Re: [PATCH v2 4/5] diff.c: initialize hash algo when running in --no-index mode

> Our "git diff" command supports running as a standalone tool. In this
> code path, we try to hash the file content but after
> 18e2588e11 (sha1_file: switch uses of SHA-1 to the_hash_algo -
> 2018-02-01), there is a chance that the_hash_algo (required by
> index_path) may still be uninitialized if no repository is found.
>
> Executing index_path() when the_hash_algo is NULL (or points to unknown
> algo) either crashes or dies. Let's make it a bit safer by explicitly
> falling back to SHA-1 (so that the diff output remains the same as
> before, compared to the alternative that we simply do not hash).
>
> dòng được

> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
> diff --git a/diff.c b/diff.c
> @@ -3995,6 +3995,18 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
> +       /*
> +        * NEEDSWORK: When running in no-index mode (and no repo is
> +        * found, thus no hash algo conifugred), fall back to SHA-1

> +        * hashing (which is used by diff_fill_oid_info below) to
> +        * avoid regression in diff output.
> +        *
> +        * In future, perhaps we can allow the user to specify their
> +        * hash algorithm from command line in this mode.
> +        */
> +       if (o->flags.no_index && !the_hash_algo)
> +               the_hash_algo = &hash_algos[GIT_HASH_SHA1];
> +
>         diff_fill_oid_info(one);
>         diff_fill_oid_info(two);