Re: [PATCH 1/1] attr: add builtin objectmode values support

>
> Junio C Hamano <gitster@pobox.com> writes:
>
> > The attached is one possible way to plug the leak; I am not sure if
> > it is the best one, though.  One thing I like about the solution is
> > that the approach makes sure that the mode attributes we would ever
> > return are very tightly controlled and does not allow a buggy code
> > to come up with "mode" to be passed to this new helper function to
> > pass random and unsupported mode bits without triggering the BUG().
> >
> >  attr.c | 30 +++++++++++++++++++++++++++---
> >  1 file changed, 27 insertions(+), 3 deletions(-)
>
> Anybody who want to propose a better leakfix (we cannot afford to do
> with UNLEAK() as the number of leaked mode string will be unbounded)?
>
> Otherwise, I'll squash it in to Jonanna's patch and merge it down to
> 'next'.
>
> Thanks.
>
> > diff --git c/attr.c w/attr.c
> > index b03c20f768..679e42258c 100644
> > --- c/attr.c
> > +++ w/attr.c
> > @@ -1250,10 +1250,34 @@ static struct object_id *default_attr_source(void)
> >       return &attr_source;
> >  }
> >
> > +static const char *interned_mode_string(unsigned int mode)
> > +{
> > +     static struct {
> > +             unsigned int val;
> > +             char str[7];
> > +     } mode_string[] = {
> > +             { .val = 0040000 },
> > +             { .val = 0100644 },
> > +             { .val = 0100755 },
> > +             { .val = 0120000 },
> > +             { .val = 0160000 },
> > +     };
> > +     int i;
> > +
> > +     for (i = 0; i < ARRAY_SIZE(mode_string); i++) {
> > +             if (mode_string[i].val != mode)
> > +                     continue;
> > +             if (!*mode_string[i].str)
> > +                     snprintf(mode_string[i].str, sizeof(mode_string[i].str),
> > +                              "%06o", mode);
> > +             return mode_string[i].str;
> > +     }
> > +     BUG("Unsupported mode 0%o", mode);
> > +}
> > +
> >  static const char *builtin_object_mode_attr(struct index_state *istate, const char *path)
> >  {
> >       unsigned int mode;
> > -     struct strbuf sb = STRBUF_INIT;
> >
> >       if (direction == GIT_ATTR_CHECKIN) {
> >               struct object_id oid;
> > @@ -1287,8 +1311,8 @@ static const char *builtin_object_mode_attr(struct index_state *istate, const ch
> >               else
> >                       return ATTR__UNSET;
> >       }
> > -     strbuf_addf(&sb, "%06o", mode);
> > -     return strbuf_detach(&sb, NULL);
> > +
> > +     return interned_mode_string(mode);
> >  }
> >
> >