path: root/src/VBox/Debugger/DBGCEval.cpp

/* $Id: DBGCEval.cpp $ */
/** @file
 * DBGC - Debugger Console, command evaluator.
 */

/*
 * Copyright (C) 2006-2022 Oracle and/or its affiliates.
 *
 * This file is part of VirtualBox base platform packages, as
 * available from https://www.virtualbox.org.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation, in version 3 of the
 * License.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <https://www.gnu.org/licenses>.
 *
 * SPDX-License-Identifier: GPL-3.0-only
 */


/*********************************************************************************************************************************
*   Header Files                                                                                                                 *
*********************************************************************************************************************************/
#define LOG_GROUP LOG_GROUP_DBGC
#include <VBox/dbg.h>
#include <VBox/err.h>
#include <VBox/log.h>

#include <iprt/asm.h>
#include <iprt/assert.h>
#include <iprt/mem.h>
#include <iprt/string.h>
#include <iprt/ctype.h>

#include <stdio.h>

#include "DBGCInternal.h"

/** Rewrite in progress.  */
#define BETTER_ARGUMENT_MATCHING


/*********************************************************************************************************************************
*   Global Variables                                                                                                             *
*********************************************************************************************************************************/
/** Bitmap where set bits indicates the characters the may start an operator name. */
static uint32_t g_bmOperatorChars[256 / (4*8)];


/*********************************************************************************************************************************
*   Internal Functions                                                                                                           *
*********************************************************************************************************************************/
static int dbgcCheckAndTypePromoteArgument(PDBGC pDbgc, DBGCVARCAT enmCategory, PDBGCVAR pArg);
static int dbgcProcessArguments(PDBGC pDbgc, const char *pszCmdOrFunc,
                                uint32_t const cArgsMin, uint32_t const cArgsMax,
                                PCDBGCVARDESC const paVarDescs, uint32_t const cVarDescs,
                                char *pszArgs, unsigned *piArg, unsigned *pcArgs);



/**
 * Initializes g_bmOperatorChars.
 */
void dbgcEvalInit(void)
{
    memset(g_bmOperatorChars, 0, sizeof(g_bmOperatorChars));
    for (unsigned iOp = 0; iOp < g_cDbgcOps; iOp++)
        ASMBitSet(&g_bmOperatorChars[0], (uint8_t)g_aDbgcOps[iOp].szName[0]);
}


/**
 * Checks whether the character may be the start of an operator.
 *
 * @returns true/false.
 * @param   ch      The character.
 */
DECLINLINE(bool) dbgcIsOpChar(char ch)
{
    return ASMBitTest(&g_bmOperatorChars[0], (uint8_t)ch);
}


/**
 * Returns the amount of free scratch space.
 *
 * @returns Number of unallocated bytes.
 * @param   pDbgc               The DBGC instance.
 */
size_t dbgcGetFreeScratchSpace(PDBGC pDbgc)
{
    return sizeof(pDbgc->achScratch) - (pDbgc->pszScratch - &pDbgc->achScratch[0]);
}


/**
 * Allocates a string from the scratch space.
 *
 * @returns Pointer to the allocated string buffer, NULL if out of space.
 * @param   pDbgc               The DBGC instance.
 * @param   cbRequested         The number of bytes to allocate.
 */
char *dbgcAllocStringScatch(PDBGC pDbgc, size_t cbRequested)
{
    if (cbRequested > dbgcGetFreeScratchSpace(pDbgc))
        return NULL;
    char *psz = pDbgc->pszScratch;
    pDbgc->pszScratch += cbRequested;
    return psz;
}


/**
 * Evals an expression into a string or symbol (single quotes).
 *
 * The string memory is allocated from the scratch buffer.
 *
 * @returns VBox status code.
 * @param   pDbgc               The DBGC instance.
 * @param   pachExpr            The string/symbol expression.
 * @param   cchExpr             The length of the expression.
 * @param   pArg                Where to return the string.
 */
static int dbgcEvalSubString(PDBGC pDbgc, const char *pachExpr, size_t cchExpr, PDBGCVAR pArg)
{
    Log2(("dbgcEvalSubString: cchExpr=%d pachExpr=%.*s\n", cchExpr, cchExpr, pachExpr));

    /*
     * Allocate scratch space for the string.
     */
    char *pszCopy = dbgcAllocStringScatch(pDbgc, cchExpr + 1);
    if (!pszCopy)
        return VERR_DBGC_PARSE_NO_SCRATCH;

    /*
     * Removing any quoting and escapings.
     */
    char const chQuote = *pachExpr;
    if (chQuote == '"' || chQuote == '\'')
    {
        if (pachExpr[--cchExpr] != chQuote)
            return VERR_DBGC_PARSE_UNBALANCED_QUOTE;

        cchExpr--;
        pachExpr++;
        if (!memchr(pachExpr, chQuote, cchExpr))
            memcpy(pszCopy, pachExpr, cchExpr);
        else
        {
            size_t offSrc = 0;
            size_t offDst = 0;
            while (offSrc < cchExpr)
            {
                char const ch = pachExpr[offSrc++];
                if (ch == chQuote)
                {
                    if (pachExpr[offSrc] != ch)
                        return VERR_DBGC_PARSE_EXPECTED_BINARY_OP;
                    offSrc++;
                }
                pszCopy[offDst++] = ch;
            }
        }
    }
    else
        memcpy(pszCopy, pachExpr, cchExpr);
    pszCopy[cchExpr] = '\0';

    /*
     * Make the argument.
     */
    pArg->pDesc         = NULL;
    pArg->pNext         = NULL;
    pArg->enmType       = chQuote == '"' ? DBGCVAR_TYPE_STRING : DBGCVAR_TYPE_SYMBOL;
    pArg->u.pszString   = pszCopy;
    pArg->enmRangeType  = DBGCVAR_RANGE_BYTES;
    pArg->u64Range      = cchExpr;

    NOREF(pDbgc);
    return VINF_SUCCESS;
}


static int dbgcEvalSubNum(const char *pachExpr, size_t cchExpr, unsigned uBase, PDBGCVAR pArg)
{
    Log2(("dbgcEvalSubNum: uBase=%d pachExpr=%.*s\n", uBase, cchExpr, pachExpr));

    /*
     * Empty expressions cannot be valid numbers.
     */
    if (!cchExpr)
        return VERR_DBGC_PARSE_INVALID_NUMBER;

    /*
     * Convert to number.
     */
    uint64_t    u64 = 0;
    while (cchExpr-- > 0)
    {
        char const ch = *pachExpr;
        uint64_t    u64Prev = u64;
        unsigned    u = ch - '0';
        if (u < 10 && u < uBase)
            u64 = u64 * uBase + u;
        else if (ch >= 'a' && (u = ch - ('a' - 10)) < uBase)
            u64 = u64 * uBase + u;
        else if (ch >= 'A' && (u = ch - ('A' - 10)) < uBase)
            u64 = u64 * uBase + u;
        else
            return VERR_DBGC_PARSE_INVALID_NUMBER;

        /* check for overflow - ARG!!! How to detect overflow correctly!?!?!? */
        if (u64Prev != u64 / uBase)
            return VERR_DBGC_PARSE_NUMBER_TOO_BIG;

        /* next */
        pachExpr++;
    }

    /*
     * Initialize the argument.
     */
    pArg->pDesc         = NULL;
    pArg->pNext         = NULL;
    pArg->enmType       = DBGCVAR_TYPE_NUMBER;
    pArg->u.u64Number   = u64;
    pArg->enmRangeType  = DBGCVAR_RANGE_NONE;
    pArg->u64Range      = 0;

    return VINF_SUCCESS;
}


/**
 * dbgcEvalSubUnary worker that handles simple numeric or pointer expressions.
 *
 * @returns VBox status code. pResult contains the result on success.
 * @param   pDbgc       Debugger console instance data.
 * @param   pszExpr     The expression string.
 * @param   cchExpr     The length of the expression.
 * @param   enmCategory The desired type category (for range / no range).
 * @param   pResult     Where to store the result of the expression evaluation.
 */
static int dbgcEvalSubNumericOrPointer(PDBGC pDbgc, char *pszExpr, size_t cchExpr, DBGCVARCAT enmCategory,
                                       PDBGCVAR pResult)
{
    char const  ch  = pszExpr[0];
    char const  ch2 = pszExpr[1];

    /* 0x<hex digits> */
    if (ch == '0' && (ch2 == 'x' || ch2 == 'X'))
        return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 16, pResult);

    /* <hex digits>h */
    if (RT_C_IS_XDIGIT(*pszExpr) && (pszExpr[cchExpr - 1] == 'h' || pszExpr[cchExpr - 1] == 'H'))
    {
        pszExpr[cchExpr] = '\0';
        return dbgcEvalSubNum(pszExpr, cchExpr - 1, 16, pResult);
    }

    /* 0i<decimal digits> */
    if (ch == '0' && ch2 == 'i')
        return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 10, pResult);

    /* 0t<octal digits> */
    if (ch == '0' && ch2 == 't')
        return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 8, pResult);

    /* 0y<binary digits> */
    if (ch == '0' && ch2 == 'y')
        return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 10, pResult);

    /* Hex number? */
    unsigned off = 0;
    while (off < cchExpr && (RT_C_IS_XDIGIT(pszExpr[off]) || pszExpr[off] == '`'))
        off++;
    if (off == cchExpr)
        return dbgcEvalSubNum(pszExpr, cchExpr, 16, pResult);

    /*
     * Some kind of symbol?  Rejected double quoted strings, only unquoted
     * and single quoted strings will be considered as symbols.
     */
    DBGCVARTYPE enmType;
    bool        fStripRange = false;
    switch (enmCategory)
    {
        case DBGCVAR_CAT_POINTER_NUMBER:            enmType = DBGCVAR_TYPE_NUMBER; break;
        case DBGCVAR_CAT_POINTER_NUMBER_NO_RANGE:   enmType = DBGCVAR_TYPE_NUMBER; fStripRange = true; break;
        case DBGCVAR_CAT_POINTER:                   enmType = DBGCVAR_TYPE_NUMBER; break;
        case DBGCVAR_CAT_POINTER_NO_RANGE:          enmType = DBGCVAR_TYPE_NUMBER; fStripRange = true; break;
        case DBGCVAR_CAT_GC_POINTER:                enmType = DBGCVAR_TYPE_GC_FLAT; break;
        case DBGCVAR_CAT_GC_POINTER_NO_RANGE:       enmType = DBGCVAR_TYPE_GC_FLAT; fStripRange = true; break;
        case DBGCVAR_CAT_NUMBER:                    enmType = DBGCVAR_TYPE_NUMBER; break;
        case DBGCVAR_CAT_NUMBER_NO_RANGE:           enmType = DBGCVAR_TYPE_NUMBER; fStripRange = true; break;
        default:
            AssertFailedReturn(VERR_DBGC_PARSE_NOT_IMPLEMENTED);
    }

    char const chQuote = *pszExpr;
    if (chQuote == '"')
        return VERR_DBGC_PARSE_INVALID_NUMBER;

    if (chQuote == '\'')
    {
        if (pszExpr[cchExpr - 1] != chQuote)
            return VERR_DBGC_PARSE_UNBALANCED_QUOTE;
        pszExpr[cchExpr - 1] = '\0';
        pszExpr++;
    }

    int rc = dbgcSymbolGet(pDbgc, pszExpr, enmType, pResult);
    if (RT_SUCCESS(rc))
    {
        if (fStripRange)
        {
            pResult->enmRangeType = DBGCVAR_RANGE_NONE;
            pResult->u64Range     = 0;
        }
    }
    else if (rc == VERR_DBGC_PARSE_NOT_IMPLEMENTED)
        rc = VERR_DBGC_PARSE_INVALID_NUMBER;
    return rc;
}


/**
 * dbgcEvalSubUnary worker that handles simple DBGCVAR_CAT_ANY expressions.
 *
 * @returns VBox status code. pResult contains the result on success.
 * @param   pDbgc       Debugger console instance data.
 * @param   pszExpr     The expression string.
 * @param   cchExpr     The length of the expression.
 * @param   pResult     Where to store the result of the expression evaluation.
 */
static int dbgcEvalSubUnaryAny(PDBGC pDbgc, char *pszExpr, size_t cchExpr, PDBGCVAR pResult)
{
    char const  ch  = pszExpr[0];
    char const  ch2 = pszExpr[1];
    unsigned    off = 2;

    /* 0x<hex digits> */
    if (ch == '0' && (ch2 == 'x' || ch2 == 'X'))
    {
        while (RT_C_IS_XDIGIT(pszExpr[off]) || pszExpr[off] == '`')
            off++;
        if (off == cchExpr)
            return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 16, pResult);
        return dbgcEvalSubString(pDbgc, pszExpr, cchExpr, pResult);
    }

    /* <hex digits>h */
    if (RT_C_IS_XDIGIT(*pszExpr) && (pszExpr[cchExpr - 1] == 'h' || pszExpr[cchExpr - 1] == 'H'))
    {
        cchExpr--;
        while (off < cchExpr && (RT_C_IS_XDIGIT(pszExpr[off]) || pszExpr[off] == '`'))
            off++;
        if (off == cchExpr)
        {
            pszExpr[cchExpr] = '\0';
            return dbgcEvalSubNum(pszExpr, cchExpr, 16, pResult);
        }
        return dbgcEvalSubString(pDbgc, pszExpr, cchExpr + 1, pResult);
    }

    /* 0n<decimal digits> or 0i<decimal digits> */
    if (ch == '0' && (ch2 == 'n' || ch2 == 'i'))
    {
        while (RT_C_IS_DIGIT(pszExpr[off]) || pszExpr[off] == '`')
            off++;
        if (off == cchExpr)
            return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 10, pResult);
        return dbgcEvalSubString(pDbgc, pszExpr, cchExpr, pResult);
    }

    /* 0t<octal digits> */
    if (ch == '0' && ch2 == 't')
    {
        while (RT_C_IS_ODIGIT(pszExpr[off]) || pszExpr[off] == '`')
            off++;
        if (off == cchExpr)
            return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 8, pResult);
        return dbgcEvalSubString(pDbgc, pszExpr, cchExpr, pResult);
    }

    /* 0y<binary digits> */
    if (ch == '0' && ch2 == 'y')
    {
        while (pszExpr[off] == '0' || pszExpr[off] == '1' || pszExpr[off] == '`')
            off++;
        if (off == cchExpr)
            return dbgcEvalSubNum(pszExpr + 2, cchExpr - 2, 10, pResult);
        return dbgcEvalSubString(pDbgc, pszExpr, cchExpr, pResult);
    }

    /* Ok, no prefix of suffix. Is it a hex number after all? If not it must
       be a string. */
    off = 0;
    while (RT_C_IS_XDIGIT(pszExpr[off]) || pszExpr[off] == '`')
        off++;
    if (off == cchExpr)
        return dbgcEvalSubNum(pszExpr, cchExpr, 16, pResult);
    return dbgcEvalSubString(pDbgc, pszExpr, cchExpr, pResult);
}


/**
 * Handles a call.
 *
 * @returns VBox status code. pResult contains the result on success.
 * @param   pDbgc               The DBGC instance.
 * @param   pszFuncNm           The function name.
 * @param   cchFuncNm           The length of the function name.
 * @param   fExternal           Whether it's an external name.
 * @param   pszArgs             The start of the arguments (after parenthesis).
 * @param   cchArgs             The length for the argument (excluding
 *                              parentesis).
 * @param   enmCategory         The desired category of the result (ignored).
 * @param   pResult             The result.
 */
static int dbgcEvalSubCall(PDBGC pDbgc, char *pszFuncNm, size_t cchFuncNm, bool fExternal, char *pszArgs, size_t cchArgs,
                           DBGCVARCAT enmCategory, PDBGCVAR pResult)
{
    RT_NOREF1(enmCategory);

    /*
     * Lookup the function.
     */
    PCDBGCFUNC pFunc = dbgcFunctionLookup(pDbgc, pszFuncNm, cchFuncNm, fExternal);
    if (!pFunc)
        return VERR_DBGC_PARSE_FUNCTION_NOT_FOUND;

    /*
     * Parse the arguments.
     */
    unsigned cArgs;
    unsigned iArg;
    pszArgs[cchArgs] = '\0';
    int rc = dbgcProcessArguments(pDbgc, pFunc->pszFuncNm,
                                  pFunc->cArgsMin, pFunc->cArgsMax, pFunc->paArgDescs, pFunc->cArgDescs,
                                  pszArgs, &iArg, &cArgs);
    if (RT_SUCCESS(rc))
        rc = pFunc->pfnHandler(pFunc, &pDbgc->CmdHlp, pDbgc->pUVM, &pDbgc->aArgs[iArg], cArgs, pResult);
    pDbgc->iArg = iArg;
    return rc;
}


/**
 * Evaluates one argument with respect to unary operators.
 *
 * @returns VBox status code. pResult contains the result on success.
 *
 * @param   pDbgc       Debugger console instance data.
 * @param   pszExpr     The expression string.
 * @param   cchExpr     The length of the expression.
 * @param   enmCategory The target category for the result.
 * @param   pResult     Where to store the result of the expression evaluation.
 */
static int dbgcEvalSubUnary(PDBGC pDbgc, char *pszExpr, size_t cchExpr, DBGCVARCAT enmCategory, PDBGCVAR pResult)
{
    Log2(("dbgcEvalSubUnary: cchExpr=%d pszExpr=%s\n", cchExpr, pszExpr));

    /*
     * The state of the expression is now such that it will start by zero or more
     * unary operators and being followed by an expression of some kind.
     * The expression is either plain or in parenthesis.
     *
     * Being in a lazy, recursive mode today, the parsing is done as simple as possible. :-)
     * ASSUME: unary operators are all of equal precedence.
     */
    int         rc  = VINF_SUCCESS;
    PCDBGCOP    pOp = dbgcOperatorLookup(pDbgc, pszExpr, false, ' ');
    if (pOp)
    {
        /* binary operators means syntax error. */
        if (pOp->fBinary)
            return VERR_DBGC_PARSE_UNEXPECTED_OPERATOR;

        /*
         * If the next expression (the one following the unary operator) is in a
         * parenthesis a full eval is needed. If not the unary eval will suffice.
         */
        /* calc and strip next expr. */
        char *pszExpr2 = pszExpr + pOp->cchName;
        while (RT_C_IS_BLANK(*pszExpr2))
            pszExpr2++;

        if (*pszExpr2)
        {
            DBGCVAR Arg;
            if (*pszExpr2 == '(')
                rc = dbgcEvalSub(pDbgc, pszExpr2, cchExpr - (pszExpr2 - pszExpr), pOp->enmCatArg1, &Arg);
            else
                rc = dbgcEvalSubUnary(pDbgc, pszExpr2, cchExpr - (pszExpr2 - pszExpr), pOp->enmCatArg1, &Arg);
            if (RT_SUCCESS(rc))
                rc = dbgcCheckAndTypePromoteArgument(pDbgc, pOp->enmCatArg1, &Arg);
            if (RT_SUCCESS(rc))
                rc = pOp->pfnHandlerUnary(pDbgc, &Arg, enmCategory, pResult);
        }
        else
            rc = VERR_DBGC_PARSE_EMPTY_ARGUMENT;
        return rc;
    }

    /*
     * Could this be a function call?
     *
     * ASSUMPTIONS:
     *    - A function name only contains alphanumerical chars and it can not
     *      start with a numerical character.
     *    - Immediately following the name is a parenthesis which must cover
     *      the remaining part of the expression.
     */
    bool    fExternal = *pszExpr == '.';
    char   *pszFun    = fExternal ? pszExpr + 1 : pszExpr;
    char   *pszFunEnd = NULL;
    if (pszExpr[cchExpr - 1] == ')' && RT_C_IS_ALPHA(*pszFun))
    {
        pszFunEnd = pszExpr + 1;
        while (*pszFunEnd != '(' && RT_C_IS_ALNUM(*pszFunEnd))
            pszFunEnd++;
        if (*pszFunEnd != '(')
            pszFunEnd = NULL;
    }
    if (pszFunEnd)
    {
        size_t cchFunNm = pszFunEnd - pszFun;
        return dbgcEvalSubCall(pDbgc, pszFun, cchFunNm, fExternal, pszFunEnd + 1, cchExpr - cchFunNm - fExternal - 2,
                               enmCategory, pResult);
    }

    /*
     * Assuming plain expression.
     * Didn't find any operators, so it must be a plain expression.
     * Go by desired category first, then if anythings go, try guess.
     */
    switch (enmCategory)
    {
        case DBGCVAR_CAT_ANY:
            return dbgcEvalSubUnaryAny(pDbgc, pszExpr, cchExpr, pResult);

        case DBGCVAR_CAT_POINTER_NUMBER:
        case DBGCVAR_CAT_POINTER_NUMBER_NO_RANGE:
        case DBGCVAR_CAT_POINTER:
        case DBGCVAR_CAT_POINTER_NO_RANGE:
        case DBGCVAR_CAT_GC_POINTER:
        case DBGCVAR_CAT_GC_POINTER_NO_RANGE:
        case DBGCVAR_CAT_NUMBER:
        case DBGCVAR_CAT_NUMBER_NO_RANGE:
            /* Pointers will be promoted later. */
            return dbgcEvalSubNumericOrPointer(pDbgc, pszExpr, cchExpr, enmCategory, pResult);

        case DBGCVAR_CAT_STRING:
        case DBGCVAR_CAT_SYMBOL:
            /* Symbols will be promoted later. */
            return dbgcEvalSubString(pDbgc, pszExpr, cchExpr, pResult);

        case DBGCVAR_CAT_OPTION:
        case DBGCVAR_CAT_OPTION_STRING:
        case DBGCVAR_CAT_OPTION_NUMBER:
            return VERR_DBGC_PARSE_NOT_IMPLEMENTED;
    }

    AssertMsgFailed(("enmCategory=%d\n", enmCategory));
    return VERR_NOT_IMPLEMENTED;
}


/**
 * Evaluates one argument.
 *
 * @returns VBox status code.
 *
 * @param   pDbgc       Debugger console instance data.
 * @param   pszExpr     The expression string.
 * @param   cchExpr     The size of the expression string.
 * @param   enmCategory The target category for the result.
 * @param   pResult     Where to store the result of the expression evaluation.
 */
int dbgcEvalSub(PDBGC pDbgc, char *pszExpr, size_t cchExpr, DBGCVARCAT enmCategory, PDBGCVAR pResult)
{
    Log2(("dbgcEvalSub: cchExpr=%d pszExpr=%s\n", cchExpr, pszExpr));

    /*
     * First we need to remove blanks in both ends.
     * ASSUMES: There is no quoting unless the entire expression is a string.
     */

    /* stripping. */
    while (cchExpr > 0 && RT_C_IS_BLANK(pszExpr[cchExpr - 1]))
        pszExpr[--cchExpr] = '\0';
    while (RT_C_IS_BLANK(*pszExpr))
        pszExpr++, cchExpr--;
    if (!*pszExpr)
        return VERR_DBGC_PARSE_EMPTY_ARGUMENT;

    /*
     * Check if there are any parenthesis which needs removing.
     */
    if (pszExpr[0] == '(' && pszExpr[cchExpr - 1] == ')')
    {
        do
        {
            unsigned cPar = 1;
            char    *psz = pszExpr + 1;
            char     ch;
            while ((ch = *psz) != '\0')
            {
                if (ch == '(')
                    cPar++;
                else if (ch == ')')
                {
                    if (cPar <= 0)
                        return VERR_DBGC_PARSE_UNBALANCED_PARENTHESIS;
                    cPar--;
                    if (cPar == 0 && psz[1]) /* If not at end, there's nothing to do. */
                        break;
                }
                /* next */
                psz++;
            }
            if (ch)
                break;

            /* remove the parenthesis. */
            pszExpr++;
            cchExpr -= 2;
            pszExpr[cchExpr] = '\0';

            /* strip blanks. */
            while (cchExpr > 0 && RT_C_IS_BLANK(pszExpr[cchExpr - 1]))
                pszExpr[--cchExpr] = '\0';
            while (RT_C_IS_BLANK(*pszExpr))
                pszExpr++, cchExpr--;
            if (!*pszExpr)
                return VERR_DBGC_PARSE_EMPTY_ARGUMENT;
        } while (pszExpr[0] == '(' && pszExpr[cchExpr - 1] == ')');
    }

    /*
     * Now, we need to look for the binary operator with the lowest precedence.
     *
     * If there are no operators we're left with a simple expression which we
     * evaluate with respect to unary operators
     */
    char       *pszOpSplit  = NULL;
    PCDBGCOP    pOpSplit    = NULL;
    unsigned    cBinaryOps  = 0;
    unsigned    cPar        = 0;
    unsigned    cchWord     = 0;
    char        chQuote     = '\0';
    char        chPrev      = ' ';
    bool        fBinary     = false;
    char       *psz         = pszExpr;
    char        ch;

    while ((ch = *psz) != '\0')
    {
        /*
         * String quoting.
         */
        if (chQuote)
        {
            if (ch == chQuote)
            {
                if (psz[1] == chQuote)
                {
                    psz++;              /* escaped quote */
                    cchWord++;
                }
                else
                {
                    chQuote = '\0';
                    fBinary = true;
                    cchWord = 0;
                }
            }
            else
                cchWord++;
        }
        else if (ch == '"' || ch == '\'')
        {
            if (fBinary || cchWord)
                return VERR_DBGC_PARSE_EXPECTED_BINARY_OP;
            chQuote = ch;
        }
        /*
         * Parentheses.
         */
        else if (ch == '(')
        {
            if (!cPar && fBinary && !cchWord)
                return VERR_DBGC_PARSE_EXPECTED_BINARY_OP;
            cPar++;
            fBinary = false;
            cchWord = 0;
        }
        else if (ch == ')')
        {
            if (cPar <= 0)
                return VERR_DBGC_PARSE_UNBALANCED_PARENTHESIS;
            cPar--;
            fBinary = true;
            cchWord = 0;
        }
        /*
         * Potential operator.
         */
        else if (cPar == 0 && !RT_C_IS_BLANK(ch))
        {
            PCDBGCOP pOp = dbgcIsOpChar(ch)
                         ? dbgcOperatorLookup(pDbgc, psz, fBinary, chPrev)
                         : NULL;
            if (pOp)
            {
                /* If not the right kind of operator we've got a syntax error. */
                if (pOp->fBinary != fBinary)
                    return VERR_DBGC_PARSE_UNEXPECTED_OPERATOR;

                /*
                 * Update the parse state and skip the operator.
                 */
                if (!pOpSplit)
                {
                    pOpSplit = pOp;
                    pszOpSplit = psz;
                    cBinaryOps = fBinary;
                }
                else if (fBinary)
                {
                    cBinaryOps++;
                    if (pOp->iPrecedence >= pOpSplit->iPrecedence)
                    {
                        pOpSplit = pOp;
                        pszOpSplit = psz;
                    }
                }

                psz += pOp->cchName - 1;
                fBinary = false;
                cchWord = 0;
            }
            else if (fBinary && !cchWord)
                return VERR_DBGC_PARSE_EXPECTED_BINARY_OP;
            else
            {
                fBinary = true;
                cchWord++;
            }
        }
        else if (cPar == 0 && RT_C_IS_BLANK(ch))
            cchWord++;

        /* next */
        psz++;
        chPrev = ch;
    } /* parse loop. */

    if (chQuote)
        return VERR_DBGC_PARSE_UNBALANCED_QUOTE;

    /*
     * Either we found an operator to divide the expression by or we didn't
     * find any.  In the first case it's divide and conquer.  In the latter
     * it's a single expression which needs dealing with its unary operators
     * if any.
     */
    int rc;
    if (    cBinaryOps
        &&  pOpSplit->fBinary)
    {
        /* process 1st sub expression. */
        *pszOpSplit = '\0';
        DBGCVAR     Arg1;
        rc = dbgcEvalSub(pDbgc, pszExpr, pszOpSplit - pszExpr, pOpSplit->enmCatArg1, &Arg1);
        if (RT_SUCCESS(rc))
        {
            /* process 2nd sub expression. */
            char       *psz2 = pszOpSplit + pOpSplit->cchName;
            DBGCVAR     Arg2;
            rc = dbgcEvalSub(pDbgc, psz2, cchExpr - (psz2 - pszExpr), pOpSplit->enmCatArg2, &Arg2);
            if (RT_SUCCESS(rc))
                rc = dbgcCheckAndTypePromoteArgument(pDbgc, pOpSplit->enmCatArg1, &Arg1);
            if (RT_SUCCESS(rc))
                rc = dbgcCheckAndTypePromoteArgument(pDbgc, pOpSplit->enmCatArg2, &Arg2);
            if (RT_SUCCESS(rc))
                rc = pOpSplit->pfnHandlerBinary(pDbgc, &Arg1, &Arg2, pResult);
        }
    }
    else if (cBinaryOps)
    {
        /* process sub expression. */
        pszOpSplit += pOpSplit->cchName;
        DBGCVAR     Arg;
        rc = dbgcEvalSub(pDbgc, pszOpSplit, cchExpr - (pszOpSplit - pszExpr), pOpSplit->enmCatArg1, &Arg);
        if (RT_SUCCESS(rc))
            rc = dbgcCheckAndTypePromoteArgument(pDbgc, pOpSplit->enmCatArg1, &Arg);
        if (RT_SUCCESS(rc))
            rc = pOpSplit->pfnHandlerUnary(pDbgc, &Arg, enmCategory, pResult);
    }
    else
        /* plain expression, quoted string, or using unary operators perhaps with parentheses. */
        rc = dbgcEvalSubUnary(pDbgc, pszExpr, cchExpr, enmCategory, pResult);

    return rc;
}


/**
 * Worker for dbgcProcessArguments that performs type checking and promoptions.
 *
 * @returns VBox status code.
 *
 * @param   pDbgc       Debugger console instance data.
 * @param   enmCategory The target category for the result.
 * @param   pArg        The argument to check and promote.
 */
static int dbgcCheckAndTypePromoteArgument(PDBGC pDbgc, DBGCVARCAT enmCategory, PDBGCVAR pArg)
{
    switch (enmCategory)
    {
        /*
         * Anything goes
         */
        case DBGCVAR_CAT_ANY:
            return VINF_SUCCESS;

        /*
         * Pointer with and without range.
         * We can try resolve strings and symbols as symbols and promote
         * numbers to flat GC pointers.
         */
        case DBGCVAR_CAT_POINTER_NO_RANGE:
        case DBGCVAR_CAT_POINTER_NUMBER_NO_RANGE:
            if (pArg->enmRangeType != DBGCVAR_RANGE_NONE)
                return VERR_DBGC_PARSE_NO_RANGE_ALLOWED;
            RT_FALL_THRU();
        case DBGCVAR_CAT_POINTER:
        case DBGCVAR_CAT_POINTER_NUMBER:
            switch (pArg->enmType)
            {
                case DBGCVAR_TYPE_GC_FLAT:
                case DBGCVAR_TYPE_GC_FAR:
                case DBGCVAR_TYPE_GC_PHYS:
                case DBGCVAR_TYPE_HC_FLAT:
                case DBGCVAR_TYPE_HC_PHYS:
                    return VINF_SUCCESS;

                case DBGCVAR_TYPE_SYMBOL:
                case DBGCVAR_TYPE_STRING:
                {
                    DBGCVAR Var;
                    int rc = dbgcSymbolGet(pDbgc, pArg->u.pszString, DBGCVAR_TYPE_GC_FLAT, &Var);
                    if (RT_SUCCESS(rc))
                    {
                        /* deal with range */
                        if (pArg->enmRangeType != DBGCVAR_RANGE_NONE)
                        {
                            Var.enmRangeType = pArg->enmRangeType;
                            Var.u64Range = pArg->u64Range;
                        }
                        else if (enmCategory == DBGCVAR_CAT_POINTER_NO_RANGE)
                            Var.enmRangeType = DBGCVAR_RANGE_NONE;
                        *pArg = Var;
                    }
                    return rc;
                }

                case DBGCVAR_TYPE_NUMBER:
                    if (   enmCategory != DBGCVAR_CAT_POINTER_NUMBER
                        && enmCategory != DBGCVAR_CAT_POINTER_NUMBER_NO_RANGE)
                    {
                        RTGCPTR GCPtr = (RTGCPTR)pArg->u.u64Number;
                        pArg->enmType = DBGCVAR_TYPE_GC_FLAT;
                        pArg->u.GCFlat = GCPtr;
                    }
                    return VINF_SUCCESS;

                default:
                    AssertMsgFailedReturn(("Invalid type %d\n", pArg->enmType), VERR_DBGC_PARSE_INCORRECT_ARG_TYPE);
            }
            break;                      /* (not reached) */

        /*
         * GC pointer with and without range.
         * We can try resolve strings and symbols as symbols and
         * promote numbers to flat GC pointers.
         */
        case DBGCVAR_CAT_GC_POINTER_NO_RANGE:
            if (pArg->enmRangeType != DBGCVAR_RANGE_NONE)
                return VERR_DBGC_PARSE_NO_RANGE_ALLOWED;
            RT_FALL_THRU();
        case DBGCVAR_CAT_GC_POINTER:
            switch (pArg->enmType)
            {
                case DBGCVAR_TYPE_GC_FLAT:
                case DBGCVAR_TYPE_GC_FAR:
                case DBGCVAR_TYPE_GC_PHYS:
                    return VINF_SUCCESS;

                case DBGCVAR_TYPE_HC_FLAT:
                case DBGCVAR_TYPE_HC_PHYS:
                    return VERR_DBGC_PARSE_CONVERSION_FAILED;

                case DBGCVAR_TYPE_SYMBOL:
                case DBGCVAR_TYPE_STRING:
                {
                    DBGCVAR Var;
                    int rc = dbgcSymbolGet(pDbgc, pArg->u.pszString, DBGCVAR_TYPE_GC_FLAT, &Var);
                    if (RT_SUCCESS(rc))
                    {
                        /* deal with range */
                        if (pArg->enmRangeType != DBGCVAR_RANGE_NONE)
                        {
                            Var.enmRangeType = pArg->enmRangeType;
                            Var.u64Range = pArg->u64Range;
                        }
                        else if (enmCategory == DBGCVAR_CAT_POINTER_NO_RANGE)
                            Var.enmRangeType = DBGCVAR_RANGE_NONE;
                        *pArg = Var;
                    }
                    return rc;
                }

                case DBGCVAR_TYPE_NUMBER:
                {
                    RTGCPTR GCPtr = (RTGCPTR)pArg->u.u64Number;
                    pArg->enmType = DBGCVAR_TYPE_GC_FLAT;
                    pArg->u.GCFlat = GCPtr;
                    return VINF_SUCCESS;
                }

                default:
                    AssertMsgFailedReturn(("Invalid type %d\n", pArg->enmType), VERR_DBGC_PARSE_INCORRECT_ARG_TYPE);
            }
            break;                      /* (not reached) */

        /*
         * Number with or without a range.
         * Numbers can be resolved from symbols, but we cannot demote a pointer
         * to a number.
         */
        case DBGCVAR_CAT_NUMBER_NO_RANGE:
            if (pArg->enmRangeType != DBGCVAR_RANGE_NONE)
                return VERR_DBGC_PARSE_NO_RANGE_ALLOWED;
            RT_FALL_THRU();
        case DBGCVAR_CAT_NUMBER:
            switch (pArg->enmType)
            {
                case DBGCVAR_TYPE_GC_FLAT:
                case DBGCVAR_TYPE_GC_FAR:
                case DBGCVAR_TYPE_GC_PHYS:
                case DBGCVAR_TYPE_HC_FLAT:
                case DBGCVAR_TYPE_HC_PHYS:
                    return VERR_DBGC_PARSE_INCORRECT_ARG_TYPE;

                case DBGCVAR_TYPE_NUMBER:
                    return VINF_SUCCESS;

                case DBGCVAR_TYPE_SYMBOL:
                case DBGCVAR_TYPE_STRING:
                {
                    DBGCVAR Var;
                    int rc = dbgcSymbolGet(pDbgc, pArg->u.pszString, DBGCVAR_TYPE_NUMBER, &Var);
                    if (RT_SUCCESS(rc))
                    {
                        /* deal with range */
                        if (pArg->enmRangeType != DBGCVAR_RANGE_NONE)
                        {
                            Var.enmRangeType = pArg->enmRangeType;
                            Var.u64Range = pArg->u64Range;
                        }
                        else if (enmCategory == DBGCVAR_CAT_POINTER_NO_RANGE)
                            Var.enmRangeType = DBGCVAR_RANGE_NONE;
                        *pArg = Var;
                    }
                    return rc;
                }

                default:
                    AssertMsgFailedReturn(("Invalid type %d\n", pArg->enmType), VERR_DBGC_PARSE_INCORRECT_ARG_TYPE);
            }
            break;                      /* (not reached) */

        /*
         * Symbols and strings are basically the same thing for the time being.
         */
        case DBGCVAR_CAT_STRING:
        case DBGCVAR_CAT_SYMBOL:
        {
            switch (pArg->enmType)
            {
                case DBGCVAR_TYPE_STRING:
                    if (enmCategory == DBGCVAR_CAT_SYMBOL)
                        pArg->enmType = DBGCVAR_TYPE_SYMBOL;
                    return VINF_SUCCESS;

                case DBGCVAR_TYPE_SYMBOL:
                    if (enmCategory == DBGCVAR_CAT_STRING)
                        pArg->enmType = DBGCVAR_TYPE_STRING;
                    return VINF_SUCCESS;
                default:
                    break;
            }

            /* Stringify numeric and pointer values. */
            size_t cbScratch = sizeof(pDbgc->achScratch) - (pDbgc->pszScratch - &pDbgc->achScratch[0]);
            size_t cch = pDbgc->CmdHlp.pfnStrPrintf(&pDbgc->CmdHlp, pDbgc->pszScratch, cbScratch, "%Dv", pArg);
            if (cch + 1 >= cbScratch)
                return VERR_DBGC_PARSE_NO_SCRATCH;

            pArg->enmType      = enmCategory == DBGCVAR_CAT_STRING ? DBGCVAR_TYPE_STRING : DBGCVAR_TYPE_SYMBOL;
            pArg->u.pszString  = pDbgc->pszScratch;
            pArg->enmRangeType = DBGCVAR_RANGE_BYTES;
            pArg->u64Range     = cch;

            pDbgc->pszScratch += cch + 1;
            return VINF_SUCCESS;
        }

        /*
         * These are not yet implemented.
         */
        case DBGCVAR_CAT_OPTION:
        case DBGCVAR_CAT_OPTION_STRING:
        case DBGCVAR_CAT_OPTION_NUMBER:
            AssertMsgFailedReturn(("Not implemented enmCategory=%d\n", enmCategory), VERR_DBGC_PARSE_NOT_IMPLEMENTED);

        default:
            AssertMsgFailedReturn(("Bad enmCategory=%d\n", enmCategory), VERR_DBGC_PARSE_NOT_IMPLEMENTED);
    }
}


/**
 * Parses the arguments of one command.
 *
 * @returns VBox statuc code. On parser errors the index of the troublesome
 *          argument is indicated by *pcArg.
 *
 * @param   pDbgc           Debugger console instance data.
 * @param   pszCmdOrFunc    The name of the function or command. (For logging.)
 * @param   cArgsMin        See DBGCCMD::cArgsMin and DBGCFUNC::cArgsMin.
 * @param   cArgsMax        See DBGCCMD::cArgsMax and DBGCFUNC::cArgsMax.
 * @param   paVarDescs      See DBGCCMD::paVarDescs and DBGCFUNC::paVarDescs.
 * @param   cVarDescs       See DBGCCMD::cVarDescs and DBGCFUNC::cVarDescs.
 * @param   pszArgs         Pointer to the arguments to parse.
 * @param   piArg           Where to return the index of the first argument in
 *                          DBGC::aArgs. Always set. Caller must restore DBGC::iArg
 *                          to this value when done, even on failure.
 * @param   pcArgs          Where to store the number of arguments.  In the event
 *                          of an error this is (ab)used to store the index of the
 *                          offending argument.
 */
static int dbgcProcessArguments(PDBGC pDbgc, const char *pszCmdOrFunc,
                                uint32_t const cArgsMin, uint32_t const cArgsMax,
                                PCDBGCVARDESC const paVarDescs, uint32_t const cVarDescs,
                                char *pszArgs, unsigned *piArg, unsigned *pcArgs)
{
    RT_NOREF1(pszCmdOrFunc);
    Log2(("dbgcProcessArguments: pszCmdOrFunc=%s pszArgs='%s'\n", pszCmdOrFunc, pszArgs));

    /*
     * Check if we have any argument and if the command takes any.
     */
    *piArg  = pDbgc->iArg;
    *pcArgs = 0;
    /* strip leading blanks. */
    while (*pszArgs && RT_C_IS_BLANK(*pszArgs))
        pszArgs++;
    if (!*pszArgs)
    {
        if (!cArgsMin)
            return VINF_SUCCESS;
        return VERR_DBGC_PARSE_TOO_FEW_ARGUMENTS;
    }
    if (!cArgsMax)
        return VERR_DBGC_PARSE_TOO_MANY_ARGUMENTS;

    /*
     * The parse loop.
     */
    PDBGCVAR        pArg        = &pDbgc->aArgs[pDbgc->iArg];
    PCDBGCVARDESC   pPrevDesc   = NULL;
    unsigned        cCurDesc    = 0;
    unsigned        iVar        = 0;
    unsigned        iVarDesc    = 0;
    *pcArgs = 0;
    do
    {
        /*
         * Can we have another argument?
         */
        if (*pcArgs >= cArgsMax)
            return VERR_DBGC_PARSE_TOO_MANY_ARGUMENTS;
        if (pDbgc->iArg >= RT_ELEMENTS(pDbgc->aArgs))
            return VERR_DBGC_PARSE_ARGUMENT_OVERFLOW;
        if (iVarDesc >= cVarDescs)
            return VERR_DBGC_PARSE_TOO_MANY_ARGUMENTS;

        /* Walk argument descriptors. */
        if (cCurDesc >= paVarDescs[iVarDesc].cTimesMax)
        {
            iVarDesc++;
            if (iVarDesc >= cVarDescs)
                return VERR_DBGC_PARSE_TOO_MANY_ARGUMENTS;
            cCurDesc = 0;
        }

        /*
         * Find the end of the argument.  This is just rough splitting,
         * dbgcEvalSub will do stricter syntax checking later on.
         */
        int     cPar    = 0;
        char    chQuote = '\0';
        char   *pszEnd  = NULL;
        char   *psz     = pszArgs;
        char    ch;
        bool    fBinary = false;
        for (;;)
        {
            /*
             * Check for the end.
             */
            if ((ch = *psz) == '\0')
            {
                if (chQuote)
                    return VERR_DBGC_PARSE_UNBALANCED_QUOTE;
                if (cPar)
                    return VERR_DBGC_PARSE_UNBALANCED_PARENTHESIS;
                pszEnd = psz;
                break;
            }
            /*
             * When quoted we ignore everything but the quotation char.
             * We use the REXX way of escaping the quotation char, i.e. double occurrence.
             */
            else if (chQuote)
            {
                if (ch == chQuote)
                {
                    if (psz[1] == chQuote)
                        psz++;          /* skip the escaped quote char */
                    else
                    {
                        chQuote = '\0'; /* end of quoted string. */
                        fBinary = true;
                    }
                }
            }
            else if (ch == '\'' || ch == '"')
            {
                if (fBinary)
                    return VERR_DBGC_PARSE_EXPECTED_BINARY_OP;
                chQuote = ch;
            }
            /*
             * Parenthesis can of course be nested.
             */
            else if (ch == '(')
            {
                cPar++;
                fBinary = false;
            }
            else if (ch == ')')
            {
                if (!cPar)
                    return VERR_DBGC_PARSE_UNBALANCED_PARENTHESIS;
                cPar--;
                fBinary = true;
            }
            else if (!cPar)
            {
                /*
                 * Encountering a comma is a definite end of parameter.
                 */
                if (ch == ',')
                {
                    pszEnd = psz++;
                    break;
                }

                /*
                 * Encountering blanks may mean the end of it all.  A binary
                 * operator will force continued parsing.
                 */
                if (RT_C_IS_BLANK(ch))
                {
                    pszEnd = psz++;         /* in case it's the end. */
                    while (RT_C_IS_BLANK(*psz))
                        psz++;

                    if (*psz == ',')
                    {
                        psz++;
                        break;
                    }

                    PCDBGCOP pOp = dbgcOperatorLookup(pDbgc, psz, fBinary, ' ');
                    if (!pOp || pOp->fBinary != fBinary)
                        break;              /* the end. */

                    psz += pOp->cchName;
                    while (RT_C_IS_BLANK(*psz))   /* skip blanks so we don't get here again */
                        psz++;
                    fBinary = false;
                    continue;
                }

                /*
                 * Look for operators without a space up front.
                 */
                if (dbgcIsOpChar(ch))
                {
                    PCDBGCOP pOp = dbgcOperatorLookup(pDbgc, psz, fBinary, ' ');
                    if (pOp)
                    {
                        if (pOp->fBinary != fBinary)
                        {
                            pszEnd = psz;
                            /** @todo this is a parsing error really. */
                            break;              /* the end. */
                        }
                        psz += pOp->cchName;
                        while (RT_C_IS_BLANK(*psz))   /* skip blanks so we don't get here again */
                            psz++;
                        fBinary = false;
                        continue;
                    }
                }
                fBinary = true;
            }

            /* next char */
            psz++;
        }
        *pszEnd = '\0';
        /* (psz = next char to process) */
        size_t cchArgs = strlen(pszArgs);

        /*
         * Try optional arguments until we find something which matches
         * or can easily be promoted to what the descriptor want.
         */
        for (;;)
        {
            char *pszArgsCopy = (char *)RTMemDup(pszArgs, cchArgs + 1);
            if (!pszArgsCopy)
                return VERR_DBGC_PARSE_NO_MEMORY;

            int rc = dbgcEvalSub(pDbgc, pszArgs, cchArgs, paVarDescs[iVarDesc].enmCategory, pArg);
            if (RT_SUCCESS(rc))
                rc = dbgcCheckAndTypePromoteArgument(pDbgc, paVarDescs[iVarDesc].enmCategory, pArg);
            if (RT_SUCCESS(rc))
            {
                pArg->pDesc = pPrevDesc = &paVarDescs[iVarDesc];
                cCurDesc++;
                RTMemFree(pszArgsCopy);
                break;
            }

            memcpy(pszArgs, pszArgsCopy, cchArgs + 1);
            RTMemFree(pszArgsCopy);

            /* Continue searching optional descriptors? */
            if (   rc != VERR_DBGC_PARSE_INCORRECT_ARG_TYPE
                && rc != VERR_DBGC_PARSE_INVALID_NUMBER
                && rc != VERR_DBGC_PARSE_NO_RANGE_ALLOWED
               )
                   return rc;

            /* Try advance to the next descriptor. */
            if (paVarDescs[iVarDesc].cTimesMin > cCurDesc)
                return rc;
            iVarDesc++;
            if (!cCurDesc)
                while (   iVarDesc < cVarDescs
                       && (paVarDescs[iVarDesc].fFlags & DBGCVD_FLAGS_DEP_PREV))
                    iVarDesc++;
            if (iVarDesc >= cVarDescs)
                return rc;
            cCurDesc = 0;
        }

        /*
         * Next argument.
         */
        iVar++;
        pArg++;
        pDbgc->iArg++;
        *pcArgs += 1;
        pszArgs = psz;
        while (*pszArgs && RT_C_IS_BLANK(*pszArgs))
            pszArgs++;
    } while (*pszArgs);

    /*
     * Check that the rest of the argument descriptors indicate optional args.
     */
    if (iVarDesc < cVarDescs)
    {
        if (cCurDesc < paVarDescs[iVarDesc].cTimesMin)
            return VERR_DBGC_PARSE_TOO_FEW_ARGUMENTS;
        iVarDesc++;
        while (iVarDesc < cVarDescs)
        {
            if (paVarDescs[iVarDesc].cTimesMin)
                return VERR_DBGC_PARSE_TOO_FEW_ARGUMENTS;
            iVarDesc++;
        }
    }

    return VINF_SUCCESS;
}


/**
 * Evaluate one command.
 *
 * @returns VBox status code. This is also stored in DBGC::rcCmd.
 *
 * @param   pDbgc       Debugger console instance data.
 * @param   pszCmd      Pointer to the command.
 * @param   cchCmd      Length of the command.
 * @param   fNoExecute  Indicates that no commands should actually be executed.
 */
int dbgcEvalCommand(PDBGC pDbgc, char *pszCmd, size_t cchCmd, bool fNoExecute)
{
    Assert(RTStrNLen(pszCmd, cchCmd) == cchCmd);
    char *pszCmdInput = pszCmd;

    /*
     * Skip blanks.
     */
    while (RT_C_IS_BLANK(*pszCmd))
        pszCmd++, cchCmd--;

    /* external command? */
    bool const fExternal = *pszCmd == '.';
    if (fExternal)
        pszCmd++, cchCmd--;

    /*
     * Find the end of the command name.
     */
    size_t cchName = 0;
    while (cchName < cchCmd)
    {
        char const ch = pszCmd[cchName];
        if (RT_C_IS_ALNUM(ch) || ch == '_')
            cchName++;
        else if (RT_C_IS_SPACE(ch))
            break;
        else
        {
            DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "Syntax error: Invalid command '%s'!\n", pszCmdInput);
            return pDbgc->rcCmd = VERR_DBGC_PARSE_INVALD_COMMAND_NAME;
        }
    }

    /*
     * Find the command.
     */
    PCDBGCCMD pCmd = dbgcCommandLookup(pDbgc, pszCmd, cchName, fExternal);
    if (!pCmd)
    {
        DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "Syntax error: Unknown command '%s'!\n", pszCmdInput);
        return pDbgc->rcCmd = VERR_DBGC_PARSE_COMMAND_NOT_FOUND;
    }

    /*
     * Parse arguments (if any).
     *
     * If the input isn't zero terminated, we have to make a copy because the
     * argument parser code is to crappy to deal with sub-strings at present.
     */
    size_t offArgs = cchName;
    while (offArgs < cchCmd && RT_C_IS_SPACE(pszCmd[offArgs]))
        offArgs++;

    char  szEmpty[]   = "";
    char *pszArgsFree = NULL;
    char *pszArgs     = offArgs < cchCmd ? &pszCmd[offArgs] : szEmpty;
    if (pszArgs[cchCmd - offArgs] != '\0')
    {
        /** @todo rewrite the code so it doesn't require modifiable input! */
        pszArgsFree = pszArgs = (char *)RTMemDupEx(pszArgs, cchCmd - offArgs, 1);
        AssertReturn(pszArgs, VERR_NO_MEMORY);
    }

    unsigned iArg;
    unsigned cArgs;
    int rc = dbgcProcessArguments(pDbgc,  pCmd->pszCmd,
                                  pCmd->cArgsMin, pCmd->cArgsMax, pCmd->paArgDescs, pCmd->cArgDescs,
                                  pszArgs, &iArg, &cArgs);
    if (RT_SUCCESS(rc))
    {
        AssertMsg(rc == VINF_SUCCESS, ("%Rrc\n",  rc));

        /*
         * Execute the command.
         */
        if (!fNoExecute)
            rc = pCmd->pfnHandler(pCmd, &pDbgc->CmdHlp, pDbgc->pUVM, &pDbgc->aArgs[iArg], cArgs);
        pDbgc->rcCmd = rc;
        pDbgc->iArg  = iArg;
        if (rc == VERR_DBGC_COMMAND_FAILED)
            rc = VINF_SUCCESS;
    }
    else
    {
        pDbgc->rcCmd = rc;
        pDbgc->iArg  = iArg;

        /* report parse / eval error. */
        switch (rc)
        {
            case VERR_DBGC_PARSE_TOO_FEW_ARGUMENTS:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Too few arguments. Minimum is %d for command '%s'.\n", pCmd->cArgsMin, pCmd->pszCmd);
                break;
            case VERR_DBGC_PARSE_TOO_MANY_ARGUMENTS:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Too many arguments. Maximum is %d for command '%s'.\n", pCmd->cArgsMax, pCmd->pszCmd);
                break;
            case VERR_DBGC_PARSE_ARGUMENT_OVERFLOW:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Too many arguments.\n");
                break;
            case VERR_DBGC_PARSE_UNBALANCED_QUOTE:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Unbalanced quote (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_UNBALANCED_PARENTHESIS:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Unbalanced parenthesis (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_EMPTY_ARGUMENT:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: An argument or subargument contains nothing useful (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_UNEXPECTED_OPERATOR:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Invalid operator usage (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_INVALID_NUMBER:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Syntax error: Invalid numeric value (argument %d). If a string was the intention, then quote it.\n", cArgs);
                break;
            case VERR_DBGC_PARSE_NUMBER_TOO_BIG:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Numeric overflow (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_INVALID_OPERATION:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Invalid operation attempted (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_FUNCTION_NOT_FOUND:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Function not found (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_NOT_A_FUNCTION:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: The function specified is not a function (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_NO_MEMORY:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Out memory in the regular heap! Expect odd stuff to happen...\n");
                break;
            case VERR_DBGC_PARSE_INCORRECT_ARG_TYPE:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Incorrect argument type (argument %d?).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_VARIABLE_NOT_FOUND:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: An undefined variable was referenced (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_CONVERSION_FAILED:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: A conversion between two types failed (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_NOT_IMPLEMENTED:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: You hit a debugger feature which isn't implemented yet (argument %d).\n", cArgs);
                break;
            case VERR_DBGC_PARSE_BAD_RESULT_TYPE:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Couldn't satisfy a request for a specific result type (argument %d). (Usually applies to symbols)\n", cArgs);
                break;
            case VERR_DBGC_PARSE_WRITEONLY_SYMBOL:
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp,
                    "Error: Cannot get symbol, it's set only (argument %d).\n", cArgs);
                break;

            case VERR_DBGC_COMMAND_FAILED:
                break;

            default:
                if (RTErrIsKnown(rc))
                    rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "Error: %Rra\n", rc);
                else
                    rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "Error: Unknown error %d (%#x)!\n", rc, rc);
                break;
        }
    }

    RTMemFree(pszArgsFree);
    return rc;
}


/**
 * Evaluate one or commands separated by ';' or '\n'.
 *
 * @returns VBox status code. This is also stored in DBGC::rcCmd.
 *
 * @param   pDbgc       Debugger console instance data.
 * @param   pszCmds     Pointer to the command.
 * @param   cchCmds     Length of the command.
 * @param   fNoExecute  Indicates that no commands should actually be executed.
 */
int dbgcEvalCommands(PDBGC pDbgc, char *pszCmds, size_t cchCmds, bool fNoExecute)
{
    /*
     * Trim the input.
     */
    while (cchCmds > 0 && RT_C_IS_SPACE(pszCmds[cchCmds]))
        cchCmds--;
    while (cchCmds > 0 && RT_C_IS_SPACE(*pszCmds))
        cchCmds--, pszCmds++;

    /*
     * Split up the commands and pass them to dbgcEvalCommand.
     */
    int    rcRet    = VINF_SUCCESS;
    char   chQuote  = 0;
    size_t offStart = 0;
    size_t off      = 0;
    while (off < cchCmds)
    {
        char const ch = pszCmds[off];
        if (ch == '"' || ch == '\'')
            chQuote = ch == chQuote ? 0 : chQuote == 0 ? ch : chQuote;
        else if (ch == ';' || ch == '\n')
        {
            /* Skip leading blanks and ignore empty commands. */
            while (offStart < off && RT_C_IS_SPACE(pszCmds[offStart]))
                offStart++;
            if (off > offStart)
            {
                int rc = dbgcEvalCommand(pDbgc, &pszCmds[offStart], off - offStart, fNoExecute);
                if (rcRet == VINF_SUCCESS || (RT_SUCCESS(rcRet) && RT_FAILURE(rc)))
                    rcRet = rc;
                if (   rc == VERR_DBGC_QUIT
                    || rc == VWRN_DBGC_CMD_PENDING)
                    break;
            }
            offStart = ++off;
            continue;
        }
        off++;
    }

    /*
     * Pending command?
     *
     * No need to skip leading blanks here in order to check for empty
     * commands, since we've already trimmed off tailing blanks.)
     */
    if (off > offStart)
    {
        int rc = dbgcEvalCommand(pDbgc, &pszCmds[offStart], off - offStart, fNoExecute);
        if (rcRet == VINF_SUCCESS || (RT_SUCCESS(rcRet) && RT_FAILURE(rc)))
            rcRet = rc;
    }

    return rcRet;
}


/**
 * Loads the script in @a pszFilename and executes the commands within.
 *
 * @returns VBox status code.  Will complain about error to console.
 * @param   pDbgc       Debugger console instance data.
 * @param   pszFilename The path to the script file.
 * @param   fAnnounce   Whether to announce the script.
 */
int dbgcEvalScript(PDBGC pDbgc, const char *pszFilename, bool fAnnounce)
{
    FILE *pFile = fopen(pszFilename, "r");
    if (!pFile)
        return DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "Failed to open '%s'.\n", pszFilename);
    if (fAnnounce)
        DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "Running script '%s'...\n", pszFilename);

    /*
     * Execute it line by line.
     */
    int rc = VINF_SUCCESS;
    unsigned iLine = 0;
    char szLine[8192];
    while (fgets(szLine, sizeof(szLine), pFile))
    {
        /* check that the line isn't too long. */
        char *pszEnd = strchr(szLine, '\0');
        if (pszEnd == &szLine[sizeof(szLine) - 1])
        {
            rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "runscript error: Line #%u is too long\n", iLine);
            break;
        }
        iLine++;

        /* strip leading blanks and check for comment / blank line. */
        char *psz = RTStrStripL(szLine);
        if (    *psz == '\0'
            ||  *psz == '\n'
            ||  *psz == '#')
            continue;

        /* strip trailing blanks and check for empty line (\r case). */
        while (     pszEnd > psz
               &&   RT_C_IS_SPACE(pszEnd[-1])) /* RT_C_IS_SPACE includes \n and \r normally. */
            *--pszEnd = '\0';

        /** @todo check for Control-C / Cancel at this point... */

        /*
         * Execute the command.
         *
         * This is a bit wasteful with scratch space btw., can fix it later.
         * The whole return code crap should be fixed too, so that it's possible
         * to know whether a command succeeded (RT_SUCCESS()) or failed, and
         * more importantly why it failed.
         */
        /** @todo optimize this.   */
        rc = pDbgc->CmdHlp.pfnExec(&pDbgc->CmdHlp, "%s", psz);
        if (RT_FAILURE(rc))
        {
            if (rc == VERR_BUFFER_OVERFLOW)
                rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "runscript error: Line #%u is too long (exec overflowed)\n", iLine);
            break;
        }
        if (rc == VWRN_DBGC_CMD_PENDING)
        {
            rc = DBGCCmdHlpPrintf(&pDbgc->CmdHlp, "runscript error: VWRN_DBGC_CMD_PENDING on line #%u, script terminated\n", iLine);
            break;
        }
    }

    fclose(pFile);
    return rc;
}