Re: hfs patch (Re: State of GRUB on PowerPC)

["Michel Dänzer" <michel@daenzer.net>]

On Mon, 2009-02-09 at 15:19 +0100, Robert Millan wrote:
> On Sat, Feb 07, 2009 at 11:38:36PM -0500, Pavel Roskin wrote:
> > Quoting Robert Millan <rmh@aybabtu.com>:
> > 
> > >On Tue, Jan 27, 2009 at 08:19:41AM +0100, Michel Dänzer wrote:
> > >>+/*
> > >>+ * unsigned char caseorder[]
> > >>+ *
> > >>+ * Defines the lexical ordering of characters on the Macintosh
> > >>+ *
> > >>+ * Composition of the 'casefold' and 'order' tables from ARDI's code
> > >>+ * with the entry for 0x20 changed to match that for 0xCA to remove
> > >>+ * special case for those two characters.
> > >>+ */
> > >>+static unsigned char caseorder[256] = {
> > >>+ 
> > >>0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F,
> > >
> > >Could you be more specific about what the table contents mean?
> > 
> > Michel may know better, but I think it's the order of characters.   
> > Those with the lower order go first in the sorted binary tree.  Those  
> > with the same order are equivalent on the filesystem level.  That is,  
> > "foo" can only be between "bar" and "quux" in the node tree.  "foo"  
> > and "Foo" are the same tree node and thus the same file.
> 
> I think what we need here is enough information so that someone can understand
> what the table means

I'm not sure what more information I can provide. :(

> and be able to modify it if need arised.

I think that's very unlikely: the Linux kernel code this is copied from
hasn't changed at all since Linus started using Git for 2.6.12-rc,
possibly much longer.

> An undocumented table just looks like a "blob" of binary data.

I guess to some extent it could be considered that - it's a blob which
is needed to correctly interpret the blobs in an HFS filesystem.


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer