Re: [PATCH v2 09/11] bisect: libify `check_good_are_ancestors_of_bad` and its dependents

> Hi Dscho,
>
> On Thu, Jan 30, 2020 at 2:46 PM Johannes Schindelin
> <Johannes.Schindelin@gmx.de> wrote:
> >
> > On Tue, 28 Jan 2020, Miriam Rubio wrote:
>
> > > +             /* Create file BISECT_ANCESTORS_OK. */
> > > +             fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
> > > +             if (fd < 0)
> > > +                     warning_errno(_("could not create file '%s'"),
> > > +                                   filename);
> > > +             else
> > > +                     close(fd);
> > > +     }
> >
> > I wonder whether this would be easier to read:
> >
> >         if (res == -11)
> >                 res = 0;
> >         else if (res)
> >                 ; /* error out */
> >         else if ((fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600)) < 0)
> >                 res = warning_errno(_("could not create file '%s'"), filename);
> >         else
> >                 close(fd);
> >
> > Note: my code explicitly assigns `res = -1` if the file could not be
> > created, which is technically a change in behavior, but I think it is
> > actually a bug fix.
>
> I don't think so. I think creating the BISECT_ANCESTORS_OK file is not
> absolutely necessary. If it doesn't exist we will just check if
> ancestors are ok again at the next bisection step, which will take a
> bit of time, but which will not make us give any false result, or
> prevent us from continuing the bisection process.
>
> I think that it's also the reason why warning_errno(...) is used in
> case we could not create the file instead of error_errno(...). We just
> want to signal with a warning that something might be wrong because we
> could not create the file, but not stop everything because of that.