Using forwarded filesystems with Windows Remote Client (e.g. accessing //TSCLIENT/L via mstsc.exe) ?

[Brian Inglis]

On 2025-01-09 08:18, Roland Mainz via Cygwin wrote:
> On Wed, Jan 8, 2025 at 5:33 PM Roland Mainz <roland.mainz@nrubsig.org> wrote:
>>
>> Hi!
>>
>> ----
>>
>> Does Cygwin 3.6 support filesystems which have been forwarded by the
>> Windows Remote Client (mstsc.exe) ?
>>
>> I tried to access such a forwarded dir, but $ ls -l # returned this:
>> ---- snip ----
>> $ bash -c 'cd //TSCLIENT/L && ls -l'
>> ls: cannot read symbolic link 'newtestmachine_dir2': Invalid argument
>> ls: cannot read symbolic link 'winserver2019_admindir2': Invalid argument
>> total 665207504417527
>> ?--xr--r-x     0 Unix_User+2       Unix_Group+1252
>> 8589934592 Jan  1  1970  builds
>> ?--xr--r-x 65535 Unix_User+0       Unix_Group+6539296
>> 8589934592 Jan  1  1970  download
>> ?--xr--r-x 65535 Unix_User+0       Unix_Group+6539296
>> 8589934592 Jan  1  1970  gitbundles
>> ?--xr--r-x 65535 Unix_User+0       Unix_Group+6539296
>> 8589934592 Jan  1  1970  newtestmachine1
>> l-----xr-x    13 Unix_User+6539088 Unix_Group+6539672
>> 4294967295 Jan  1  1970  newtestmachine_dir2
>> ?-ws-wS--t 65535 Unix_User+0       Unix_Group+6539296
>> 4294967296000 Jan  1  1970  newtestmachine_dir3
>> ?--xr--r-x 65535 Unix_User+0       Unix_Group+6539296
>> 8589934592 Jan  1  1970  rde
>> ?--xr--r-x 65535 Unix_User+0       Unix_Group+6539296
>> 8589934592 Jan  1  1970  rde.zip
>> ?-ws-wS--t 65535 Unix_User+0       Unix_Group+6539296
>> 4294967296000 Mar 17  1970  te_install
>> l-----x-wx    11 Unix_User+6539088 Unix_Group+6539672
>> 4294967295 Jan  1  1970  winserver2019_admindir2
>> ---- snip ----
>>
>> Any idea what is going wrong in this case ?
> 
> Short update:
> On the machine which got the forwarded filesystems I get this:
> ---- snip ----
> $ nfs_ea '\??\UNC\TSCLIENT\T\test1' getnfs3attr
> Querying extended attribute 'NfsV3Attributes' on file
> '\??\UNC\TSCLIENT\T\test1':
> ZwQueryEaFile('"') failed with 0xc0000002
> ---- snip ----
> 
> 0xC0000002 == STATUS_NOT_IMPLEMENTED
> 
> The Windows NFSv3 and NFSv4.1/NFSv.2 drivers implement support for
> "NfsV3Attributes", so it seems filesystem forwarding in RDP does not
> support EAs (=extended attributes).
> Powershell itself can handle files&&cd etc., it seems only
> applications which rely on "NfsV3Attributes" are affected...
> 
> ... maybe in Cygwin there are places where the return code for
> |nfs_fetch_fattr3()| isn't checked ?

Run a Cygwin program under Cygwin strace and redirect the output to prog.strace 
which is a time stamped text log of Cygwin internal and Windows "system calls".

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry