int git_root_diff(GIT_DIFF diff, const GIT_HASH hash, GIT_FILE* file, int* count, int isstat)
{
	int ret;
	struct object_id oid;
	struct rev_info *p_Rev;
	struct diff_queue_struct *q = &diff_queued_diff;

	p_Rev = (struct rev_info *)diff;

	hashcpy(oid.hash, hash);

	ret = diff_root_tree_oid(&oid, "", &p_Rev->diffopt);

	if(ret)
		return ret;

	if(isstat)
	{
		diffcore_std(&p_Rev->diffopt);

		memset(&p_Rev->diffstat, 0, sizeof(struct diffstat_t));
		for (int i = 0; i < q->nr; ++i) {
			struct diff_filepair *p = q->queue[i];
			//if (check_pair_status(p))
			diff_flush_stat(p, &p_Rev->diffopt, &p_Rev->diffstat);
		}
	}

	if (file)
		*file = q;
	if (count)
		*count = q->nr;

	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);
}

int log_tree_diff_flush(struct rev_info *opt)
{
	diffcore_std(&opt->diffopt);

	if (diff_queue_is_empty()) {
		int saved_fmt = opt->diffopt.output_format;
		opt->diffopt.output_format = DIFF_FORMAT_NO_OUTPUT;
		diff_flush(&opt->diffopt);
		opt->diffopt.output_format = saved_fmt;
		return 0;
	}

	if (opt->loginfo && !opt->no_commit_id) {
		/* When showing a verbose header (i.e. log message),
		 * and not in --pretty=oneline format, we would want
		 * an extra newline between the end of log and the
		 * output for readability.
		 */
		show_log(opt);
		if ((opt->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT) &&
		    opt->verbose_header &&
		    opt->commit_format != CMIT_FMT_ONELINE) {
			int pch = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_PATCH;
			if ((pch & opt->diffopt.output_format) == pch)
				printf("---");
			putchar('\n');
		}
	}
	diff_flush(&opt->diffopt);
	return 1;
}

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]);
}

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);
}

static int builtin_diff_b_f(struct rev_info *revs,
			    int argc, const char **argv,
			    struct blobinfo *blob,
			    const char *path)
{
	/* Blob vs file in the working tree*/
	struct stat st;

	if (argc > 1)
		usage(builtin_diff_usage);

	if (lstat(path, &st))
		die_errno("failed to stat '%s'", path);
	if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
		die("'%s': not a regular file or symlink", path);

	diff_set_mnemonic_prefix(&revs->diffopt, "o/", "w/");

	if (blob[0].mode == S_IFINVALID)
		blob[0].mode = canon_mode(st.st_mode);

	stuff_change(&revs->diffopt,
		     blob[0].mode, canon_mode(st.st_mode),
		     blob[0].sha1, null_sha1,
		     path, path);
	diffcore_std(&revs->diffopt);
	diff_flush(&revs->diffopt);
	return 0;
}

int git_do_diff(GIT_DIFF diff, GIT_HASH hash1, GIT_HASH hash2, GIT_FILE * file, int *count,int isstat)
{
	struct rev_info *p_Rev;
	int ret;
	int i;
	struct diff_queue_struct *q = &diff_queued_diff;

	p_Rev = (struct rev_info *)diff;

	ret = diff_tree_sha1(hash1,hash2,"",&p_Rev->diffopt);
	if( ret )
	{
		free_all_pack();
		return ret;
	}

	if(isstat)
	{
		diffcore_std(&p_Rev->diffopt);
		memset(&p_Rev->diffstat, 0, sizeof(struct diffstat_t));
		for (i = 0; i < q->nr; i++) {
			struct diff_filepair *p = q->queue[i];
			//if (check_pair_status(p))
			diff_flush_stat(p, &p_Rev->diffopt, &p_Rev->diffstat);
		}
	}
	free_all_pack();
	if(file)
		*file = q;
	if(count)
		*count = q->nr;
	return 0;
}

static int read_from_tree(const char *prefix, const char **argv,
		unsigned char *tree_sha1, int refresh_flags)
{
	struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
	int index_fd, index_was_discarded = 0;
	struct diff_options opt;

	memset(&opt, 0, sizeof(opt));
	diff_tree_setup_paths(get_pathspec(prefix, (const char **)argv), &opt);
	opt.output_format = DIFF_FORMAT_CALLBACK;
	opt.format_callback = update_index_from_diff;
	opt.format_callback_data = &index_was_discarded;

	index_fd = hold_locked_index(lock, 1);
	index_was_discarded = 0;
	read_cache();
	if (do_diff_cache(tree_sha1, &opt))
		return 1;
	diffcore_std(&opt);
	diff_flush(&opt);
	diff_tree_release_paths(&opt);

	if (!index_was_discarded)
		/* The index is still clobbered from do_diff_cache() */
		discard_cache();
	return update_index_refresh(index_fd, lock, refresh_flags);
}

static int builtin_diff_b_f(struct rev_info *revs,
			    int argc, const char **argv,
			    struct blobinfo *blob)
{
	/* Blob vs file in the working tree*/
	struct stat st;
	const char *path;

	if (argc > 1)
		usage(builtin_diff_usage);

	GUARD_PATHSPEC(&revs->prune_data, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
	path = revs->prune_data.items[0].match;

	if (lstat(path, &st))
		die_errno(_("failed to stat '%s'"), path);
	if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
		die(_("'%s': not a regular file or symlink"), path);

	diff_set_mnemonic_prefix(&revs->diffopt, "o/", "w/");

	if (blob[0].mode == S_IFINVALID)
		blob[0].mode = canon_mode(st.st_mode);

	stuff_change(&revs->diffopt,
		     blob[0].mode, canon_mode(st.st_mode),
		     blob[0].sha1, null_sha1,
		     1, 0,
		     path, path);
	diffcore_std(&revs->diffopt);
	diff_flush(&revs->diffopt);
	return 0;
}

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));
}

static void patch_diff(const char *a, const char *b,
			      struct diff_options *diffopt)
{
	diff_queue(&diff_queued_diff,
		   get_filespec("a", a), get_filespec("b", b));

	diffcore_std(diffopt);
	diff_flush(diffopt);
}

/*
 * 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 log_tree_diff_flush(struct rev_info *opt)
{
	opt->shown_dashes = 0;
	diffcore_std(&opt->diffopt);

	if (diff_queue_is_empty()) {
		int saved_fmt = opt->diffopt.output_format;
		opt->diffopt.output_format = DIFF_FORMAT_NO_OUTPUT;
		diff_flush(&opt->diffopt);
		opt->diffopt.output_format = saved_fmt;
		return 0;
	}

	if (opt->loginfo && !opt->no_commit_id) {
		show_log(opt);
		if ((opt->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT) &&
		    opt->verbose_header &&
		    opt->commit_format != CMIT_FMT_ONELINE &&
		    !commit_format_is_empty(opt->commit_format)) {
			/*
			 * When showing a verbose header (i.e. log message),
			 * and not in --pretty=oneline format, we would want
			 * an extra newline between the end of log and the
			 * diff/diffstat output for readability.
			 */
			int pch = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_PATCH;
			if (opt->diffopt.output_prefix) {
				struct strbuf *msg = NULL;
				msg = opt->diffopt.output_prefix(&opt->diffopt,
					opt->diffopt.output_prefix_data);
				fwrite(msg->buf, msg->len, 1, stdout);
			}

			/*
			 * We may have shown three-dashes line early
			 * between notes and the log message, in which
			 * case we only want a blank line after the
			 * notes without (an extra) three-dashes line.
			 * Otherwise, we show the three-dashes line if
			 * we are showing the patch with diffstat, but
			 * in that case, there is no extra blank line
			 * after the three-dashes line.
			 */
			if (!opt->shown_dashes &&
			    (pch & opt->diffopt.output_format) == pch)
				printf("---");
			putchar('\n');
		}
	}
	diff_flush(&opt->diffopt);
	return 1;
}

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);
}

int commit_patch_id(struct commit *commit, struct diff_options *options,
		    unsigned char *sha1, int diff_header_only)
{
	if (!patch_id_defined(commit))
		return -1;

	if (commit->parents)
		diff_tree_sha1(commit->parents->item->object.oid.hash,
			       commit->object.oid.hash, "", options);
	else
		diff_root_tree_sha1(commit->object.oid.hash, "", options);
	diffcore_std(options);
	return diff_flush_patch_id(options, sha1, diff_header_only);
}

int commit_patch_id(struct commit *commit, struct diff_options *options,
		    struct object_id *oid, int diff_header_only)
{
	if (!patch_id_defined(commit))
		return -1;

	if (commit->parents)
		diff_tree_oid(&commit->parents->item->object.oid,
			      &commit->object.oid, "", options);
	else
		diff_root_tree_oid(&commit->object.oid, "", options);
	diffcore_std(options);
	return diff_flush_patch_id(options, oid, diff_header_only);
}

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);
}

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;
}

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 int read_from_tree(const char **pathspec, unsigned char *tree_sha1)
{
	struct diff_options opt;

	memset(&opt, 0, sizeof(opt));
	diff_tree_setup_paths(pathspec, &opt);
	opt.output_format = DIFF_FORMAT_CALLBACK;
	opt.format_callback = update_index_from_diff;

	read_cache();
	if (do_diff_cache(tree_sha1, &opt))
		return 1;
	diffcore_std(&opt);
	diff_flush(&opt);
	diff_tree_release_paths(&opt);

	return 0;
}