Re: [PATCH v2 07/34] sequencer (rebase -i): add support for the 'fixup' and 'squash' commands

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 15, 2016, 18:42 UTC
Message-ID: <xmqqlgvhuj82.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <ae521f75a105c6b9e54595d68bda3c5b62f313b6.1481642927.git.johannes.schindelin@gmx.de>

Johannes Schindelin <johannes.schindelin@gmx.de> writes:

Show 15 quoted lines

> diff --git a/sequencer.c b/sequencer.c
> index f6e20b142a..271c21581d 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -45,6 +45,35 @@ static GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
>   */
>  static GIT_PATH_FUNC(rebase_path_done, "rebase-merge/done")
>  /*
> + * The commit message that is planned to be used for any changes that
> + * need to be committed following a user interaction.
> + */
> +static GIT_PATH_FUNC(rebase_path_message, "rebase-merge/message")
> +/*
> + * The file into which is accumulated the suggested commit message for
> + * squash/fixup commands. When the first of a series of squash/fixups

The same comment as 03/34 applies here, regarding blank line to separate logical unit.

Show 30 quoted lines

> +static int update_squash_messages(enum todo_command command,
> +		struct commit *commit, struct replay_opts *opts)
> +{
> +	struct strbuf buf = STRBUF_INIT;
> +	int count, res;
> +	const char *message, *body;
> +
> +	if (file_exists(rebase_path_squash_msg())) {
> +		char *p, *p2;
> +
> +		if (strbuf_read_file(&buf, rebase_path_squash_msg(), 2048) <= 0)
> +			return error(_("could not read '%s'"),
> +				rebase_path_squash_msg());
> +
> +		if (buf.buf[0] != comment_line_char ||
> +		    !skip_prefix(buf.buf + 1, " This is a combination of ",
> +				 (const char **)&p))
> +			return error(_("unexpected 1st line of squash message:"
> +				       "\n\n\t%.*s"),
> +				     (int)(strchrnul(buf.buf, '\n') - buf.buf),
> +				     buf.buf);
> +		count = strtol(p, &p2, 10);
> +
> +		if (count < 1 || *p2 != ' ')
> +			return error(_("invalid 1st line of squash message:\n"
> +				       "\n\t%.*s"),
> +				     (int)(strchrnul(buf.buf, '\n') - buf.buf),
> +				     buf.buf);
> +
> +		sprintf((char *)p, "%d", ++count);

Do we know the area pointed at p (which is inside buf) long enough not to overflow? If the original were 9 and you incremented to get 10, you would need one extra byte.

> +		if (!*p2)
> +			*p2 = ' ';
> +		else {
> +			*(++p2) = 'c';

p2 points into buf; do we know this increment does not step beyond its end? What is the meaning of a letter 'c' here (I do not see a corresponding one in the scripted update_squash_messages)?

> +			strbuf_insert(&buf, p2 - buf.buf, " ", 1);
> +		}
> +	}
> +	else {

Style: "} else {" (I won't repeat this, as it will become too noisy).

Show 16 quoted lines

> +		unsigned char head[20];
> +		struct commit *head_commit;
> +		const char *head_message, *body;
> +
> +		if (get_sha1("HEAD", head))
> +			return error(_("need a HEAD to fixup"));
> +		if (!(head_commit = lookup_commit_reference(head)))
> +			return error(_("could not read HEAD"));
> +		if (!(head_message = get_commit_buffer(head_commit, NULL)))
> +			return error(_("could not read HEAD's commit message"));
> +
> +		body = strstr(head_message, "\n\n");
> +		if (!body)
> +			body = "";
> +		else
> +			body = skip_blank_lines(body + 2);

I think I saw you used a helper function find_commit_subject() to do the above in an earlier patch for "edit" in this series. Would it make this part (and another one for "commit" we have after this if/else) shorter?

Show 45 quoted lines

>  static int do_pick_commit(enum todo_command command, struct commit *commit,
> -		struct replay_opts *opts)
> +		struct replay_opts *opts, int final_fixup)
>  {
> +	int edit = opts->edit, cleanup_commit_message = 0;
> +	const char *msg_file = edit ? NULL : git_path_merge_msg();
>  	unsigned char head[20];
>  	struct commit *base, *next, *parent;
>  	const char *base_label, *next_label;
>  	struct commit_message msg = { NULL, NULL, NULL, NULL };
>  	struct strbuf msgbuf = STRBUF_INIT;
> -	int res, unborn = 0, allow;
> +	int res, unborn = 0, amend = 0, allow;
>  
>  	if (opts->no_commit) {
>  		/*
> @@ -749,7 +885,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
>  	else
>  		parent = commit->parents->item;
>  
> -	if (opts->allow_ff &&
> +	if (opts->allow_ff && !is_fixup(command) &&
>  	    ((parent && !hashcmp(parent->object.oid.hash, head)) ||
>  	     (!parent && unborn)))
>  		return fast_forward_to(commit->object.oid.hash, head, unborn, opts);
> @@ -813,6 +949,28 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
>  		}
>  	}
>  
> +	if (is_fixup(command)) {
> +		if (update_squash_messages(command, commit, opts))
> +			return -1;
> +		amend = 1;
> +		if (!final_fixup)
> +			msg_file = rebase_path_squash_msg();
> +		else if (file_exists(rebase_path_fixup_msg())) {
> +			cleanup_commit_message = 1;
> +			msg_file = rebase_path_fixup_msg();
> +		}
> +		else {
> +			const char *dest = git_path("SQUASH_MSG");
> +			unlink(dest);
> +			if (copy_file(dest, rebase_path_squash_msg(), 0666))
> +				return error(_("could not rename '%s' to '%s'"),
> +					     rebase_path_squash_msg(), dest);

Perhaps an error from unlink(dest) before copy_file() should also result in an error return? After all, that unlink() was added to mimick the "cp" in the scripted one and copy_file() does not want to overwrite an existing destination.

> +			unlink(git_path("MERGE_MSG"));

Errors from this and other unlink() that emulates "rm -f" were unchecked in the scripted original, so not checking for errors is not a regression. I would check for an error if I were writing this, however, because I know I would forget updating these after I am done with the series.

Show 16 quoted lines

> +			msg_file = dest;
> +			edit = 1;
> +		}
> +	}
> +
>  	if (!opts->strategy || !strcmp(opts->strategy, "recursive") || command == TODO_REVERT) {
>  		res = do_recursive_merge(base, next, base_label, next_label,
>  					 head, &msgbuf, opts);
> @@ -868,8 +1026,13 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
>  		goto leave;
>  	}
>  	if (!opts->no_commit)
> -		res = run_git_commit(opts->edit ? NULL : git_path_merge_msg(),
> -				     opts, allow, opts->edit, 0, 0);
> +		res = run_git_commit(msg_file, opts, allow, edit, amend,
> +				     cleanup_commit_message);

The introduction of msg_file variable made this call (actually, the logic to decide which file is affected) much nicer to understand.

Show 21 quoted lines

> +	if (!res && final_fixup) {
> +		unlink(rebase_path_fixup_msg());
> +		unlink(rebase_path_squash_msg());
> +	}
>  
> @@ -1475,6 +1660,21 @@ static int do_exec(const char *command_line)
>  	return status;
>  }
>  
> +static int is_final_fixup(struct todo_list *todo_list)
> +{
> +	int i = todo_list->current;
> +
> +	if (!is_fixup(todo_list->items[i].command))
> +		return 0;
> +
> +	while (++i < todo_list->nr)
> +		if (is_fixup(todo_list->items[i].command))
> +			return 0;
> +		else if (todo_list->items[i].command < TODO_NOOP)
> +			break;

What follows NOOP are comment and "drop" which is another comment in disguise, so this one is excluding all the no-op commands in various shapes, which makes sense but is clear only to a reader who bothered to go back to "enum todo_command" and checked that fact. If a check for "is it one of the no-op commands?" appears only here, a single liner comment may be sufficient (but necessary) to help readers. Otherwise a single-liner helper function (similar to is_fixup() you have) with a descriptive name would be better than a single liner comment.