static void update_index_from_diff(struct diff_queue_struct *q,
		struct diff_options *opt, void *data)
{
	int i;
	int *discard_flag = data;

	/* do_diff_cache() mangled the index */
	discard_cache();
	*discard_flag = 1;
	read_cache();

	for (i = 0; i < q->nr; i++) {
		struct diff_filespec *one = q->queue[i]->one;
		if (one->mode) {
			struct cache_entry *ce;
			ce = make_cache_entry(one->mode, one->sha1, one->path,
				0, 0);
			if (!ce)
				die("make_cache_entry failed for path '%s'",
				    one->path);
			add_cache_entry(ce, ADD_CACHE_OK_TO_ADD |
				ADD_CACHE_OK_TO_REPLACE);
		} else
			remove_file_from_cache(one->path);
	}
}

int try_merge_command(const char *strategy, size_t xopts_nr,
		      const char **xopts, struct commit_list *common,
		      const char *head_arg, struct commit_list *remotes)
{
	struct argv_array args = ARGV_ARRAY_INIT;
	int i, ret;
	struct commit_list *j;

	argv_array_pushf(&args, "merge-%s", strategy);
	for (i = 0; i < xopts_nr; i++)
		argv_array_pushf(&args, "--%s", xopts[i]);
	for (j = common; j; j = j->next)
		argv_array_push(&args, merge_argument(j->item));
	argv_array_push(&args, "--");
	argv_array_push(&args, head_arg);
	for (j = remotes; j; j = j->next)
		argv_array_push(&args, merge_argument(j->item));

	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
	argv_array_clear(&args);

	discard_cache();
	if (read_cache() < 0)
		die(_("failed to read the cache"));
	resolve_undo_clear();

	return ret;
}

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);
}

int git_run_cmd(char *cmd, char *arg)
{

	int i=0;
	char ** argv=0;
	int argc=0;

	git_init();

	for(i=0;i<	sizeof(commands) / sizeof(struct cmd_struct);i++)
	{
		if(strcmp(cmd,commands[i].cmd)==0)
		{
			int ret;
			if(arg != NULL)
				argv = strtoargv(arg,&argc);

			ret = commands[i].fn(argc, argv, NULL);

			if(argv)
				free(argv);

			discard_cache();
			free_all_pack();

			return ret;


		}
	}
	return -1;
}

static void create_base_index(const struct commit *current_head)
{
	struct tree *tree;
	struct unpack_trees_options opts;
	struct tree_desc t;

	if (!current_head) {
		discard_cache();
		return;
	}

	memset(&opts, 0, sizeof(opts));
	opts.head_idx = 1;
	opts.index_only = 1;
	opts.merge = 1;
	opts.src_index = &the_index;
	opts.dst_index = &the_index;

	opts.fn = oneway_merge;
	tree = parse_tree_indirect(current_head->object.sha1);
	if (!tree)
		die(_("failed to unpack HEAD tree object"));
	parse_tree(tree);
	init_tree_desc(&t, tree->buffer, tree->size);
	if (unpack_trees(1, &t, &opts))
		exit(128); /* We've already reported the error, finish dying */
}

/* truncate the file to the specified length */
static int ftruncate_internal(struct filestr_desc *file, file_size_t size,
                              bool write_now)
{
    int rc = 0, rc2 = 1;

    file_size_t cursize = *file->sizep;
    file_size_t truncsize = MIN(size, cursize);

    if (write_now)
    {
        unsigned long sector = filesize_sectors(truncsize);
        struct filestr_cache *const cachep = file->stream.cachep;

        if (cachep->flags == (FSC_NEW|FSC_DIRTY) &&
            cachep->sector + 1 == sector)
        {
            /* sector created but may have never been added to the cluster
               chain; flush it now or the subsequent may fail */
            rc2 = flush_cache(file);
            if (rc2 == FAT_RC_ENOSPC)
            {
                /* no space left on device; further truncation needed */
                discard_cache(file);
                truncsize = ALIGN_DOWN(truncsize - 1, SECTOR_SIZE);
                sector--;
                rc = rc2;
            }
            else if (rc2 < 0)
                FILE_ERROR(ERRNO, rc2 * 10 - 1);
        }

        rc2 = fat_seek(&file->stream.fatstr, sector);
        if (rc2 < 0)
            FILE_ERROR(EIO, rc2 * 10 - 2);

        rc2 = fat_truncate(&file->stream.fatstr);
        if (rc2 < 0)
            FILE_ERROR(EIO, rc2 * 10 - 3);
    }
    /* else just change the cached file size */

    if (truncsize < cursize)
    {
        *file->sizep = truncsize;
        fileop_ontruncate_internal(&file->stream);
    }

    /* if truncation was partially successful, it effectively destroyed
       everything after the truncation point; still, indicate failure
       after adjusting size */
    if (rc2 == 0)
        FILE_ERROR(EIO, -4);
    else if (rc2 < 0)
        FILE_ERROR(ERRNO, rc2);

file_error:
    return rc;
}

int cmd_main(int argc, const char **argv)
{
	int i, cnt = 1;
	if (argc == 2)
		cnt = strtol(argv[1], NULL, 0);
	setup_git_directory();
	for (i = 0; i < cnt; i++) {
		read_cache();
		discard_cache();
	}
	return 0;
}

/* flush back all outstanding writes to the file */
static int fsync_internal(struct filestr_desc *file)
{
    /* call only when holding WRITER lock (updates directory entries) */
    int rc = 0;

    file_size_t size = *file->sizep;
    unsigned int foflags = fileobj_get_flags(&file->stream);

    /* flush sector cache? */
    struct filestr_cache *const cachep = file->stream.cachep;
    if (cachep->flags & FSC_DIRTY)
    {
        int rc2 = flush_cache(file);
        if (rc2 == FAT_RC_ENOSPC && (cachep->flags & FSC_NEW))
        {
            /* no space left on device so this must be dropped */
            discard_cache(file);
            size = ALIGN_DOWN(size - 1, SECTOR_SIZE);
            foflags |= FO_TRUNC;
            rc = rc2;
        }
        else if (rc2 < 0)
            FILE_ERROR(ERRNO, rc2 * 10 - 1);
    }

    /* truncate? */
    if (foflags & FO_TRUNC)
    {
        int rc2 = ftruncate_internal(file, size, rc == 0);
        if (rc2 < 0)
            FILE_ERROR(ERRNO, rc2 * 10 - 2);

        /* never needs to be done this way again since any data beyond the
           cached size is now gone */
        fileobj_change_flags(&file->stream, 0, FO_TRUNC);
    }

file_error:;
    /* tie up all loose ends (try to close the file even if failing) */
    int rc2 = fat_closewrite(&file->stream.fatstr, size,
                             get_dir_fatent_dircache());
    if (rc2 >= 0)
        fileop_onsync_internal(&file->stream); /* dir_fatent is implicit arg */

    if (rc2 < 0 && rc >= 0)
    {
        errno = EIO;
        rc = rc2 * 10 - 3;
    }

    return rc;
}

static void refresh_index_quietly(void)
{
	struct lock_file lock_file = LOCK_INIT;
	int fd;

	fd = hold_locked_index(&lock_file, 0);
	if (fd < 0)
		return;
	discard_cache();
	read_cache();
	refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
	update_index_if_able(&the_index, &lock_file);
}

static void refresh_index_quietly(void)
{
	struct lock_file *lock_file;
	int fd;

	lock_file = xcalloc(1, sizeof(struct lock_file));
	fd = hold_locked_index(lock_file, 0);
	if (fd < 0)
		return;
	discard_cache();
	read_cache();
	refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
	update_index_if_able(&the_index, lock_file);
}

int try_merge_command(const char *strategy, size_t xopts_nr,
		      const char **xopts, struct commit_list *common,
		      const char *head_arg, struct commit_list *remotes)
{
	const char **args;
	int i = 0, x = 0, ret;
	struct commit_list *j;
	struct strbuf buf = STRBUF_INIT;

	args = xmalloc((4 + xopts_nr + commit_list_count(common) +
			commit_list_count(remotes)) * sizeof(char *));
	strbuf_addf(&buf, "merge-%s", strategy);
	args[i++] = buf.buf;
	for (x = 0; x < xopts_nr; x++) {
		char *s = xmalloc(strlen(xopts[x])+2+1);
		strcpy(s, "--");
		strcpy(s+2, xopts[x]);
		args[i++] = s;
	}
	for (j = common; j; j = j->next)
		args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
	args[i++] = "--";
	args[i++] = head_arg;
	for (j = remotes; j; j = j->next)
		args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
	args[i] = NULL;
	ret = run_command_v_opt(args, RUN_GIT_CMD);
	strbuf_release(&buf);
	i = 1;
	for (x = 0; x < xopts_nr; x++)
		free((void *)args[i++]);
	for (j = common; j; j = j->next)
		free((void *)args[i++]);
	i += 2;
	for (j = remotes; j; j = j->next)
		free((void *)args[i++]);
	free(args);
	discard_cache();
	if (read_cache() < 0)
		die(_("failed to read the cache"));
	resolve_undo_clear();

	return ret;
}

static void refresh_index_quietly(void)
{
	struct lock_file *lock_file;
	int fd;

	lock_file = xcalloc(1, sizeof(struct lock_file));
	fd = hold_locked_index(lock_file, 0);
	if (fd < 0)
		return;
	discard_cache();
	read_cache();
	refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);

	if (active_cache_changed &&
	    !write_cache(fd, active_cache, active_nr))
		commit_locked_index(lock_file);

	rollback_lock_file(lock_file);
}

int git_update_index(void)
{
	char** argv = NULL;
	int argc = 0;
	int ret;

	argv = strtoargv("-q --refresh", &argc);
	if (!argv)
		return -1;

	cleanup_chdir_notify();
	drop_all_attr_stacks();

	ret = cmd_update_index(argc, argv, NULL);
	free(argv);

	discard_cache();
	free_all_pack();

	return ret;
}

static int sequencer_skip(struct replay_opts *opts)
{
	const char *argv[3]; /* reset --hard + NULL */
	struct string_list merge_rr = STRING_LIST_INIT_DUP;
	int ret;

	if (setup_rerere(&merge_rr, 0) >= 0) {
		rerere_clear(&merge_rr);
		string_list_clear(&merge_rr, 1);
	}

	argv[0] = "reset";
	argv[1] = "--hard";
	argv[2] = NULL;
	ret = run_command_v_opt(argv, RUN_GIT_CMD);
	if (ret)
		return ret;

	discard_cache();
	read_cache();

	return sequencer_continue(opts, 1);
}

//.........这里部分代码省略.........
				"# with '#' will be ignored, and an empty"
				" message aborts the commit.\n");
		else /* CLEANUP_SPACE, that is. */
			fprintf(fp,
				" Lines starting\n"
				"# with '#' will be kept; you may remove them"
				" yourself if you want to.\n"
				"# An empty message aborts the commit.\n");
		if (only_include_assumed)
			fprintf(fp, "# %s\n", only_include_assumed);

		author_ident = xstrdup(fmt_name(author_name, author_email));
		committer_ident = fmt_name(getenv("GIT_COMMITTER_NAME"),
					   getenv("GIT_COMMITTER_EMAIL"));
		if (strcmp(author_ident, committer_ident))
			fprintf(fp,
				"%s"
				"# Author:    %s\n",
				ident_shown++ ? "" : "#\n",
				author_ident);
		free(author_ident);

		if (!user_ident_sufficiently_given())
			fprintf(fp,
				"%s"
				"# Committer: %s\n",
				ident_shown++ ? "" : "#\n",
				committer_ident);

		if (ident_shown)
			fprintf(fp, "#\n");

		saved_color_setting = s->use_color;
		s->use_color = 0;
		commitable = run_status(fp, index_file, prefix, 1, s);
		s->use_color = saved_color_setting;
	} else {
		unsigned char sha1[20];
		const char *parent = "HEAD";

		if (!active_nr && read_cache() < 0)
			die("Cannot read index");

		if (amend)
			parent = "HEAD^1";

		if (get_sha1(parent, sha1))
			commitable = !!active_nr;
		else
			commitable = index_differs_from(parent, 0);
	}

	fclose(fp);

	if (!commitable && !in_merge && !allow_empty &&
	    !(amend && is_a_merge(head_sha1))) {
		run_status(stdout, index_file, prefix, 0, s);
		if (amend)
			fputs(empty_amend_advice, stderr);
		return 0;
	}

	/*
	 * Re-read the index as pre-commit hook could have updated it,
	 * and write it out as a tree.  We must do this before we invoke
	 * the editor and after we invoke run_status above.
	 */
	discard_cache();
	read_cache_from(index_file);
	if (!active_cache_tree)
		active_cache_tree = cache_tree();
	if (cache_tree_update(active_cache_tree,
			      active_cache, active_nr, 0, 0) < 0) {
		error("Error building trees");
		return 0;
	}

	if (run_hook(index_file, "prepare-commit-msg",
		     git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
		return 0;

	if (use_editor) {
		char index[PATH_MAX];
		const char *env[2] = { NULL };
		env[0] =  index;
		snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
		if (launch_editor(git_path(commit_editmsg), NULL, env)) {
			fprintf(stderr,
			"Please supply the message using either -m or -F option.\n");
			exit(1);
		}
	}

	if (!no_verify &&
	    run_hook(index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
		return 0;
	}

	return 1;
}

static char *prepare_index(int argc, const char **argv, const char *prefix)
{
	int fd;
	struct path_list partial;
	const char **pathspec = NULL;

	if (interactive) {
		interactive_add(argc, argv, prefix);
		commit_style = COMMIT_AS_IS;
		return get_index_file();
	}

	if (read_cache() < 0)
		die("index file corrupt");

	if (*argv)
		pathspec = get_pathspec(prefix, argv);

	/*
	 * Non partial, non as-is commit.
	 *
	 * (1) get the real index;
	 * (2) update the_index as necessary;
	 * (3) write the_index out to the real index (still locked);
	 * (4) return the name of the locked index file.
	 *
	 * The caller should run hooks on the locked real index, and
	 * (A) if all goes well, commit the real index;
	 * (B) on failure, rollback the real index.
	 */
	if (all || (also && pathspec && *pathspec)) {
		int fd = hold_locked_index(&index_lock, 1);
		add_files_to_cache(0, also ? prefix : NULL, pathspec);
		refresh_cache(REFRESH_QUIET);
		if (write_cache(fd, active_cache, active_nr) ||
		    close_lock_file(&index_lock))
			die("unable to write new_index file");
		commit_style = COMMIT_NORMAL;
		return index_lock.filename;
	}

	/*
	 * As-is commit.
	 *
	 * (1) return the name of the real index file.
	 *
	 * The caller should run hooks on the real index, and run
	 * hooks on the real index, and create commit from the_index.
	 * We still need to refresh the index here.
	 */
	if (!pathspec || !*pathspec) {
		fd = hold_locked_index(&index_lock, 1);
		refresh_cache(REFRESH_QUIET);
		if (write_cache(fd, active_cache, active_nr) ||
		    commit_locked_index(&index_lock))
			die("unable to write new_index file");
		commit_style = COMMIT_AS_IS;
		return get_index_file();
	}

	/*
	 * A partial commit.
	 *
	 * (0) find the set of affected paths;
	 * (1) get lock on the real index file;
	 * (2) update the_index with the given paths;
	 * (3) write the_index out to the real index (still locked);
	 * (4) get lock on the false index file;
	 * (5) reset the_index from HEAD;
	 * (6) update the_index the same way as (2);
	 * (7) write the_index out to the false index file;
	 * (8) return the name of the false index file (still locked);
	 *
	 * The caller should run hooks on the locked false index, and
	 * create commit from it.  Then
	 * (A) if all goes well, commit the real index;
	 * (B) on failure, rollback the real index;
	 * In either case, rollback the false index.
	 */
	commit_style = COMMIT_PARTIAL;

	if (file_exists(git_path("MERGE_HEAD")))
		die("cannot do a partial commit during a merge.");

	memset(&partial, 0, sizeof(partial));
	partial.strdup_paths = 1;
	if (list_paths(&partial, initial_commit ? NULL : "HEAD", prefix, pathspec))
		exit(1);

	discard_cache();
	if (read_cache() < 0)
		die("cannot read the index");

	fd = hold_locked_index(&index_lock, 1);
	add_remove_files(&partial);
	refresh_cache(REFRESH_QUIET);
	if (write_cache(fd, active_cache, active_nr) ||
	    close_lock_file(&index_lock))
		die("unable to write new_index file");

//.........这里部分代码省略.........

static int do_pick_commit(void)
{
	unsigned char head[20];
	struct commit *base, *next, *parent;
	const char *base_label, *next_label;
	struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
	char *defmsg = NULL;
	struct strbuf msgbuf = STRBUF_INIT;

	if (no_commit) {
		/*
		 * We do not intend to commit immediately.  We just want to
		 * merge the differences in, so let's compute the tree
		 * that represents the "current" state for merge-recursive
		 * to work on.
		 */
		if (write_cache_as_tree(head, 0, NULL))
			die ("Your index file is unmerged.");
	} else {
		if (get_sha1("HEAD", head))
			die ("You do not have a valid HEAD");
		if (index_differs_from("HEAD", 0))
			die_dirty_index(me);
	}
	discard_cache();

	if (!commit->parents) {
		if (action == REVERT)
			die ("Cannot revert a root commit");
		parent = NULL;
	}
	else if (commit->parents->next) {
		/* Reverting or cherry-picking a merge commit */
		int cnt;
		struct commit_list *p;

		if (!mainline)
			die("Commit %s is a merge but no -m option was given.",
			    sha1_to_hex(commit->object.sha1));

		for (cnt = 1, p = commit->parents;
		     cnt != mainline && p;
		     cnt++)
			p = p->next;
		if (cnt != mainline || !p)
			die("Commit %s does not have parent %d",
			    sha1_to_hex(commit->object.sha1), mainline);
		parent = p->item;
	} else if (0 < mainline)
		die("Mainline was specified but commit %s is not a merge.",
		    sha1_to_hex(commit->object.sha1));
	else
		parent = commit->parents->item;

	if (allow_ff && !hashcmp(parent->object.sha1, head))
		return fast_forward_to(commit->object.sha1, head);

	if (parent && parse_commit(parent) < 0)
		die("%s: cannot parse parent commit %s",
		    me, sha1_to_hex(parent->object.sha1));

	if (get_message(commit->buffer, &msg) != 0)
		die("Cannot get commit message for %s",
				sha1_to_hex(commit->object.sha1));

	/*
	 * "commit" is an existing commit.  We would want to apply
	 * the difference it introduces since its first parent "prev"
	 * on top of the current HEAD if we are cherry-pick.  Or the
	 * reverse of it if we are revert.
	 */

	defmsg = git_pathdup("MERGE_MSG");

	if (action == REVERT) {
		base = commit;
		base_label = msg.label;
		next = parent;
		next_label = msg.parent_label;
		strbuf_addstr(&msgbuf, "Revert \"");
		strbuf_addstr(&msgbuf, msg.subject);
		strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
		strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));

		if (commit->parents->next) {
			strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
			strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
		}
		strbuf_addstr(&msgbuf, ".\n");
	} else {
		base = parent;
		base_label = msg.parent_label;
		next = commit;
		next_label = msg.label;
		set_author_ident_env(msg.message);
		add_message_to_msg(&msgbuf, msg.message);
		if (no_replay) {
			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
			strbuf_addstr(&msgbuf, ")\n");
//.........这里部分代码省略.........

static int try_merge_strategy(const char *strategy, struct commit_list *common,
			      const char *head_arg)
{
	const char **args;
	int i = 0, ret;
	struct commit_list *j;
	struct strbuf buf = STRBUF_INIT;
	int index_fd;
	struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));

	index_fd = hold_locked_index(lock, 1);
	refresh_cache(REFRESH_QUIET);
	if (active_cache_changed &&
			(write_cache(index_fd, active_cache, active_nr) ||
			 commit_locked_index(lock)))
		return error("Unable to write index.");
	rollback_lock_file(lock);

	if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
		int clean;
		struct commit *result;
		struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
		int index_fd;
		struct commit_list *reversed = NULL;
		struct merge_options o;

		if (remoteheads->next) {
			error("Not handling anything other than two heads merge.");
			return 2;
		}

		init_merge_options(&o);
		if (!strcmp(strategy, "subtree"))
			o.subtree_merge = 1;

		o.branch1 = head_arg;
		o.branch2 = remoteheads->item->util;

		for (j = common; j; j = j->next)
			commit_list_insert(j->item, &reversed);

		index_fd = hold_locked_index(lock, 1);
		clean = merge_recursive(&o, lookup_commit(head),
				remoteheads->item, reversed, &result);
		if (active_cache_changed &&
				(write_cache(index_fd, active_cache, active_nr) ||
				 commit_locked_index(lock)))
			die ("unable to write %s", get_index_file());
		rollback_lock_file(lock);
		return clean ? 0 : 1;
	} else {
		args = xmalloc((4 + commit_list_count(common) +
					commit_list_count(remoteheads)) * sizeof(char *));
		strbuf_addf(&buf, "merge-%s", strategy);
		args[i++] = buf.buf;
		for (j = common; j; j = j->next)
			args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
		args[i++] = "--";
		args[i++] = head_arg;
		for (j = remoteheads; j; j = j->next)
			args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
		args[i] = NULL;
		ret = run_command_v_opt(args, RUN_GIT_CMD);
		strbuf_release(&buf);
		i = 1;
		for (j = common; j; j = j->next)
			free((void *)args[i++]);
		i += 2;
		for (j = remoteheads; j; j = j->next)
			free((void *)args[i++]);
		free(args);
		discard_cache();
		if (read_cache() < 0)
			die("failed to read the cache");
		return ret;
	}
}

static char *prepare_index(int argc, const char **argv, const char *prefix,
			   const struct commit *current_head, int is_status)
{
	int fd;
	struct string_list partial;
	struct pathspec pathspec;
	int refresh_flags = REFRESH_QUIET;

	if (is_status)
		refresh_flags |= REFRESH_UNMERGED;
	parse_pathspec(&pathspec, 0,
		       PATHSPEC_PREFER_FULL,
		       prefix, argv);

	if (read_cache_preload(&pathspec) < 0)
		die(_("index file corrupt"));

	if (interactive) {
		char *old_index_env = NULL;
		fd = hold_locked_index(&index_lock, 1);

		refresh_cache_or_die(refresh_flags);

		if (write_cache(fd, active_cache, active_nr) ||
		    close_lock_file(&index_lock))
			die(_("unable to create temporary index"));

		old_index_env = getenv(INDEX_ENVIRONMENT);
		setenv(INDEX_ENVIRONMENT, index_lock.filename, 1);

		if (interactive_add(argc, argv, prefix, patch_interactive) != 0)
			die(_("interactive add failed"));

		if (old_index_env && *old_index_env)
			setenv(INDEX_ENVIRONMENT, old_index_env, 1);
		else
			unsetenv(INDEX_ENVIRONMENT);

		discard_cache();
		read_cache_from(index_lock.filename);

		commit_style = COMMIT_NORMAL;
		return index_lock.filename;
	}

	/*
	 * Non partial, non as-is commit.
	 *
	 * (1) get the real index;
	 * (2) update the_index as necessary;
	 * (3) write the_index out to the real index (still locked);
	 * (4) return the name of the locked index file.
	 *
	 * The caller should run hooks on the locked real index, and
	 * (A) if all goes well, commit the real index;
	 * (B) on failure, rollback the real index.
	 */
	if (all || (also && pathspec.nr)) {
		fd = hold_locked_index(&index_lock, 1);
		add_files_to_cache(also ? prefix : NULL, &pathspec, 0);
		refresh_cache_or_die(refresh_flags);
		update_main_cache_tree(WRITE_TREE_SILENT);
		if (write_cache(fd, active_cache, active_nr) ||
		    close_lock_file(&index_lock))
			die(_("unable to write new_index file"));
		commit_style = COMMIT_NORMAL;
		return index_lock.filename;
	}

	/*
	 * As-is commit.
	 *
	 * (1) return the name of the real index file.
	 *
	 * The caller should run hooks on the real index,
	 * and create commit from the_index.
	 * We still need to refresh the index here.
	 */
	if (!only && !pathspec.nr) {
		fd = hold_locked_index(&index_lock, 1);
		refresh_cache_or_die(refresh_flags);
		if (active_cache_changed) {
			update_main_cache_tree(WRITE_TREE_SILENT);
			if (write_cache(fd, active_cache, active_nr) ||
			    commit_locked_index(&index_lock))
				die(_("unable to write new_index file"));
		} else {
			rollback_lock_file(&index_lock);
		}
		commit_style = COMMIT_AS_IS;
		return get_index_file();
	}

	/*
	 * A partial commit.
	 *
	 * (0) find the set of affected paths;
	 * (1) get lock on the real index file;
	 * (2) update the_index with the given paths;
	 * (3) write the_index out to the real index (still locked);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		if (cleanup_mode == CLEANUP_ALL)
			fprintf(fp, "not be included)\n");
		else /* CLEANUP_SPACE, that is. */
			fprintf(fp, "be kept.\n"
				"# You can remove them yourself if you want to)\n");
		if (only_include_assumed)
			fprintf(fp, "# %s\n", only_include_assumed);

		author_ident = xstrdup(fmt_name(author_name, author_email));
		committer_ident = fmt_name(getenv("GIT_COMMITTER_NAME"),
					   getenv("GIT_COMMITTER_EMAIL"));
		if (strcmp(author_ident, committer_ident))
			fprintf(fp,
				"%s"
				"# Author:    %s\n",
				ident_shown++ ? "" : "#\n",
				author_ident);
		free(author_ident);

		if (!user_ident_explicitly_given)
			fprintf(fp,
				"%s"
				"# Committer: %s\n",
				ident_shown++ ? "" : "#\n",
				committer_ident);

		if (ident_shown)
			fprintf(fp, "#\n");

		saved_color_setting = wt_status_use_color;
		wt_status_use_color = 0;
		commitable = run_status(fp, index_file, prefix, 1);
		wt_status_use_color = saved_color_setting;
	} else {
		struct rev_info rev;
		unsigned char sha1[20];
		const char *parent = "HEAD";

		if (!active_nr && read_cache() < 0)
			die("Cannot read index");

		if (amend)
			parent = "HEAD^1";

		if (get_sha1(parent, sha1))
			commitable = !!active_nr;
		else {
			init_revisions(&rev, "");
			rev.abbrev = 0;
			setup_revisions(0, NULL, &rev, parent);
			DIFF_OPT_SET(&rev.diffopt, QUIET);
			DIFF_OPT_SET(&rev.diffopt, EXIT_WITH_STATUS);
			run_diff_index(&rev, 1 /* cached */);

			commitable = !!DIFF_OPT_TST(&rev.diffopt, HAS_CHANGES);
		}
	}

	fclose(fp);

	if (!commitable && !in_merge && !allow_empty &&
	    !(amend && is_a_merge(head_sha1))) {
		run_status(stdout, index_file, prefix, 0);
		unlink(commit_editmsg);
		return 0;
	}

	/*
	 * Re-read the index as pre-commit hook could have updated it,
	 * and write it out as a tree.  We must do this before we invoke
	 * the editor and after we invoke run_status above.
	 */
	discard_cache();
	read_cache_from(index_file);
	if (!active_cache_tree)
		active_cache_tree = cache_tree();
	if (cache_tree_update(active_cache_tree,
			      active_cache, active_nr, 0, 0) < 0) {
		error("Error building trees");
		return 0;
	}

	if (run_hook(index_file, "prepare-commit-msg",
		     git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
		return 0;

	if (use_editor) {
		char index[PATH_MAX];
		const char *env[2] = { index, NULL };
		snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
		launch_editor(git_path(commit_editmsg), NULL, env);
	}

	if (!no_verify &&
	    run_hook(index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
		return 0;
	}

	return 1;
}