exnames.c

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/******************************************************************************
 *
 * Module Name: exnames - interpreter/scanner name load/execute
 *
 *****************************************************************************/

/*
 * 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 "acinterp.h"
#include "amlcode.h"

#define _COMPONENT          ACPI_EXECUTER
ACPI_MODULE_NAME("exnames")

/* Local prototypes */
static char *acpi_ex_allocate_name_string(u32 prefix_count, u32 num_name_segs);

static acpi_status
acpi_ex_name_segment(u8 ** in_aml_address, char *name_string);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_allocate_name_string
 *
 * PARAMETERS:  prefix_count        - Count of parent levels. Special cases:
 *                                    (-1)==root,  0==none
 *              num_name_segs       - count of 4-character name segments
 *
 * RETURN:      A pointer to the allocated string segment.  This segment must
 *              be deleted by the caller.
 *
 * DESCRIPTION: Allocate a buffer for a name string. Ensure allocated name
 *              string is long enough, and set up prefix if any.
 *
 ******************************************************************************/

static char *acpi_ex_allocate_name_string(u32 prefix_count, u32 num_name_segs)
{
    char *temp_ptr;
    char *name_string;
    u32 size_needed;

    ACPI_FUNCTION_TRACE(ex_allocate_name_string);

    /*
     * Allow room for all \ and ^ prefixes, all segments and a multi_name_prefix.
     * Also, one byte for the null terminator.
     * This may actually be somewhat longer than needed.
     */
    if (prefix_count == ACPI_UINT32_MAX) {

        /* Special case for root */

        size_needed = 1 + (ACPI_NAME_SIZE * num_name_segs) + 2 + 1;
    } else {
        size_needed =
            prefix_count + (ACPI_NAME_SIZE * num_name_segs) + 2 + 1;
    }

    /*
     * Allocate a buffer for the name.
     * This buffer must be deleted by the caller!
     */
    name_string = ACPI_ALLOCATE(size_needed);
    if (!name_string) {
        ACPI_ERROR((AE_INFO,
                "Could not allocate size %u", size_needed));
        return_PTR(NULL);
    }

    temp_ptr = name_string;

    /* Set up Root or Parent prefixes if needed */

    if (prefix_count == ACPI_UINT32_MAX) {
        *temp_ptr++ = AML_ROOT_PREFIX;
    } else {
        while (prefix_count--) {
            *temp_ptr++ = AML_PARENT_PREFIX;
        }
    }

    /* Set up Dual or Multi prefixes if needed */

    if (num_name_segs > 2) {

        /* Set up multi prefixes   */

        *temp_ptr++ = AML_MULTI_NAME_PREFIX_OP;
        *temp_ptr++ = (char)num_name_segs;
    } else if (2 == num_name_segs) {

        /* Set up dual prefixes */

        *temp_ptr++ = AML_DUAL_NAME_PREFIX;
    }

    /*
     * Terminate string following prefixes. acpi_ex_name_segment() will
     * append the segment(s)
     */
    *temp_ptr = 0;

    return_PTR(name_string);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_name_segment
 *
 * PARAMETERS:  in_aml_address  - Pointer to the name in the AML code
 *              name_string     - Where to return the name. The name is appended
 *                                to any existing string to form a namepath
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Extract an ACPI name (4 bytes) from the AML byte stream
 *
 ******************************************************************************/

static acpi_status acpi_ex_name_segment(u8 ** in_aml_address, char *name_string)
{
    char *aml_address = (void *)*in_aml_address;
    acpi_status status = AE_OK;
    u32 index;
    char char_buf[5];

    ACPI_FUNCTION_TRACE(ex_name_segment);

    /*
     * If first character is a digit, then we know that we aren't looking at a
     * valid name segment
     */
    char_buf[0] = *aml_address;

    if ('0' <= char_buf[0] && char_buf[0] <= '9') {
        ACPI_ERROR((AE_INFO, "Invalid leading digit: %c", char_buf[0]));
        return_ACPI_STATUS(AE_CTRL_PENDING);
    }

    ACPI_DEBUG_PRINT((ACPI_DB_LOAD, "Bytes from stream:\n"));

    for (index = 0; (index < ACPI_NAME_SIZE)
         && (acpi_ut_valid_acpi_char(*aml_address, 0)); index++) {
        char_buf[index] = *aml_address++;
        ACPI_DEBUG_PRINT((ACPI_DB_LOAD, "%c\n", char_buf[index]));
    }

    /* Valid name segment  */

    if (index == 4) {

        /* Found 4 valid characters */

        char_buf[4] = '\0';

        if (name_string) {
            ACPI_STRCAT(name_string, char_buf);
            ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
                      "Appended to - %s\n", name_string));
        } else {
            ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
                      "No Name string - %s\n", char_buf));
        }
    } else if (index == 0) {
        /*
         * First character was not a valid name character,
         * so we are looking at something other than a name.
         */
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Leading character is not alpha: %02Xh (not a name)\n",
                  char_buf[0]));
        status = AE_CTRL_PENDING;
    } else {
        /*
         * Segment started with one or more valid characters, but fewer than
         * the required 4
         */
        status = AE_AML_BAD_NAME;
        ACPI_ERROR((AE_INFO,
                "Bad character 0x%02x in name, at %p",
                *aml_address, aml_address));
    }

    *in_aml_address = ACPI_CAST_PTR(u8, aml_address);
    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_get_name_string
 *
 * PARAMETERS:  data_type           - Object type to be associated with this
 *                                    name
 *              in_aml_address      - Pointer to the namestring in the AML code
 *              out_name_string     - Where the namestring is returned
 *              out_name_length     - Length of the returned string
 *
 * RETURN:      Status, namestring and length
 *
 * DESCRIPTION: Extract a full namepath from the AML byte stream,
 *              including any prefixes.
 *
 ******************************************************************************/

acpi_status
acpi_ex_get_name_string(acpi_object_type data_type,
            u8 * in_aml_address,
            char **out_name_string, u32 * out_name_length)
{
    acpi_status status = AE_OK;
    u8 *aml_address = in_aml_address;
    char *name_string = NULL;
    u32 num_segments;
    u32 prefix_count = 0;
    u8 has_prefix = FALSE;

    ACPI_FUNCTION_TRACE_PTR(ex_get_name_string, aml_address);

    if (ACPI_TYPE_LOCAL_REGION_FIELD == data_type ||
        ACPI_TYPE_LOCAL_BANK_FIELD == data_type ||
        ACPI_TYPE_LOCAL_INDEX_FIELD == data_type) {

        /* Disallow prefixes for types associated with field_unit names */

        name_string = acpi_ex_allocate_name_string(0, 1);
        if (!name_string) {
            status = AE_NO_MEMORY;
        } else {
            status =
                acpi_ex_name_segment(&aml_address, name_string);
        }
    } else {
        /*
         * data_type is not a field name.
         * Examine first character of name for root or parent prefix operators
         */
        switch (*aml_address) {
        case AML_ROOT_PREFIX:

            ACPI_DEBUG_PRINT((ACPI_DB_LOAD,
                      "RootPrefix(\\) at %p\n",
                      aml_address));

            /*
             * Remember that we have a root_prefix --
             * see comment in acpi_ex_allocate_name_string()
             */
            aml_address++;
            prefix_count = ACPI_UINT32_MAX;
            has_prefix = TRUE;
            break;

        case AML_PARENT_PREFIX:

            /* Increment past possibly multiple parent prefixes */

            do {
                ACPI_DEBUG_PRINT((ACPI_DB_LOAD,
                          "ParentPrefix (^) at %p\n",
                          aml_address));

                aml_address++;
                prefix_count++;

            } while (*aml_address == AML_PARENT_PREFIX);

            has_prefix = TRUE;
            break;

        default:

            /* Not a prefix character */

            break;
        }

        /* Examine first character of name for name segment prefix operator */

        switch (*aml_address) {
        case AML_DUAL_NAME_PREFIX:

            ACPI_DEBUG_PRINT((ACPI_DB_LOAD,
                      "DualNamePrefix at %p\n",
                      aml_address));

            aml_address++;
            name_string =
                acpi_ex_allocate_name_string(prefix_count, 2);
            if (!name_string) {
                status = AE_NO_MEMORY;
                break;
            }

            /* Indicate that we processed a prefix */

            has_prefix = TRUE;

            status =
                acpi_ex_name_segment(&aml_address, name_string);
            if (ACPI_SUCCESS(status)) {
                status =
                    acpi_ex_name_segment(&aml_address,
                             name_string);
            }
            break;

        case AML_MULTI_NAME_PREFIX_OP:

            ACPI_DEBUG_PRINT((ACPI_DB_LOAD,
                      "MultiNamePrefix at %p\n",
                      aml_address));

            /* Fetch count of segments remaining in name path */

            aml_address++;
            num_segments = *aml_address;

            name_string =
                acpi_ex_allocate_name_string(prefix_count,
                             num_segments);
            if (!name_string) {
                status = AE_NO_MEMORY;
                break;
            }

            /* Indicate that we processed a prefix */

            aml_address++;
            has_prefix = TRUE;

            while (num_segments &&
                   (status =
                acpi_ex_name_segment(&aml_address,
                             name_string)) == AE_OK) {
                num_segments--;
            }

            break;

        case 0:

            /* null_name valid as of 8-12-98 ASL/AML Grammar Update */

            if (prefix_count == ACPI_UINT32_MAX) {
                ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                          "NameSeg is \"\\\" followed by NULL\n"));
            }

            /* Consume the NULL byte */

            aml_address++;
            name_string =
                acpi_ex_allocate_name_string(prefix_count, 0);
            if (!name_string) {
                status = AE_NO_MEMORY;
                break;
            }

            break;

        default:

            /* Name segment string */

            name_string =
                acpi_ex_allocate_name_string(prefix_count, 1);
            if (!name_string) {
                status = AE_NO_MEMORY;
                break;
            }

            status =
                acpi_ex_name_segment(&aml_address, name_string);
            break;
        }
    }

    if (AE_CTRL_PENDING == status && has_prefix) {

        /* Ran out of segments after processing a prefix */

        ACPI_ERROR((AE_INFO, "Malformed Name at %p", name_string));
        status = AE_AML_BAD_NAME;
    }

    if (ACPI_FAILURE(status)) {
        if (name_string) {
            ACPI_FREE(name_string);
        }
        return_ACPI_STATUS(status);
    }

    *out_name_string = name_string;
    *out_name_length = (u32) (aml_address - in_aml_address);

    return_ACPI_STATUS(status);
}