[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: HFS Utils?

In article <32dd8097.104325927@netnews.worldnet.att.net>,
Bruce Maples <themaples@worldnet.att.net> wrote:
>I have been told that there are no HFS utilities for the GS. Is this
>true?  If so, how hard would it be to write some?  Is HFS very hard to
>work with? What level of interest would there be?

   For file-level utilities (move, copy, rename, delete, make directory),
there are a fair number of GS/OS programs (Finder, Orca or GNO shell,
ProSEL, etc) that'll talk to HFS disks just as easily as ProDOS disks.

   There are no disk level HFS utils though, for verifying integrity
of the catalog tree, bad block scans, and checking the volume bitmap
against actual disk usage. Any one of those faults can be serious
enough to cause lost data, and there have been many (myself included)
who've had HFS volumes go sour on them. [The patch for the 6.0.1 FST
only is supposed to affect volumes >96MB in size, and I've had 80MB
volumes go bad]

   The main difficulty in writing them is the HFS disk layout itself.
It's documented in the 'Inside Macintosh' volumes, available in .PDF
somewhere on Apple's web/ftp sites. If you print out the dox on it,
you'll see it's pointer and data structure heavy, with a B-Tree data
structure for the files on acid stored in a B-Tree on crack for the
catalog blocks on disk. With multiple layers of indirection for stuff,
and these data structures, you can see why a suble bug to corrupt the
disks is more than likely to show up and go unnoticed.

   If you've got a strong CS background and a lot of time to play
around with things, you could probably write a HFS volume repair for
the GS. I've ovbiously investigated it, but other GS projects and a
lot of FAQs have eaten all my spare GS time.

Nathan Mates

--
<*> Nathan Mates http://www.visi.com/~nathan/      <*>
# What are the facts? Again and again and again-- what are the _facts_?
# Shun wishful thinking, avoid opinion, care not what the neighbors
# think-- what are the facts, and to how many decimal places?  -R.A. Heinlein