Subject: Re: [PATCH v8 1/6] interpret-trailers: factor trailer rewriting

From: Junio C Hamano <[email-masked]>
Date: Fri, 06 Mar 2026 13:04:46 -0800

Phillip Wood <[email-masked]> writes:

> From: Li Chen <[email-masked]>
>
> Extract the trailer rewriting logic into a helper that appends to an
> output strbuf.
>
> Update interpret_trailers() to handle file I/O only: read input once,
> call the helper, and write the buffered result.
>
> This separation makes it easier to move the helper into trailer.c in the
> next commit.
>
> Signed-off-by: Phillip Wood <[email-masked]>
> Signed-off-by: Li Chen <[email-masked]>
> ---

If "Li wrote it and signed it off, Phillip is relaying" is what is
happening, the sign-offs are in reverse order.  If "Li incorporated
what Phillip wrote earlier in his larger work", then the sign-offs
may be fine, but it would be necessary to hint that that is what
happened in the proposed log message.  I cannot quite tell which is
the case.

>  builtin/interpret-trailers.c | 57 ++++++++++++++++++++----------------
>  1 file changed, 32 insertions(+), 25 deletions(-)
>
> diff --git a/builtin/interpret-trailers.c b/builtin/interpret-trailers.c
> index 41b0750e5af..69f9d67ec0e 100644
> --- a/builtin/interpret-trailers.c
> +++ b/builtin/interpret-trailers.c
> @@ -136,32 +136,21 @@ static void read_input_file(struct strbuf *sb, const char *file)
>  	strbuf_complete_line(sb);
>  }
>  
> -static void interpret_trailers(const struct process_trailer_options *opts,
> -			       struct list_head *new_trailer_head,
> -			       const char *file)
> +static void process_trailers(const struct process_trailer_options *opts,
> +			     struct list_head *new_trailer_head,
> +			     struct strbuf *input, struct strbuf *out)
>  {
>  	LIST_HEAD(head);
> -	struct strbuf sb = STRBUF_INIT;
> -	struct strbuf trailer_block_sb = STRBUF_INIT;
>  	struct trailer_block *trailer_block;
> -	FILE *outfile = stdout;
> -
> -	trailer_config_init();
> -
> -	read_input_file(&sb, file);
> -
> -	if (opts->in_place)
> -		outfile = create_in_place_tempfile(file);
> -
> -	trailer_block = parse_trailers(opts, sb.buf, &head);
> +
> +	trailer_block = parse_trailers(opts, input->buf, &head);
>  
>  	/* Print the lines before the trailer block */
>  	if (!opts->only_trailers)
> -		fwrite(sb.buf, 1, trailer_block_start(trailer_block), outfile);
> +		strbuf_add(out, input->buf, trailer_block_start(trailer_block));
>  
>  	if (!opts->only_trailers && !blank_line_before_trailer_block(trailer_block))
> -		fprintf(outfile, "\n");
> -
> +		strbuf_addch(out, '\n');
>  
>  	if (!opts->only_input) {
>  		LIST_HEAD(config_head);
> @@ -173,22 +162,40 @@ static void interpret_trailers(const struct process_trailer_options *opts,
>  	}
>  
>  	/* Print trailer block. */
> -	format_trailers(opts, &head, &trailer_block_sb);
> +	format_trailers(opts, &head, out);
>  	free_trailers(&head);
> -	fwrite(trailer_block_sb.buf, 1, trailer_block_sb.len, outfile);
> -	strbuf_release(&trailer_block_sb);
>  
>  	/* Print the lines after the trailer block as is. */
>  	if (!opts->only_trailers)
> -		fwrite(sb.buf + trailer_block_end(trailer_block), 1,
> -		       sb.len - trailer_block_end(trailer_block), outfile);
> +		strbuf_add(out, input->buf + trailer_block_end(trailer_block),
> +			   input->len - trailer_block_end(trailer_block));
>  	trailer_block_release(trailer_block);
> -
> +}
> +
> +static void interpret_trailers(const struct process_trailer_options *opts,
> +			       struct list_head *new_trailer_head,
> +			       const char *file)
> +{
> +	struct strbuf input = STRBUF_INIT;
> +	struct strbuf out = STRBUF_INIT;
> +	FILE *outfile = stdout;
> +
> +	trailer_config_init();
> +
> +	read_input_file(&input, file);
> +
> +	if (opts->in_place)
> +		outfile = create_in_place_tempfile(file);
> +
> +	process_trailers(opts, new_trailer_head, &input, &out);
> +
> +	strbuf_write(&out, outfile);
>  	if (opts->in_place)
>  		if (rename_tempfile(&trailers_tempfile, file))
>  			die_errno(_("could not rename temporary file to %s"), file);
>  
> -	strbuf_release(&sb);
> +	strbuf_release(&input);
> +	strbuf_release(&out);
>  }
>  
>  int cmd_interpret_trailers(int argc,