Storing ReparsePoints on filesystems

[lundman]

Hello, I'm a dev for ZFS on Windows, and I am looking at various ways to store a ReparsePoint on the filesystem, with compatibility in mind.

From the Unix world, for example illumos, when using Samba, they appear to convert ReparsePoint to string format:

* Format of reparse data:
 * @{REPARSE@{servicetype:data} [@{servicetype:data}] ...}
 * REPARSE_TAG_STR@{REPARSE_TOKEN} [@{REPARSE_TOKEN}] ... REPARSE_TAG_END

then call VOP_SYMLINK() to store it as string, with XAT_REPARSE set (which maps to FILE_ATTRIBUTE_REPARSE_POINT.)

But this is missing a parser from the Windows struct REPARSE_DATA_BUFFER to string, and back.

How does WSL2 store ReparsePoints when over a Linux (ext3/4) mountpoints? Does it only allow type SYMLINK (posix), and reject all other types? Or does it store full ReparsePoints in some format? (EA/xattr?)