exposing Windows mountpoints in Cygwin

[Jeremy Drake]

On Fri, 7 Feb 2025, Corinna Vinschen via Cygwin wrote:

> On Feb  6 13:31, Jeremy Drake via Cygwin wrote:
> > Now that my patch to escape characters in /proc/mounts has been applied,
> > I'll get back to what I was thinking about back in June.  I would like to
> > have a way to list Windows volume roots in Cygwin, and it seems to make
> > sense to me to expose them via getmntent, /proc/mounts, etc.  The way I
> > see this working is probably to replace the available_drives mechanism for
> > enumerating mounts in favor of using FindFirst/NextVolumeW and
> > GetVolumePathNamesForVolumeNameW to enumerate cygdrive mount points.
>
> Been there, done that, but that was more than 10 years ago, so things
> might have changed.  At the time, the volume manager was incredibly
> slow.  Enumerating and converting volume paths from one style into the
> other just took too much time.  And, as you know, Cygwin already is
> slow...
>
> Still, if you want to do that, it should not be part of the standard
> mount points becasue this is another level of implementation.  These are
> the POSIX mount points handled by Cygwin.  That should be part of the
> cygdrive handling.  Sounds like you were mulling over this anyway.

Right, the cygdrive_getmntent function in mount.cc.

> But it's not quite clear what the expected output should be.

> So what is the expected output in the cygdrive dir?
>
> What I could imagine is something like this.  Assuming two drives, one
> of them mounted into a dir:
>
>   C:		\Device\HarddiskVolume1
>   C:\foo	\Device\HarddiskVolume2
>
>   $ ls -gG /cygdrive
>   d---r-x---+ 1  0 Feb  7 03:38 c
>   drwxrwxr-x  1  0 Jan  8 11:02 c_foo -> /mnt/c/foo

I'm thinking much simpler than that.  I'm just thinking about enumerating
directory mounts in the cygdrive_getmntent function.  So /cygdrive looks
the same as it does now, just the roots of drives, but for instance mount
would show something like

C: on /cygdrive/c type ntfs (binary,noacl,posix=0,user,noumount,auto)
C:/foo on /cygdrive/c/foo type ntfs (binary,noacl,posix=0,user,noumount,auto)

Presumably this would also make df privy to them.