Re: [PATCH 3/5] rebase -i: add exec commands via the rebase--helper

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Nov 27, 2017, 22:42 UTC
Message-ID: <alpine.DEB.2.21.1.1711272241590.6482@virtualbox>
In-Reply-To: <20171127045514.25647-4-liambeguin@gmail.com>

Hi Liam,

could I ask for a favor? I'd like the oneline to start with

	rebase -i -x: ...

(this would help future me to realize what this commit touches already from the concise graph output I favor).

On Sun, 26 Nov 2017, Liam Beguin wrote:

> Recent work on `git-rebase--interactive` aim to convert shell code to C.
> Even if this is most likely not a big performance enhacement, let's
> convert it too since a comming change to abbreviate command names requires
> it to be updated.

Since Junio did not comment on the commit message: could you replace `aim` by `aims`, `enhacement` by `enhancement` and `comming` by `coming`?

Show 6 quoted lines

> @@ -36,6 +37,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
>  			N_("skip unnecessary picks"), SKIP_UNNECESSARY_PICKS),
>  		OPT_CMDMODE(0, "rearrange-squash", &command,
>  			N_("rearrange fixup/squash lines"), REARRANGE_SQUASH),
> +		OPT_CMDMODE(0, "add-exec", &command,
> +			N_("insert exec commands in todo list"), ADD_EXEC),

Maybe `add-exec-commands`? I know it is longer to type, but these options do not need to be typed interactively and the longer name would be consistent with the function name.

Show 8 quoted lines

> diff --git a/sequencer.c b/sequencer.c
> index fa94ed652d2c..810b7850748e 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -2492,6 +2492,52 @@ int sequencer_make_script(int keep_empty, FILE *out,
>  	return 0;
>  }
>

As the code in add_exec_commands() may appear convoluted (why not simply append the command after any pick?), the original comment would be really nice here:

	/*
	 * Add commands after pick and (series of) squash/fixup commands
	 * in the todo list.
	 */

Show 8 quoted lines

> +int add_exec_commands(const char *command)
> +{
> +	const char *todo_file = rebase_path_todo();
> +	struct todo_list todo_list = TODO_LIST_INIT;
> +	int fd, res, i, first = 1;
> +	FILE *out;
> +
> +	strbuf_reset(&todo_list.buf);

The todo_list.buf has been initialized already (via TODO_LIST_INIT), no need to reset it again.

Show 8 quoted lines

> +	fd = open(todo_file, O_RDONLY);
> +	if (fd < 0)
> +		return error_errno(_("could not open '%s'"), todo_file);
> +	if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
> +		close(fd);
> +		return error(_("could not read '%s'."), todo_file);
> +	}
> +	close(fd);

As Junio pointed out so gently: there is a helper function that does this all very conveniently for us:

	if (strbuf_read_file(&todo_list.buf, todo_file, 0) < 0)
		return error_errno(_("could not read '%s'"), todo_file);

And as I realized looking at the surrounding code: you probably just inherited my inelegant code by copy-editing from another function in sequencer.c. Should you decide to add a preparatory patch to your patch series that converts these other callers, or even refactors all that code that reads the git-rebase-todo file and then parses it, I would be quite happy... :-) (although I would understand if you deemed this outside the purpose of your patch series).

Show 5 quoted lines

> +	res = parse_insn_buffer(todo_list.buf.buf, &todo_list);
> +	if (res) {
> +		todo_list_release(&todo_list);
> +		return error(_("unusable todo list: '%s'"), todo_file);
> +	}

The variable `res` is not really used here. Let's just put the parse_insn_buffer() call inside the if ().

Show 12 quoted lines

> +	out = fopen(todo_file, "w");
> +	if (!out) {
> +		todo_list_release(&todo_list);
> +		return error(_("unable to open '%s' for writing"), todo_file);
> +	}
> +	for (i = 0; i < todo_list.nr; i++) {
> +		struct todo_item *item = todo_list.items + i;
> +		int bol = item->offset_in_buf;
> +		const char *p = todo_list.buf.buf + bol;
> +		int eol = i + 1 < todo_list.nr ?
> +			todo_list.items[i + 1].offset_in_buf :
> +			todo_list.buf.len;

This smells like another copy-edited snippet that originated from my brain, and I am not at all proud by the complexity I used there.

The function should also check for errors during writing. So how about something like this instead?

	struct strbuf *buf = &todo_list.buf;
	size_t offset = 0, command_len = strlen(command);
	int first = 1, i;
	struct todo_item *item;

...

	/* insert <command> before every pick except the first one */
	for (item = todo_list.items, i = 0; i < todo_list.nr; i++, item++)
		if (item->command == TODO_PICK) {
			if (first)
				first = 0;
			else {
				strbuf_splice(buf,
					      item->offset_in_buf + offset, 0,
					      command, command_len);
				offset += command_len;
			}
		}

	/* append a final <command> */
	strbuf_complete_list(buf);
	strbuf_add(buf, command, command_len);

	i = write_message(buf->buf, buf->len, todo_file, 0);
	todo_list_release(&todo_list);
	return i;

Ciao, Dscho