static char *find_branch_name(struct rev_info *rev)
{
	int i, positive = -1;
	struct object_id branch_oid;
	const struct object_id *tip_oid;
	const char *ref, *v;
	char *full_ref, *branch = NULL;

	for (i = 0; i < rev->cmdline.nr; i++) {
		if (rev->cmdline.rev[i].flags & UNINTERESTING)
			continue;
		if (positive < 0)
			positive = i;
		else
			return NULL;
	}
	if (positive < 0)
		return NULL;
	ref = rev->cmdline.rev[positive].name;
	tip_oid = &rev->cmdline.rev[positive].item->oid;
	if (dwim_ref(ref, strlen(ref), branch_oid.hash, &full_ref) &&
	    skip_prefix(full_ref, "refs/heads/", &v) &&
	    !oidcmp(tip_oid, &branch_oid))
		branch = xstrdup(v);
	free(full_ref);
	return branch;
}

static void wt_status_get_detached_from(struct wt_status_state *state)
{
	struct grab_1st_switch_cbdata cb;
	struct commit *commit;
	unsigned char sha1[20];
	char *ref = NULL;

	strbuf_init(&cb.buf, 0);
	if (for_each_reflog_ent_reverse("HEAD", grab_1st_switch, &cb) <= 0) {
		strbuf_release(&cb.buf);
		return;
	}

	if (dwim_ref(cb.buf.buf, cb.buf.len, sha1, &ref) == 1 &&
	    /* sha1 is a commit? match without further lookup */
	    (!hashcmp(cb.nsha1, sha1) ||
	     /* perhaps sha1 is a tag, try to dereference to a commit */
	     ((commit = lookup_commit_reference_gently(sha1, 1)) != NULL &&
	      !hashcmp(cb.nsha1, commit->object.sha1)))) {
		int ofs;
		if (!prefixcmp(ref, "refs/tags/"))
			ofs = strlen("refs/tags/");
		else if (!prefixcmp(ref, "refs/remotes/"))
			ofs = strlen("refs/remotes/");
		else
			ofs = 0;
		state->detached_from = xstrdup(ref + ofs);
	} else
		state->detached_from =
			xstrdup(find_unique_abbrev(cb.nsha1, DEFAULT_ABBREV));
	hashcpy(state->detached_sha1, cb.nsha1);

	free(ref);
	strbuf_release(&cb.buf);
}

static int handle_fork_point(int argc, const char **argv)
{
	struct object_id oid;
	char *refname;
	struct commit *derived, *fork_point;
	const char *commitname;

	switch (dwim_ref(argv[0], strlen(argv[0]), &oid, &refname)) {
	case 0:
		die("No such ref: '%s'", argv[0]);
	case 1:
		break; /* good */
	default:
		die("Ambiguous refname: '%s'", argv[0]);
	}

	commitname = (argc == 2) ? argv[1] : "HEAD";
	if (get_oid(commitname, &oid))
		die("Not a valid object name: '%s'", commitname);

	derived = lookup_commit_reference(the_repository, &oid);

	fork_point = get_fork_point(refname, derived);

	if (!fork_point)
		return 1;

	printf("%s\n", oid_to_hex(&fork_point->object.oid));
	return 0;
}

static char *find_branch_name(struct rev_info *rev)
{
	int i, positive = -1;
	unsigned char branch_sha1[20];
	const unsigned char *tip_sha1;
	const char *ref, *v;
	char *full_ref, *branch = NULL;

	for (i = 0; i < rev->cmdline.nr; i++) {
		if (rev->cmdline.rev[i].flags & UNINTERESTING)
			continue;
		if (positive < 0)
			positive = i;
		else
			return NULL;
	}
	if (positive < 0)
		return NULL;
	ref = rev->cmdline.rev[positive].name;
	tip_sha1 = rev->cmdline.rev[positive].item->sha1;
	if (dwim_ref(ref, strlen(ref), branch_sha1, &full_ref) &&
	    skip_prefix(full_ref, "refs/heads/", &v) &&
	    !hashcmp(tip_sha1, branch_sha1))
		branch = xstrdup(v);
	free(full_ref);
	return branch;
}

static int handle_fork_point(int argc, const char **argv)
{
	unsigned char sha1[20];
	char *refname;
	const char *commitname;
	struct rev_collect revs;
	struct commit *derived;
	struct commit_list *bases;
	int i, ret = 0;

	switch (dwim_ref(argv[0], strlen(argv[0]), sha1, &refname)) {
	case 0:
		die("No such ref: '%s'", argv[0]);
	case 1:
		break; /* good */
	default:
		die("Ambiguous refname: '%s'", argv[0]);
	}

	commitname = (argc == 2) ? argv[1] : "HEAD";
	if (get_sha1(commitname, sha1))
		die("Not a valid object name: '%s'", commitname);

	derived = lookup_commit_reference(sha1);
	memset(&revs, 0, sizeof(revs));
	revs.initial = 1;
	for_each_reflog_ent(refname, collect_one_reflog_ent, &revs);

	for (i = 0; i < revs.nr; i++)
		revs.commit[i]->object.flags &= ~TMP_MARK;

	bases = get_merge_bases_many_dirty(derived, revs.nr, revs.commit);

	/*
	 * There should be one and only one merge base, when we found
	 * a common ancestor among reflog entries.
	 */
	if (!bases || bases->next) {
		ret = 1;
		goto cleanup_return;
	}

	/* And the found one must be one of the reflog entries */
	for (i = 0; i < revs.nr; i++)
		if (&bases->item->object == &revs.commit[i]->object)
			break; /* found */
	if (revs.nr <= i) {
		ret = 1; /* not found */
		goto cleanup_return;
	}

	printf("%s\n", oid_to_hex(&bases->item->object.oid));

cleanup_return:
	free_commit_list(bases);
	return ret;
}

static void parse_treeish_arg(const char **argv,
		struct archiver_args *ar_args, const char *prefix,
		int remote)
{
	const char *name = argv[0];
	const unsigned char *commit_sha1;
	time_t archive_time;
	struct tree *tree;
	const struct commit *commit;
	struct object_id oid;

	/* Remotes are only allowed to fetch actual refs */
	if (remote && !remote_allow_unreachable) {
		char *ref = NULL;
		const char *colon = strchrnul(name, ':');
		int refnamelen = colon - name;

		if (!dwim_ref(name, refnamelen, &oid, &ref))
			die(_("no such ref: %.*s"), refnamelen, name);
		free(ref);
	}

	if (get_oid(name, &oid))
		die(_("not a valid object name: %s"), name);

	commit = lookup_commit_reference_gently(ar_args->repo, &oid, 1);
	if (commit) {
		commit_sha1 = commit->object.oid.hash;
		archive_time = commit->date;
	} else {
		commit_sha1 = NULL;
		archive_time = time(NULL);
	}

	tree = parse_tree_indirect(&oid);
	if (tree == NULL)
		die(_("not a tree object: %s"), oid_to_hex(&oid));

	if (prefix) {
		struct object_id tree_oid;
		unsigned int mode;
		int err;

		err = get_tree_entry(&tree->object.oid, prefix, &tree_oid,
				     &mode);
		if (err || !S_ISDIR(mode))
			die(_("current working directory is untracked"));

		tree = parse_tree_indirect(&tree_oid);
	}
	ar_args->tree = tree;
	ar_args->commit_sha1 = commit_sha1;
	ar_args->commit = commit;
	ar_args->time = archive_time;
}

static void parse_treeish_arg(const char **argv,
		struct archiver_args *ar_args, const char *prefix,
		int remote)
{
	const char *name = argv[0];
	const unsigned char *commit_sha1;
	time_t archive_time;
	struct tree *tree;
	const struct commit *commit;
	unsigned char sha1[20];

	/* Remotes are only allowed to fetch actual refs */
	if (remote && !remote_allow_unreachable) {
		char *ref = NULL;
		const char *colon = strchr(name, ':');
		int refnamelen = colon ? colon - name : strlen(name);

		if (!dwim_ref(name, refnamelen, sha1, &ref))
			die("no such ref: %.*s", refnamelen, name);
		free(ref);
	}

	if (get_sha1(name, sha1))
		die("Not a valid object name");

	commit = lookup_commit_reference_gently(sha1, 1);
	if (commit) {
		commit_sha1 = commit->object.sha1;
		archive_time = commit->date;
	} else {
		commit_sha1 = NULL;
		archive_time = time(NULL);
	}

	tree = parse_tree_indirect(sha1);
	if (tree == NULL)
		die("not a tree object");

	if (prefix) {
		unsigned char tree_sha1[20];
		unsigned int mode;
		int err;

		err = get_tree_entry(tree->object.sha1, prefix,
				     tree_sha1, &mode);
		if (err || !S_ISDIR(mode))
			die("current working directory is untracked");

		tree = parse_tree_indirect(tree_sha1);
	}
	ar_args->tree = tree;
	ar_args->commit_sha1 = commit_sha1;
	ar_args->commit = commit;
	ar_args->time = archive_time;
}

static int write_refs_to_temp_dir(struct strbuf *temp_dir,
		int refspec_nr, const char **refspec)
{
	int i;

	for (i = 0; i < refspec_nr; i++) {
		unsigned char sha1[20];
		char *ref;

		if (dwim_ref(refspec[i], strlen(refspec[i]), sha1, &ref) != 1)
			return error("Could not get ref %s", refspec[i]);

		if (write_one_ref(ref, sha1, 0, temp_dir)) {
			free(ref);
			return -1;
		}
		free(ref);
	}
	return 0;
}

static int write_refs_to_temp_dir(struct strbuf *temp_dir,
				  int refspec_nr, const char **refspec)
{
	int i;

	for (i = 0; i < refspec_nr; i++) {
		struct object_id oid;
		char *ref;

		if (dwim_ref(refspec[i], strlen(refspec[i]), oid.hash, &ref) != 1)
			return error("Could not get ref %s", refspec[i]);

		if (write_one_ref(ref, &oid, 0, temp_dir)) {
			free(ref);
			return -1;
		}
		free(ref);
	}
	return 0;
}

/* Output a revision, only if filter allows it */
static void show_rev(int type, const unsigned char *sha1, const char *name)
{
	if (!(filter & DO_REVS))
		return;
	def = NULL;

	if ((symbolic || abbrev_ref) && name) {
		if (symbolic == SHOW_SYMBOLIC_FULL || abbrev_ref) {
			unsigned char discard[20];
			char *full;

			switch (dwim_ref(name, strlen(name), discard, &full)) {
			case 0:
				/*
				 * Not found -- not a ref.  We could
				 * emit "name" here, but symbolic-full
				 * users are interested in finding the
				 * refs spelled in full, and they would
				 * need to filter non-refs if we did so.
				 */
				break;
			case 1: /* happy */
				if (abbrev_ref)
					full = shorten_unambiguous_ref(full,
						abbrev_ref_strict);
				show_with_type(type, full);
				break;
			default: /* ambiguous */
				error("refname '%s' is ambiguous", name);
				break;
			}
			free(full);
		} else {
			show_with_type(type, name);
		}
	}
	else if (abbrev)
		show_with_type(type, find_unique_abbrev(sha1, abbrev));
	else
		show_with_type(type, sha1_to_hex(sha1));
}

static char *find_branch_name(struct rev_info *rev)
{
	int i, positive = -1;
	unsigned char branch_sha1[20];
	const unsigned char *tip_sha1;
	const char *ref;
	char *full_ref, *branch = NULL;

	for (i = 0; i < rev->cmdline.nr; i++) {
		if (rev->cmdline.rev[i].flags & UNINTERESTING)
			continue;
		if (positive < 0)
			positive = i;
		else
			return NULL;
	}
	if (0 <= positive) {
		ref = rev->cmdline.rev[positive].name;
		tip_sha1 = rev->cmdline.rev[positive].item->sha1;
	} else if (!rev->cmdline.nr && rev->pending.nr == 1 &&
		   !strcmp(rev->pending.objects[0].name, "HEAD")) {
		/*
		 * No actual ref from command line, but "HEAD" from
		 * rev->def was added in setup_revisions()
		 * e.g. format-patch --cover-letter -12
		 */
		ref = "HEAD";
		tip_sha1 = rev->pending.objects[0].item->sha1;
	} else {
		return NULL;
	}
	if (dwim_ref(ref, strlen(ref), branch_sha1, &full_ref) &&
	    !prefixcmp(full_ref, "refs/heads/") &&
	    !hashcmp(tip_sha1, branch_sha1))
		branch = xstrdup(full_ref + strlen("refs/heads/"));
	free(full_ref);
	return branch;
}

static void get_tags_and_duplicates(struct rev_cmdline_info *info)
{
	int i;

	for (i = 0; i < info->nr; i++) {
		struct rev_cmdline_entry *e = info->rev + i;
		struct object_id oid;
		struct commit *commit;
		char *full_name;

		if (e->flags & UNINTERESTING)
			continue;

		if (dwim_ref(e->name, strlen(e->name), &oid, &full_name) != 1)
			continue;

		if (refspecs.nr) {
			char *private;
			private = apply_refspecs(&refspecs, full_name);
			if (private) {
				free(full_name);
				full_name = private;
			}
		}

int create_bundle(struct bundle_header *header, const char *path,
		int argc, const char **argv)
{
	static struct lock_file lock;
	int bundle_fd = -1;
	int bundle_to_stdout;
	const char **argv_boundary = xmalloc((argc + 4) * sizeof(const char *));
	const char **argv_pack = xmalloc(6 * sizeof(const char *));
	int i, ref_count = 0;
	struct strbuf buf = STRBUF_INIT;
	struct rev_info revs;
	struct child_process rls;
	FILE *rls_fout;

	bundle_to_stdout = !strcmp(path, "-");
	if (bundle_to_stdout)
		bundle_fd = 1;
	else
		bundle_fd = hold_lock_file_for_update(&lock, path,
						      LOCK_DIE_ON_ERROR);

	/* write signature */
	write_or_die(bundle_fd, bundle_signature, strlen(bundle_signature));

	/* init revs to list objects for pack-objects later */
	save_commit_buffer = 0;
	init_revisions(&revs, NULL);

	/* write prerequisites */
	memcpy(argv_boundary + 3, argv + 1, argc * sizeof(const char *));
	argv_boundary[0] = "rev-list";
	argv_boundary[1] = "--boundary";
	argv_boundary[2] = "--pretty=oneline";
	argv_boundary[argc + 2] = NULL;
	memset(&rls, 0, sizeof(rls));
	rls.argv = argv_boundary;
	rls.out = -1;
	rls.git_cmd = 1;
	if (start_command(&rls))
		return -1;
	rls_fout = xfdopen(rls.out, "r");
	while (strbuf_getwholeline(&buf, rls_fout, '\n') != EOF) {
		unsigned char sha1[20];
		if (buf.len > 0 && buf.buf[0] == '-') {
			write_or_die(bundle_fd, buf.buf, buf.len);
			if (!get_sha1_hex(buf.buf + 1, sha1)) {
				struct object *object = parse_object(sha1);
				object->flags |= UNINTERESTING;
				add_pending_object(&revs, object, xstrdup(buf.buf));
			}
		} else if (!get_sha1_hex(buf.buf, sha1)) {
			struct object *object = parse_object(sha1);
			object->flags |= SHOWN;
		}
	}
	strbuf_release(&buf);
	fclose(rls_fout);
	if (finish_command(&rls))
		return error("rev-list died");

	/* write references */
	argc = setup_revisions(argc, argv, &revs, NULL);

	if (argc > 1)
		return error("unrecognized argument: %s", argv[1]);

	object_array_remove_duplicates(&revs.pending);

	for (i = 0; i < revs.pending.nr; i++) {
		struct object_array_entry *e = revs.pending.objects + i;
		unsigned char sha1[20];
		char *ref;
		const char *display_ref;
		int flag;

		if (e->item->flags & UNINTERESTING)
			continue;
		if (dwim_ref(e->name, strlen(e->name), sha1, &ref) != 1)
			continue;
		if (read_ref_full(e->name, sha1, 1, &flag))
			flag = 0;
		display_ref = (flag & REF_ISSYMREF) ? e->name : ref;

		if (e->item->type == OBJ_TAG &&
				!is_tag_in_date_range(e->item, &revs)) {
			e->item->flags |= UNINTERESTING;
			continue;
		}

		/*
		 * Make sure the refs we wrote out is correct; --max-count and
		 * other limiting options could have prevented all the tips
		 * from getting output.
		 *
		 * Non commit objects such as tags and blobs do not have
		 * this issue as they are not affected by those extra
		 * constraints.
		 */
		if (!(e->item->flags & SHOWN) && e->item->type == OBJ_COMMIT) {
			warning("ref '%s' is excluded by the rev-list options",
//.........这里部分代码省略.........

/* Get the name for the merge commit's message. */
static void merge_name(const char *remote, struct strbuf *msg)
{
	struct commit *remote_head;
	unsigned char branch_head[20];
	struct strbuf buf = STRBUF_INIT;
	struct strbuf bname = STRBUF_INIT;
	const char *ptr;
	char *found_ref;
	int len, early;

	strbuf_branchname(&bname, remote);
	remote = bname.buf;

	memset(branch_head, 0, sizeof(branch_head));
	remote_head = get_merge_parent(remote);
	if (!remote_head)
		die(_("'%s' does not point to a commit"), remote);

	if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
		if (!prefixcmp(found_ref, "refs/heads/")) {
			strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
				    sha1_to_hex(branch_head), remote);
			goto cleanup;
		}
		if (!prefixcmp(found_ref, "refs/tags/")) {
			strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
				    sha1_to_hex(branch_head), remote);
			goto cleanup;
		}
		if (!prefixcmp(found_ref, "refs/remotes/")) {
			strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
				    sha1_to_hex(branch_head), remote);
			goto cleanup;
		}
	}

	/* See if remote matches <name>^^^.. or <name>~<number> */
	for (len = 0, ptr = remote + strlen(remote);
	     remote < ptr && ptr[-1] == '^';
	     ptr--)
		len++;
	if (len)
		early = 1;
	else {
		early = 0;
		ptr = strrchr(remote, '~');
		if (ptr) {
			int seen_nonzero = 0;

			len++; /* count ~ */
			while (*++ptr && isdigit(*ptr)) {
				seen_nonzero |= (*ptr != '0');
				len++;
			}
			if (*ptr)
				len = 0; /* not ...~<number> */
			else if (seen_nonzero)
				early = 1;
			else if (len == 1)
				early = 1; /* "name~" is "name~1"! */
		}
	}
	if (len) {
		struct strbuf truname = STRBUF_INIT;
		strbuf_addstr(&truname, "refs/heads/");
		strbuf_addstr(&truname, remote);
		strbuf_setlen(&truname, truname.len - len);
		if (ref_exists(truname.buf)) {
			strbuf_addf(msg,
				    "%s\t\tbranch '%s'%s of .\n",
				    sha1_to_hex(remote_head->object.sha1),
				    truname.buf + 11,
				    (early ? " (early part)" : ""));
			strbuf_release(&truname);
			goto cleanup;
		}
	}

	if (!strcmp(remote, "FETCH_HEAD") &&
			!access(git_path("FETCH_HEAD"), R_OK)) {
		const char *filename;
		FILE *fp;
		struct strbuf line = STRBUF_INIT;
		char *ptr;

		filename = git_path("FETCH_HEAD");
		fp = fopen(filename, "r");
		if (!fp)
			die_errno(_("could not open '%s' for reading"),
				  filename);
		strbuf_getline(&line, fp, '\n');
		fclose(fp);
		ptr = strstr(line.buf, "\tnot-for-merge\t");
		if (ptr)
			strbuf_remove(&line, ptr-line.buf+1, 13);
		strbuf_addbuf(msg, &line);
		strbuf_release(&line);
		goto cleanup;
	}
//.........这里部分代码省略.........

static int get_sha1_basic(const char *str, int len, unsigned char *sha1, int warn_ambiguous_refs)
{
	static const char *warn_msg = "refname '%.*s' is ambiguous.";
	char *real_ref = NULL;
	int refs_found = 0;
	int at = 0, reflog_len = 0;

	int get_sha1_hex_val = 0;
	get_sha1_hex_val = get_sha1_hex(str, sha1);
	if (len >= 40 && get_sha1_hex_val >= 0)
		return 0;

	/* [email protected]{time or number or -number} format to query ref-log */
	if (len > 0 && select(str,len-1) >= '}') {
		for (at = len - 2; at >= 0; at--) {
			if (select(str,at) >= '@' && select(str,at+1) >= '{') {
				if (upstream_mark(str + at, len - at) > 0) {
					reflog_len = (len-1) - (at+2);
					len = at;
				}
				break;
			}
		}
	}

	// Accept only unambiguous ref paths.
	if (len > 0 && ambiguous_path(str, len) > 0)
		return -1;

	if (len <= 0 && reflog_len > 0) {
		struct strbuf buf = STRBUF_INIT;
		int ret = 0;
		// try the @{-N} syntax for n-th checkout
		ret = interpret_branch_name(str+at, &buf);
		if (ret > 0) {
			// substitute this branch name and restart
			return get_sha1_1(buf.buf, buf.len, sha1, 0);
		} else if (ret >= 0) {
			return -1;
		}
		// allow "@{...}" to mean the current branch reflog
		refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
	}
	else if (reflog_len > 0)
		refs_found = dwim_log(str, len, sha1, &real_ref);
	else
		refs_found = dwim_ref(str, len, sha1, &real_ref);

	if (refs_found <= 0)
		return -1;

	if (warn_ambiguous_refs > 0 && refs_found > 1)
		warning(warn_msg, len, str);

	if (reflog_len > 0) {
		int nth = 0, i = 0;
		unsigned long at_time = 0;
		unsigned long co_time = 0;
		int co_tz = 0, co_cnt = 0;

		// a @{-N} placed anywhere except the start is an error
		if (select(str,at+2) >= '-')
			return -1;

//		// Is it asking for N-th entry, or approxidate?
		for (; 0 <= nth && i < reflog_len; i++) {
			char ch = 0;
			ch = select(str,at+2+i);
			if ('0' <= ch && ch <= '9')
				nth = nth * 10 + ch - '0';
			else
				nth = -1;
		}
		if (100000000 <= nth) {
			at_time = nth;
			nth = -1;
		} else if (0 <= nth)
			at_time = 0;
		else {
			int errors = 0;
			char *tmp = xstrndup(str + at + 2, reflog_len);
			at_time = approxidate_careful(tmp, &errors);
			free(tmp);
			if (errors)
				return -1;
		}
		if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
				&co_time, &co_tz, &co_cnt) > 0) {
			if (at_time > 0)
				warning("Log for '%.*s' only goes "
					"back to %s.", len, str,
					show_date(co_time, co_tz, DATE_RFC2822));
			else {
				free(real_ref);
				die("Log for '%.*s' only has %d entries.",
				    len, str, co_cnt);
			}
		}
	}

//.........这里部分代码省略.........

void create_branch(const char *head,
		   const char *name, const char *start_name,
		   int force, int reflog, enum branch_track track)
{
	struct ref_lock *lock;
	struct commit *commit;
	unsigned char sha1[20];
	char *real_ref, msg[PATH_MAX + 20];
	struct strbuf ref = STRBUF_INIT;
	int forcing = 0;
	int len;

	len = strlen(name);
	if (interpret_nth_last_branch(name, &ref) != len) {
		strbuf_reset(&ref);
		strbuf_add(&ref, name, len);
	}
	strbuf_splice(&ref, 0, 0, "refs/heads/", 11);

	if (check_ref_format(ref.buf))
		die("'%s' is not a valid branch name.", name);

	if (resolve_ref(ref.buf, sha1, 1, NULL)) {
		if (!force)
			die("A branch named '%s' already exists.", name);
		else if (!is_bare_repository() && !strcmp(head, name))
			die("Cannot force update the current branch.");
		forcing = 1;
	}

	real_ref = NULL;
	if (get_sha1(start_name, sha1))
		die("Not a valid object name: '%s'.", start_name);

	switch (dwim_ref(start_name, strlen(start_name), sha1, &real_ref)) {
	case 0:
		/* Not branching from any existing branch */
		if (track == BRANCH_TRACK_EXPLICIT)
			die("Cannot setup tracking information; starting point is not a branch.");
		break;
	case 1:
		/* Unique completion -- good, only if it is a real ref */
		if (track == BRANCH_TRACK_EXPLICIT && !strcmp(real_ref, "HEAD"))
			die("Cannot setup tracking information; starting point is not a branch.");
		break;
	default:
		die("Ambiguous object name: '%s'.", start_name);
		break;
	}

	if ((commit = lookup_commit_reference(sha1)) == NULL)
		die("Not a valid branch point: '%s'.", start_name);
	hashcpy(sha1, commit->object.sha1);

	lock = lock_any_ref_for_update(ref.buf, NULL, 0);
	if (!lock)
		die("Failed to lock ref for update: %s.", strerror(errno));

	if (reflog)
		log_all_ref_updates = 1;

	if (forcing)
		snprintf(msg, sizeof msg, "branch: Reset from %s",
			 start_name);
	else
		snprintf(msg, sizeof msg, "branch: Created from %s",
			 start_name);

	if (real_ref && track)
		setup_tracking(name, real_ref, track);

	if (write_ref_sha1(lock, sha1, msg) < 0)
		die("Failed to write ref: %s.", strerror(errno));

	strbuf_release(&ref);
	free(real_ref);
}

/*
 * Write out bundle refs based on the tips already
 * parsed into revs.pending. As a side effect, may
 * manipulate revs.pending to include additional
 * necessary objects (like tags).
 *
 * Returns the number of refs written, or negative
 * on error.
 */
static int write_bundle_refs(int bundle_fd, struct rev_info *revs)
{
	int i;
	int ref_count = 0;

	for (i = 0; i < revs->pending.nr; i++) {
		struct object_array_entry *e = revs->pending.objects + i;
		unsigned char sha1[20];
		char *ref;
		const char *display_ref;
		int flag;

		if (e->item->flags & UNINTERESTING)
			continue;
		if (dwim_ref(e->name, strlen(e->name), sha1, &ref) != 1)
			goto skip_write_ref;
		if (read_ref_full(e->name, RESOLVE_REF_READING, sha1, &flag))
			flag = 0;
		display_ref = (flag & REF_ISSYMREF) ? e->name : ref;

		if (e->item->type == OBJ_TAG &&
				!is_tag_in_date_range(e->item, revs)) {
			e->item->flags |= UNINTERESTING;
			goto skip_write_ref;
		}

		/*
		 * Make sure the refs we wrote out is correct; --max-count and
		 * other limiting options could have prevented all the tips
		 * from getting output.
		 *
		 * Non commit objects such as tags and blobs do not have
		 * this issue as they are not affected by those extra
		 * constraints.
		 */
		if (!(e->item->flags & SHOWN) && e->item->type == OBJ_COMMIT) {
			warning(_("ref '%s' is excluded by the rev-list options"),
				e->name);
			goto skip_write_ref;
		}
		/*
		 * If you run "git bundle create bndl v1.0..v2.0", the
		 * name of the positive ref is "v2.0" but that is the
		 * commit that is referenced by the tag, and not the tag
		 * itself.
		 */
		if (hashcmp(sha1, e->item->sha1)) {
			/*
			 * Is this the positive end of a range expressed
			 * in terms of a tag (e.g. v2.0 from the range
			 * "v1.0..v2.0")?
			 */
			struct commit *one = lookup_commit_reference(sha1);
			struct object *obj;

			if (e->item == &(one->object)) {
				/*
				 * Need to include e->name as an
				 * independent ref to the pack-objects
				 * input, so that the tag is included
				 * in the output; otherwise we would
				 * end up triggering "empty bundle"
				 * error.
				 */
				obj = parse_object_or_die(sha1, e->name);
				obj->flags |= SHOWN;
				add_pending_object(revs, obj, e->name);
			}
			goto skip_write_ref;
		}

		ref_count++;
		write_or_die(bundle_fd, sha1_to_hex(e->item->sha1), 40);
		write_or_die(bundle_fd, " ", 1);
		write_or_die(bundle_fd, display_ref, strlen(display_ref));
		write_or_die(bundle_fd, "\n", 1);
 skip_write_ref:
		free(ref);
	}

	/* end header */
	write_or_die(bundle_fd, "\n", 1);
	return ref_count;
}

/* Get the name for the merge commit's message. */
static void merge_name(const char *remote, struct strbuf *msg)
{
	struct commit *remote_head;
	unsigned char branch_head[20];
	struct strbuf buf = STRBUF_INIT;
	struct strbuf bname = STRBUF_INIT;
	const char *ptr;
	char *found_ref;
	int len, early;

	strbuf_branchname(&bname, remote);
	remote = bname.buf;

	memset(branch_head, 0, sizeof(branch_head));
	remote_head = get_merge_parent(remote);
	if (!remote_head)
		die(_("'%s' does not point to a commit"), remote);

	if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
		if (starts_with(found_ref, "refs/heads/")) {
			strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
				    sha1_to_hex(branch_head), remote);
			goto cleanup;
		}
		if (starts_with(found_ref, "refs/tags/")) {
			strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
				    sha1_to_hex(branch_head), remote);
			goto cleanup;
		}
		if (starts_with(found_ref, "refs/remotes/")) {
			strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
				    sha1_to_hex(branch_head), remote);
			goto cleanup;
		}
	}

	/* See if remote matches <name>^^^.. or <name>~<number> */
	for (len = 0, ptr = remote + strlen(remote);
	     remote < ptr && ptr[-1] == '^';
	     ptr--)
		len++;
	if (len)
		early = 1;
	else {
		early = 0;
		ptr = strrchr(remote, '~');
		if (ptr) {
			int seen_nonzero = 0;

			len++; /* count ~ */
			while (*++ptr && isdigit(*ptr)) {
				seen_nonzero |= (*ptr != '0');
				len++;
			}
			if (*ptr)
				len = 0; /* not ...~<number> */
			else if (seen_nonzero)
				early = 1;
			else if (len == 1)
				early = 1; /* "name~" is "name~1"! */
		}
	}
	if (len) {
		struct strbuf truname = STRBUF_INIT;
		strbuf_addf(&truname, "refs/heads/%s", remote);
		strbuf_setlen(&truname, truname.len - len);
		if (ref_exists(truname.buf)) {
			strbuf_addf(msg,
				    "%s\t\tbranch '%s'%s of .\n",
				    oid_to_hex(&remote_head->object.oid),
				    truname.buf + 11,
				    (early ? " (early part)" : ""));
			strbuf_release(&truname);
			goto cleanup;
		}
		strbuf_release(&truname);
	}

	if (remote_head->util) {
		struct merge_remote_desc *desc;
		desc = merge_remote_util(remote_head);
		if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
			strbuf_addf(msg, "%s\t\t%s '%s'\n",
				    oid_to_hex(&desc->obj->oid),
				    typename(desc->obj->type),
				    remote);
			goto cleanup;
		}
	}

static int get_stash_info(struct stash_info *info, int argc, const char **argv)
{
	int ret;
	char *end_of_rev;
	char *expanded_ref;
	const char *revision;
	const char *commit = NULL;
	struct object_id dummy;
	struct strbuf symbolic = STRBUF_INIT;

	if (argc > 1) {
		int i;
		struct strbuf refs_msg = STRBUF_INIT;

		for (i = 0; i < argc; i++)
			strbuf_addf(&refs_msg, " '%s'", argv[i]);

		fprintf_ln(stderr, _("Too many revisions specified:%s"),
			   refs_msg.buf);
		strbuf_release(&refs_msg);

		return -1;
	}

	if (argc == 1)
		commit = argv[0];

	strbuf_init(&info->revision, 0);
	if (!commit) {
		if (!ref_exists(ref_stash)) {
			free_stash_info(info);
			fprintf_ln(stderr, _("No stash entries found."));
			return -1;
		}

		strbuf_addf(&info->revision, "%[email protected]{0}", ref_stash);
	} else if (strspn(commit, "0123456789") == strlen(commit)) {
		strbuf_addf(&info->revision, "%[email protected]{%s}", ref_stash, commit);
	} else {
		strbuf_addstr(&info->revision, commit);
	}

	revision = info->revision.buf;

	if (get_oid(revision, &info->w_commit)) {
		error(_("%s is not a valid reference"), revision);
		free_stash_info(info);
		return -1;
	}

	assert_stash_like(info, revision);

	info->has_u = !get_oidf(&info->u_tree, "%s^3:", revision);

	end_of_rev = strchrnul(revision, '@');
	strbuf_add(&symbolic, revision, end_of_rev - revision);

	ret = dwim_ref(symbolic.buf, symbolic.len, &dummy, &expanded_ref);
	strbuf_release(&symbolic);
	switch (ret) {
	case 0: /* Not found, but valid ref */
		info->is_stash_ref = 0;
		break;
	case 1:
		info->is_stash_ref = !strcmp(expanded_ref, ref_stash);
		break;
	default: /* Invalid or ambiguous */
		free_stash_info(info);
	}

	free(expanded_ref);
	return !(ret == 0 || ret == 1);
}

//.........这里部分代码省略.........
			 * make sense.  --list is Ok.
			 *
			 * Also --all and --remotes do not make sense either.
			 */
			usage(show_branch_usage_reflog);
	}

	/* If nothing is specified, show all branches by default */
	if (ac + all_heads + all_remotes == 0)
		all_heads = 1;

	if (reflog) {
		unsigned char sha1[20];
		char nth_desc[256];
		char *ref;
		int base = 0;

		if (ac == 0) {
			static const char *fake_av[2];
			const char *refname;

			refname = resolve_ref("HEAD", sha1, 1, NULL);
			fake_av[0] = xstrdup(refname);
			fake_av[1] = NULL;
			av = fake_av;
			ac = 1;
		}
		if (ac != 1)
			die("--reflog option needs one branch name");

		if (MAX_REVS < reflog)
			die("Only %d entries can be shown at one time.",
			    MAX_REVS);
		if (!dwim_ref(*av, strlen(*av), sha1, &ref))
			die("No such ref %s", *av);

		/* Has the base been specified? */
		if (reflog_base) {
			char *ep;
			base = strtoul(reflog_base, &ep, 10);
			if (*ep) {
				/* Ah, that is a date spec... */
				unsigned long at;
				at = approxidate(reflog_base);
				read_ref_at(ref, at, -1, sha1, NULL,
					    NULL, NULL, &base);
			}
		}

		for (i = 0; i < reflog; i++) {
			char *logmsg, *m;
			const char *msg;
			unsigned long timestamp;
			int tz;

			if (read_ref_at(ref, 0, base+i, sha1, &logmsg,
					&timestamp, &tz, NULL)) {
				reflog = i;
				break;
			}
			msg = strchr(logmsg, '\t');
			if (!msg)
				msg = "(none)";
			else
				msg++;
			m = xmalloc(strlen(msg) + 200);