win7重定向函数引发的问题
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(
__outPVOID *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(
__inPVOID 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;
HINSTANCEhlibrary;
typedef int (__stdcall*Wow64DisableWow64FsRedirection)(LPVOID);
Wow64DisableWow64FsRedirectionf_Wow64DisableWow64FsRedirection=NULL;
typedef int (__stdcall*Wow64RevertWow64FsRedirection)(LPVOID);
Wow64RevertWow64FsRedirectionf_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！
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