X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
X-Trace-PostClient-IP: 68.147.131.211
From: Brian Inglis <Brian DOT Inglis AT SystematicSw DOT Invalid>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Environment Variables
Organization: Systematic Software
Message-ID: <ufn7h0p3s00qq4vqmq3odgnt67i4hisdfn@4ax.com>
References: <cepqfs$jts AT odak26 DOT prod DOT google DOT com> <vY6Qc.33228$vX4 DOT 11673 AT cyclops DOT nntpserver DOT com> <41115A5F DOT 7DDC6318 AT yahoo DOT com> <bNtQc.58210$vX4 DOT 56203 AT cyclops DOT nntpserver DOT com> <41127AF9 DOT 26DEA37C AT yahoo DOT com> <4112BE04 DOT 3B151CA1 AT yahoo DOT com> <7494-Fri06Aug2004121205+0300-eliz AT gnu DOT org>
X-Newsreader: Forte Agent 1.93/32.576 English (American)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 65
Date: Fri, 06 Aug 2004 19:57:39 GMT
NNTP-Posting-Host: 24.71.223.147
X-Complaints-To: abuse AT shaw DOT ca
X-Trace: pd7tw3no 1091822259 24.71.223.147 (Fri, 06 Aug 2004 13:57:39 MDT)
NNTP-Posting-Date: Fri, 06 Aug 2004 13:57:39 MDT
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

On Fri, 06 Aug 2004 12:12:06 +0300 in comp.os.msdos.djgpp, "Eli
Zaretskii" <eliz AT gnu DOT org> wrote:

>> From: CBFalconer <cbfalconer AT yahoo DOT com>
>> Newsgroups: comp.lang.c,comp.os.msdos.djgpp
>> Date: Thu, 05 Aug 2004 23:27:28 GMT
>> 
>> Changing the 'environ' name makes things become correct.  gcc
>> seems to be creating a parameter to main, which is being accessed
>> by the identifier environ, even though the parameters are
>> specified to be void. gcc -E creates no reference to 'environ'.
>
>`environ' is a symbol that comes from the library.  It is a pointer to
>an array of char *, where each array element is a string of the form
>"foo=bar": these are the environment variables and their values.
>
>I guess if this happens even under "-ansi -pedantic", it's a bug that
>we pollute the ANSI namespace with a non-ANSI symbol that doesn't bgin
>with an underscore.  But given that Unix programs expect that symbol,
>I'm not sure we can change that.

FWIW below is a list of library symbols that pollute the user global
namespace in *ALL* C programs and are not mentioned in the libc
documentation.
It was produced by compiling and linking a small dummy program, then
running nm -Cg, stripping the addresses, and editing out the
documented names. 
The first letter tells you whether it's defined in a text, data or bss
segment. 

D djgpp_first_ctor
D djgpp_first_dtor
D djgpp_last_ctor
D djgpp_last_dtor
D edata
B end
B environ
T etext
B exception_stack
T start

ISTM that a reasonable first step would be to document the existence
of these symbols in the libc documentation, and possibly add useful
public interfaces to some header file, perhaps only for the case of
environ, which seems to be the only symbol likely to be accessed by
user level code. 

A useful place for at least defining environ so that it could at least
be found in a header file might be in .../include/libc/environ.h
between the ANSI and POSIX excludes [1], unless _POSIX_SOURCE has to
be defined to include it, in which case [2]: 

#ifndef __STRICT_ANSI__

extern char **environ;	[1]

#ifndef _POSIX_SOURCE

extern char **environ;	[2]

-- 
Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada

Brian DOT Inglis AT CSi DOT com 	(Brian dot Inglis at SystematicSw dot ab dot ca)
    fake address		use address above to reply