Searched entire namespace level, not found */

	ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
			  "Name [%4.4s] (%s) not found in search in scope [%4.4s] %p first child %p\n",
			  ACPI_CAST_PTR(char, &target_name),
			  acpi_ut_get_type_name(type),
			  acpi_ut_get_node_name(node), node, node->child));

	return_ACPI_STATUS(AE_NOT_FOUND);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_search_parent_tree
 *
 * PARAMETERS:  target_name     - Ascii ACPI name to search for
 *              Node            - Starting node where search will begin
 *              Type            - Object type to match
 *              return_node     - Where the matched Node is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Called when a name has not been found in the current namespace
 *              level.  Before adding it or giving up, ACPI scope rules require
 *              searching enclosing scopes in cases identified by acpi_ns_local().
 *
 *              "A name is located by finding the matching name in the current
 *              name space, and then in the parent name space. If the parent
 *              name space does not contain the name, the search continues
 *              recursively until either the name is found or the name space
 *              does not have a parent (the root of the name space).  This
 *              indicates that the name is not found" (From ACPI Specification,
 *              section 5.3)
 *
 ******************************************************************************/

static acpi_status
acpi_ns_search_parent_tree(u32 target_name,
			   struct acpi_namespace_node *node,
			   acpi_object_type type,
			   struct acpi_namespace_node **return_node)
{
	acpi_status status;
	struct acpi_namespace_node *parent_node;

	ACPI_FUNCTION_TRACE("ns_search_parent_tree");

	parent_node = acpi_ns_get_parent_node(node);

	/*
	 * If there is no parent (i.e., we are at the root) or type is "local",
	 * we won't be searching the parent tree.
	 */
	if (!parent_node) {
		ACPI_DEBUG_PRINT((ACPI_DB_NAMES, "[%4.4s] has no parent\n",
				  ACPI_CAST_PTR(char, &target_name)));
		return_ACPI_STATUS(AE_NOT_FOUND);
	}

	if (acpi_ns_local(type)) {
		ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
				  "[%4.4s] type [%s] must be local to this scope (no parent search)\n",
				  ACPI_CAST_PTR(char, &target_name),
				  acpi_ut_get_type_name(type)));
		return_ACPI_STATUS(AE_NOT_FOUND);
	}

	/* Search the parent tree */

	ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
			  "Searching parent [%4.4s] for [%4.4s]\n",
			  acpi_ut_get_node_name(parent_node),
			  ACPI_CAST_PTR(char, &target_name)));

	/*
	 * Search parents until target is found or we have backed up to the root
	 */
	while (parent_node) {
		/*
		 * Search parent scope.  Use TYPE_ANY because we don't care about the
		 * object type at this point, we only care about the existence of
		 * the actual name we are searching for.  Typechecking comes later.
		 */
		status = acpi_ns_search_node(target_name, parent_node,
					     ACPI_TYPE_ANY, return_node);
		if (ACPI_SUCCESS(status)) {
			return_ACPI_STATUS(status);
		}

		/*
		 * Not found here, go up another level
		 * (until we reach the root)
		 */
		parent_node = acpi_ns_get_parent_node(parent_node);
	}

	/* Not found in parent tree */

	return_ACPI_STATUS(AE_NOT_FOUND);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_search_and_enter
 *
 * PARAMETERS:  target_name         - Ascii ACPI name to search for (4 chars)
 *              walk_state          - Current state of the walk
 *              Node                - Starting node where search will begin
 *              interpreter_mode    - Add names only in ACPI_MODE_LOAD_PASS_x.
 *                                    Otherwise,search only.
 *              Type                - Object type to match
 *              Flags               - Flags describing the search restrictions
 *              return_node         - Where the Node is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Search for a name segment in a single namespace level,
 *              optionally adding it if it is not found.  If the passed
 *              Type is not Any and the type previously stored in the
 *              entry was Any (i.e. unknown), update the stored type.
 *
 *              In ACPI_IMODE_EXECUTE, search only.
 *              In other modes, search and add if not found.
 *
 ******************************************************************************/

acpi_status
acpi_ns_search_and_enter(u32 target_name,
			 struct acpi_walk_state *walk_state,
			 struct acpi_namespace_node *node,
			 acpi_interpreter_mode interpreter_mode,
			 acpi_object_type type,
			 u32 flags, struct acpi_namespace_node **return_node)
{
	acpi_status status;
	struct acpi_namespace_node *new_node;

	ACPI_FUNCTION_TRACE("ns_search_and_enter");

	/* Parameter validation */

	if (!node || !target_name || !return_node) {
		ACPI_ERROR((AE_INFO,
			    "Null param: Node %p Name %X return_node %p",
			    node, target_name, return_node));
		return_ACPI_STATUS(AE_BAD_PARAMETER);
	}

	/* Name must consist of printable characters */

	if (!acpi_ut_valid_acpi_name(target_name)) {
		ACPI_ERROR((AE_INFO, "Bad character in ACPI Name: %X",
			    target_name));
		return_ACPI_STATUS(AE_BAD_CHARACTER);
	}

	/* Try to find the name in the namespace level specified by the caller */

	*return_node = ACPI_ENTRY_NOT_FOUND;
	status = acpi_ns_search_node(target_name, node, type, return_node);
	if (status != AE_NOT_FOUND) {
		/*
		 * If we found it AND the request specifies that a find is an error,
		 * return the error
		 */
		if ((status == AE_OK) && (flags & ACPI_NS_ERROR_IF_FOUND)) {
			status = AE_ALREADY_EXISTS;
		}

		/*
		 * Either found it or there was an error
		 * -- finished either way
		 */
		return_ACPI_STATUS(status);
	}

	/*
	 * The name was not found.  If we are NOT performing the first pass
	 * (name entry) of loading the namespace, search the parent tree (all the
	 * way to the root if necessary.) We don't want to perform the parent
	 * search when the namespace is actually being loaded.  We want to perform
	 * the search when namespace references are being resolved (load pass 2)
	 * and during the execution phase.
	 */
	if ((interpreter_mode != ACPI_IMODE_LOAD_PASS1) &&
	    (flags & ACPI_NS_SEARCH_PARENT)) {
		/*
		 * Not found at this level - search parent tree according to the
		 * ACPI specification
		 */
		status =
		    acpi_ns_search_parent_tree(target_name, node, type,
					       return_node);
		if (ACPI_SUCCESS(status)) {
			return_ACPI_STATUS(status);
		}
	}

	/*
	 * In execute mode, just search, never add names.  Exit now.
	 */
	if (interpreter_mode == ACPI_IMODE_EXECUTE) {
		ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
				  "%4.4s Not found in %p [Not adding]\n",
				  ACPI_CAST_PTR(char, &target_name), node));

		return_ACPI_STATUS(AE_NOT_FOUND);
	}

	/* Create the new named object */

	new_node = acpi_ns_create_node(target_name);
	if (!new_node) {
		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	/* Install the new object into the parent's list of children */

	acpi_ns_install_node(walk_state, node, new_node, type);
	*return_node = new_node;

	return_ACPI_STATUS(AE_OK);
}