Re: [PATCH 1/4] bisect--helper: `bisect_clean_state` shell function in C

[Eric Sunshine <sunshine@sunshineco.com>]

On Tue, Jun 7, 2016 at 4:54 PM, Pranit Bauva <pranit.bauva@gmail.com> wrote:
> Reimplement `bisect_clean_state` shell function in C and add a
> `bisect-clean-state` subcommand to `git bisect--helper` to call it from
> git-bisect.sh .
> [...]
> Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
> ---
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> @@ -78,11 +87,43 @@ static int write_terms(const char *bad, const char *good)
> +int mark_for_removal(const char *refname, const struct object_id *oid,
> +                      int flag, void *cb_data)
> +{
> +       struct string_list *refs = cb_data;
> +       char *ref = xstrfmt("refs/bisect/%s", refname);

Here you're allocating a string...

> +       string_list_append(refs, ref);
> +       return 0;
> +}
> +
> +int bisect_clean_state(void)
> +{
> +       int result = 0;
> +       struct string_list refs_for_removal = STRING_LIST_INIT_DUP;
> +       for_each_ref_in("refs/bisect/", mark_for_removal, (void *) &refs_for_removal);

...and the allocated string gets inserted into a string_list which
itself duplicates the string (STRING_LIST_INIT_DUP), so this is
leaking the string you created with xstrfmt(), isn't it?

> +       string_list_append(&refs_for_removal, "BISECT_HEAD");
> +       result |= delete_refs(&refs_for_removal);

Not sure I understand the point of using |= here rather than merely =
since this is the only place 'result' is assigned in this function.

> +       string_list_clear(&refs_for_removal, 0);
> +       remove_path(git_path_bisect_expected_rev());
> +       remove_path(git_path_bisect_ancestors_ok());
> +       remove_path(git_path_bisect_log());
> +       remove_path(git_path_bisect_names());
> +       remove_path(git_path_bisect_run());
> +       remove_path(git_path_bisect_write_terms());
> +       /* Cleanup head-name if it got left by an old version of git-bisect */
> +       remove_path(git_path_head_name());
> +       /* Cleanup BISECT_START last */
> +       remove_path(git_path_bisect_start());

The BISECT_START comment merely repeats what the code itself already
says. I realize that you merely copied this from the shell code, but
it isn't helpful in its current form. Much more helpful would be to
explain *why* this needs to be done last. Perhaps the commit message
of the commit which introduced the comment originally would give a
clue (I haven't checked).

> +       return result;
> +}
> diff --git a/git-bisect.sh b/git-bisect.sh
> @@ -430,27 +430,7 @@ bisect_reset() {
> -bisect_clean_state() {
> -       # There may be some refs packed during bisection.

This comment doesn't seem to be reproduced in the C version. Should it
be? Is it no longer relevant in the C version? What does it mean
exactly?

> -       git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* |
> -       while read ref hash
> -       do
> -               git update-ref -d $ref $hash || exit
> -       done
> -       rm -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
> -       rm -f "$GIT_DIR/BISECT_ANCESTORS_OK" &&
> -       rm -f "$GIT_DIR/BISECT_LOG" &&
> -       rm -f "$GIT_DIR/BISECT_NAMES" &&
> -       rm -f "$GIT_DIR/BISECT_RUN" &&
> -       rm -f "$GIT_DIR/BISECT_TERMS" &&
> -       # Cleanup head-name if it got left by an old version of git-bisect
> -       rm -f "$GIT_DIR/head-name" &&
> -       git update-ref -d --no-deref BISECT_HEAD &&
> -       # clean up BISECT_START last
> -       rm -f "$GIT_DIR/BISECT_START"
> +       git bisect--helper --bisect-clean-state || exit
>  }