Sophie: hfsplusutils-1.0.4-6mdv2010.1 x86

hfsplusutils-1.0.4-6mdv2010.1.x86_64.rpm

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    <title>What is HFS+</title>
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<h2>What is HFS+</h2>
<p>  
HFS+ is the new Filesystem intodruced my Apple around MacOS8.
It became necessary because its predecessor, HFS, had a fixed numer
of blocks (2^16), and on large volumes theses block became very
large, wasting a lot of space. HFS+ solves this problem and
intodruces some new concepts like Unicode file names.
</p><p>
Detailed Documentation can be found in
<a href="http://developer.apple.com/technotes/tn/tn1150.html"
>Technote 1150 HFS+ Volume format</a> and in
<a href="http://developer.apple.com/techpubs/macos8/Files/FileManager/filemanager.html"
>File Manager</a>.
</p><p>
In contrast to unix-like file Systems, HFS+ (and HFS+) work like indexes
in a database. As with databases The index is composed of keys structered
in a B*-Tree. (A B*Tree is basically a n-ary tree located in nodes on a volume.
This way acces to any file is pretty fast at the price of a complex
insert / delete management. I migt provide some O(..) notation
here but dont want to get blamed by some Theoritican :) . 
The B*-tree is composed of index nodes and leaf nodes. Index nodes
contain ordered keys that point to deeper index- or leaf-nodes.
Leaf nodes contain keys and associated file or folder records.
The keys and records have variable length but an additional
index at the end of every node allows indexed acces.
</p><p>
Apple places additional restrictions on the B*-Tree:<ul>
<li> All leaf nodes are found a the same depth</li>
<li> All nodes of the same depth are linked foreward and backward</li>
<li> ... More I dont remember right now.</li>
</ul>
</p><p>
The keys are composed of the unique id of the parent folder and
the (specially encoded) unicode name of the file. The folder
THREADS are needed to retrive the parent folder for a given
folder id. Theese use an empty name and are simliar to the
'.' directory in unix.
</p><p>
Files and the B*Trees themselfes are stored in forks. For files these
are the Apple-like data- and resource-fork. With HFS+ every files
may have up to 8 not continuos parts until the additional parts
are found in the Extends record. This Extends record is used
for the catalog file (fork) and other forks, too. So that theese
have fixed record ids, too. 
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