rtti.cpp

一个实时的驱动支持库

/*
    This is a C++ run-time library for Windows kernel-mode drivers.
    Copyright (C) 2004 Bo Brant閚.
*/

/*
    The following is a modified subset of wine/dlls/msvcrt/cpp.c
    from version wine20040505.
*/

/*
 * msvcrt.dll C++ objects
 *
 * Copyright 2000 Jon Griffiths
 * Copyright 2003 Alexandre Julliard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <typeinfo.h>

extern "C" unsigned char __stdcall IsBadReadPtr(const void*, unsigned int);

typedef void (*v_table_ptr)();

typedef struct _cpp_object
{
    v_table_ptr*    vtable;
} cpp_object;

typedef struct _rtti_base_descriptor
{
    type_info*      type_descriptor;
    int             num_base_classes;
    int             base_class_offset;
    unsigned int    flags;
    int             unknown1;
    int             unknown2;
} rtti_base_descriptor;

typedef struct _rtti_base_array
{
    const rtti_base_descriptor* bases[3];   /* First element is the class itself */
} rtti_base_array;

typedef struct _rtti_object_hierachy
{
    int                     unknown1;
    int                     unknown2;
    int                     array_len;  /* Size of the array pointed to by 'base_classes' */
    const rtti_base_array*  base_classes;
} rtti_object_hierachy;

typedef struct _rtti_object_locator
{
    int                         unknown1;
    int                         base_class_offset;
    unsigned int                flags;
    type_info*                  type_descriptor;
    const rtti_object_hierachy* type_hierachy;
} rtti_object_locator;

/* Get type info from an object (internal) */
static const rtti_object_locator* RTTI_GetObjectLocator(void* inptr)
{
    cpp_object* cppobj = (cpp_object*) inptr;
    const rtti_object_locator* obj_locator = 0;

    if (!IsBadReadPtr(cppobj, sizeof(void*)) &&
        !IsBadReadPtr(cppobj->vtable - 1, sizeof(void*)) &&
        !IsBadReadPtr((void*)cppobj->vtable[-1], sizeof(rtti_object_locator)))
    {
        obj_locator = (rtti_object_locator*) cppobj->vtable[-1];
    }

    return obj_locator;
}

/******************************************************************
 *      __RTtypeid (MSVCRT.@)
 *
 * Retrieve the Run Time Type Information (RTTI) for a C++ object.
 *
 * PARAMS
 *  cppobj [I] C++ object to get type information for.
 *
 * RETURNS
 *  Success: A type_info object describing cppobj.
 *  Failure: If the object to be cast has no RTTI, a __non_rtti_object
 *           exception is thrown. If cppobj is NULL, a bad_typeid exception
 *           is thrown. In either case, this function does not return.
 *
 * NOTES
 *  This function is usually called by compiler generated code as a result
 *  of using one of the C++ dynamic cast statements.
 */
extern "C" void* __cdecl __RTtypeid(void* inptr)
{
    cpp_object* cppobj = (cpp_object*) inptr;
    const rtti_object_locator* obj_locator = RTTI_GetObjectLocator(cppobj);

    if (!obj_locator)
    {
        if (!cppobj)
        {
            throw bad_typeid();
        }
        else
        {
            throw __non_rtti_object();
        }
    }

    return obj_locator->type_descriptor;
}

/******************************************************************
 *      __RTDynamicCast (MSVCRT.@)
 *
 * Dynamically cast a C++ object to one of its base classes.
 *
 * PARAMS
 *  inptr       [I] Any C++ object to cast
 *  unknown     [I] Reserved, set to 0
 *  SrcType     [I] type_info object describing cppobj
 *  TargetType  [I] type_info object describing the base class to cast to
 *  isReference [I] TRUE = throw an exception if the cast fails, FALSE = don't
 *
 * RETURNS
 *  Success: The address of cppobj, cast to the object described by dst.
 *  Failure: NULL, If the object to be cast has no RTTI, or dst is not a
 *           valid cast for cppobj. If isReference is TRUE, a bad_cast exception
 *           is thrown and this function does not return.
 *
 * NOTES
 *  This function is usually called by compiler generated code as a result
 *  of using one of the C++ dynamic cast statements.
 */
extern "C" void* __cdecl __RTDynamicCast(void* inptr, long unknown, void* SrcType, void* TargetType, int isReference)
{
    cpp_object* cppobj = (cpp_object*) inptr;
    type_info* src = (type_info*) SrcType;
    type_info* dst = (type_info*) TargetType;
    const rtti_object_locator* obj_locator;

    if (unknown)
    {
        //DbgPrint("Unknown parameter is non-zero: please report\n");
    }

    if (!cppobj)
    {
        return 0;
    }

    obj_locator = RTTI_GetObjectLocator(cppobj);

    /* To cast an object at runtime:
     * 1.Find out the true type of the object from the typeinfo at vtable[-1]
     * 2.Search for the destination type in the class hierarchy
     * 3.If destination type is found, return base object address + dest offset
     *   Otherwise, fail the cast
     */
    if (obj_locator)
    {
        int count = 0;
        const rtti_object_hierachy* obj_bases = obj_locator->type_hierachy;
        const rtti_base_descriptor* const * base_desc = obj_bases->base_classes->bases;
        int src_offset = obj_locator->base_class_offset, dst_offset = -1;

        while (count < obj_bases->array_len)
        {
            const type_info* typ = (*base_desc)->type_descriptor;

            if (typ == dst)
            {
                dst_offset = (*base_desc)->base_class_offset;
                break;
            }
            base_desc++;
            count++;
        }
        if (dst_offset >= 0)
        {
            return (void*)((unsigned long)cppobj - src_offset + dst_offset);
        }
    }

    /* VC++ sets isReference to 1 when the result of a dynamic_cast is assigned
     * to a reference, since references cannot be NULL.
     */
    if (isReference)
    {
        throw bad_cast();
    }

    return 0;
}

/******************************************************************
 *      __RTCastToVoid (MSVCRT.@)
 *
 * Dynamically cast a C++ object to a void*.
 *
 * PARAMS
 *  cppobj [I] The C++ object to cast
 *
 * RETURNS
 *  Success: The base address of the object as a void*.
 *  Failure: NULL, if cppobj is NULL or has no RTTI.
 *
 * NOTES
 *  This function is usually called by compiler generated code as a result
 *  of using one of the C++ dynamic cast statements.
 */
extern "C" void* __cdecl __RTCastToVoid(void* inptr)
{
    cpp_object* cppobj = (cpp_object*) inptr;
    const rtti_object_locator* obj_locator = RTTI_GetObjectLocator(cppobj);

    if (!obj_locator)
    {
        return 0;
    }

    /* Casts to void* simply cast to the base object */
    return (void*)((unsigned long)cppobj - obj_locator->base_class_offset);
}