Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

[Matt D.]

On Windows you can create symbolic links which point to volume UUIDs as 
a way of mounting and unmounting them without having to use the 
administrative disk management tools.

For example, in cmd:

mountvol
...
     \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
         C:\
...
mklink /d test \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
...
dir test

I call mounvol to get a list of volumes and create a symbolic link 
'test' which points to the C:\ UUID. When I then 'dir test' it will list 
all files on that volume.

If I try to access it through Cygwin Bash I get the following error:

$ dir test/
dir: cannot access 'test/': No such file or directory

This makes it difficult to work with unmounted volumes as it's not 
always possible to access the administrative disk management snap-in and 
the mountvol/mklink has always been my go-to for this type of 
functionality. It would be great if Cygwin would support it.


Matt D.

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Re: Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

[L. A. Walsh]

Matt D. wrote:
> On Windows you can create symbolic links which point to volume UUIDs 
> as a way of mounting and unmounting them without having to use the 
> administrative disk management tools.
>
> For example, in cmd:
>
> mountvol
> ...
>     \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
>         C:\
> ...
> mklink /d test \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
---
    mklink and mklink /d create SYMLINKs (and SYMLINKDs).  To create
MS mount points you need to create them as junctions (mklink /J) and
I think that should work for what you are doing.

    Unfortunately, cygwin breaks MS-mounts by treating them as symlinks,
so if you use standard *nix utils to copy that dir, it won't be read as a
dir, but as a symlink, so when it's written to a destination, it seems like
it would attempt to overwrite the directory with a symlink. 

    I know it messes up being able to keep cygwin dirs on a separate disk
unless you _only_ store 1 cygwin-dir/mount point.

    For example, if you have a cygwin on a "D" drive, you won't be
able to use junctions to mount D:/usr on /usr and D:/bin on /bin without
cygwin destroying the mountpoints when software is installed. 

    Very unfortunate, since linux DOES have the dynamic-mount points
with its 'bind' options.

    Somehow, having users be able to destroy mount-points doesn't seem
that secure.


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Re: Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

[Corinna Vinschen]

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On Feb 15 07:30, Matt D. wrote:
> On Windows you can create symbolic links which point to volume UUIDs as a
> way of mounting and unmounting them without having to use the administrative
> disk management tools.
> 
> For example, in cmd:
> 
> mountvol
> ...
>     \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
>         C:\
> ...
> mklink /d test \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
> ...
> dir test
> 
> I call mounvol to get a list of volumes and create a symbolic link 'test'
> which points to the C:\ UUID. When I then 'dir test' it will list all files
> on that volume.
> 
> If I try to access it through Cygwin Bash I get the following error:
> 
> $ dir test/
> dir: cannot access 'test/': No such file or directory
> 
> This makes it difficult to work with unmounted volumes as it's not always
> possible to access the administrative disk management snap-in and the
> mountvol/mklink has always been my go-to for this type of functionality. It
> would be great if Cygwin would support it.

This type of directory symlink to a GUID volume path isn't supported
at all yet in Cygwin.  However, you can access the directory directly
without having to go through MKLINK.  In Cygwin:

  $ cd /proc/sys/GLOBAL\?\?/Volume{079b79c9-0000-0000-0000-100000000000}/

or

  $ ln -s \
  /proc/sys/GLOBAL\?\?/Volume\{079b79c9-0000-0000-0000-100000000000}/ \
  my_vol
  $ cd my_vol

Note the trailing slash.  Volume{079b79c9-0000-0000-0000-100000000000}
without the slash is the block device.
Volume{079b79c9-0000-0000-0000-100000000000}/ with trailing slash is the
filesystem on the block device.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
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Red Hat

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Re: Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

[Andrey Repin]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=utf-8, Size: 3655 bytes --]

Greetings, Matt D.!

> On Windows you can create symbolic links which point to volume UUIDs as 
> a way of mounting and unmounting them without having to use the 
> administrative disk management tools.

> For example, in cmd:

> mountvol
> ...
>      \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
>          C:\
> ...
> mklink /d test \\?\Volume{079b79c9-0000-0000-0000-100000000000}\
> ...
> dir test

> I call mounvol to get a list of volumes and create a symbolic link 
> 'test' which points to the C:\ UUID. When I then 'dir test' it will list 
> all files on that volume.

> If I try to access it through Cygwin Bash I get the following error:

> $ dir test/
> dir: cannot access 'test/': No such file or directory

> This makes it difficult to work with unmounted volumes as it's not 
> always possible to access the administrative disk management snap-in and 
> the mountvol/mklink has always been my go-to for this type of 
> functionality. It would be great if Cygwin would support it.

$ (mountvol; cmd /C dir /N) | iconv -f CP866; dir sd?1/

...

    \\?\Volume{80006d80-c2bb-4297-93c1-2f6d1a2a8acb}\
        C:\
        C:\dev\sda1\

    \\?\Volume{6833c423-2223-11e4-b07d-806e6f6e6963}\
        *** НЕТ ТОЧЕК ПОДКЛЮЧЕНИЯ ***

    \\?\Volume{9d412aba-0e54-4628-9c6b-b84fb18d062a}\
        *** НЕТ ТОЧЕК ПОДКЛЮЧЕНИЯ ***

    \\?\Volume{6833c424-2223-11e4-b07d-806e6f6e6963}\
        *** НЕТ ТОЧЕК ПОДКЛЮЧЕНИЯ ***

    \\?\Volume{51810762-adac-11e4-9801-902b3437d8e4}\
        W:\

    \\?\Volume{152b5e11-3180-11e4-9bb8-806e6f6e6963}\
        R:\

...

13.08.2016  23:13    <DIR>          .
13.08.2016  23:13    <DIR>          ..
21.08.2015  00:30    <JUNCTION>     sda1 [\\?\Volume{80006d80-c2bb-4297-93c1-2f6d1a2a8acb}\]
31.08.2014  23:57    <JUNCTION>     sdb1 [\\?\Volume{9d412aba-0e54-4628-9c6b-b84fb18d062a}\]
31.08.2014  23:55    <JUNCTION>     sdc1 [\\?\Volume{6833c423-2223-11e4-b07d-806e6f6e6963}\]
31.08.2014  23:55    <JUNCTION>     sdd1 [\\?\Volume{6833c424-2223-11e4-b07d-806e6f6e6963}\]
16.02.2017  13:43    <DIR>          temp

...

sda1/:
$Recycle.Bin  Documents\ and\ Settings  hiberfil.sys  Program\ Files               Users
arc           DrWeb                     home          Program\ Files\ (x86)        usr
Config.Msi    DrWeb\ Quarantine         os792636.bin  ProgramData                  var
cygwin        ftn                       pagefile.sys  Programs                     Windows
dev           Games                     PerfLogs      System\ Volume\ Information

sdb1/:
$RECYCLE.BIN  DirectoryHotlist.reg  Program\ Files  reg   System\ Volume\ Information
dev           Fraps                 Programs        reg~  url.nobrain

sdc1/:
$RECYCLE.BIN        EDIUS-Data     Profiles  src                          usr
10-remote-vpn.conf  eventcuts.zip  Programs  System\ Volume\ Information  var
CapCharges.jpg      FCPF9C.html    RECYCLER  temp                         VirtualBox
default.wjr         ftn            REINST    Thumbs.db                    VirtualPad
Disks               Other          Reserv    Track12-2.wav                xD-2010-07-23.rar

sdd1/:
$RECYCLE.BIN  arc  Games  Scratch  System\ Volume\ Information


-- 
With best regards,
Andrey Repin
Thursday, February 16, 2017 16:55:19

Sorry for my terrible english...\0ТÒÐÐ¥\a&ö&ÆVÒ\a&W\x06÷'G3¢\x02\x02\x02\x02\x02\x02\x06‡GG\x03¢òö7–wv–âæ6öÒ÷\a&ö&ÆV×2æ‡FÖÀФd\x15\x13¢\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x02\x06‡GG\x03¢òö7–wv–âæ6öÒöf\x17\x12ðФFö7VÖVçF\x17F–öã¢\x02\x02\x02\x02\x02\x02\x02\x02\x06‡GG\x03¢òö7–wv–âæ6öÒöFö72æ‡FÖÀÐ¥Vç7V'67&–&R\x06–æfó¢\x02\x02\x02\x02\x02\x06‡GG\x03¢òö7–wv–âæ6öÒöÖÂò7Vç7V'67&–&R×6–×\x06ÆPРÐ

Re: Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

[L. A. Walsh]

Corinna Vinschen wrote:
> This type of directory symlink to a GUID volume path isn't supported
> at all yet in Cygwin.  
As I mentioned, symlinks don't support volume destinations
under windows, but Junctions should be used instead.  They
half-way work under Cygwin (junctions to volumes look like
mounted file systems look under linux, but junctions to
pathnames get converted by cygwin to symlinks -- losing
information when such junctions are restored.

Corinna -- could you _please_ re-look at supporting both
types of junctions as mount points?  Then Cygwin could have
"mount-parity" with linux! ;-)

Thanks!


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Re: Cannot access volumes mounted with 'mklink /d' which point to a volume UUID

[Corinna Vinschen]

[-- Attachment #1: Type: text/plain, Size: 1348 bytes --]

On Feb 24 13:49, L. A. Walsh wrote:
> Corinna Vinschen wrote:
> > This type of directory symlink to a GUID volume path isn't supported
> > at all yet in Cygwin.
> As I mentioned, symlinks don't support volume destinations
> under windows, but Junctions should be used instead.  They
> half-way work under Cygwin (junctions to volumes look like
> mounted file systems look under linux, but junctions to
> pathnames get converted by cygwin to symlinks -- losing
> information when such junctions are restored.
> 
> Corinna -- could you _please_ re-look at supporting both
> types of junctions as mount points?  Then Cygwin could have
> "mount-parity" with linux! ;-)

That's not easily possible.  Mount points in Cygwin are virtual entries
stored in the per-user session, in-memory mount table.  You can't easily
fetch all dir junctions on a volume, and the mount table is also
restricted in size.  Volume junctions look like mount points because the
device id changes below the reparse point, while they don't for dir
junctions to the same volume.  If you want them handled as mount points,
add the path as a Cygwin mount point to /etc/fstab or /etc/fstab.d/$USER


Corinna

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Red Hat

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showing all JUNCTIONS as normal dirs as w/linux --bind (was Re: Cannot access volumes mounted with 'mklink...)

[L. A. Walsh]

Corinna Vinschen wrote:
>
>>  They
>> half-way work under Cygwin (junctions to volumes look like
>> mounted file systems look under linux, but junctions to
>> pathnames get converted by cygwin to symlinks -- losing
>> information when such junctions are restored.
>>
>> Corinna -- could you _please_ re-look at supporting both
>> types of junctions as mount points?  Then Cygwin could have
>> "mount-parity" with linux! ;-)
>>     
>
> That's not easily possible.  Mount points in Cygwin are virtual entries
> stored in the per-user session, in-memory mount table. 
---
    Ahh.. you are making it more complicated than what I'm
asking! (yey! this should be simpler)...

    If I have a junction to the root of another volume, in
cygwin it looks like a normal directory:

Using mountvol...

C:\>mountvol mountedVol \\?\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}
03/02/2017  01:24 PM    <JUNCTION>     mountedVol 
[\??\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}\]
01/11/2017  04:17 PM    <JUNCTION>     var [C:\Windows\System32\cygwin\var]

### a junction is created ... under Cygwin. 
Note, BTW, that 'var' is also a JUNCTION (a MS-mount point).


C:\>exit
exit
/> ll
total 100672654
drwxrwx---+  1            0 Nov 20  2010 $RECYCLE.BIN/
...
drwxrwx---+  1            0 May 15  2015 mountedVol/
lrwxrwxrwx   1           28 Jan 11 16:17 var -> 
/Windows/System32/cygwin/var/

/> ls mountedVol
$RECYCLE.BIN/  System Volume Information/

### mountedVol looks like a normal directory ^^^, but 'var' shows
### as a symlink.  That's the problem I'm referring to.  I'm saying
### JUNCTIONs (MS-mountpoints) should show up as the 'same' in
### Cygwin -- i.e. --

### But is not necessary that it be shown in Cygwin's "mount table":

/> mount
C:/bin on /usr/bin type ntfs (binary,auto)
C:/lib on /usr/lib type ntfs (binary,auto)
C: on / type ntfs (binary,auto)
B: on /b type smbfs (binary,user,noumount,auto)
...

----
It's the same on linux.
linux> stat -c %D /var
822
linux> sudo mount --rbind /var/rtmp /tmp
linux> stat -c %D /tmp
822

----
A mount from the same fs to another place on the same fs,
looks like a normal directory (not a symlink).

This is the behavior I would want for 'JUNCTION's under
Cygwin. 

On Windows, mklink creates a 'SYMLINK' or 'SYMLINKD' when
directories are linked.  Those would stay as "Symlinks".








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Treating Junctions consistently, as "normal dirs" as w/linux "bind"-type mount

[L. A. Walsh]

Didn't see a response to this, so reposting, as this
would provide a needed vol and subdir mount facility as
exists on linux...

Especially, since there was a misunderstanding of what
was needed or wanted w/regards to the JUNCTION file-system
mounts in Windows.   Didn't need mount table updated, just
needed it to look like a normal mount (as 1 of the 
2 junction usages already does).  So it's just a matter of
making the other junction type w/a path be treated as
a normal dir instead of a symlink.  As it is now, it's 
inconsistent with junctions created with mountvol being
different from junctions created with linkd.

Symlink(D)s would stay as they are now and provide the
symlink functionality.

Original note:

Corinna Vinschen wrote:
>
>>  They
>> half-way work under Cygwin (junctions to volumes look like
>> mounted file systems look under linux, but junctions to
>> pathnames get converted by cygwin to symlinks -- losing
>> information when such junctions are restored.
>>
>> Corinna -- could you _please_ re-look at supporting both
>> types of junctions as mount points?  Then Cygwin could have
>> "mount-parity" with linux! ;-)
>>     
>
> That's not easily possible.  Mount points in Cygwin are virtual entries
> stored in the per-user session, in-memory mount table. 
---
   Ahh.. you are making it more complicated than what I'm
asking! (yey! this should be simpler)...

   If I have a junction to the root of another volume, in
cygwin it looks like a normal directory:

Using mountvol...

C:\>mountvol mountedVol \\?\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}
03/02/2017  01:24 PM    <JUNCTION>     mountedVol 
[\??\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}\]
01/11/2017  04:17 PM    <JUNCTION>     var [C:\Windows\System32\cygwin\var]

### a junction is created ... under Cygwin. 
Note, BTW, that 'var' is also a JUNCTION (a MS-mount point).


C:\>exit
exit
/> ll
total 100672654
drwxrwx---+  1            0 Nov 20  2010 $RECYCLE.BIN/
...
drwxrwx---+  1            0 May 15  2015 mountedVol/
lrwxrwxrwx   1           28 Jan 11 16:17 var -> 
/Windows/System32/cygwin/var/

/> ls mountedVol
$RECYCLE.BIN/  System Volume Information/

### mountedVol looks like a normal directory ^^^, but 'var' shows
### as a symlink.  That's the problem I'm referring to.  I'm saying
### JUNCTIONs (MS-mountpoints) should show up as the 'same' in
### Cygwin -- i.e. --

### But is not necessary that it be shown in Cygwin's "mount table":

/> mount
C:/bin on /usr/bin type ntfs (binary,auto)
C:/lib on /usr/lib type ntfs (binary,auto)
C: on / type ntfs (binary,auto)
B: on /b type smbfs (binary,user,noumount,auto)
...

----
It's the same on linux.
linux> stat -c %D /var
822
linux> sudo mount --rbind /var/rtmp /tmp
linux> stat -c %D /tmp
822

----
A mount from the same fs to another place on the same fs,
looks like a normal directory (not a symlink).

This is the behavior I would want for 'JUNCTION's under
Cygwin. 

On Windows, mklink creates a 'SYMLINK' or 'SYMLINKD' when
directories are linked.  Those would stay as "Symlinks".









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Re: Treating Junctions consistently, as "normal dirs" as w/linux "bind"-type mount

[Andrey Repin]

Greetings, L. A. Walsh!

> Didn't see a response to this, so reposting, as this
> would provide a needed vol and subdir mount facility as
> exists on linux...

> Especially, since there was a misunderstanding of what
> was needed or wanted w/regards to the JUNCTION file-system
> mounts in Windows.   Didn't need mount table updated, just
> needed it to look like a normal mount (as 1 of the 
> 2 junction usages already does).  So it's just a matter of
> making the other junction type w/a path be treated as
> a normal dir instead of a symlink.  As it is now, it's 
> inconsistent with junctions created with mountvol being
> different from junctions created with linkd.

> Symlink(D)s would stay as they are now and provide the
> symlink functionality.

I would argue against all junctions being treated blindly.
The difference with bind mounts in Linux is that in Linux you don't have the
information available within the filesystem itself, and have no other option,
than to treat them as regular directories.
Only direct volume junctions cause an issue, and this is what should be fixed,
if possible, not sidetracked with questionable workarounds.

> Original note:

> Corinna Vinschen wrote:
>>
>>>  They
>>> half-way work under Cygwin (junctions to volumes look like
>>> mounted file systems look under linux, but junctions to
>>> pathnames get converted by cygwin to symlinks -- losing
>>> information when such junctions are restored.
>>>
>>> Corinna -- could you _please_ re-look at supporting both
>>> types of junctions as mount points?  Then Cygwin could have
>>> "mount-parity" with linux! ;-)
>>>     
>>
>> That's not easily possible.  Mount points in Cygwin are virtual entries
>> stored in the per-user session, in-memory mount table. 
> ---
>    Ahh.. you are making it more complicated than what I'm
> asking! (yey! this should be simpler)...

>    If I have a junction to the root of another volume, in
> cygwin it looks like a normal directory:

> Using mountvol...

> C:\>mountvol mountedVol \\?\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}
> 03/02/2017  01:24 PM    <JUNCTION>     mountedVol 
> [\??\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}\]
> 01/11/2017  04:17 PM    <JUNCTION>     var [C:\Windows\System32\cygwin\var]

> ### a junction is created ... under Cygwin. 
> Note, BTW, that 'var' is also a JUNCTION (a MS-mount point).


> C:\>exit
> exit
/>> ll
> total 100672654
> drwxrwx---+  1            0 Nov 20  2010 $RECYCLE.BIN/
> ...
> drwxrwx---+  1            0 May 15  2015 mountedVol/
> lrwxrwxrwx   1           28 Jan 11 16:17 var -> 
> /Windows/System32/cygwin/var/

/>> ls mountedVol
> $RECYCLE.BIN/  System Volume Information/

> ### mountedVol looks like a normal directory ^^^, but 'var' shows
> ### as a symlink.  That's the problem I'm referring to.  I'm saying
> ### JUNCTIONs (MS-mountpoints) should show up as the 'same' in
> ### Cygwin -- i.e. --

> ### But is not necessary that it be shown in Cygwin's "mount table":

/>> mount
> C:/bin on /usr/bin type ntfs (binary,auto)
> C:/lib on /usr/lib type ntfs (binary,auto)
> C: on / type ntfs (binary,auto)
> B: on /b type smbfs (binary,user,noumount,auto)
> ...

> ----
> It's the same on linux.
> linux> stat -c %D /var
> 822
> linux> sudo mount --rbind /var/rtmp /tmp
> linux> stat -c %D /tmp
> 822

> ----
> A mount from the same fs to another place on the same fs,
> looks like a normal directory (not a symlink).

> This is the behavior I would want for 'JUNCTION's under
> Cygwin. 

> On Windows, mklink creates a 'SYMLINK' or 'SYMLINKD' when
> directories are linked.  Those would stay as "Symlinks".









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-- 
With best regards,
Andrey Repin
Thursday, March 9, 2017 16:33:49

Sorry for my terrible english...


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Re: Treating Junctions consistently, as "normal dirs" as w/linux "bind"-type mount

[L A Walsh]

Andrey Repin wrote:
> I would argue against all junctions being treated blindly.
> The difference with bind mounts in Linux is that in Linux 
> you don't have the
> information available within the filesystem itself, and have 
> no other option,
> than to treat them as regular directories.
> Only direct volume junctions cause an issue, and this is what 
> should be fixed,
> if possible, not sidetracked with questionable workarounds.
----
	Could you describe the benefits of your proposed solution?

	You do know that MS originally called junctions "mountpoints",
right?  So why would cygwin treating them as such be a "questionable 
workaround"?

	How would you want to treat them?

	



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Re: Treating Junctions consistently, as "normal dirs" as w/linux "bind"-type mount

[Corinna Vinschen]

[-- Attachment #1: Type: text/plain, Size: 1287 bytes --]

On Mar  9 07:48, L A Walsh wrote:
> Andrey Repin wrote:
> > I would argue against all junctions being treated blindly.
> > The difference with bind mounts in Linux is that in Linux you don't have
> > the
> > information available within the filesystem itself, and have no other
> > option,
> > than to treat them as regular directories.
> > Only direct volume junctions cause an issue, and this is what should be
> > fixed,
> > if possible, not sidetracked with questionable workarounds.
> ----
> 	Could you describe the benefits of your proposed solution?
> 
> 	You do know that MS originally called junctions "mountpoints",
> right?  So why would cygwin treating them as such be a "questionable
> workaround"?

He's right.  The mount point handling in Cygwin is based on the
in-memory mount table.  There's no reasonable way to fake some
reparse point to look like a mount point.  We can either handle it
as normal dir, or as symlink.  Handling it as normal dir is 
problematic in terms of find/rsync etc, bacause the cross-device
check would fail and files are potentially visited multiple times.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: Treating Junctions consistently, as "normal dirs" as w/linux "bind"-type mount

[L A Walsh]

Corinna Vinschen wrote:
> He's right. The mount point handling in Cygwin is based on the
> in-memory mount table.  
----
    I'm not wanting a mount point fake.  Just wanting it to look
like a normal dir just like the mountvol-junctions.

> There's no reasonable way to fake some
> reparse point to look like a mount point.  We can either handle it
> as normal dir, or as symlink.  Handling it as normal dir is 
> problematic in terms of find/rsync
----
    T All of the core utils are loop-protected in that respect.
same-dev file systems already exist on linux and cygwin.

    File system loops are already present just using mountvol:

>  mountvol
...
\\?\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}\
        C:\mountedVol\
/mountedVol> mkdir remounted

# note, next "2" lines are really 1 wrapped line:

/mountedVol> mountvol remounted  
'\\?\Volume{578b2172-f917-11e4-b3d9-a0369f15ce28}\'


So the same volume is mounted at C:\mountedVol and at
C:\mountedVol\remounted.
>  etc, bacause the cross-device
> check would fail and files are potentially visited multiple times.
>   
----
That isn't what happens right now with mountvol:

find shows:

/> find mountedVol/ -type d
mountedVol/
mountedVol/$RECYCLE.BIN
mountedVol/$RECYCLE.BIN/S-1-5-21-1885695451-752926663-1105222378-1000
mountedVol/$RECYCLE.BIN/S-1-5-21-1885695451-752926663-1105222378-1025
mountedVol/$RECYCLE.BIN/S-1-5-21-1885695451-752926663-1105222378-500
mountedVol/$RECYCLE.BIN/S-1-5-21-33333-77777-33333-5013
find: File system loop detected; ‘mountedVol/remounted’ is part of the 
same file system loop as ‘mountedVol/’.
mountedVol/System Volume Information

I.e. 'find' (and other coreutils) detect the loop even though
they are the same file system.

Sure, you can find program(s) that are broken and don't detect
such loops, but at least the core utils do check -- and besides,
no one HAS to create junctions -- they can use symlinks as they do
today and no risk of such problems.

But treating linkd-junctions the same as mountvol-junctions allows
those bind-style mounts that are supported on linux and Windows
to be supported on Cygwin.


   

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Re: Treating Junctions consistently, as "normal dirs" as w/linux "bind"-type mount

[Andrey Repin]

Greetings, L A Walsh!

> Andrey Repin wrote:
>> I would argue against all junctions being treated blindly.
>> The difference with bind mounts in Linux is that in Linux 
>> you don't have the
>> information available within the filesystem itself, and have 
>> no other option,
>> than to treat them as regular directories.
>> Only direct volume junctions cause an issue, and this is what 
>> should be fixed,
>> if possible, not sidetracked with questionable workarounds.
> ----
>         Could you describe the benefits of your proposed solution?

>         You do know that MS originally called junctions "mountpoints",
> right?  So why would cygwin treating them as such be a "questionable 
> workaround"?

How they are called, and how they behave is a two different questions.

>         How would you want to treat them?

Easy way: As symlinks, just like now, unless it's a volume mount point that
can't be normalized to a disk letter.

Preferred way: Fix volume mounts accessibility
 \\?\{UUID} -> /dev/disk/by-uuid/UUID


-- 
With best regards,
Andrey Repin
Friday, March 10, 2017 16:10:57

Sorry for my terrible english...


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