Re: [Question] UFS/FFS: why a block is always allocated at EOF when truncating up

Frank Leonhardt <[email protected]> writes:
> Dag-Erling Smørgrav <[email protected]> writes:
> > XNU (macOS, iOS etc.) has them too. They seem to have been added in
> > 2017, ten years after FreeBSD got them.
> I think they were added at 10.15, which is even more recent and were
> considered quite buggy* until 12.0. Odd, because APFS does support
> sparse files.

I wasn't asking.  They were added in 10.13 / Mavericks (xnu-4570.1.46)
and work perfectly fine, though APFS hole semantics are a little weird;
it tends not to want to create holes smaller than about 1 MB.

You can see for youself here, but note that you have to look at the
author date rather than the commit date, because everything older than
12 / Monterey has the same commit date of 2021-10-06:

    https://github.com/apple-oss-distributions/xnu/

The repository gets updated a few weeks to a couple of months after each
A (fall) and E (spring) release.

copyfile(3) got support for copying holes in 10.15 / Catalina:

    https://github.com/apple-oss-distributions/copyfile/

cp(1) got it in 14 / Sonoma, install(1) in 15 / Sequoia:

    https://github.com/apple-oss-distributions/file_cmds/

DES
-- 
Dag-Erling Smørgrav - [email protected]