Re: [PATCH v2] bisect: don't use invalid oid as rev when starting

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Christian,

On Thu, 24 Sep 2020, Christian Couder wrote:

> In 06f5608c14 (bisect--helper: `bisect_start` shell function
> partially in C, 2019-01-02), we changed the following shell
> code:
>
> -                       rev=$(git rev-parse -q --verify "$arg^{commit}") || {
> -                               test $has_double_dash -eq 1 &&
> -                               die "$(eval_gettext "'\$arg' does not appear to be a valid revision")"
> -                               break
> -                       }
> -                       revs="$revs $rev"

These are awfully long lines. The reason is that you kept the indentation
of the diff. But that's actually not necessary, because we do not need to
apply a diff here; This code snippet is intended purely for human
consumption.

What I suggested in my adaptation of your patch was to lose the diff
markers and to decrease the insane amount of indentation to just one (and
two) horizontal tabs.

> into:
>
> +                       char *commit_id = xstrfmt("%s^{commit}", arg);
> +                       if (get_oid(commit_id, &oid) && has_double_dash)
> +                               die(_("'%s' does not appear to be a valid "
> +                                     "revision"), arg);
> +
> +                       string_list_append(&revs, oid_to_hex(&oid));
> +                       free(commit_id);
>
> In case of an invalid "arg" when "has_double_dash" is false, the old
> code would "break" out of the argument loop.
>
> In the new C code though, `oid_to_hex(&oid)` is unconditonally
> appended to "revs". This is wrong first because "oid" is junk as
> `get_oid(commit_id, &oid)` failed and second because it doesn't break
> out of the argument loop.
>
> Not breaking out of the argument loop means that "arg" is then not
> treated as a path restriction.
>
> Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> This patch is made on top of e1cfff6765 (Sixteenth batch, 2020-09-22)
> and incorporates Dscho's suggestions.
>
> Thanks to Junio and Dscho for reviewing the first version.
>
>  builtin/bisect--helper.c    | 14 ++++++--------
>  t/t6030-bisect-porcelain.sh |  7 +++++++
>  2 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> index 7dcc1b5188..f4762e1774 100644
> --- a/builtin/bisect--helper.c
> +++ b/builtin/bisect--helper.c
> @@ -484,15 +484,13 @@ static int bisect_start(struct bisect_terms *terms, const char **argv, int argc)
>  			terms->term_bad = xstrdup(arg);
>  		} else if (starts_with(arg, "--")) {
>  			return error(_("unrecognized option: '%s'"), arg);
> -		} else {
> -			char *commit_id = xstrfmt("%s^{commit}", arg);
> -			if (get_oid(commit_id, &oid) && has_double_dash)
> -				die(_("'%s' does not appear to be a valid "
> -				      "revision"), arg);
> -
> +		} else if (!get_oid_committish(arg, &oid))
>  			string_list_append(&revs, oid_to_hex(&oid));
> -			free(commit_id);
> -		}
> +		else if (has_double_dash)
> +			die(_("'%s' does not appear to be a valid "
> +			      "revision"), arg);
> +		else
> +			break;

Thank you!

>  	}
>  	pathspec_pos = i;
>
> diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
> index b886529e59..70c39a9459 100755
> --- a/t/t6030-bisect-porcelain.sh
> +++ b/t/t6030-bisect-porcelain.sh
> @@ -82,6 +82,13 @@ test_expect_success 'bisect fails if given any junk instead of revs' '
>  	git bisect bad $HASH4
>  '
>
> +test_expect_success 'bisect start without -- uses unknown arg as path restriction' '

To avoid the overly long line (and also to re-use existing naming
conventions), I replaced "path restrictions" by "pathspecs" here. What do
you think?

Ciao,
Dscho

> +	git bisect reset &&
> +	git bisect start foo bar &&
> +	grep foo ".git/BISECT_NAMES" &&
> +	grep bar ".git/BISECT_NAMES"
> +'
> +
>  test_expect_success 'bisect reset: back in the master branch' '
>  	git bisect reset &&
>  	echo "* master" > branch.expect &&
> --
> 2.28.0.585.ge1cfff6765
>
>