Re: ms-nfs41 mount: Where does Unix_User+0 and Unix_Group+0 come from?

[Martin Wege <martin.l.wege@gmail.com>]

On Thu, Aug 3, 2023 at 8:46 PM Martin Wege <martin.l.wege@gmail.com> wrote:
>
> Hello,
>
> We are working to deploy the ms-nfs41-nfs-filesystem on our Windows
> machines, and encounter some issues with Cygwin (latest stable).
>
> For example, if we go to the ms-nfs41-nfs-filesystem (not the NFS
> version 3 client from Windows!!!) with cd X: ; cd tmp/data9/, and do a
> ls -l we get 'Unix_User+0' and 'Unix_Group+0' for user and group
> names.
> The question is: Where do these names come from - Windows,
> ms-nfs41-nfs-filesystem or Cygwin?
> getent passwd and getent group do not list this on Cygwin.
> NFS version 4 server "lordbatman" has user mlw=uid(3620) and group mlw=gid(3620)
>
> Steps to reproduce:
> 1. Download and install cygwin.
> 2. Download http://www.citi.umich.edu/projects/nfsv4/windows/120612/
> and install it.
> 3. Start NFS version 4 client daemon:
> ms-nfs41-client-x64/nfsd_debug.exe -d 3 --noldap --gid 3620 --uid 3620
> 4. Mount NFS version 4 directory:
> ms-nfs41-client-x64/ms-nfs41-client-x64/nfs_mount.exe -p -o sec=sys X
> 'lordbatman.bias.dfn.de:/export/home/mlw'
>
> Expectation:
> Cygwin ls -l should list file user/group as mlw/mlw
>
> Actual results:
> Cygwin ls -l lists file user/group as Unix_User+0/Unix_Group+0

Did a cygwin source clone, and found this:
cygwin$ grep -r -E  'Unix_(User|Group)' .
./newlib-cygwin/winsup/utils/mkgroup.c:             "Unix_Group",
./newlib-cygwin/winsup/utils/mkgroup.c:                 "Unix_Group",
./newlib-cygwin/winsup/utils/mkpasswd.c:                    "Unix_User",
./newlib-cygwin/winsup/utils/mkpasswd.c:

But I do not understand this code. In which cases are Unix_User+0 and
Unix_Group+0 used?

Martin