Move copy_note_for_rewrite + friends from builtin/notes.c to notes-utils.c

This is a pure code movement of the machinery for copying notes to
rewritten objects. This code was located in builtin/notes.c for
historical reasons. In order to make it available to builtin/commit.c
it was declared in builtin.h. This was more of an accident of history
than a concious design, and we now want to make this machinery more
widely available.

Hence, this patch moves the code into the new notes-utils.[hc] files
which are included into libgit.a. Except for adjusting #includes
accordingly, this patch merely moves the relevant functions verbatim
into the new files.

Cc: Thomas Rast <trast@inf.ethz.ch>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

notes-utils.c

@@ -0,0 +1,132 @@
+#include "cache.h"
+#include "commit.h"
+#include "refs.h"
+#include "notes-utils.h"
+#include "notes-merge.h" /* for create_notes_commit() */
+
+void commit_notes(struct notes_tree *t, const char *msg)
+{
+	struct strbuf buf = STRBUF_INIT;
+	unsigned char commit_sha1[20];
+
+	if (!t)
+		t = &default_notes_tree;
+	if (!t->initialized || !t->ref || !*t->ref)
+		die(_("Cannot commit uninitialized/unreferenced notes tree"));
+	if (!t->dirty)
+		return; /* don't have to commit an unchanged tree */
+
+	/* Prepare commit message and reflog message */
+	strbuf_addstr(&buf, msg);
+	if (buf.buf[buf.len - 1] != '\n')
+		strbuf_addch(&buf, '\n'); /* Make sure msg ends with newline */
+
+	create_notes_commit(t, NULL, &buf, commit_sha1);
+	strbuf_insert(&buf, 0, "notes: ", 7); /* commit message starts at index 7 */
+	update_ref(buf.buf, t->ref, commit_sha1, NULL, 0, DIE_ON_ERR);
+
+	strbuf_release(&buf);
+}
+
+static combine_notes_fn parse_combine_notes_fn(const char *v)
+{
+	if (!strcasecmp(v, "overwrite"))
+		return combine_notes_overwrite;
+	else if (!strcasecmp(v, "ignore"))
+		return combine_notes_ignore;
+	else if (!strcasecmp(v, "concatenate"))
+		return combine_notes_concatenate;
+	else if (!strcasecmp(v, "cat_sort_uniq"))
+		return combine_notes_cat_sort_uniq;
+	else
+		return NULL;
+}
+
+static int notes_rewrite_config(const char *k, const char *v, void *cb)
+{
+	struct notes_rewrite_cfg *c = cb;
+	if (!prefixcmp(k, "notes.rewrite.") && !strcmp(k+14, c->cmd)) {
+		c->enabled = git_config_bool(k, v);
+		return 0;
+	} else if (!c->mode_from_env && !strcmp(k, "notes.rewritemode")) {
+		if (!v)
+			config_error_nonbool(k);
+		c->combine = parse_combine_notes_fn(v);
+		if (!c->combine) {
+			error(_("Bad notes.rewriteMode value: '%s'"), v);
+			return 1;
+		}
+		return 0;
+	} else if (!c->refs_from_env && !strcmp(k, "notes.rewriteref")) {
+		/* note that a refs/ prefix is implied in the
+		 * underlying for_each_glob_ref */
+		if (!prefixcmp(v, "refs/notes/"))
+			string_list_add_refs_by_glob(c->refs, v);
+		else
+			warning(_("Refusing to rewrite notes in %s"
+				" (outside of refs/notes/)"), v);
+		return 0;
+	}
+
+	return 0;
+}
+
+
+struct notes_rewrite_cfg *init_copy_notes_for_rewrite(const char *cmd)
+{
+	struct notes_rewrite_cfg *c = xmalloc(sizeof(struct notes_rewrite_cfg));
+	const char *rewrite_mode_env = getenv(GIT_NOTES_REWRITE_MODE_ENVIRONMENT);
+	const char *rewrite_refs_env = getenv(GIT_NOTES_REWRITE_REF_ENVIRONMENT);
+	c->cmd = cmd;
+	c->enabled = 1;
+	c->combine = combine_notes_concatenate;
+	c->refs = xcalloc(1, sizeof(struct string_list));
+	c->refs->strdup_strings = 1;
+	c->refs_from_env = 0;
+	c->mode_from_env = 0;
+	if (rewrite_mode_env) {
+		c->mode_from_env = 1;
+		c->combine = parse_combine_notes_fn(rewrite_mode_env);
+		if (!c->combine)
+			/* TRANSLATORS: The first %s is the name of the
+			   environment variable, the second %s is its value */
+			error(_("Bad %s value: '%s'"), GIT_NOTES_REWRITE_MODE_ENVIRONMENT,
+					rewrite_mode_env);
+	}
+	if (rewrite_refs_env) {
+		c->refs_from_env = 1;
+		string_list_add_refs_from_colon_sep(c->refs, rewrite_refs_env);
+	}
+	git_config(notes_rewrite_config, c);
+	if (!c->enabled || !c->refs->nr) {
+		string_list_clear(c->refs, 0);
+		free(c->refs);
+		free(c);
+		return NULL;
+	}
+	c->trees = load_notes_trees(c->refs);
+	string_list_clear(c->refs, 0);
+	free(c->refs);
+	return c;
+}
+
+int copy_note_for_rewrite(struct notes_rewrite_cfg *c,
+			  const unsigned char *from_obj, const unsigned char *to_obj)
+{
+	int ret = 0;
+	int i;
+	for (i = 0; c->trees[i]; i++)
+		ret = copy_note(c->trees[i], from_obj, to_obj, 1, c->combine) || ret;
+	return ret;
+}
+
+void finish_copy_notes_for_rewrite(struct notes_rewrite_cfg *c, const char *msg)
+{
+	int i;
+	for (i = 0; c->trees[i]; i++) {
+		commit_notes(c->trees[i], msg);
+		free_notes(c->trees[i]);
+	}
+	free(c->trees);
+	free(c);
+}