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Re: Bug: Setup tool doesn't respect managed mountpoints/filesystems
On Mon, 19 Sep 2005, Brian Dessent wrote:
> Igor Pechtchanski wrote:
>
> > OTOH, one of the changes that would be worth making in the managed mount
> > code is to leave the filename alone unless there's a clash, in which case
> > the clashing filename becomes encoded.
>
> But then any file creation/renaming operation would have to check and
> see if there was a clash first. That would kill performance. It would
> also create race conditions, like two processes trying to create
> clashing files at the same time.
Yes, there are issues to work out here, but they are not very different
from, say, those arising when two programs try creating a file with the
same name simultaneously... In fact, the case-insensitivity of both NTFS
and VFAT plays into our hands here, as you say below: creating a new file
that differs only in case will always fail, so Cygwin simply has to encode
the file name if its creation failed.
> > This should work since both NTFS and FAT are case-preserving
> > filesystems (of course, Cygwin will have to
>
> Preserving, yes, but not sensitive. As far as I know it is impossible
> to make (V)FAT case sensitive, so creating a new file that differs only
> in case will always fail. NTFS is only case sensitive if you use the
> Native API, otherwise it is not case sensitive either. I seem to
> remember a paragraph on MSDN that states this.
>
> Even if Cygwin did use the Native API, this would only work for NT with
> NTFS volumes. 9x/ME has no way to do this, so you're back to encoding
> filenames anyway.
How is this relevant? I didn't say we don't need to encode filenames -- I
said that we only need to encode filenames *if* there is a clash (or the
name is special). If there is no clash, a file like "README" should be
stored as-is.
The only caveat I see here is that now *accesses* to files on managed
mounts would have to check for case -- i.e., the managed mount code would
need to replicate some of the "check_case:strict" logic. Otherwise,
creating "README" and accessing it as "readme" would work (which we don't
want to happen).
Igor
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