Case sensitive filenames for non-NTFS filesystems

Corinna Vinschen
Fri Aug 2 08:31:00 GMT 2013

On Aug  2 16:50, Shaddy Baddah wrote:
> Hi,
> As per:
> Cygwin act on filenames on NTFS in with case preservation/sensitivity.

Correction, not only NTFS.  Here's the source code comment:

  /* Case sensitivity is supported if FILE_CASE_SENSITIVE_SEARCH is set,
     except on Samba which handles Windows clients case insensitive.

     NFS doesn't set the FILE_CASE_SENSITIVE_SEARCH flag but is case

     UDF on NT 5.x is broken (at least) in terms of case sensitivity.
     The UDF driver reports the FILE_CASE_SENSITIVE_SEARCH capability
     - Opening the root directory for query seems to work at first,
       but the filenames in the directory listing are mutilated.
     - When trying to open a file or directory case sensitive, the file
       appears to be non-existant. */

> As this was a feature configured in the Windows kernel, the pre-existing
> limitation whereby the same case sensitivity was not available for FAT32
> was an understandable compromise.
> Unfortunately, in providing EXFAT, Microsoft has not seen fit to carry
> over the same handling in the kernel as it does in NTFS.

ExFAT is based on FAT/FAT32, so it's understandable.  I don't have ExFAT
available.  Assuming your ExFAT drive is drive X:, can you please show
me the output of

  /usr/lib/csih/getVolInfo.exe /cygdrive/x

If it returns different values than FAT, it might be worth to handle
specificially in Cygwin's mount code.

> Can I suggest that if it is a) feasible b) doable without too much added
> degradation in performance/complexity to the file handling code, that
> Cygwin add some limited support itself.
> I'm not talking about going back to something like the old managed
> mounts, but more to its replacement function. That being the same
> handling of special characters like :, |, etc that Cygwin employs.
> That is, the use of the special Unicode breakout character. It can
> be used when a name collision is detected (yes, detection code required.
> I don't know how costly that would be). eg.
> [...]
> Is the trade-off large enough to fall back on the "just use NTFS"
> argument?

Well, from my POV, yes.  It doesn't make sense to use ExFAT for serious
work anyway, it's for SD cards and stuff like that.


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

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