Re: New HFS Patch 12.5 fix a dangerous bug

[Andrew Clausen]

On Tue, Sep 07, 2004 at 03:34:55PM +0200, K.G. wrote:
> There _is_ HFS support in Linux (though limited).
> You have :
> 1) hfsutils and hfsplusutils for access in userspace
> 2) The kernel implementation (very buggy in 2.4 but quite good in 2.6)
> 3) A port of newfs_hfs I've corrected (an endianess issue was remaining in
> wrapped HFS+) and quickly hack for Linux 2.4 support (userspace can't access
> end of partitions)
> ( http://xilun.nerim.net/Projet/Parted/Newfs_hfs/newfs_hfs_4_linux-2.tar.gz )

So, this is adequate for testing?

> My own main concern was stability during the past year, but is more 
> performance now... I've been testing the futur patch 13 during two weeks
> (and I'm still testing it right now) and could discover some remaining bugs.
> Of course it would be better if some other people do read the HFS
> specifications and my code...
> 
> My main concern is now speed : it took about 5 hours to resize 10->5 Go
> with hundred thousand of fragmented files, which is slow :p
> I know what I've have to do to make things go faster, and I'll start to work
> on that in next versions.

Does MacOSX provide a defragmenter?  We can tell users that are in a
hurry to use it.

> Of course I'll also try to write working automatic regression tests for HFS
> in next versions. But I must switch to a 2.6 kernel because of HFS bugs in 2.4
> and I still haven't done it for other reasons.

You might find user-mode-linux helpful.

> But to be efficient I must find a reliable way to generate fragmentation in
> the catalog and extent overflow files.

By "reliable", do you mean atomic?  If you explain the problem in
detail, maybe someone on the list will have an idea...  (or maybe not!)

> Also there is a part of my code that has never been tested (attributes
> file) because I could never find a FS using that feature (which in
> anyway not completly defined in Apple specs, and I doubt there is one
> computer in the world with that feature anyway).

I suggest you put in an exception which tells the user:

        "You have an HFS file system that has a feature that I haven't
        seen used anywhere.  Please email me, so I can have a look at
        how it works!  <address@hidden>"

> > Speaking of testing, I think we could probably do a lot better than
> > Parted's current regression tests.  e2fsprogs has much better tests.
> > Any volunteers?
> 
> What new tests are you thinking of ?

Well, the Parted tests only test the semantics, but they aren't
especially thorough.  The e2fsck contain file system images of
"before" and "after" running e2fsck.  When you run the tests,
it runs e2fsck on the before image, and compares the output to the
after image in the test suite.

Cheers,
Andrew