win7重定向函数引发的问题

http://blog.csdn.net/linfei2707/article/details/6765092

在Win7 64位系统下，调用CopyFile函数进行函数拷贝，如果希望拷贝文件到System32目录下，需要考虑程序是不是也是64位的，否则，程序会被重定向到Syswow64目录下，为了防止出现文件被重定向，就需要调用函数Wow64DisableWow64FsRedirection取消文件的重定向，并在完成指定功能后调用Wow64RevertWow64FsRedirection函数进行恢复。
MSDN中关于函数Wow64DisableWow64FsRedirection的声明：
BOOL WINAPI Wow64DisableWow64FsRedirection(
  __out  PVOID *OldValue
);
http://msdn.microsoft.com/en-us/library/aa365743(v=vs.85).aspx
MSDN中关于函数Wow64RevertWow64FsRedirection的声明：
BOOL WINAPI Wow64RevertWow64FsRedirection(
  __in  PVOID OldValue
);
http://msdn.microsoft.com/en-us/library/aa365745(v=vs.85).aspx
关于函数的使用，摘一段msdn中的代码：
#ifdef _WIN32_WINNT
#undef _WIN32_WINNT
#endif
#define _WIN32_WINNT 0x0501
#ifdef NTDDI_VERSION
#undef NTDDI_VERSION
#endif
#define NTDDI_VERSION 0x05010000
#include <Windows.h>
void main()
{
    HANDLE hFile = INVALID_HANDLE_VALUE;
    PVOID OldValue = NULL;
    //  Disable redirection immediately prior to the native API
    //  function call.
    if( Wow64DisableWow64FsRedirection(&OldValue) )
    {
        //  Any function calls in this block of code should be as concise
        //  and as simple as possible to avoid unintended results.
        hFile = CreateFile(TEXT("C://Windows//System32//Notepad.exe"),
            GENERIC_READ,
            FILE_SHARE_READ,
            NULL,
            OPEN_EXISTING,
            FILE_ATTRIBUTE_NORMAL,
            NULL);
        //  Immediately re-enable redirection. Note that any resources
        //  associated with OldValue are cleaned up by this call.
        if ( FALSE == Wow64RevertWow64FsRedirection(OldValue) )
        {
            //  Failure to re-enable redirection should be considered
            //  a criticial failure and execution aborted.
            return;
        }
    }
    //  The handle, if valid, now can be used as usual, and without
    //  leaving redirection disabled.
    if( INVALID_HANDLE_VALUE != hFile ) 
    {
        // Use the file handle
    }
}
这段代码在win764位下调用没有问题，在xp 32位下面就会出现问题，即使加上判断系统是否为64位的代码也会导致程序出现如下图的错误：
解决方案是使用动态加载的方式对Wow64DisableWow64FsRedirection和Wow64RevertWow64FsRedirection进行加载，这样问题就解决了
PVOID OldValue = NULL;
HINSTANCE  hlibrary;
typedef    int        (__stdcall  *  Wow64DisableWow64FsRedirection)(LPVOID);
Wow64DisableWow64FsRedirection  f_Wow64DisableWow64FsRedirection  =  NULL;
typedef    int        (__stdcall  *  Wow64RevertWow64FsRedirection)(LPVOID);
Wow64RevertWow64FsRedirection  f_Wow64RevertWow64FsRedirection  =  NULL;
hlibrary  =  LoadLibrary(L"Kernel32.dll");
   f_Wow64DisableWow64FsRedirection  =  (Wow64DisableWow64FsRedirection)  GetProcAddress(hlibrary,"Wow64DisableWow64FsRedirection");
   if(!f_Wow64DisableWow64FsRedirection) {
    return 0;
   }
   f_Wow64RevertWow64FsRedirection  =  (Wow64RevertWow64FsRedirection)  GetProcAddress(hlibrary,"Wow64RevertWow64FsRedirection");
   if(!f_Wow64RevertWow64FsRedirection) {
    return 0;
   }
   f_Wow64DisableWow64FsRedirection  (&OldValue);
   if(CopyFile(wNativePath,wSystemPath,FALSE)==0)
   {
    if ( FALSE == Wow64RevertWow64FsRedirection(OldValue) )
    {
     return 0;
    }
    return 0;
   }
   f_Wow64RevertWow64FsRedirection  (OldValue);
   FreeLibrary(hlibrary);
在使用这段代码前最好判断一下系统类型及位数！