Re: [PATCH 3/8] vcs-svn: Introduce repo_read_path to check the content at a path

[Jonathan Nieder <jrnieder@gmail.com>]

Hi,

Jonathan Nieder wrote:

> repo_modify_path returns the mode.
>
> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

Another cryptic commit message.

A long-winded explanation follows.  Please feel free to ignore it, or
even better, come up with a summary to use as change description that
people can refer to for this patch in the future. :)

It is currently possible to _modify_ both the mode and the text at a
path but there is only public functionality to retrieve the mode.  In
its original context, this patch added analogous functionality to
retrieve the text (indexed by a blob name) as preparation for applying
a delta to it.

In the vcs-svn-incremental series, it will allow us to restructure
handle_node() a little: instead of making little modifications to an
in-memory cache managed by the repo-tree library (saying, "change the
mode this way but keep the content; now keep the mode but change the
content"), handle_node can take responsibility for figuring out what
will be the final mode and content for the path in question.

In other words, a later patch will change handle_node (in the
Node-action: change case) from looking like

	/* Change text at path. */
	mode = repo_modify_path(path, 0, have_text ? text : 0);

	/* Change mode at path. */
	if (have_props) {
		read_props(&new_mode);
		if (new_mode != mode)
			repo_modify_path(path, new_mode, have_text ? text : 0);
	}

to

	/* Determine desired text and mode at path. */
	old_text = repo_read_path(path);
	old_mode = repo_modify_path(path, 0, 0);
	if (have_props)
		read_props(old_mode, &mode);
	if (!have_text)
		text = old_text;

	/* Make it so. */
	repo_add(path, mode, text);

It is also just nice to have a function like this, to make the API
less surprising.