判断文件是否PE文件，是否GUI程序

BOOL IsWindowsApp( CString strPathName )
 {
     if ( ! PathFileExists( strPathName ) )
         return FALSE;
 
     // 根据 PE 签名判断当前文件是否合法的 PE 文件
     HANDLE hFile = CreateFile( strPathName, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL );
     if ( hFile == INVALID_HANDLE_VALUE ) {
         TRACE1( "Failed To Open File %s !\n", strPathName );
         return FALSE;
     }
 
     HANDLE hMMFile = CreateFileMapping( hFile, NULL, PAGE_READONLY, 0, 0, NULL );
     if ( hMMFile == INVALID_HANDLE_VALUE ) {
         CloseHandle( hFile );
         return FALSE;
     }
 
     LPVOID pvMem = MapViewOfFile( hMMFile, FILE_MAP_READ, 0, 0, 0 );
     if ( ! pvMem ) {
         CloseHandle( hMMFile );
         CloseHandle( hFile );
         return FALSE;
     }
 
     // 是否包含有 DOS 签名
     if ( *( USHORT* ) pvMem != IMAGE_DOS_SIGNATURE ) {
         UnmapViewOfFile( pvMem );
         CloseHandle( hMMFile );
         CloseHandle( hFile );
         return FALSE;
     }
 
     // 是否包含有 NT 签名
     if ( *( ( DWORD* ) ( ( PBYTE ) pvMem + ( ( PIMAGE_DOS_HEADER ) pvMem )->e_lfanew ) ) != IMAGE_NT_SIGNATURE ) {
         UnmapViewOfFile( pvMem );
         CloseHandle( hMMFile );
         CloseHandle( hFile );
         return FALSE;
     }
 
     LPVOID pvOptionalHeader =  ( PBYTE ) pvMem + ( ( PIMAGE_DOS_HEADER ) pvMem )->e_lfanew + sizeof( DWORD ) + sizeof( IMAGE_FILE_HEADER );
 
     IMAGE_OPTIONAL_HEADER ioh;
     CopyMemory( & ioh, pvOptionalHeader, sizeof( IMAGE_OPTIONAL_HEADER ) );
 
     if ( ioh.Subsystem == IMAGE_SUBSYSTEM_WINDOWS_GUI ) {
         UnmapViewOfFile( pvMem );
         CloseHandle( hMMFile );
         CloseHandle( hFile );   
 
         return TRUE;
     }
 
     return FALSE;
 }