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Re: Error accessing mapped drive >2TB?

On Sep 14 14:34, Warren Young wrote:
> On Sep 12, 2015, at 11:14 AM, Nem W Schlecht <> wrote:
> > 
> > The only thing I can think of is that the 2nd drive is >2TB.
> The same thing happens here with a 3.1 TB Fusion drive and a 500 GB external drive, so no, I donât think the volume size is the real issue.
> I assume you are seeing the same thing that I am, that Explorer shows the root contents of both drives just fine?
> When I straceâd an ls of one of these root shares here, I got 764 lines ofâemissions, of which this section seems the most interesting to me:
> 1051  263166 [main] ls 4720 stat64: entering
>   625  263791 [main] ls 4720 normalize_posix_path: src /p
>   609  264400 [main] ls 4720 normalize_posix_path: /p = normalize_posix_path (/p)
>   630  265030 [main] ls 4720 mount_info::conv_to_win32_path: conv_to_win32_path (/p)
>   653  265683 [main] ls 4720 mount_info::cygdrive_win32_path: src '/p', dst 'P:\'
>   668  266351 [main] ls 4720 set_flags: flags: binary (0x2)
>   674  267025 [main] ls 4720 mount_info::conv_to_win32_path: src_path /p, dst P:\, flags 0x4022, rc 0
>  1168  268193 [main] ls 4720 symlink_info::check: 0x0 = NtCreateFile (\??\P:\)
> 10641  278834 [main] ls 4720 symlink_info::check_reparse_point: NtFsControlFile(FSCTL_GET_REPARSE_POINT) failed, 0xC0000275
>   839  279673 [main] ls 4720 symlink_info::check: not a symlink
>  1049  280722 [main] ls 4720 symlink_info::check: 0 = symlink.check(P:\, 0x24B620) (0x4022)
>   655  281377 [main] ls 4720 path_conv::check: this->path(P:\), has_acls(0)
>   640  282017 [main] ls 4720 stat_worker: got 5 error from path_conv
>   757  282774 [main] ls 4720 __set_errno: int stat_worker(path_conv&, stat*):1933 setting errno 5
>   714  283488 [main] ls 4720 stat_worker: -1 = (\??\P:\,0x600042080)
> Why errno 5 from path_conv?

Probably because of the above

  symlink_info::check_reparse_point: NtFsControlFile(FSCTL_GET_REPARSE_POINT)
  failed, 0xC0000275

This is in fact a weird error code in this scenario.

Consider that symlink_info::check_reparse_point is *only* called, if the
file to check (here "P:\") has the FILE_ATTRIBUTE_REPARSE_POINT flag
set.  So from the Windows perspective it is certainly a reparse point.

Cygwin checks the flag to allow evaluating of reparse points as symlinks.
If the flag is set, it calls symlink_info::check_reparse_point which in
turn calls

  status = NtFsControlFile (..., FSCTL_GET_REPARSE_POINT, ...);

to fetch the target information the reparse point points to, in POSIX
terms the symlink target.  But *this* call returns a status of 0xC0000275,
which means STATUS_NOT_A_REPARSE_POINT.  And since it's totally unexpected
that NtFsControlFile fails on a reparse point, the code sets errno to EIO.

Hang on.

The FILE_ATTRIBUTE_REPARSE_POINT flag is set but when calling a function
to fetch the reparse data it's no reparse point anymore?  How dumb is

I can't reproduce this bug with my Samba drives, but it's not actually a
bug in Cygwin from my perspective.

Yeah, that observation doesn't really help, so I applied a potential
workaround to Cygwin.  If you're set up to build your own Cygwin, please
give it a try.  Otherwise I'll upload a new snapshot in the next couple of


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

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