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nswalk.c

/******************************************************************************
 *
 * Module Name: nswalk - Functions for walking the ACPI namespace
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2007, 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("nswalk")

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_get_next_node
 *
 * PARAMETERS:  Type                - Type of node to be searched for
 *              parent_node         - Parent node whose children we are
 *                                    getting
 *              child_node          - Previous child that was found.
 *                                    The NEXT child will be returned
 *
 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
 *                                    none is found.
 *
 * DESCRIPTION: Return the next peer node within the namespace.  If Handle
 *              is valid, Scope is ignored.  Otherwise, the first node
 *              within Scope is returned.
 *
 ******************************************************************************/
struct acpi_namespace_node *acpi_ns_get_next_node(acpi_object_type type, struct acpi_namespace_node
                                      *parent_node, struct acpi_namespace_node
                                      *child_node)
{
      struct acpi_namespace_node *next_node = NULL;

      ACPI_FUNCTION_ENTRY();

      if (!child_node) {

            /* It's really the parent's _scope_ that we want */

            if (parent_node->child) {
                  next_node = parent_node->child;
            }
      }

      else {
            /* Start search at the NEXT node */

            next_node = acpi_ns_get_next_valid_node(child_node);
      }

      /* If any type is OK, we are done */

      if (type == ACPI_TYPE_ANY) {

            /* next_node is NULL if we are at the end-of-list */

            return (next_node);
      }

      /* Must search for the node -- but within this scope only */

      while (next_node) {

            /* If type matches, we are done */

            if (next_node->type == type) {
                  return (next_node);
            }

            /* Otherwise, move on to the next node */

            next_node = acpi_ns_get_next_valid_node(next_node);
      }

      /* Not found */

      return (NULL);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_walk_namespace
 *
 * PARAMETERS:  Type                - acpi_object_type to search for
 *              start_node          - Handle in namespace where search begins
 *              max_depth           - Depth to which search is to reach
 *              Flags               - Whether to unlock the NS before invoking
 *                                    the callback routine
 *              user_function       - Called when an object of "Type" is found
 *              Context             - Passed to user function
 *              return_value        - from the user_function if terminated early.
 *                                    Otherwise, returns NULL.
 * RETURNS:     Status
 *
 * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
 *              starting (and ending) at the node specified by start_handle.
 *              The user_function is called whenever a node that matches
 *              the type parameter is found.  If the user function returns
 *              a non-zero value, the search is terminated immediately and this
 *              value is returned to the caller.
 *
 *              The point of this procedure is to provide a generic namespace
 *              walk routine that can be called from multiple places to
 *              provide multiple services;  the User Function can be tailored
 *              to each task, whether it is a print function, a compare
 *              function, etc.
 *
 ******************************************************************************/

acpi_status
acpi_ns_walk_namespace(acpi_object_type type,
                   acpi_handle start_node,
                   u32 max_depth,
                   u32 flags,
                   acpi_walk_callback user_function,
                   void *context, void **return_value)
{
      acpi_status status;
      acpi_status mutex_status;
      struct acpi_namespace_node *child_node;
      struct acpi_namespace_node *parent_node;
      acpi_object_type child_type;
      u32 level;

      ACPI_FUNCTION_TRACE(ns_walk_namespace);

      /* Special case for the namespace Root Node */

      if (start_node == ACPI_ROOT_OBJECT) {
            start_node = acpi_gbl_root_node;
      }

      /* Null child means "get first node" */

      parent_node = start_node;
      child_node = NULL;
      child_type = ACPI_TYPE_ANY;
      level = 1;

      /*
       * Traverse the tree of nodes until we bubble back up to where we
       * started. When Level is zero, the loop is done because we have
       * bubbled up to (and passed) the original parent handle (start_entry)
       */
      while (level > 0) {

            /* Get the next node in this scope.  Null if not found */

            status = AE_OK;
            child_node =
                acpi_ns_get_next_node(ACPI_TYPE_ANY, parent_node,
                                child_node);
            if (child_node) {

                  /* Found next child, get the type if we are not searching for ANY */

                  if (type != ACPI_TYPE_ANY) {
                        child_type = child_node->type;
                  }

                  /*
                   * Ignore all temporary namespace nodes (created during control
                   * method execution) unless told otherwise. These temporary nodes
                   * can cause a race condition because they can be deleted during the
                   * execution of the user function (if the namespace is unlocked before
                   * invocation of the user function.) Only the debugger namespace dump
                   * will examine the temporary nodes.
                   */
                  if ((child_node->flags & ANOBJ_TEMPORARY) &&
                      !(flags & ACPI_NS_WALK_TEMP_NODES)) {
                        status = AE_CTRL_DEPTH;
                  }

                  /* Type must match requested type */

                  else if (child_type == type) {
                        /*
                         * Found a matching node, invoke the user callback function.
                         * Unlock the namespace if flag is set.
                         */
                        if (flags & ACPI_NS_WALK_UNLOCK) {
                              mutex_status =
                                  acpi_ut_release_mutex
                                  (ACPI_MTX_NAMESPACE);
                              if (ACPI_FAILURE(mutex_status)) {
                                    return_ACPI_STATUS
                                        (mutex_status);
                              }
                        }

                        status =
                            user_function(child_node, level, context,
                                      return_value);

                        if (flags & ACPI_NS_WALK_UNLOCK) {
                              mutex_status =
                                  acpi_ut_acquire_mutex
                                  (ACPI_MTX_NAMESPACE);
                              if (ACPI_FAILURE(mutex_status)) {
                                    return_ACPI_STATUS
                                        (mutex_status);
                              }
                        }

                        switch (status) {
                        case AE_OK:
                        case AE_CTRL_DEPTH:

                              /* Just keep going */
                              break;

                        case AE_CTRL_TERMINATE:

                              /* Exit now, with OK status */

                              return_ACPI_STATUS(AE_OK);

                        default:

                              /* All others are valid exceptions */

                              return_ACPI_STATUS(status);
                        }
                  }

                  /*
                   * Depth first search: Attempt to go down another level in the
                   * namespace if we are allowed to.  Don't go any further if we have
                   * reached the caller specified maximum depth or if the user
                   * function has specified that the maximum depth has been reached.
                   */
                  if ((level < max_depth) && (status != AE_CTRL_DEPTH)) {
                        if (acpi_ns_get_next_node
                            (ACPI_TYPE_ANY, child_node, NULL)) {

                              /* There is at least one child of this node, visit it */

                              level++;
                              parent_node = child_node;
                              child_node = NULL;
                        }
                  }
            } else {
                  /*
                   * No more children of this node (acpi_ns_get_next_node failed), go
                   * back upwards in the namespace tree to the node's parent.
                   */
                  level--;
                  child_node = parent_node;
                  parent_node = acpi_ns_get_parent_node(parent_node);
            }
      }

      /* Complete walk, not terminated by user function */

      return_ACPI_STATUS(AE_OK);
}

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