Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!rice!uw-beaver!ubc-cs!alberta!calgary!enel!steven
From: steven@enel.ucalgary.ca (Steven Leikeim)
Newsgroups: comp.sys.apple
Subject: Re: FST's
Message-ID: <2200@cs-spool.calgary.UUCP>
Date: 5 Dec 89 19:22:23 GMT
References: <2634.cortland.info-apple@pro-houston> <5205@internal.Apple.COM> <3762@puff.cs.wisc.edu>
Sender: news@calgary.UUCP
Reply-To: steven@enel.UCalgary.ca (Steven Leikeim)
Organization: U. of Calgary, Calgary, Alberta, Canada
Lines: 68

In article <3762@puff.cs.wisc.edu> blochowi@rt3.cs.wisc.edu (Jason Blochowiak) writes:
>In article <5205@internal.Apple.COM> farrier@Apple.COM (Cary Farrier) writes:
>>	*Using* an FST is _not_ the same as *writing* an FST!  One of the
>>intracacies of creating an FST involves how closely it interacts with
>>the rest of the OS.  Sometimes these details change in an OS revision.  When
>>this happens, we can update the FSTs, but we can't update a 3d party FST.
>
>	If everything were "the way it should be" GS/OS and the FSTs wouldn't
>be interdependent like they (apparently) are. 

They cannot be completely independent. GS/OS needs to know something about
the filesystem that it is working on so that it can create absolute pathnames
from relative pathnames if necessary. As well, there may be some dependancy
here where GS/OS needs to know what sort of pathname separator (eg "/")
to use when automatically starting a program. As an example of this, can
you create a file with a "/" in the filename under UNIX. Without resorting
to patching the disk, you can't do this. Under GS/OS you can't create a file
with both a ":" and a "/" in it.

>                                             GS/OS would serve as a front
>end, basically, to the FSTs. The application would make a call to GS/OS, which
>would figure out if 1) A device driver should handle the call, 2) GS/OS itself
>should handle the call, or 3) A FST should handle the call. Just as GS/OS
>provides some primitives for device drivers, it would provide some primitives
>for the FSTs - say, keeping track of lists of open files, which FST is
>responsible for them, etc. If the interaction were nice and neat (not an
>impossibility), then 3rd party FSTs would become completely possible.
>

Unfortunately, interactions between FST's and GS/OS are not likely to be neat.
There are a large number of factors to consider here. The factor of file
attribute handling has been discussed by others. Filename construction however,
is probably more of a problem. Currently GS/OS - ProDOS FST does not
differentiate between the files "testing", "Testing", "TESTING" or even
"TeStInG". Clearly, there may be a problem here in dealing with file 
systems where the file names above refer to 4 different files.

How about file systems that permit "Illegal characters" in filenames. On
some filesystems you can have a space in a filename. GS/OS - ProDOS FST
doesn't allow this. How do you handle control characters in filenames???

Finally, we have to deal with the length of filenames. GS/OS - ProDOS FST
currently limits filename segments to 15 characters (I think). We may have
to deal with filesystems which permit more than this. DOS 3.3 for instance
allows 31 character file names. Actually, DOS 3.3 has allows most of what
I have described above.

There are probably other considerations that I have missed here, but this
is enough for one day. Some of what is listed above may be moot as I do not
have any knowledge about how GS/OS and FST's interact. This is why I used
the terminology "GS/OS - ProDOS FST" in this article. Some of the above
might only require code in the FST but some of it may require changes to
GS/OS itself.

>	Anyone with the urge to flame me should probably do so by email.

No flames here. Just some information for some, hopefully, reasoned
discussion on this topic. Maybe we can come up with some ideas that Matt
or Dave or whoever can go to their bosses at Apple and say, "Maybe we
should try this". Who knows, stranger things have happened.

>      Jason Blochowiak - blochowi@garfield.cs.wisc.edu or jason@madnix.uucp
>       "Education, like neurosis, begins at home." - Milton R. Sapirstein

Steven Leikeim                        |
University of Calgary                 |   There are lies, damned lies,
Department of Electrical Engineering  |        and statistics.
.uunet!{ubc-cs,utai,alberta}!calgary!enel!steven