Ring3层 UNICODE_STRING

今天写驱动用到UNICODE_STRING，就在Ring3层抠了一些源代码，学习一下，不多说了上代码了

#pragma once

#include <windows.h>
#include <iostream>
using namespace std;
#define BUFFER_SIZE 0x400
typedef struct _UNICODE_STRING 
{
    USHORT Length;
    USHORT MaximumLength;
    PWCHAR Buffer;
}UNICODE_STRING,*PUNICODE_STRING;


/************************************************************************/
/* 初始化                                                               */
/************************************************************************/
void Sub_1();
VOID
RtlInitUnicodeString(
    OUT PUNICODE_STRING DestinationString,
    IN PCWSTR SourceString OPTIONAL);//微软源代码


void Sub_2();
void Sub_3();
void Sub_4();   
VOID
RtlCopyUnicodeString(
    OUT PUNICODE_STRING DestinationString,
    IN PUNICODE_STRING SourceString OPTIONAL);//微软源代码
VOID
RtlFreeUnicodeString(
    IN OUT PUNICODE_STRING UnicodeString);     //微软源代码

#include "UnicodeString(User).h"
int main()
{
    Sub_1();
    Sub_2();
    Sub_3();
    Sub_4();
    printf("Input AnyKey To Exit
");
    getchar();

    return 0;
}

void Sub_1()
{
    //常量指针直接灌上去
    UNICODE_STRING v1;
    RtlInitUnicodeString(&v1, L"HelloWorld");
    printf("%Z
", &v1);
}
//Windows源代码
VOID 
RtlInitUnicodeString(
    OUT PUNICODE_STRING DestinationString,
    IN PCWSTR SourceString OPTIONAL)
{
    USHORT Length = 0;
     DestinationString->Length = 0;
     DestinationString->Buffer = (PWCHAR)SourceString;
     
     if (SourceString!=NULL)
     {
         while (*SourceString++)//源地址头
         {
             Length += sizeof(*SourceString);
             DestinationString->Length = Length;
             DestinationString->MaximumLength = Length + sizeof(UNICODE_NULL);
         }
     }
     else
     {
         DestinationString->Length = 0;
         DestinationString->MaximumLength = 0;
     }

}
void Sub_2()
{
    //栈区内存通过缓存区灌上去
    UNICODE_STRING v1;
    WCHAR BufferData[] = L"HelloWorld";
    v1.Buffer = BufferData;
    v1.Length = wcslen(BufferData) * sizeof(WCHAR);
    v1.MaximumLength = (wcslen(BufferData) + 1) * sizeof(WCHAR);
    printf("%Z
", &v1);
}
void Sub_3()
{
    //堆区内存通过动态申请
    UNICODE_STRING v1;
    WCHAR BufferData[] = L"HelloWorld";

    v1.Length = wcslen(BufferData) * sizeof(WCHAR);
    v1.MaximumLength = (wcslen(BufferData) + 1) * sizeof(WCHAR);
    v1.Buffer = (WCHAR*)malloc(v1.MaximumLength);
    RtlZeroMemory(v1.Buffer, v1.MaximumLength);
    RtlCopyMemory(v1.Buffer, BufferData, v1.Length);

    printf("%Z
", &v1);
    if (v1.Buffer != NULL)
    {
        free(v1.Buffer);
        v1.Buffer = NULL;
        v1.Length = v1.MaximumLength = 0;
    }
}

void Sub_4()
{

    UNICODE_STRING SourceString;
    RtlInitUnicodeString(&SourceString, L"HelloWorld");
    UNICODE_STRING DestinationString = { 0 };
    
    DestinationString.Buffer = (PWSTR)malloc(BUFFER_SIZE);
    DestinationString.MaximumLength = BUFFER_SIZE;
    
    RtlCopyUnicodeString(&DestinationString, &SourceString);
    
    printf("SourceString:%wZ
", &SourceString);
    printf("DestinationString:%wZ
", &DestinationString);
    
    RtlFreeUnicodeString(&DestinationString);
}


VOID
RtlCopyUnicodeString(
    OUT PUNICODE_STRING DestinationString,
    IN PUNICODE_STRING SourceString OPTIONAL
)
{
    WCHAR *v1, *v2;
    ULONG SourceStringLength = 0;
    if (SourceString != NULL)
    {

        v1 = DestinationString->Buffer;
        v2 = SourceString->Buffer;
        SourceStringLength = SourceString->Length;
        if ((USHORT)SourceStringLength > DestinationString->MaximumLength) //这个UHORT转换挺重要不然gg
        {
            SourceStringLength = DestinationString->MaximumLength;//一个是目标长度小于源目标
        }
        
        DestinationString->Length = (USHORT)SourceStringLength;

        RtlCopyMemory(v1, v2, SourceStringLength);

        if (DestinationString->Length < DestinationString->MaximumLength)
        {
            v1[SourceStringLength / sizeof(WCHAR)] = UNICODE_NULL;//清空操作
            //或者v2[SourceStringLength] = UNICODE_NULL;//清空操作
        }
    }
    else
    {
        DestinationString->Length = 0;
        DestinationString->MaximumLength = 0;
    }
    return;
}

VOID
RtlFreeUnicodeString(
    IN OUT PUNICODE_STRING UnicodeString
    )
{

    if (UnicodeString->Buffer) 
    {
        free(UnicodeString->Buffer);
        memset( UnicodeString, 0, sizeof( *UnicodeString ) );    
    }
}