[bug?] cygwin cannot mount smb shares beginning with underscore; "Invalid argument"

[Jeremy Hetzler]

All,

First, thank you for many years of Cygwin.

I'm unable to get Cygwin to mount Windows SMB shares where the share
name begins with underscore. mount gives an error "Invalid argument".

Windows Explorer can use the share fine. Cygwin itself can chdir to
the path fine. It just can't mount it. Shares that do not begin with
underscore work fine. Client and server are both Windows 11.

I don't see anything in the mount docs about this behavior. If this is
a known limitation, it would be helpful if it could be documented.

Cygcheck attached. Repro steps below. If I can provide more
information, let me know. Thanks.

---

~ @x13 [ELEV]
$ uname -a
CYGWIN_NT-10.0-22621 x13 3.4.3-1.x86_64 2022-12-16 12:38 UTC x86_64 Cygwin

~ @x13 [ELEV]
$ mount --version
mount (cygwin) 3.4.3
Mount filesystem utility
Copyright (C) 1996 - 2022 Cygwin Authors
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

~ @x13 [ELEV]
$ ls -la //nzxt/_test_share/
total 0
d---rwxrwx+ 1 Unknown+User Unknown+Group 0 Jan 21 11:07 .
dr-xr-xr-x  1 jhetzler     None          0 Jan 21 11:18 ..
----rwxrwx+ 1 Unknown+User Unknown+Group 0 Jan 21 11:07 foo.txt

~ @x13 [ELEV]
$ cd //nzxt/_test_share

//nzxt/_test_share @x13 [ELEV]
$ ls -la
total 0
d---rwxrwx+ 1 Unknown+User Unknown+Group 0 Jan 21 11:07 .
dr-xr-xr-x  1 jhetzler     None          0 Jan 21 11:18 ..
----rwxrwx+ 1 Unknown+User Unknown+Group 0 Jan 21 11:07 foo.txt

//nzxt/_test_share @x13 [ELEV]
$ cd /mnt

/mnt @x13 [ELEV]
$ mkdir test_mount

/mnt @x13 [ELEV]
$ mount //nzxt/_test_share/ /mnt/test_mount/
mount: defaulting to 'notexec' mount option for speed since native path
       references a remote share.  Use '-f' option to override.
mount: /mnt/test_mount/: Invalid argument

/mnt @x13 [ELEV]
$ ls -la test_mount
total 0
drwxr-xr-x 1 jhetzler None 0 Jan 21 11:19 .
drwxr-xr-x 1 jhetzler None 0 Jan 21 11:19 ..


-- 
Thanks,
Jeremy Hetzler
(he/him)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cygcheck.out
Type: application/octet-stream
Size: 195348 bytes
Desc: not available
URL: <https://cygwin.com/pipermail/cygwin/attachments/20230121/d6b2d202/attachment-0001.obj>