Disables file system redirection in 64bit OS

Tip - Wow64DisableWow64FsRedirection() Wow64RevertWow64FsRedirection()

Details - This function is useful for 32-bit applications that want to gain access to the native “%SystemRoot%\System32” directory in 64bit OS. By default, WOW64 file system redirection is enabled.

BOOL WINAPI Wow64DisableWow64FsRedirection(

  __out  PVOID *OldValue

);

To restore file system redirection, the Wow64RevertWow64FsRedirection function is used. Every successful call to the Wow64DisableWow64FsRedirection function must have a matching call to the Wow64RevertWow64FsRedirection function. This will ensure redirection is re-enabled and frees associated system resources.

BOOL WINAPI Wow64RevertWow64FsRedirection(

  __in  PVOID OldValue

);

The following example uses Wow64DisableWow64FsRedirection to disable file system redirection so that a 32-bit application that is running under WOW64 can open the 64-bit version of Notepad.exe in %SystemRoot%\System32 instead of being redirected to the 32-bit version in %SystemRoot%\SysWOW64.

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     } }

Reference   -

http://msdn.microsoft.com/en-us/library/aa365743(v=VS.85).aspx

Posted By : Velayudhan Pillai K