[PATCH 2/2] shared.c: Only setenv() if value is non-null

[Lukas Fleischer]

On Tue, Jul 26, 2011 at 06:15:07PM +0200, Ferry Huberts wrote:
> On 07/26/2011 04:48 PM, Lukas Fleischer wrote:
> > On Tue, Jul 26, 2011 at 04:24:14PM +0200, Ferry Huberts wrote:
> >> On 07/26/2011 03:32 PM, Lukas Fleischer wrote:
> >>> On Tue, Jul 26, 2011 at 01:18:14PM +0200, Ferry Huberts wrote:
> >>>> On 07/22/2011 05:15 PM, Lukas Fleischer wrote:
> >>>>> Some setenv() implementations (e.g. the one in OpenBSD's stdlib)
> >>>>> segfault if we pass a NULL value. Add an additional check to avoid this.
> >>>>>
> >>>>> Signed-off-by: Lukas Fleischer <cgit at cryptocrack.de>
> >>>>> ---
> >>>>>  shared.c |    2 +-
> >>>>>  1 files changed, 1 insertions(+), 1 deletions(-)
> >>>>>
> >>>>> diff --git a/shared.c b/shared.c
> >>>>> index 75c4b5c..0c8ce3e 100644
> >>>>> --- a/shared.c
> >>>>> +++ b/shared.c
> >>>>> @@ -392,7 +392,7 @@ void cgit_prepare_repo_env(struct cgit_repo * repo)
> >>>>>  	p = env_vars;
> >>>>>  	q = p + env_var_count;
> >>>>>  	for (; p < q; p++)
> >>>>> -		if (setenv(p->name, p->value, 1))
> >>>>> +		if (p->value && setenv(p->name, p->value, 1))
> >>>>>  			fprintf(stderr, warn, p->name, p->value);
> >>>>>  }
> >>>>>  
> >>>>
> >>>> Lukas,
> >>>>
> >>>> I don't agree with this patch.
> >>>> >From cgitrc.5.txt, lines 501-503:
> >>>>
> >>>>> If a setting is not defined for a repository and the corresponding global
> >>>>> setting is also not defined (if applicable), then the corresponding
> >>>>> environment variable will be an empty string.
> >>>>
> >>>> So I'd like this differently, an empty string must be set.
> >>>
> >>> -1. Is there any reason to do this? Imho, we should leave undefined
> >>> variables unset and fix the documentation here. This is way more
> >>> straightforward and allows for distinguishing between unset and empty
> >>> values (this is cleaner, even though there might not be a use case yet).
> >>
> >> Not true, I run this code on my servers.
> >>
> >> I agree with the fact that it is cleaner but am reluctant to have this
> >> change.
> > 
> > Wait, do you actually depend on having these environment variables
> > defined? Leaving environment variables unset instead of initializing
> > them to an empty string shouldn't make any difference if you use a shell
> > script (unless you check for it explicitly or do some fancy stuff).
> > 
> 
> unless you use 'set -u', which I do.

In that case just use "${CGIT_*-}" or do some manual checking. Easy
enough to fix.

> > If you use C (other any other programming language that uses getenv() or
> > behaves similarly), making your code compatible is as easy as modifying
> > the NULL check branch after getenv() to set the result to an empty
> > string instead of bailing out. It literally is a one-line diff.
> > 
> > Given that this is a real improvement and we only break backwards
> > compatibility for a few corner cases, +1 to changing this here.
> 
> >From my point of view it is an ABI change...
> 
> Granted, there don't seem to be many users of this yet but an ABI change
> nonetheless

It is a minor ABI change, yeah. Well, let's let Lars decide. If he says
we're not gonna change this now, I'll send an amended patch.