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nssearch.c

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

/*
 * 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("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_one_scope
 *
 * PARAMETERS:  target_name     - Ascii ACPI name to search for
 *              parent_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.
 *
 *      Note: CPU execution analysis has shown that the AML interpreter spends
 *      a very small percentage of its time searching the namespace. Therefore,
 *      the linear search seems to be sufficient, as there would seem to be
 *      little value in improving the search.
 *
 ******************************************************************************/

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

      ACPI_FUNCTION_TRACE(ns_search_one_scope);

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

            scope_name = acpi_ns_get_external_pathname(parent_node);
            if (scope_name) {
                  ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
                                "Searching %s (%p) For [%4.4s] (%s)\n",
                                scope_name, parent_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
       */
      node = parent_node->child;
      while (node) {

            /* Check for match against the name */

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

                  /* Resolve a control method alias if any */

                  if (acpi_ns_get_type(node) ==
                      ACPI_TYPE_LOCAL_METHOD_ALIAS) {
                        node =
                            ACPI_CAST_PTR(struct acpi_namespace_node,
                                      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(node->type),
                                node,
                                acpi_ut_get_node_name(parent_node),
                                parent_node));

                  *return_node = 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 (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 */

            node = 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(parent_node), parent_node,
                    parent_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_one_scope(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 parameter: Node %p Name %X ReturnNode %p",
                      node, target_name, return_node));
            return_ACPI_STATUS(AE_BAD_PARAMETER);
      }

      /*
       * Name must consist of valid ACPI characters. We will repair the name if
       * necessary because we don't want to abort because of this, but we want
       * all namespace names to be printable. A warning message is appropriate.
       *
       * This issue came up because there are in fact machines that exhibit
       * this problem, and we want to be able to enable ACPI support for them,
       * even though there are a few bad names.
       */
      if (!acpi_ut_valid_acpi_name(target_name)) {
            target_name =
                acpi_ut_repair_name(ACPI_CAST_PTR(char, &target_name));

            /* Report warning only if in strict mode or debug mode */

            if (!acpi_gbl_enable_interpreter_slack) {
                  ACPI_WARNING((AE_INFO,
                              "Found bad character(s) in name, repaired: [%4.4s]\n",
                              ACPI_CAST_PTR(char, &target_name)));
            } else {
                  ACPI_DEBUG_PRINT((ACPI_DB_WARN,
                                "Found bad character(s) in name, repaired: [%4.4s]\n",
                                ACPI_CAST_PTR(char, &target_name)));
            }
      }

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

      *return_node = ACPI_ENTRY_NOT_FOUND;
      status = acpi_ns_search_one_scope(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);
      }
#ifdef ACPI_ASL_COMPILER
      /*
       * Node is an object defined by an External() statement
       */
      if (flags & ACPI_NS_EXTERNAL) {
            new_node->flags |= ANOBJ_IS_EXTERNAL;
      }
#endif

      if (flags & ACPI_NS_TEMPORARY) {
            new_node->flags |= ANOBJ_TEMPORARY;
      }

      /* 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);
}

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