bug in cygwin tar reading unexpected input(s)...

L A Walsh cygwin@tlinx.org
Tue Jun 15 21:13:01 GMT 2021

On 2021/06/15 00:16, Russell VT wrote:
> I think we need more context, here... as what does Windows versus Cygwin 
> think those permissions are...???
	Which permissions?  The error is 'no such object', not
'access denied'.  I believe it is similar to trying to read (or
modify) xattr's or acl's on linux symlinks.  

> Are you running your terminal, as you... or did you run it as Administrator?
	I am in group Administrators as well as Domain Admins
(Samba Domain).  Domain Admins and System are both in the
local Administrators group.

> Have you run an update, and not rebooted?
	I don't believe so at that time, but I have rebooted since then.
The problem only occurred on files that were symlinks as seen by Windows
and Cygwin.
> There should be some "basic shell debugging" done here, first...
	I'm not sure what you mean.  Oops, I forgot to list the
command line, but thought that "--xattrs" might be implied from the 
fact that the error was about retrieving xattrs.

	Cmdline was using shell script calling a function, "backup_dir"
with "ProgramData" from the root directory, where the function was:

backup_dir() {
  my DIR=${1:?}
  tar c --acls --xattrs --sparse -b 2048 --one-file-system "$DIR" | 
    dd bs=1M iflag=fullblock of="/b/June_backups/$DIR" oflag=nonblock

> since 
> there's a disconnect from when tar gets its file list, and when it 
> physically goes to retrieve a (possibly temporary) file. It will also 
> complain about directories it can read, but not access.
	Those were symlinks, not directories.
> So, it would be 
> better to figure out what the "difference" is between what you expect, 
> and what actually happened with the tar.
	I would expect it might not complain about not being
able to read xattr's on symlinks?  I don't think it complains about
not being able to read them on linux -- or at least I've never seen

> Unfortunately, permission issues between Windows and Cygwin can be 
> */extremely/* complex (ie. there are a ton of details missing here, 
> which might make it easier to help troubleshoot).
	What necessary details are missing?

> Hope that helps point you in a good direction.
	Not sure. I thought I was reporting a bug in cygwin tar
giving an error about trying to read xattrs on symlinks, as I don't
believe it gives an error on linux doing the same thing.  Does it?
Thanks for your questions, but I'm still not very clear on what
I left out.

	I'd tend to ignore the error on what appeared to be
a misspelled filename, as I'm not even sure how to recreate
that file, but attempting to dump xattrs on a symlink seems like
a pretty straight forward symptom/testcase.  What more details
do you think would be pertinent?  


> Cheers!
> Russell VT
> On Mon, Jun 14, 2021 at 9:22 PM L A Walsh <cygwin@tlinx.org 
> <mailto:cygwin@tlinx.org>> wrote:
>     Tar'ing up a windows dir (ProgData) had some unexected failures:
>     Several of the sort:
>     tar: Dbgview: Warning: Cannot llistxattrat: No such file or directory
>     tar: Desktops: Warning: Cannot llistxattrat: No such file or directory
>     tar: DiskView: Warning: Cannot llistxattrat: No such file or directory
>     tar: LoadOrd: Warning: Cannot llistxattrat: No such file or directory
>     tar: portmon: Warning: Cannot llistxattrat: No such file or directory
>     Where the item listed (Dbgview, DiskView, etc) is a
>     windows symlink like:
>     2019/02/07  22:53    <SYMLINK>      Dbgview [SI\Dbgview.exe]
>     2019/02/07  22:53    <SYMLINK>      Desktops [SI\Desktops.exe]
>     2019/02/07  22:53    <SYMLINK>      DiskView [SI\DiskView.exe]
>     and stems from the use of the --xattrs switch.
>     Win7SP1x64
>     cygcheck (cygwin) 3.2.0
>     The tar continued and finished much as it would after an unreadable
>     file.
>     Another error, maybe similar,
>     tar: C\:Prog64FastPictureViewer: Warning: Cannot file_has_acl_at: No
>     such file or directory
>      From a file in "C:\Program Files\FastPictureViewer" [likely mis-]named
>     "C:Prog64FastPictureViewer"
>     It seems to be a .dll, that somehow got its name mangled.
>     Not sure what it was trying to do, but the file seems to be 'in-use'.
> -- 
> Russell M. Van Tassell <russellvt@gmail.com <mailto:russellvt@gmail.com>>

More information about the Cygwin mailing list