Determine whether a file is a junction (in Windows) or not?

Question

I\'ve been searching around trying to find a way to determine if a file is a junction or not, and have not found any satisfactory answers.

First thing I tried was:

Answer 1

If you can write native code in JNA, you can directly call the Win32 API GetFileAttributes() function and check for the FILE_ATTRIBUTE_REPARSE_POINT flag (junctions are implemented as reparse points).

Update: To differentiate between different types of reparse points, you have to retreive the ReparseTag of the actual reparse point. For a junction point, it will be set to IO_REPARSE_TAG_MOUNT_POINT (0xA0000003).

There are two ways to retreive the ReparseTag:

1. Use DeviceIoControl() with the FSCTL_GET_REPARSE_POINT control code to obtain an REPARSE_DATA_BUFFER struct, which as a ReparseTag field. You can see an example of an IsDirectoryJunction() implementation using this technique in the following article:

   NTFS Hard Links, Directory Junctions, and Windows Shortcuts

2. Use FindFirstFile() to obtain a WIN32_FIND_DATA struct. If the path has the FILE_ATTRIBUTE_REPARSE_POINT attribute, the dwReserved0 field will contain the ReparseTag.