nssearch.c

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

/*
 * Copyright (C) 2000 - 2012, Intel Corp.
 * 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 "accommon.h"
#include "acnamesp.h"

#ifdef ACPI_ASL_COMPILER
#include "amlcode.h"
#endif

#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);
        }

        /* 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 = node->parent;

    /*
     * 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 = parent_node->parent;
    }

    /* 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 0x%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_INFO,
                      "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);
}