Re: putenv()/environ bug

["Sean C. Farley" <scf@xxxxxxxxxxx>]

On Sat, 28 Jul 2007, Andrey Borzenkov wrote:

> 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.

OK.  That would be old.  I cannot think of any relatively current system
that does not have unsetenv().

> > > 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.

Well, the comment comes after the use of zputenv().  The block of code
under the comment does not use *putenv().

> > > 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.

That would work for me.  If anyone would like me to test any patches, I
will.

Sean
--
scf@xxxxxxxxxxx