void cgit_diff_tree(const unsigned char *old_sha1,
		    const unsigned char *new_sha1,
		    filepair_fn fn, const char *prefix, int ignorews)
{
	struct diff_options opt;
	struct pathspec_item item;

	diff_setup(&opt);
	opt.output_format = DIFF_FORMAT_CALLBACK;
	opt.detect_rename = 1;
	opt.rename_limit = ctx.cfg.renamelimit;
	DIFF_OPT_SET(&opt, RECURSIVE);
	if (ignorews)
		DIFF_XDL_SET(&opt, IGNORE_WHITESPACE);
	opt.format_callback = cgit_diff_tree_cb;
	opt.format_callback_data = fn;
	if (prefix) {
		item.match = prefix;
		item.len = strlen(prefix);
		opt.pathspec.nr = 1;
		opt.pathspec.items = &item;
	}
	diff_setup_done(&opt);

	if (old_sha1 && !is_null_sha1(old_sha1))
		diff_tree_sha1(old_sha1, new_sha1, "", &opt);
	else
		diff_root_tree_sha1(new_sha1, "", &opt);
	diffcore_std(&opt);
	diff_flush(&opt);
}

void check_for_new_submodule_commits(unsigned char new_sha1[20])
{
	struct rev_info rev;
	struct commit *commit;
	const char *argv[] = {NULL, NULL, "--not", "--all", NULL};
	int argc = ARRAY_SIZE(argv) - 1;

	init_revisions(&rev, NULL);
	argv[1] = xstrdup(sha1_to_hex(new_sha1));
	setup_revisions(argc, argv, &rev, NULL);
	if (prepare_revision_walk(&rev))
		die("revision walk setup failed");

	/*
	 * Collect all submodules (whether checked out or not) for which new
	 * commits have been recorded upstream in "changed_submodule_paths".
	 */
	while ((commit = get_revision(&rev))) {
		struct commit_list *parent = commit->parents;
		while (parent) {
			struct diff_options diff_opts;
			diff_setup(&diff_opts);
			diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
			diff_opts.format_callback = submodule_collect_changed_cb;
			if (diff_setup_done(&diff_opts) < 0)
				die("diff_setup_done failed");
			diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
			diffcore_std(&diff_opts);
			diff_flush(&diff_opts);
			parent = parent->next;
		}
	}
	free((char *)argv[1]);
}

static int check_changes_tracked_files(struct pathspec ps)
{
	int result;
	struct rev_info rev;
	struct object_id dummy;

	/* No initial commit. */
	if (get_oid("HEAD", &dummy))
		return -1;

	if (read_cache() < 0)
		return -1;

	init_revisions(&rev, NULL);
	rev.prune_data = ps;

	rev.diffopt.flags.quick = 1;
	rev.diffopt.flags.ignore_submodules = 1;
	rev.abbrev = 0;

	add_head_to_pending(&rev);
	diff_setup_done(&rev.diffopt);

	result = run_diff_index(&rev, 1);
	if (diff_result_code(&rev.diffopt, result))
		return 1;

	object_array_clear(&rev.pending);
	result = run_diff_files(&rev, 0);
	if (diff_result_code(&rev.diffopt, result))
		return 1;

	return 0;
}

void cgit_diff_tree(const unsigned char *old_sha1,
		    const unsigned char *new_sha1,
		    filepair_fn fn, const char *prefix)
{
	struct diff_options opt;
	int ret;
	int prefixlen;

	diff_setup(&opt);
	opt.output_format = DIFF_FORMAT_CALLBACK;
	opt.detect_rename = 1;
	opt.rename_limit = ctx.cfg.renamelimit;
	DIFF_OPT_SET(&opt, RECURSIVE);
	opt.format_callback = cgit_diff_tree_cb;
	opt.format_callback_data = fn;
	if (prefix) {
		opt.nr_paths = 1;
		opt.paths = &prefix;
		prefixlen = strlen(prefix);
		opt.pathlens = &prefixlen;
	}
	diff_setup_done(&opt);

	if (old_sha1 && !is_null_sha1(old_sha1))
		ret = diff_tree_sha1(old_sha1, new_sha1, "", &opt);
	else
		ret = diff_root_tree_sha1(new_sha1, "", &opt);
	diffcore_std(&opt);
	diff_flush(&opt);
}

void diff_no_index(struct rev_info *revs,
		   int argc, const char **argv,
		   const char *prefix)
{
	int i, prefixlen;
	const char *paths[2];

	diff_setup(&revs->diffopt);
	for (i = 1; i < argc - 2; ) {
		int j;
		if (!strcmp(argv[i], "--no-index"))
			i++;
		else if (!strcmp(argv[i], "--"))
			i++;
		else {
			j = diff_opt_parse(&revs->diffopt, argv + i, argc - i);
			if (j <= 0)
				die("invalid diff option/value: %s", argv[i]);
			i += j;
		}
	}

	prefixlen = prefix ? strlen(prefix) : 0;
	for (i = 0; i < 2; i++) {
		const char *p = argv[argc - 2 + i];
		if (!strcmp(p, "-"))
			/*
			 * stdin should be spelled as "-"; if you have
			 * path that is "-", spell it as "./-".
			 */
			p = file_from_standard_input;
		else if (prefixlen)
			p = xstrdup(prefix_filename(prefix, prefixlen, p));
		paths[i] = p;
	}
	revs->diffopt.skip_stat_unmatch = 1;
	if (!revs->diffopt.output_format)
		revs->diffopt.output_format = DIFF_FORMAT_PATCH;

	DIFF_OPT_SET(&revs->diffopt, NO_INDEX);

	revs->max_count = -2;
	diff_setup_done(&revs->diffopt);

	setup_diff_pager(&revs->diffopt);
	DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);

	if (queue_diff(&revs->diffopt, paths[0], paths[1]))
		exit(1);
	diff_set_mnemonic_prefix(&revs->diffopt, "1/", "2/");
	diffcore_std(&revs->diffopt);
	diff_flush(&revs->diffopt);

	/*
	 * The return code for --no-index imitates diff(1):
	 * 0 = no changes, 1 = changes, else error
	 */
	exit(diff_result_code(&revs->diffopt, 0));
}

/*
 * Get information of all renames which occurred between 'o_tree' and
 * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 * 'b_tree') to be able to associate the correct cache entries with
 * the rename information. 'tree' is always equal to either a_tree or b_tree.
 */
static struct string_list *get_renames(struct merge_options *o,
				       struct tree *tree,
				       struct tree *o_tree,
				       struct tree *a_tree,
				       struct tree *b_tree,
				       struct string_list *entries)
{
	int i;
	struct string_list *renames;
	struct diff_options opts;

	renames = xcalloc(1, sizeof(struct string_list));
	diff_setup(&opts);
	DIFF_OPT_SET(&opts, RECURSIVE);
	opts.detect_rename = DIFF_DETECT_RENAME;
	opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
			    o->diff_rename_limit >= 0 ? o->diff_rename_limit :
			    500;
	opts.warn_on_too_large_rename = 1;
	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
	if (diff_setup_done(&opts) < 0)
		die("diff setup failed");
	diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
	diffcore_std(&opts);
	for (i = 0; i < diff_queued_diff.nr; ++i) {
		struct string_list_item *item;
		struct rename *re;
		struct diff_filepair *pair = diff_queued_diff.queue[i];
		if (pair->status != 'R') {
			diff_free_filepair(pair);
			continue;
		}
		re = xmalloc(sizeof(*re));
		re->processed = 0;
		re->pair = pair;
		item = string_list_lookup(re->pair->one->path, entries);
		if (!item)
			re->src_entry = insert_stage_data(re->pair->one->path,
					o_tree, a_tree, b_tree, entries);
		else
			re->src_entry = item->util;

		item = string_list_lookup(re->pair->two->path, entries);
		if (!item)
			re->dst_entry = insert_stage_data(re->pair->two->path,
					o_tree, a_tree, b_tree, entries);
		else
			re->dst_entry = item->util;
		item = string_list_insert(pair->one->path, renames);
		item->util = re;
	}
	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
	diff_queued_diff.nr = 0;
	diff_flush(&opts);
	return renames;
}

int init_patch_ids(struct patch_ids *ids)
{
	memset(ids, 0, sizeof(*ids));
	diff_setup(&ids->diffopts);
	ids->diffopts.detect_rename = 0;
	DIFF_OPT_SET(&ids->diffopts, RECURSIVE);
	diff_setup_done(&ids->diffopts);
	hashmap_init(&ids->patches, (hashmap_cmp_fn)patch_id_cmp, 256);
	return 0;
}

int init_patch_ids(struct patch_ids *ids)
{
	memset(ids, 0, sizeof(*ids));
	diff_setup(&ids->diffopts);
	ids->diffopts.detect_rename = 0;
	ids->diffopts.flags.recursive = 1;
	diff_setup_done(&ids->diffopts);
	hashmap_init(&ids->patches, patch_id_neq, &ids->diffopts, 256);
	return 0;
}

/**
 * Returns 1 if there are unstaged changes, 0 otherwise.
 */
static int has_unstaged_changes(const char *prefix)
{
	struct rev_info rev_info;
	int result;

	init_revisions(&rev_info, prefix);
	DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
	DIFF_OPT_SET(&rev_info.diffopt, QUICK);
	diff_setup_done(&rev_info.diffopt);
	result = run_diff_files(&rev_info, 0);
	return diff_result_code(&rev_info.diffopt, result);
}

static void show_local_changes(struct object *head,
			       const struct diff_options *opts)
{
	struct rev_info rev;
	/* I think we want full paths, even if we're in a subdirectory. */
	repo_init_revisions(the_repository, &rev, NULL);
	rev.diffopt.flags = opts->flags;
	rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
	diff_setup_done(&rev.diffopt);
	add_pending_object(&rev, head, NULL);
	run_diff_index(&rev, 0);
}

static void finish(struct commit *head_commit,
		   struct commit_list *remoteheads,
		   const unsigned char *new_head, const char *msg)
{
	struct strbuf reflog_message = STRBUF_INIT;
	const unsigned char *head = head_commit->object.oid.hash;

	if (!msg)
		strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
	else {
		if (verbosity >= 0)
			printf("%s\n", msg);
		strbuf_addf(&reflog_message, "%s: %s",
			getenv("GIT_REFLOG_ACTION"), msg);
	}
	if (squash) {
		squash_message(head_commit, remoteheads);
	} else {
		if (verbosity >= 0 && !merge_msg.len)
			printf(_("No merge message -- not updating HEAD\n"));
		else {
			const char *argv_gc_auto[] = { "gc", "--auto", NULL };
			update_ref(reflog_message.buf, "HEAD",
				new_head, head, 0,
				UPDATE_REFS_DIE_ON_ERR);
			/*
			 * We ignore errors in 'gc --auto', since the
			 * user should see them.
			 */
			close_all_packs();
			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
		}
	}
	if (new_head && show_diffstat) {
		struct diff_options opts;
		diff_setup(&opts);
		opts.stat_width = -1; /* use full terminal width */
		opts.stat_graph_width = -1; /* respect statGraphWidth config */
		opts.output_format |=
			DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
		opts.detect_rename = DIFF_DETECT_RENAME;
		diff_setup_done(&opts);
		diff_tree_sha1(head, new_head, "", &opts);
		diffcore_std(&opts);
		diff_flush(&opts);
	}

	/* Run a post-merge hook */
	run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);

	strbuf_release(&reflog_message);
}

static void finish(const unsigned char *new_head, const char *msg)
{
	struct strbuf reflog_message = STRBUF_INIT;

	if (!msg)
		strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
	else {
		if (verbosity >= 0)
			printf("%s\n", msg);
		strbuf_addf(&reflog_message, "%s: %s",
			getenv("GIT_REFLOG_ACTION"), msg);
	}
	if (squash) {
		squash_message();
	} else {
		if (verbosity >= 0 && !merge_msg.len)
			printf(_("No merge message -- not updating HEAD\n"));
		else {
			const char *argv_gc_auto[] = { "gc", "--auto", NULL };
			update_ref(reflog_message.buf, "HEAD",
				new_head, head, 0,
				DIE_ON_ERR);
			/*
			 * We ignore errors in 'gc --auto', since the
			 * user should see them.
			 */
			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
		}
	}
	if (new_head && show_diffstat) {
		struct diff_options opts;
		diff_setup(&opts);
		opts.output_format |=
			DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
		opts.detect_rename = DIFF_DETECT_RENAME;
		if (diff_use_color_default > 0)
			DIFF_OPT_SET(&opts, COLOR_DIFF);
		if (diff_setup_done(&opts) < 0)
			die(_("diff_setup_done failed"));
		diff_tree_sha1(head, new_head, "", &opts);
		diffcore_std(&opts);
		diff_flush(&opts);
	}

	/* Run a post-merge hook */
	run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);

	strbuf_release(&reflog_message);
}

static void prepare_bases(struct base_tree_info *bases,
			  struct commit *base,
			  struct commit **list,
			  int total)
{
	struct commit *commit;
	struct rev_info revs;
	struct diff_options diffopt;
	int i;

	if (!base)
		return;

	diff_setup(&diffopt);
	DIFF_OPT_SET(&diffopt, RECURSIVE);
	diff_setup_done(&diffopt);

	oidcpy(&bases->base_commit, &base->object.oid);

	init_revisions(&revs, NULL);
	revs.max_parents = 1;
	revs.topo_order = 1;
	for (i = 0; i < total; i++) {
		list[i]->object.flags &= ~UNINTERESTING;
		add_pending_object(&revs, &list[i]->object, "rev_list");
		list[i]->util = (void *)1;
	}
	base->object.flags |= UNINTERESTING;
	add_pending_object(&revs, &base->object, "base");

	if (prepare_revision_walk(&revs))
		die(_("revision walk setup failed"));
	/*
	 * Traverse the commits list, get prerequisite patch ids
	 * and stuff them in bases structure.
	 */
	while ((commit = get_revision(&revs)) != NULL) {
		unsigned char sha1[20];
		struct object_id *patch_id;
		if (commit->util)
			continue;
		if (commit_patch_id(commit, &diffopt, sha1))
			die(_("cannot get patch id"));
		ALLOC_GROW(bases->patch_id, bases->nr_patch_id + 1, bases->alloc_patch_id);
		patch_id = bases->patch_id + bases->nr_patch_id;
		hashcpy(patch_id->hash, sha1);
		bases->nr_patch_id++;
	}
}

int main(int ac, const char **av)
{
	int stage1, stage2;

	setup_git_directory();

	git_config(git_diff_config);
	read_cache();
	diff_setup(&diff_options);
	while (1 < ac && av[1][0] == '-') {
		const char *arg = av[1];
		if (!strcmp(arg, "-r"))
			; /* as usual */
		else {
			int diff_opt_cnt;
			diff_opt_cnt = diff_opt_parse(&diff_options,
						      av+1, ac-1);
			if (diff_opt_cnt < 0)
				usage(diff_stages_usage);
			else if (diff_opt_cnt) {
				av += diff_opt_cnt;
				ac -= diff_opt_cnt;
				continue;
			}
			else
				usage(diff_stages_usage);
		}
		ac--; av++;
	}

	if (ac < 3 ||
	    sscanf(av[1], "%d", &stage1) != 1 ||
	    ! (0 <= stage1 && stage1 <= 3) ||
	    sscanf(av[2], "%d", &stage2) != 1 ||
	    ! (0 <= stage2 && stage2 <= 3))
		usage(diff_stages_usage);

	av += 3; /* The rest from av[0] are for paths restriction. */
	diff_options.paths = av;

	if (diff_setup_done(&diff_options) < 0)
		usage(diff_stages_usage);

	diff_stages(stage1, stage2);
	diffcore_std(&diff_options);
	diff_flush(&diff_options);
	return 0;
}

/**
 * Returns 1 if there are uncommitted changes, 0 otherwise.
 */
static int has_uncommitted_changes(const char *prefix)
{
	struct rev_info rev_info;
	int result;

	if (is_cache_unborn())
		return 0;

	init_revisions(&rev_info, prefix);
	DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
	DIFF_OPT_SET(&rev_info.diffopt, QUICK);
	add_head_to_pending(&rev_info);
	diff_setup_done(&rev_info.diffopt);
	result = run_diff_index(&rev_info, 1);
	return diff_result_code(&rev_info.diffopt, result);
}

static void calculate_changed_submodule_paths(void)
{
	struct rev_info rev;
	struct commit *commit;
	struct argv_array argv = ARGV_ARRAY_INIT;

	/* No need to check if there are no submodules configured */
	if (!config_name_for_path.nr)
		return;

	init_revisions(&rev, NULL);
	argv_array_push(&argv, "--"); /* argv[0] program name */
	sha1_array_for_each_unique(&ref_tips_after_fetch,
				   add_sha1_to_argv, &argv);
	argv_array_push(&argv, "--not");
	sha1_array_for_each_unique(&ref_tips_before_fetch,
				   add_sha1_to_argv, &argv);
	setup_revisions(argv.argc, argv.argv, &rev, NULL);
	if (prepare_revision_walk(&rev))
		die("revision walk setup failed");

	/*
	 * Collect all submodules (whether checked out or not) for which new
	 * commits have been recorded upstream in "changed_submodule_paths".
	 */
	while ((commit = get_revision(&rev))) {
		struct commit_list *parent = commit->parents;
		while (parent) {
			struct diff_options diff_opts;
			diff_setup(&diff_opts);
			DIFF_OPT_SET(&diff_opts, RECURSIVE);
			diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
			diff_opts.format_callback = submodule_collect_changed_cb;
			if (diff_setup_done(&diff_opts) < 0)
				die("diff_setup_done failed");
			diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
			diffcore_std(&diff_opts);
			diff_flush(&diff_opts);
			parent = parent->next;
		}
	}

	argv_array_clear(&argv);
	sha1_array_clear(&ref_tips_before_fetch);
	sha1_array_clear(&ref_tips_after_fetch);
	initialized_fetch_ref_tips = 0;
}

static void print_summary(const char *prefix, const unsigned char *sha1)
{
	struct rev_info rev;
	struct commit *commit;
	static const char *format = "format:%h: \"%s\"";
	unsigned char junk_sha1[20];
	const char *head = resolve_ref("HEAD", junk_sha1, 0, NULL);

	commit = lookup_commit(sha1);
	if (!commit)
		die("couldn't look up newly created commit");
	if (!commit || parse_commit(commit))
		die("could not parse newly created commit");

	init_revisions(&rev, prefix);
	setup_revisions(0, NULL, &rev, NULL);

	rev.abbrev = 0;
	rev.diff = 1;
	rev.diffopt.output_format =
		DIFF_FORMAT_SHORTSTAT | DIFF_FORMAT_SUMMARY;

	rev.verbose_header = 1;
	rev.show_root_diff = 1;
	get_commit_format(format, &rev);
	rev.always_show_header = 0;
	rev.diffopt.detect_rename = 1;
	rev.diffopt.rename_limit = 100;
	rev.diffopt.break_opt = 0;
	diff_setup_done(&rev.diffopt);

	printf("[%s%s]: created ",
		!prefixcmp(head, "refs/heads/") ?
			head + 11 :
			!strcmp(head, "HEAD") ?
				"detached HEAD" :
				head,
		initial_commit ? " (root-commit)" : "");

	if (!log_tree_commit(&rev, commit)) {
		struct strbuf buf = STRBUF_INIT;
		format_commit_message(commit, format + 7, &buf, DATE_NORMAL);
		printf("%s\n", buf.buf);
		strbuf_release(&buf);
	}
}

static void print_summary(const char *prefix, const unsigned char *sha1)
{
	struct rev_info rev;
	struct commit *commit;

	commit = lookup_commit(sha1);
	if (!commit)
		die("couldn't look up newly created commit");
	if (!commit || parse_commit(commit))
		die("could not parse newly created commit");

	init_revisions(&rev, prefix);
	setup_revisions(0, NULL, &rev, NULL);

	rev.abbrev = 0;
	rev.diff = 1;
	rev.diffopt.output_format =
		DIFF_FORMAT_SHORTSTAT | DIFF_FORMAT_SUMMARY;

	rev.verbose_header = 1;
	rev.show_root_diff = 1;
	get_commit_format("format:%h: %s", &rev);
	rev.always_show_header = 0;
	rev.diffopt.detect_rename = 1;
	rev.diffopt.rename_limit = 100;
	rev.diffopt.break_opt = 0;
	diff_setup_done(&rev.diffopt);

	printf("Created %scommit ", initial_commit ? "initial " : "");

	if (!log_tree_commit(&rev, commit)) {
		struct strbuf buf = STRBUF_INIT;
		format_commit_message(commit, "%h: %s", &buf);
		printf("%s\n", buf.buf);
		strbuf_release(&buf);
	}
}

/*
 * We have an origin -- find the path that corresponds to it in its
 * parent and return an origin structure to represent it.
 */
static struct blame_origin *find_rename(struct commit *parent,
				  struct blame_origin *origin)
{
	struct blame_origin *porigin = NULL;
	struct diff_options diff_opts;
	int i;

	diff_setup(&diff_opts);
	DIFF_OPT_SET(&diff_opts, RECURSIVE);
	diff_opts.detect_rename = DIFF_DETECT_RENAME;
	diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
	diff_opts.single_follow = origin->path;
	diff_setup_done(&diff_opts);

	if (is_null_oid(&origin->commit->object.oid))
		do_diff_cache(&parent->tree->object.oid, &diff_opts);
	else
		diff_tree_oid(&parent->tree->object.oid,
			      &origin->commit->tree->object.oid,
			      "", &diff_opts);
	diffcore_std(&diff_opts);

	for (i = 0; i < diff_queued_diff.nr; i++) {
		struct diff_filepair *p = diff_queued_diff.queue[i];
		if ((p->status == 'R' || p->status == 'C') &&
		    !strcmp(p->two->path, origin->path)) {
			porigin = get_origin(parent, p->one->path);
			oidcpy(&porigin->blob_oid, &p->one->oid);
			porigin->mode = p->one->mode;
			break;
		}
	}
	diff_flush(&diff_opts);
	clear_pathspec(&diff_opts.pathspec);
	return porigin;
}

static void print_summary(const char *prefix, const unsigned char *sha1,
			  int initial_commit)
{
	struct rev_info rev;
	struct commit *commit;
	struct strbuf format = STRBUF_INIT;
	unsigned char junk_sha1[20];
	const char *head;
	struct pretty_print_context pctx = {0};
	struct strbuf author_ident = STRBUF_INIT;
	struct strbuf committer_ident = STRBUF_INIT;

	commit = lookup_commit(sha1);
	if (!commit)
		die(_("couldn't look up newly created commit"));
	if (parse_commit(commit))
		die(_("could not parse newly created commit"));

	strbuf_addstr(&format, "format:%h] %s");

	format_commit_message(commit, "%an <%ae>", &author_ident, &pctx);
	format_commit_message(commit, "%cn <%ce>", &committer_ident, &pctx);
	if (strbuf_cmp(&author_ident, &committer_ident)) {
		strbuf_addstr(&format, "\n Author: ");
		strbuf_addbuf_percentquote(&format, &author_ident);
	}
	if (!committer_ident_sufficiently_given()) {
		strbuf_addstr(&format, "\n Committer: ");
		strbuf_addbuf_percentquote(&format, &committer_ident);
		if (advice_implicit_identity) {
			strbuf_addch(&format, '\n');
			strbuf_addstr(&format, _(implicit_ident_advice));
		}
	}
	strbuf_release(&author_ident);
	strbuf_release(&committer_ident);

	init_revisions(&rev, prefix);
	setup_revisions(0, NULL, &rev, NULL);

	rev.diff = 1;
	rev.diffopt.output_format =
		DIFF_FORMAT_SHORTSTAT | DIFF_FORMAT_SUMMARY;

	rev.verbose_header = 1;
	rev.show_root_diff = 1;
	get_commit_format(format.buf, &rev);
	rev.always_show_header = 0;
	rev.diffopt.detect_rename = 1;
	rev.diffopt.break_opt = 0;
	diff_setup_done(&rev.diffopt);

	head = resolve_ref_unsafe("HEAD", junk_sha1, 0, NULL);
	printf("[%s%s ",
		starts_with(head, "refs/heads/") ?
			head + 11 :
			!strcmp(head, "HEAD") ?
				_("detached HEAD") :
				head,
		initial_commit ? _(" (root-commit)") : "");

	if (!log_tree_commit(&rev, commit)) {
		rev.always_show_header = 1;
		rev.use_terminator = 1;
		log_tree_commit(&rev, commit);
	}

	strbuf_release(&format);
}