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From: wes@harem.clydeunix.com (Wes Peters)
Newsgroups: comp.unix.wizards
Subject: Re: BSD tty security, part 3: How to Fix It
Summary: Write rejecting piped input?
Message-ID: <235@harem.clydeunix.com>
Date: 2 May 91 18:55:27 GMT
References: <7299:Apr2510:22:2091@kramden.acf.nyu.edu> <12535@dog.ee.lbl.gov> <73525@eerie.acsu.Buffalo.EDU>
Organization: Raxco, Inc., Orem, UT
Lines: 23

In article <15896:Apr2714:35:3991@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
> 3. Do people think it's a problem that ``write'' can flood a terminal
> with output before the recipient has a chance to react? My version
> limits output to 500 characters per line and one line a second. Does
> anyone think that this affects legitimate uses of ``write''? If not, is
> there any harm in adding the protection against accidents and abuse?

I think write should reject any input not from a terminal:

    if (!isatty(fileno(stdin))) {
        fprintf(stderr, "write: input must be a terminal!\n");
        exit(-1);
    }

I know this will take care of 'cat longfile | write sucker', but does it
also take care of a 'here is' document (i.e. shell << document)?

	Wes Peters
-- 
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     Wes Peters:  wes@harem.clydeunix.com   ...!sun!unislc!harem!wes