Re: sizeof environment variables array = 1?

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: sizeof environment variables array = 1?
Date	2017-06-09 08:41 -0700
Organization	None to speak of
Message-ID	<lnefuti2wt.fsf@kst-u.example.com> (permalink)
References	(4 earlier) <ohc2ha$7n2$1@dont-email.me> <ohcbeq$1cbo$1@gioia.aioe.org> <ohcfh3$m23$2@dont-email.me> <lnink6i0x9.fsf@kst-u.example.com> <ohee4g$ege$1@dont-email.me>

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DFS <nospam@dfs.com> writes:
> On 6/8/2017 6:12 PM, Keith Thompson wrote:
>> Instead, I strongly suggest you define what constitutes valid input
>> for your program, and check for that.
>
> 'file' returns ASCII in the description, or the extension is .txt.
>
> That's it.

I don't believe the file command reads the entire file, so it might
report ASCII for something that contains non-ASCII characters.

On systems that support symbolic links, "file" on a symbolic link
just says it's a symbolic link; it doesn't report on the contents
of a file.  I would expect a symlink to a pure ASCII text file to
be acceptable, but you would reject it.  Unless the target of the
symlink happens to have the string ASCII in its name.

I can rename any binary file to give it a ".txt" extension.  If your
program is vulnerable to bad input, that's how someone can break it.

If those are your requirements, that's up to you -- but I don't
see how the requrements you've given make any sense.

There must be some logical basis for the requirements you've
stated, but if you're unwilling to discuss that basis (your *real*
requirements), we can't help you.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Thread

sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 11:13 -0400
  Re: sizeof environment variables array = 1? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-06-08 11:25 -0400
    Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 09:34 -0700
      Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 13:14 -0400
        Re: sizeof environment variables array = 1? jameskuyper@verizon.net - 2017-06-08 10:51 -0700
  Re: sizeof environment variables array = 1? Gareth Owen <gwowen@gmail.com> - 2017-06-08 16:56 +0100
    Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 12:18 -0400
      Re: sizeof environment variables array = 1? scott@slp53.sl.home (Scott Lurndal) - 2017-06-08 16:35 +0000
      Re: sizeof environment variables array = 1? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-06-08 12:43 -0400
        Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 13:49 -0400
          Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-08 13:58 -0400
            Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 14:45 -0400
          Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 12:10 -0700
            Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-09 11:21 -0400
            Re: sizeof environment variables array = 1? Richard Heathfield <rjh@cpax.org.uk> - 2017-06-09 16:23 +0100
              Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-09 11:48 -0400
                Re: sizeof environment variables array = 1? Richard Heathfield <rjh@cpax.org.uk> - 2017-06-09 16:53 +0100
                Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-09 12:18 -0400
                Re: sizeof environment variables array = 1? Richard Heathfield <rjh@cpax.org.uk> - 2017-06-09 17:28 +0100
                Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-09 09:12 -0700
              Re: sizeof environment variables array = 1? "Patrick.Schluter" <Patrick.Schluter@free.fr> - 2017-06-10 09:28 +0200
          Re: sizeof environment variables array = 1? jak <please@nospam.tnx> - 2017-06-08 22:18 +0200
            Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 17:31 -0400
              Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 15:12 -0700
                Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-09 11:21 -0400
                Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-09 16:39 +0100
                Re: sizeof environment variables array = 1? Gareth Owen <gwowen@gmail.com> - 2017-06-10 07:26 +0100
                Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-10 13:21 +0100
                Re: sizeof environment variables array = 1? gordonb.q80bx@burditt.org (Gordon Burditt) - 2017-06-10 17:32 -0500
                Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-11 01:01 +0100
                Re: sizeof environment variables array = 1? luser droog <luser.droog@gmail.com> - 2017-06-11 01:28 -0700
                Re: sizeof environment variables array = 1? raltbos@xs4all.nl (Richard Bos) - 2017-06-17 18:38 +0000
                Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-09 08:41 -0700
                Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-09 11:50 -0400
                Re: sizeof environment variables array = 1? raltbos@xs4all.nl (Richard Bos) - 2017-06-17 18:37 +0000
                Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-18 09:11 -0400
          Re: sizeof environment variables array = 1? "Patrick.Schluter" <Patrick.Schluter@free.fr> - 2017-06-10 09:19 +0200
      Re: sizeof environment variables array = 1? Robert Wessel <robertwessel2@yahoo.com> - 2017-06-08 12:44 -0500
    Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-08 18:01 +0100
      Re: sizeof environment variables array = 1? Gareth Owen <gwowen@gmail.com> - 2017-06-08 18:45 +0100
    Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 11:51 -0700

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