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Re: putenv()/environ bug

On Thursday 26 July 2007, Sean C. Farley wrote:
> On Wed, 25 Jul 2007, Peter Stephenson wrote:
> > On Wed, 25 Jul 2007 10:09:22 -0500 (CDT)
> >
> > "Sean C. Farley" <scf@xxxxxxxxxxx> wrote:
> >> As noticed here following a change in FreeBSD's *env() functions, zsh
> >> is mixing *env() (putenv() in this case) functions with direct access
> >> to the environ variable's contents against the IEEE Std 1003.1
> >> specification.
> >>
> >> BTW, is there a particular reason the standard *env() functions
> >> cannot be used for all operations to environ if found?
> >

The code in question is quite old and I believe it predates (un-)setenv. And 
you simply did not have any way to *unset* environment string in some 
systems; I think (un-)setenv is BSD extension.

> > There's a long history of fiddling with these for problems on various
> > systems, so I'm a little unwilling to change it without some guidance.
> >
> > For example,
> >
> >    /*
> >     * Under Cygwin we must use putenv() to maintain consistency.
> >     * Unfortunately, current version (1.1.2) copies argument and may
> >     * silently reuse existing environment string. This tries to
> >     * check for both cases
> >     */
> I understand.
> > This is a little confusing since the code in question (addenv in
> > params.c) doesn't actually use putenv().
> Legacy comments are only meant to throw developers off the track.  :)

Huh? addenv() is using zputenv() that is using putenv() where avaialable. Now 
it may be legacy in the sense Cygwin implemenation has changed; but 
unfortunately I use Cygwin no more nor have environment to check it.

> > Given we manipulate environ quite a lot anyway, is there any harm in
> > using only the zsh versions of zgetenv() and zputenv()?  There's a
> > getenv() instead of a zgetenv() in init.c:  I think that was just a
> > typo by me.
> *code snipped*
> Unfortunately, this does not fix the problem.  unsets are only affecting
> the zsh environment but not environ.

What about - check if (un-)setenv is available and use them. On legacy systems 
use existing implementation. This probably will mean we will be using native 
utilities everywhere on modern systems.


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