Microsoft KB Archive/105306

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HOWTO: Get and Use a Handle to a Directory

Q105306

The information in this article applies to:

Microsoft Win32 Application Programming Interface (API), used with:
- the operating system: Microsoft Windows NT, versions 3.1, 3.5, 3.51, 4.0
- the operating system: Microsoft Windows 2000

SUMMARY

CreateDirectory() can be used to open a new directory. An existing directory can be opened by calling CreateFile(). To open an existing directory with CreateFile(), it is necessary to specify the flag FILE_FLAG_BACKUP_SEMANTICS. The following code shows how this can be done:

   HANDLE hFile;

   hFile = CreateFile( "c:\\mstools",
              GENERIC_READ | GENERIC_WRITE,
              FILE_SHARE_READ | FILE_SHARE_WRITE,
              NULL,
              OPEN_EXISTING,
              FILE_FLAG_BACKUP_SEMANTICS,
              NULL
           );
   if( hFile == INVALID_HANDLE_VALUE )
      MessageBox( NULL, "CreateFile() failed", NULL, MB_OK );

The handle obtained can be used to obtain information about the directory or to set information about the directory. For example:

   BY_HANDLE_FILE_INFORMATION fiBuf;
   FILETIME ftBuf;
   SYSTEMTIME stBuf;
   char msg[40];

   GetFileInformationByHandle( hFile, &fiBuf );
   FileTimeToLocalFileTime( &fiBuf.ftLastWriteTime, &ftBuf );
   FileTimeToSystemTime( &ftBuf, &stBuf );
   wsprintf( msg, "Last write time is %d:%d  %d/%d/%d",
      stBuf.wHour,stBuf.wMinute,stBuf.wMonth,stBuf.wDay,stBuf.wYear );
   MessageBox( NULL, msg, NULL, MB_OK );

MORE INFORMATION

Opening directories with CreateFile is not supported on Windows 95.

This code does not work on Win32s, because MS-DOS does not support opening a directory. If you are looking for the creation time of a directory, use FindFirstFile(), because it works on all platforms.

Additional query words:

Keywords : kbAPI kbFileIO kbKernBase kbOSWin2000 kbDSupport kbGrpDSKernBase
Issue type : kbhowto
Technology : kbAudDeveloper kbWin32sSearch kbWin32API