Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!NISC.SRI.COM!cwilson
From: cwilson@NISC.SRI.COM (Chan Wilson)
Newsgroups: comp.sys.apple
Subject: Prodos symbolic Linkes (was Re: Matt D. / MAC FST)
Message-ID: <13033@fs2.NISC.SRI.COM>
Date: 10 Feb 90 03:34:57 GMT
References: <2463@ttardis.UUCP> <38482@apple.Apple.COM>
Reply-To: cwilson@NISC.SRI.COM (Chan Wilson)
Organization: Network Info Systems Ctr., SRI Intl., Menlo Park, CA.
Lines: 47

In article <38482@apple.Apple.COM> farrier@Apple.COM (Cary Farrier) writes:
>In article <2463@ttardis.UUCP> rlw@ttardis.UUCP (Ron Wilson) writes:
>>A symbolic link is a directory entry that either:
>>	a) contains the path name of the target file
>>or	b) points to a file with one data block, which, in turn, contains
>>		the pathname of the target file
>>
>>Method b could easily be implemented on ProDOS and GS/OS.  Method a would
[snip]
>Option B would require an FST to implement this, and is not as easy as you
>might think.
>
>The thing that really makes soft links useable is that under UNIX you
>don't swap disks at your leisure.  Under GS/OS, you would have to either
>limit soft links to the same volume, or you would end up doing alot of
>disk swapping if you don't have a hard drive (or multiple hds).  They
>are a nice idea, but IMHO probably not worth the time to implement.

Hmm, I can think of a fairly easy way to make soft symbolic links. 
Make two more storage types, a type 6 and type 7 for argument sake.
Type 6 would be a file that would have symbolic links attached to it;
type 7 would be files that are linked to type 6.   This is a nice, simple
way to do it, since existing utilities would leave these types of files
alone.  It'd probably make things simpler if you devoted two more for type
5 files (data/resource files).   

Now, this is just casual thinking.  On deeper thought, one realizes
that you need to keep track of which files are linked to the master
file, so you'd need a header block like type 5 files.  This way, you
can either delete all associated files (type 7) when you delete the
master file (type 6), or you can change the storage type when all
links are gone (back to existing type).

Of course, I've contemplated just doing a primitive example of this, writing
a hack to 'link' a file to another by just mucking with the pointers; problem
here is that if you delete the master file, you're SOL....

Yup, this would require a new prodos fst, at least so these types of
files would be usable on GS/OS.  Tell me, how hard would it be to
update Prodos 8 so it could know what to do with the type 5 files?

--Chan
			   ................
  Chan Wilson -- cwilson@nisc.sri.com <or> radius!cwilson@apple.com
Janitor/Architect of comp.binaries.apple2 archive on wuarchive.wustl.edu
	      I don't speak for SRI, someone else does.
			   ................