Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Message-ID: <af67552e0501121328106002cd@mail.gmail.com>
Date: Wed, 12 Jan 2005 22:28:44 +0100
From: Eric Hoffman <clallosy AT gmail DOT com>
Reply-To: Eric Hoffman <clallosy AT gmail DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: execv and then socket: "operation not permitted"
In-Reply-To: <20050111122015.GP23702@cygbert.vinschen.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
References: <af67552e05010812586e656b9e AT mail DOT gmail DOT com> <20050109121953 DOT GA5017 AT cygbert DOT vinschen DOT de> <af67552e05011013546a132992 AT mail DOT gmail DOT com> <20050111122015 DOT GP23702 AT cygbert DOT vinschen DOT de>
X-IsSubscribed: yes

Thanks for the help! 

That's about the only significant change in about 37000 lines of C
code of a legacy application dating back to 1998... quite a testimony
to both the original programmer (not me!) skills and Cygwin
conformance to standards.

Cheers,

Eric


On Tue, 11 Jan 2005 13:20:15 +0100, Corinna Vinschen
<corinna-cygwin AT cygwin DOT com> wrote:
> On Jan 10 22:54, Eric Hoffman wrote:
> > On Sun, 9 Jan 2005 13:19:53 +0100, Corinna Vinschen wrote:
> > > Could you please prepare a short testcase, only containing the
> > > necessary lines to reproduce the problem?
> >
> > I have attached 2 files to reproduce the problem. It is linked to the
> > putenv() call and the env variable then being reset.
> 
> Thanks for the testcase.
> 
> >       strcpy(fooflags,"fooflags=1");
> >       putenv(fooflags);
> >       *fooflags = '\0'; /* remove from environment after all */
> 
> Oh well.  What happens is that your empty string results in a fatal
> change in the Win32 environment propagated to the child application.
> A Win32 environment consists of a long string of \0-terminated strings.
> The end of the environment is indicated by a second \0, like this:
> 
>  "a=b\0c=d\0e=f\0\0"
> 
> By setting one of the strings to \0 as you do, the propagated environment
> contains an early \0:
> 
>  "\0\0c=d\0e=f\0\0"
> 
> The result is that the propagated Win32 environment is actually empty.
> Missing $PATH and $SYSTEMROOT are fatal and explain the socket problem
> you encountered.
> 
> This is a bug in Cygwin insofar as Cygwin should not allow to propagate
> empty strings to the child application.  I'm preparing a patch right now.
> In the meantime, don't do that.  Replace
> 
>  *fooflags = '\0';
> 
> by
> 
>  unsetenv ("fooflags");
> 
> NB: The use of setenv/unsetenv is preferrable over using putenv anyway.
> 
> 
> Corinna
> 
> --
> Corinna Vinschen                  Please, send mails regarding Cygwin to
> Cygwin Project Co-Leader          mailto:cygwin AT cygwin DOT com
> Red Hat, Inc.
> 
> --
> Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
> Problem reports:       http://cygwin.com/problems.html
> Documentation:         http://cygwin.com/docs.html
> FAQ:                   http://cygwin.com/faq/
> 
>

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/