[PATCH 2/5] env: Fix env_get() when returning empty string using env_get_f()

[Pali Rohár]

On Thursday 28 October 2021 21:17:38 Simon Glass wrote:
> Hi Marek,
> 
> On Wed, 27 Oct 2021 at 21:28, Marek Behún <kabel at kernel.org> wrote:
> >
> > From: Marek Behún <marek.behun at nic.cz>
> >
> > The env_get_f() function returns -1 on failure. Returning 0 means that
> > the variable exists, and is empty string.
> >
> > Signed-off-by: Marek Behún <marek.behun at nic.cz>
> > ---
> >  env/common.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Reviewed-by: Simon Glass <sjg at chromium.org>
> 
> But it isn't normally possible to set an env var to an empty string.
> How does this happen?

IIRC you can set variable to empty string via e.g.:

setenv abc ''

> >
> > diff --git a/env/common.c b/env/common.c
> > index 2aa23545ba..757c5f9ecd 100644
> > --- a/env/common.c
> > +++ b/env/common.c
> > @@ -125,7 +125,7 @@ char *env_get(const char *name)
> >         }
> >
> >         /* restricted capabilities before import */
> > -       if (env_get_f(name, (char *)(gd->env_buf), sizeof(gd->env_buf)) > 0)
> > +       if (env_get_f(name, (char *)(gd->env_buf), sizeof(gd->env_buf)) >= 0)
> >                 return (char *)(gd->env_buf);
> >
> >         return NULL;
> > --
> > 2.32.0
> >
> 
> Regards,
> Simon