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

[Junio C Hamano <gitster@pobox.com>]

Christian Couder <christian.couder@gmail.com> writes:

> In 06f5608c14 (bisect--helper: `bisect_start` shell function
> partially in C, 2019-01-02), we changed the following shell
> code:

Wow, that's an ancient breakage (goes back to 2.21 or something).

Thanks; will queue.

>
> -                       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"
>
> 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 (which is wrong).
>
> Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
> ---
> This is a bug fix for the bug Miriam talks about in:
>
> https://lore.kernel.org/git/20200923072740.20772-1-mirucam@gmail.com/
>
> and:
>
> https://lore.kernel.org/git/CAN7CjDDVp_i7dhpbAq5zrGW69nE6+SfivJQ-dembmu+WyqKiQQ@mail.gmail.com/
>
>  builtin/bisect--helper.c    | 14 +++++++++-----
>  t/t6030-bisect-porcelain.sh |  7 +++++++
>  2 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> index 7dcc1b5188..538fa6f16b 100644
> --- a/builtin/bisect--helper.c
> +++ b/builtin/bisect--helper.c
> @@ -486,12 +486,16 @@ static int bisect_start(struct bisect_terms *terms, const char **argv, int argc)
>  			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);
> -
> -			string_list_append(&revs, oid_to_hex(&oid));
> +			int res = get_oid(commit_id, &oid);
>  			free(commit_id);
> +			if (res) {
> +				if (has_double_dash)
> +					die(_("'%s' does not appear to be a valid "
> +					      "revision"), arg);
> +				break;
> +			} else {
> +				string_list_append(&revs, oid_to_hex(&oid));
> +			}
>  		}
>  	}
>  	pathspec_pos = i;
> diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
> index b886529e59..cb645cf8c8 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 stuff as path restriction' '
> +	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 &&