Path: utzoo!mnetor!uunet!sdrc!scjones
From: scjones@sdrc.UUCP (Larry Jones)
Newsgroups: comp.os.vms
Subject: Re: ARC
Message-ID: <237@sdrc.UUCP>
Date: 3 Mar 88 23:43:33 GMT
References: <8802250714.AA18420@ucbvax.Berkeley.EDU>
Organization: Structural Dynamics Research Corp., Cincinnati
Lines: 42

In article <8802250714.AA18420@ucbvax.Berkeley.EDU>, EVERHART%ARISIA.DECnet@GE-CRD.ARPA writes:
> 
> I finally received (thanks!) the ARC part 1 of the vms ARC posting.
> I now have tried it...
> 	ARC does work on files created as archives either BY ARC,
> or by other transfer methods that store the files on disk as bitstreams
> or their equivalents. For example, XMODEMs typically use fixed
> 128 byte records in downloads. It (arc) fails badly on archives
> created by Kermit in binary mode (even though sweep has no problems
> with them and both msdos and Amiga ARC like 'em fine when transferred
> to those machines.) I believe ARC must be ignoring the fact that
> on variable length records (used by Kermit in binary files) there
> are two bytes of record length before each record. Accordingly,
> the file must be read by RECORDS, not by BLOCKS, to give the
> correct effect.
> 	Can anyone shed more light on the situation?

Well, as the "author" of the VMS version, I suppose I can.  You are correct
that ARC is using block access to the archive and thus variable length records
are not processed correctly.  This is necessitated by the way ARC manipulates
the file - it is necessary to seek forward and backward to arbitrary positions
within the file and this is not possible with variable length records.

> 	I suppose one can try using vms kermit FILE TYPE FIXED to
> work around the problem, though there used to be a problem where
> the last record was less than 512 bytes which has led me not to
> use fixed filetypes much.

Bingo!  Apparently you did not get the (meager) documentation that I sent out
since this was mentioned explicitly as a way to transfer archives in it.  I
don't know which version you have (or even off hand which version I have), but
it works without any problems for me.

> 	Is the fix straightforward in C?

as I said above, the fix is nigh-on impossible.  Use fixed length records.

----
Larry Jones                         UUCP: uunet!sdrc!scjones
SDRC                                MAIL: 2000 Eastman Dr., Milford, OH  45150
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"When all else fails, read the directions."