SEEK_HOLE Support in Cygwin?

[Cedric Blancher]

On Wed, 9 Aug 2023 at 17:30, Corinna Vinschen <corinna-cygwin@cygwin.com> wrote:
>
> On Aug  7 10:33, Corinna Vinschen wrote:
> > Wrong mailing list, use cygwin AT cygwin DOT com for user questions.
> >
> > On Aug  6 19:14, Cedric Blancher wrote:
> > > Good evening!
> > >
> > > Are there plans for a SEEK_HOLE support to Cygwin, e.g. on top of the
> > > FSCTL_QUERY_ALLOCATED_RANGES api (if appropriate)?
> >
> > No plans, but patches are welcome.  This looks like a fun task for a
> > rainy weekend.
>
> Today was a really rainy day and I had to wait for a test system to
> come up, so I hacked on SEEK_DATA/SEEK_HOLE support.
>
> Check out the next Cygwin test release 3.5.0-0.384.g9939aa7d0945.

Thank you!
Or should I thank the weather gods? ;)

How can I download this version?

>
> Note that this defaults to the default behaviour described in the
> Linux man page, see https://man7.org/linux/man-pages/man2/lseek.2.html
>
> I.e., "In the simplest implementation, a filesystem can support the
> operations by making SEEK_HOLE always return the offset of the end of
> the file, and making SEEK_DATA always return offset"

So this supports multiple holes in one file, right?

>
> The real deal obviously requires a filesystem supporting sparse files,
> *and* it requires that you access the file via a mount point with the
> "sparse" option set!  The mount option "sparse" is not set by default.

Why is "sparse" not the default mount option?

Ced
-- 
Cedric Blancher <cedric.blancher@gmail.com>
[https://plus.google.com/u/0/+CedricBlancher/]
Institute Pasteur