NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/comp/sys/atari/st/tech/4199

Internet Message Format | 1992-07-30 | 2.1 KB

Path: sparky!uunet!mcsun!uknet!fulcrum!its!silver.its.bt.co.uk!jvt
From: [e-mail] (John Trickey)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: Problems with ARGV
Message-ID: <[e-mail]>
Date: 30 Jul 92 17:11:18 GMT
References: <[e-mail]> <[e-mail]> <[e-mail]>
Sender: @its.bt.co.uk
Organization: BT Group Computing Unix Support, Birmingham, UK
Lines: 53

In article <[e-mail]> [e-mail] (Ian Lepore) writes:
>
> > ARGV doesn't allow passing empty arguments
> > use another env var to pass the position of the empty args
>
> I don't like it.  It sounds needlessly complicated to create a whole
>'nother env var for this.

Yes and no. I don't see the point of duplicating the information.

>  I have two variations on an idea for coping with this.  The first variation
>assumes that we never pass binary values in the ARGV.  (IE, isprint() is
>TRUE for all chars appearing in the args in the ARGV area.)  In this case,
>I'd recommend using \001 as a placeholder for an empty arg.  Using this,
>
>   grep "" *.c
>
> would be passed as ARGV=\0grep\0\1\0*.c\0\0.  If my assumption is invalid,
>and folks do pass binary data in ARGV, then use an escape system where an
>empty arg is \1\1, but a true binary 1 is \1\2.  (You could even extend
>this to allow passing binary zeros, escaped as \1\3 for example.)
>
>  Thoughts?

Am I missing something? It seems all too easy for me. Why not pass ARGC ?

so in the above example:

ARGC="3"

(assuming the cli does not interpret the *.c) and

ARGV="grep\0\0*.c\0"

(yes there are 2 \0 's on the end --- remember a str is terminated by \0)

then the startup code mimics
    tmp = argc = atoi(getenv("ARGC"));
    while (--tmp) {
        . argv processing
        .
    }
    . argv tidy up
    main(argc, argv);

and you can pass null strings, binary data (as long as it does not
contain \0) as much as you like.

--
John Trickey <[e-mail]>
       Voice: [phone]     Fax: [phone]
(Home) <[e-mail]> || <[e-mail]> || G4REV @ GB7FLG
       [phone]