Path: utzoo!attcan!uunet!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Indicating end of file
Message-ID: <14935@cbmvax.commodore.com>
Date: 8 Oct 90 01:29:12 GMT
References: <924@ucsvc.ucs.unimelb.edu.au> <1990Sep23.174736.16118@lavaca.uh.edu> <83986@tut.cis.ohio-state.edu> <14646@cbmvax.commodore.com> <MWM.90Sep25180852@raven.pa.dec.com> <14669@cbmvax.commodore.com> <1990Oct3.172801.26802@jato.jpl.nasa.gov>
Reply-To: jesup@cbmvax.commodore.com (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 55

In article <1990Oct3.172801.26802@jato.jpl.nasa.gov> jdickson@jato.Jpl.Nasa.Gov (Jeff Dickson) writes:
>	copy SID:2400,1,8,N,031 sidout
...
>	If the file exists, Copy concludes by printing the message,
>"Error during writing - sidout removed". Otherwise, copy doesn't
>print an error, but I can't Type the file because (I guess) the 
>end of file (^J ?) has been obscured. Funny thing is according to
>the List command, the file contains the same number of bytes as
>the characters I typed on the terminal.

	There is no "end of file" character in amigados.  It almost sounds
like the file was never closed.

>		ACTION_LOCATE_OBJECT
>		ACTION_EXAMINE_OBJECT
>			...so that the whatever is inputing from
>			the SID doesn't give up because there is
>			nothing to read, I block the DOS packet
>			until something does become available.
>
>		        When the DOS request can be satisfied, I
>			insert the number of bytes available in
>			the 'fib_Size' field and the number of
>			blocks in the 'fib_NumBlocks' field (usally
>			zero). I have no idea what to initialize
>			the 'fib_DiskKey' field as. I've tried -1
>			and 0.

	Copy makes use of the fib_Size field.  You actually might wish to
reject the ACTION_LOCATE_OBJECT packet with ERROR_ACTION_NOT_KNOWN.  This
tells copy (and other system routines/commands) that you're a handler and
not a filesystem (2.0 has an ACTION_IS_FILESYSTEM packet).  The standard
SER:, PAR:, etc reject lock attempts.

...
>		ACTION_END
>
>	I have a rather old Transactor magazine that includes an article
>on AmigaDOS. It says on end of file that the 'RES1' field of the DOS packet
>is to contain a -1 (DOSFALSE) and that the 'RES2' is to contain the end of
>file indication (in my case zero). I tried that, but it didn't work. So
>now, I just put zero in the 'RES1' field when end of file occurs.

	URK!  DOSTRUE is -1, DOSFALSE is 0 (aka FALSE).  Most boolean
routines/actions return this.  Read and Write return the length read or
written, or 0 for end of file, or -1 for an error.  For all routines, the
reason for the error is put in dp_Res2 (eventually it can be retrieved from
pr_Result2 by IoErr()).  See dos/dos.h for a listing of error codes.

	There is an example of a port-handler on the Washington devcon disk.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"