Re: Regression in v2.23

> Subject: [PATCH] range-diff: don't segfault with mode-only changes
>
> If we don't have a new file, deleted file or renamed file in a diff,
> we currently add 'patch.new_name' to the range-diff header.  This
> works well for files that are changed.  However if we have a pure mode
> change, 'patch.new_name' is NULL, and thus range-diff segfaults.
>
> We can however rely on 'patch.def_name' in that case, which is
> extracted from the 'diff --git' line and should be equal to
> 'patch.new_name'.  Use that instead to avoid the segfault.
>
> Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
> ---
>  range-diff.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/range-diff.c b/range-diff.c
> index ba1e9a4265..d8d906b3c6 100644
> --- a/range-diff.c
> +++ b/range-diff.c
> @@ -116,20 +116,20 @@ static int read_patches(const char *range, struct string_list *list)
>  			if (len < 0)
>  				die(_("could not parse git header '%.*s'"), (int)len, line);
>  			strbuf_addstr(&buf, " ## ");
> -			if (patch.is_new > 0)
> +			free(current_filename);
> +			if (patch.is_new > 0) {
>  				strbuf_addf(&buf, "%s (new)", patch.new_name);
> -			else if (patch.is_delete > 0)
> +				current_filename = xstrdup(patch.new_name);
> +			} else if (patch.is_delete > 0) {
>  				strbuf_addf(&buf, "%s (deleted)", patch.old_name);
> -			else if (patch.is_rename)
> -				strbuf_addf(&buf, "%s => %s", patch.old_name, patch.new_name);
> -			else
> -				strbuf_addstr(&buf, patch.new_name);
> -
> -			free(current_filename);
> -			if (patch.is_delete > 0)
>  				current_filename = xstrdup(patch.old_name);
> -			else
> +			} else if (patch.is_rename) {
> +				strbuf_addf(&buf, "%s => %s", patch.old_name, patch.new_name);
>  				current_filename = xstrdup(patch.new_name);
> +			} else {
> +				strbuf_addstr(&buf, patch.def_name);
> +				current_filename = xstrdup(patch.def_name);
> +			}
>
>  			if (patch.new_mode && patch.old_mode &&
>  			    patch.old_mode != patch.new_mode)
> --