Re: putenv()/environ bug

["Sean C. Farley" <scf@FreeBSD.org>]

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@FreeBSD.org> 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@FreeBSD.org