Re: [PATCH 08/29] bisect: libify `check_merge_bases` and its dependents

>
> Hi,
>
> On Mon, 20 Jan 2020, Miriam Rubio wrote:
>
> > From: Pranit Bauva <pranit.bauva@gmail.com>
> >
> > Since we want to get rid of git-bisect.sh it would be necessary to
> > convert those exit() calls to return statements so that errors can be
> > reported.
> >
> > Emulate try catch in C by converting `exit(<positive-value>)` to
> > `return <negative-value>`. Follow POSIX conventions to return
> > <negative-value> to indicate error.
> >
> > Turn `exit()` to `return` calls in `check_merge_bases()`.
> >
> > In `check_merge_bases()` there is an early success special case,
> > so we have introduced special error code `-11` which indicates early
> > success. This `-11` is converted back to `0` in `check_good_are_ancestors_of_bad()`.
> >
> > Handle the return value in dependent function `check_good_are_ancestors_of_bad()`.
>
> This is a lot of repeated text from earlier commit messages. It might make
> sense to condense it a bit, and while at it, to remove sentences that
> essentially repeat what the diff says.
>

> >
> > Mentored-by: Christian Couder <chriscool@tuxfamily.org>
> > Mentored by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
> > Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
> > Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
> > Signed-off-by: Miriam Rubio <mirucam@gmail.com>
> > ---
> >  bisect.c | 21 ++++++++++++++++-----
> >  1 file changed, 16 insertions(+), 5 deletions(-)
> >
> > diff --git a/bisect.c b/bisect.c
> > index 385afaf875..367258b0dd 100644
> > --- a/bisect.c
> > +++ b/bisect.c
> > @@ -806,13 +806,16 @@ static void handle_skipped_merge_base(const struct object_id *mb)
> >   * "check_merge_bases" checks that merge bases are not "bad" (or "new").
> >   *
> >   * - If one is "bad" (or "new"), it means the user assumed something wrong
> > - * and we must exit with a non 0 error code.
> > + * and we must return error with a non 0 error code.
> >   * - If one is "good" (or "old"), that's good, we have nothing to do.
> >   * - If one is "skipped", we can't know but we should warn.
> >   * - If we don't know, we should check it out and ask the user to test.
> > + * - If a merge base must be tested, on success return -11 a special condition
> > + * for early success, this will be converted back to 0 in check_good_are_ancestors_of_bad().
> >   */
> > -static void check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
> > +static int check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
> >  {
> > +     int res = 0;
> >       struct commit_list *result;
> >
> >       result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
> > @@ -827,11 +830,16 @@ static void check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
> >                       handle_skipped_merge_base(mb);
> >               } else {
> >                       printf(_("Bisecting: a merge base must be tested\n"));
> > -                     exit(bisect_checkout(mb, no_checkout));
> > +                     res = bisect_checkout(mb, no_checkout);
> > +                     if (!res)
> > +                             /* indicate early success */
> > +                             res = -11;
>
> This is yet another good candidate for an `enum`.
>
> > +                     break;
> >               }
> >       }
> >
> >       free_commit_list(result);
> > +     return res;
> >  }
> >
> >  static int check_ancestors(struct repository *r, int rev_nr,
> > @@ -865,7 +873,7 @@ static void check_good_are_ancestors_of_bad(struct repository *r,
> >  {
> >       char *filename = git_pathdup("BISECT_ANCESTORS_OK");
> >       struct stat st;
> > -     int fd, rev_nr;
> > +     int fd, rev_nr, res = 0;
> >       struct commit **rev;
> >
> >       if (!current_bad_oid)
> > @@ -880,10 +888,13 @@ static void check_good_are_ancestors_of_bad(struct repository *r,
> >               goto done;
> >
> >       /* Check if all good revs are ancestor of the bad rev. */
> > +
> >       rev = get_bad_and_good_commits(r, &rev_nr);
> >       if (check_ancestors(r, rev_nr, rev, prefix))
> > -             check_merge_bases(rev_nr, rev, no_checkout);
> > +             res = check_merge_bases(rev_nr, rev, no_checkout);
> >       free(rev);
> > +     if(res)
>
> Please put a space between the `if` keyword and the `(` following it.

>
> Thanks,
> Johannes
>
> > +             exit(res == -11 ? 0 : -res);
> >
> >       /* Create file BISECT_ANCESTORS_OK. */
> >       fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
> > --
> > 2.21.1 (Apple Git-122.3)
> >
> >