예제 #1
0
/* 5ALT: ancest:*, head:head, remote:head = result:head */
void test_merge_workdir_trivial__5alt_2(void)
{
	const git_index_entry *entry;

	cl_git_pass(merge_trivial("trivial-5alt-2", "trivial-5alt-2-branch", 0));

	cl_assert(entry = git_index_get_bypath(repo_index, "modified-to-same.txt", 0));
	cl_assert(git_index_reuc_entrycount(repo_index) == 0);
	cl_assert(merge_trivial_conflict_entrycount() == 0);
}
예제 #2
0
/* 3ALT: ancest:(empty)+, head:head, remote:*empty* = result:head */
void test_merge_workdir_trivial__3alt(void)
{
	const git_index_entry *entry;

	cl_git_pass(merge_trivial("trivial-3alt", "trivial-3alt-branch", 0));

	cl_assert(entry = git_index_get_bypath(repo_index, "new-in-3alt.txt", 0));
	cl_assert(git_index_reuc_entrycount(repo_index) == 0);
	cl_assert(merge_trivial_conflict_entrycount() == 0);
}
예제 #3
0
/* 6: ancest:ancest+, head:(empty), remote:(empty) = result:no merge */
void test_merge_workdir_trivial__6(void)
{
	const git_index_entry *entry;

	cl_git_pass(merge_trivial("trivial-6", "trivial-6-branch", 0));

	cl_assert((entry = git_index_get_bypath(repo_index, "removed-in-both.txt", 0)) == NULL);
	cl_assert(git_index_reuc_entrycount(repo_index) == 0);

	cl_assert(merge_trivial_conflict_entrycount() == 1);
	cl_assert(entry = git_index_get_bypath(repo_index, "removed-in-both.txt", 1));
}
예제 #4
0
/* 4: ancest:(empty)^, head:head, remote:remote = result:no merge */
void test_merge_workdir_trivial__4(void)
{
	const git_index_entry *entry;

	cl_git_pass(merge_trivial("trivial-4", "trivial-4-branch", 0));

	cl_assert((entry = git_index_get_bypath(repo_index, "new-and-different.txt", 0)) == NULL);
	cl_assert(git_index_reuc_entrycount(repo_index) == 0);

	cl_assert(merge_trivial_conflict_entrycount() == 2);
	cl_assert(entry = git_index_get_bypath(repo_index, "new-and-different.txt", 2));
	cl_assert(entry = git_index_get_bypath(repo_index, "new-and-different.txt", 3));
}
예제 #5
0
/* 11: ancest:ancest+, head:head, remote:remote = result:no merge */
void test_merge_workdir_trivial__11(void)
{
	const git_index_entry *entry;

	cl_git_pass(merge_trivial("trivial-11", "trivial-11-branch", 0));

	cl_assert((entry = git_index_get_bypath(repo_index, "modified-in-both.txt", 0)) == NULL);
	cl_assert(git_index_reuc_entrycount(repo_index) == 0);

	cl_assert(merge_trivial_conflict_entrycount() == 3);
	cl_assert(entry = git_index_get_bypath(repo_index, "modified-in-both.txt", 1));
	cl_assert(entry = git_index_get_bypath(repo_index, "modified-in-both.txt", 2));
	cl_assert(entry = git_index_get_bypath(repo_index, "modified-in-both.txt", 3));
}
예제 #6
0
/* 14: ancest:ancest+, head:ancest, remote:remote = result:remote */
void test_merge_workdir_trivial__14(void)
{
	const git_index_entry *entry;
	git_oid expected_oid;

	cl_git_pass(merge_trivial("trivial-14", "trivial-14-branch", 0));

	cl_assert(entry = git_index_get_bypath(repo_index, "modified-in-14-branch.txt", 0));
	cl_git_pass(git_oid_fromstr(&expected_oid, "26153a3ff3649b6c2bb652d3f06878c6e0a172f9"));
	cl_assert(git_oid_cmp(&entry->oid, &expected_oid) == 0);

	cl_assert(git_index_reuc_entrycount(repo_index) == 0);
	cl_assert(merge_trivial_conflict_entrycount() == 0);
}
예제 #7
0
/* 13: ancest:ancest+, head:head, remote:ancest = result:head */
void test_merge_workdir_trivial__13(void)
{
	const git_index_entry *entry;
	git_oid expected_oid;

	cl_git_pass(merge_trivial("trivial-13", "trivial-13-branch", 0));

	cl_assert(entry = git_index_get_bypath(repo_index, "modified-in-13.txt", 0));
	cl_git_pass(git_oid_fromstr(&expected_oid, "1cff9ec6a47a537380dedfdd17c9e76d74259a2b"));
	cl_assert(git_oid_cmp(&entry->oid, &expected_oid) == 0);

	cl_assert(git_index_reuc_entrycount(repo_index) == 0);
	cl_assert(merge_trivial_conflict_entrycount() == 0);
}
예제 #8
0
파일: merge.c 프로젝트: carey94tt/git
int cmd_merge(int argc, const char **argv, const char *prefix)
{
	unsigned char result_tree[20];
	unsigned char stash[20];
	unsigned char head_sha1[20];
	struct commit *head_commit;
	struct strbuf buf = STRBUF_INIT;
	const char *head_arg;
	int flag, i, ret = 0, head_subsumed;
	int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
	struct commit_list *common = NULL;
	const char *best_strategy = NULL, *wt_strategy = NULL;
	struct commit_list *remoteheads, *p;
	void *branch_to_free;

	if (argc == 2 && !strcmp(argv[1], "-h"))
		usage_with_options(builtin_merge_usage, builtin_merge_options);

	/*
	 * Check if we are _not_ on a detached HEAD, i.e. if there is a
	 * current branch.
	 */
	branch = branch_to_free = resolve_refdup("HEAD", head_sha1, 0, &flag);
	if (branch && !prefixcmp(branch, "refs/heads/"))
		branch += 11;
	if (!branch || is_null_sha1(head_sha1))
		head_commit = NULL;
	else
		head_commit = lookup_commit_or_die(head_sha1, "HEAD");

	git_config(git_merge_config, NULL);

	if (branch_mergeoptions)
		parse_branch_merge_options(branch_mergeoptions);
	argc = parse_options(argc, argv, prefix, builtin_merge_options,
			builtin_merge_usage, 0);
	if (shortlog_len < 0)
		shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;

	if (verbosity < 0 && show_progress == -1)
		show_progress = 0;

	if (abort_current_merge) {
		int nargc = 2;
		const char *nargv[] = {"reset", "--merge", NULL};

		if (!file_exists(git_path("MERGE_HEAD")))
			die(_("There is no merge to abort (MERGE_HEAD missing)."));

		/* Invoke 'git reset --merge' */
		ret = cmd_reset(nargc, nargv, prefix);
		goto done;
	}

	if (read_cache_unmerged())
		die_resolve_conflict("merge");

	if (file_exists(git_path("MERGE_HEAD"))) {
		/*
		 * There is no unmerged entry, don't advise 'git
		 * add/rm <file>', just 'git commit'.
		 */
		if (advice_resolve_conflict)
			die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
				  "Please, commit your changes before you can merge."));
		else
			die(_("You have not concluded your merge (MERGE_HEAD exists)."));
	}
	if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
		if (advice_resolve_conflict)
			die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
			    "Please, commit your changes before you can merge."));
		else
			die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
	}
	resolve_undo_clear();

	if (verbosity < 0)
		show_diffstat = 0;

	if (squash) {
		if (!allow_fast_forward)
			die(_("You cannot combine --squash with --no-ff."));
		option_commit = 0;
	}

	if (!allow_fast_forward && fast_forward_only)
		die(_("You cannot combine --no-ff with --ff-only."));

	if (!abort_current_merge) {
		if (!argc) {
			if (default_to_upstream)
				argc = setup_with_upstream(&argv);
			else
				die(_("No commit specified and merge.defaultToUpstream not set."));
		} else if (argc == 1 && !strcmp(argv[0], "-"))
			argv[0] = "@{-1}";
	}
	if (!argc)
		usage_with_options(builtin_merge_usage,
			builtin_merge_options);

	/*
	 * This could be traditional "merge <msg> HEAD <commit>..."  and
	 * the way we can tell it is to see if the second token is HEAD,
	 * but some people might have misused the interface and used a
	 * committish that is the same as HEAD there instead.
	 * Traditional format never would have "-m" so it is an
	 * additional safety measure to check for it.
	 */

	if (!have_message && head_commit &&
	    is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
		strbuf_addstr(&merge_msg, argv[0]);
		head_arg = argv[1];
		argv += 2;
		argc -= 2;
		remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
	} else if (!head_commit) {
		struct commit *remote_head;
		/*
		 * If the merged head is a valid one there is no reason
		 * to forbid "git merge" into a branch yet to be born.
		 * We do the same for "git pull".
		 */
		if (argc != 1)
			die(_("Can merge only exactly one commit into "
				"empty head"));
		if (squash)
			die(_("Squash commit into empty head not supported yet"));
		if (!allow_fast_forward)
			die(_("Non-fast-forward commit does not make sense into "
			    "an empty head"));
		remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
		remote_head = remoteheads->item;
		if (!remote_head)
			die(_("%s - not something we can merge"), argv[0]);
		read_empty(remote_head->object.sha1, 0);
		update_ref("initial pull", "HEAD", remote_head->object.sha1,
			   NULL, 0, DIE_ON_ERR);
		goto done;
	} else {
		struct strbuf merge_names = STRBUF_INIT;

		/* We are invoked directly as the first-class UI. */
		head_arg = "HEAD";

		/*
		 * All the rest are the commits being merged; prepare
		 * the standard merge summary message to be appended
		 * to the given message.
		 */
		remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
		for (p = remoteheads; p; p = p->next)
			merge_name(merge_remote_util(p->item)->name, &merge_names);

		if (!have_message || shortlog_len) {
			struct fmt_merge_msg_opts opts;
			memset(&opts, 0, sizeof(opts));
			opts.add_title = !have_message;
			opts.shortlog_len = shortlog_len;

			fmt_merge_msg(&merge_names, &merge_msg, &opts);
			if (merge_msg.len)
				strbuf_setlen(&merge_msg, merge_msg.len - 1);
		}
	}

	if (!head_commit || !argc)
		usage_with_options(builtin_merge_usage,
			builtin_merge_options);

	strbuf_addstr(&buf, "merge");
	for (p = remoteheads; p; p = p->next)
		strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
	setenv("GIT_REFLOG_ACTION", buf.buf, 0);
	strbuf_reset(&buf);

	for (p = remoteheads; p; p = p->next) {
		struct commit *commit = p->item;
		strbuf_addf(&buf, "GITHEAD_%s",
			    sha1_to_hex(commit->object.sha1));
		setenv(buf.buf, merge_remote_util(commit)->name, 1);
		strbuf_reset(&buf);
		if (!fast_forward_only &&
		    merge_remote_util(commit) &&
		    merge_remote_util(commit)->obj &&
		    merge_remote_util(commit)->obj->type == OBJ_TAG)
			allow_fast_forward = 0;
	}

	if (option_edit < 0)
		option_edit = default_edit_option();

	if (!use_strategies) {
		if (!remoteheads)
			; /* already up-to-date */
		else if (!remoteheads->next)
			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
		else
			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
	}

	for (i = 0; i < use_strategies_nr; i++) {
		if (use_strategies[i]->attr & NO_FAST_FORWARD)
			allow_fast_forward = 0;
		if (use_strategies[i]->attr & NO_TRIVIAL)
			allow_trivial = 0;
	}

	if (!remoteheads)
		; /* already up-to-date */
	else if (!remoteheads->next)
		common = get_merge_bases(head_commit, remoteheads->item, 1);
	else {
		struct commit_list *list = remoteheads;
		commit_list_insert(head_commit, &list);
		common = get_octopus_merge_bases(list);
		free(list);
	}

	update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
		   NULL, 0, DIE_ON_ERR);

	if (remoteheads && !common)
		; /* No common ancestors found. We need a real merge. */
	else if (!remoteheads ||
		 (!remoteheads->next && !common->next &&
		  common->item == remoteheads->item)) {
		/*
		 * If head can reach all the merge then we are up to date.
		 * but first the most common case of merging one remote.
		 */
		finish_up_to_date("Already up-to-date.");
		goto done;
	} else if (allow_fast_forward && !remoteheads->next &&
			!common->next &&
			!hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
		/* Again the most common case of merging one remote. */
		struct strbuf msg = STRBUF_INIT;
		struct commit *commit;
		char hex[41];

		strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));

		if (verbosity >= 0)
			printf(_("Updating %s..%s\n"),
				hex,
				find_unique_abbrev(remoteheads->item->object.sha1,
				DEFAULT_ABBREV));
		strbuf_addstr(&msg, "Fast-forward");
		if (have_message)
			strbuf_addstr(&msg,
				" (no commit created; -m option ignored)");
		commit = remoteheads->item;
		if (!commit) {
			ret = 1;
			goto done;
		}

		if (checkout_fast_forward(head_commit->object.sha1,
					  commit->object.sha1,
					  overwrite_ignore)) {
			ret = 1;
			goto done;
		}

		finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
		drop_save();
		goto done;
	} else if (!remoteheads->next && common->next)
		;
		/*
		 * We are not doing octopus and not fast-forward.  Need
		 * a real merge.
		 */
	else if (!remoteheads->next && !common->next && option_commit) {
		/*
		 * We are not doing octopus, not fast-forward, and have
		 * only one common.
		 */
		refresh_cache(REFRESH_QUIET);
		if (allow_trivial && !fast_forward_only) {
			/* See if it is really trivial. */
			git_committer_info(IDENT_STRICT);
			printf(_("Trying really trivial in-index merge...\n"));
			if (!read_tree_trivial(common->item->object.sha1,
					       head_commit->object.sha1,
					       remoteheads->item->object.sha1)) {
				ret = merge_trivial(head_commit, remoteheads);
				goto done;
			}
			printf(_("Nope.\n"));
		}
	} else {
		/*
		 * An octopus.  If we can reach all the remote we are up
		 * to date.
		 */
		int up_to_date = 1;
		struct commit_list *j;

		for (j = remoteheads; j; j = j->next) {
			struct commit_list *common_one;

			/*
			 * Here we *have* to calculate the individual
			 * merge_bases again, otherwise "git merge HEAD^
			 * HEAD^^" would be missed.
			 */
			common_one = get_merge_bases(head_commit, j->item, 1);
			if (hashcmp(common_one->item->object.sha1,
				j->item->object.sha1)) {
				up_to_date = 0;
				break;
			}
		}
		if (up_to_date) {
			finish_up_to_date("Already up-to-date. Yeeah!");
			goto done;
		}
	}

	if (fast_forward_only)
		die(_("Not possible to fast-forward, aborting."));

	/* We are going to make a new commit. */
	git_committer_info(IDENT_STRICT);

	/*
	 * At this point, we need a real merge.  No matter what strategy
	 * we use, it would operate on the index, possibly affecting the
	 * working tree, and when resolved cleanly, have the desired
	 * tree in the index -- this means that the index must be in
	 * sync with the head commit.  The strategies are responsible
	 * to ensure this.
	 */
	if (use_strategies_nr == 1 ||
	    /*
	     * Stash away the local changes so that we can try more than one.
	     */
	    save_state(stash))
		hashcpy(stash, null_sha1);

	for (i = 0; i < use_strategies_nr; i++) {
		int ret;
		if (i) {
			printf(_("Rewinding the tree to pristine...\n"));
			restore_state(head_commit->object.sha1, stash);
		}
		if (use_strategies_nr != 1)
			printf(_("Trying merge strategy %s...\n"),
				use_strategies[i]->name);
		/*
		 * Remember which strategy left the state in the working
		 * tree.
		 */
		wt_strategy = use_strategies[i]->name;

		ret = try_merge_strategy(use_strategies[i]->name,
					 common, remoteheads,
					 head_commit, head_arg);
		if (!option_commit && !ret) {
			merge_was_ok = 1;
			/*
			 * This is necessary here just to avoid writing
			 * the tree, but later we will *not* exit with
			 * status code 1 because merge_was_ok is set.
			 */
			ret = 1;
		}

		if (ret) {
			/*
			 * The backend exits with 1 when conflicts are
			 * left to be resolved, with 2 when it does not
			 * handle the given merge at all.
			 */
			if (ret == 1) {
				int cnt = evaluate_result();

				if (best_cnt <= 0 || cnt <= best_cnt) {
					best_strategy = use_strategies[i]->name;
					best_cnt = cnt;
				}
			}
			if (merge_was_ok)
				break;
			else
				continue;
		}

		/* Automerge succeeded. */
		write_tree_trivial(result_tree);
		automerge_was_ok = 1;
		break;
	}

	/*
	 * If we have a resulting tree, that means the strategy module
	 * auto resolved the merge cleanly.
	 */
	if (automerge_was_ok) {
		ret = finish_automerge(head_commit, head_subsumed,
				       common, remoteheads,
				       result_tree, wt_strategy);
		goto done;
	}

	/*
	 * Pick the result from the best strategy and have the user fix
	 * it up.
	 */
	if (!best_strategy) {
		restore_state(head_commit->object.sha1, stash);
		if (use_strategies_nr > 1)
			fprintf(stderr,
				_("No merge strategy handled the merge.\n"));
		else
			fprintf(stderr, _("Merge with strategy %s failed.\n"),
				use_strategies[0]->name);
		ret = 2;
		goto done;
	} else if (best_strategy == wt_strategy)
		; /* We already have its result in the working tree. */
	else {
		printf(_("Rewinding the tree to pristine...\n"));
		restore_state(head_commit->object.sha1, stash);
		printf(_("Using the %s to prepare resolving by hand.\n"),
			best_strategy);
		try_merge_strategy(best_strategy, common, remoteheads,
				   head_commit, head_arg);
	}

	if (squash)
		finish(head_commit, remoteheads, NULL, NULL);
	else
		write_merge_state(remoteheads);

	if (merge_was_ok)
		fprintf(stderr, _("Automatic merge went well; "
			"stopped before committing as requested\n"));
	else
		ret = suggest_conflicts(option_renormalize);

done:
	free(branch_to_free);
	return ret;
}
예제 #9
0
파일: builtin-merge.c 프로젝트: samv/git
int cmd_merge(int argc, const char **argv, const char *prefix)
{
	unsigned char result_tree[20];
	struct strbuf buf = STRBUF_INIT;
	const char *head_arg;
	int flag, head_invalid = 0, i;
	int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
	struct commit_list *common = NULL;
	const char *best_strategy = NULL, *wt_strategy = NULL;
	struct commit_list **remotes = &remoteheads;

	if (file_exists(git_path("MERGE_HEAD")))
		die("You have not concluded your merge. (MERGE_HEAD exists)");
	if (read_cache_unmerged())
		die("You are in the middle of a conflicted merge."
				" (index unmerged)");

	/*
	 * Check if we are _not_ on a detached HEAD, i.e. if there is a
	 * current branch.
	 */
	branch = resolve_ref("HEAD", head, 0, &flag);
	if (branch && !prefixcmp(branch, "refs/heads/"))
		branch += 11;
	if (is_null_sha1(head))
		head_invalid = 1;

	git_config(git_merge_config, NULL);

	/* for color.ui */
	if (diff_use_color_default == -1)
		diff_use_color_default = git_use_color_default;

	argc = parse_options(argc, argv, prefix, builtin_merge_options,
			builtin_merge_usage, 0);
	if (verbosity < 0)
		show_diffstat = 0;

	if (squash) {
		if (!allow_fast_forward)
			die("You cannot combine --squash with --no-ff.");
		option_commit = 0;
	}

	if (!allow_fast_forward && fast_forward_only)
		die("You cannot combine --no-ff with --ff-only.");

	if (!argc)
		usage_with_options(builtin_merge_usage,
			builtin_merge_options);

	/*
	 * This could be traditional "merge <msg> HEAD <commit>..."  and
	 * the way we can tell it is to see if the second token is HEAD,
	 * but some people might have misused the interface and used a
	 * committish that is the same as HEAD there instead.
	 * Traditional format never would have "-m" so it is an
	 * additional safety measure to check for it.
	 */

	if (!have_message && is_old_style_invocation(argc, argv)) {
		strbuf_addstr(&merge_msg, argv[0]);
		head_arg = argv[1];
		argv += 2;
		argc -= 2;
	} else if (head_invalid) {
		struct object *remote_head;
		/*
		 * If the merged head is a valid one there is no reason
		 * to forbid "git merge" into a branch yet to be born.
		 * We do the same for "git pull".
		 */
		if (argc != 1)
			die("Can merge only exactly one commit into "
				"empty head");
		if (squash)
			die("Squash commit into empty head not supported yet");
		if (!allow_fast_forward)
			die("Non-fast-forward commit does not make sense into "
			    "an empty head");
		remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
		if (!remote_head)
			die("%s - not something we can merge", argv[0]);
		update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
				DIE_ON_ERR);
		reset_hard(remote_head->sha1, 0);
		return 0;
	} else {
		struct strbuf msg = STRBUF_INIT;

		/* We are invoked directly as the first-class UI. */
		head_arg = "HEAD";

		/*
		 * All the rest are the commits being merged;
		 * prepare the standard merge summary message to
		 * be appended to the given message.  If remote
		 * is invalid we will die later in the common
		 * codepath so we discard the error in this
		 * loop.
		 */
		if (!have_message) {
			for (i = 0; i < argc; i++)
				merge_name(argv[i], &msg);
			fmt_merge_msg(option_log, &msg, &merge_msg);
			if (merge_msg.len)
				strbuf_setlen(&merge_msg, merge_msg.len-1);
		}
	}

	if (head_invalid || !argc)
		usage_with_options(builtin_merge_usage,
			builtin_merge_options);

	strbuf_addstr(&buf, "merge");
	for (i = 0; i < argc; i++)
		strbuf_addf(&buf, " %s", argv[i]);
	setenv("GIT_REFLOG_ACTION", buf.buf, 0);
	strbuf_reset(&buf);

	for (i = 0; i < argc; i++) {
		struct object *o;
		struct commit *commit;

		o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
		if (!o)
			die("%s - not something we can merge", argv[i]);
		commit = lookup_commit(o->sha1);
		commit->util = (void *)argv[i];
		remotes = &commit_list_insert(commit, remotes)->next;

		strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
		setenv(buf.buf, argv[i], 1);
		strbuf_reset(&buf);
	}

	if (!use_strategies) {
		if (!remoteheads->next)
			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
		else
			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
	}

	for (i = 0; i < use_strategies_nr; i++) {
		if (use_strategies[i]->attr & NO_FAST_FORWARD)
			allow_fast_forward = 0;
		if (use_strategies[i]->attr & NO_TRIVIAL)
			allow_trivial = 0;
	}

	if (!remoteheads->next)
		common = get_merge_bases(lookup_commit(head),
				remoteheads->item, 1);
	else {
		struct commit_list *list = remoteheads;
		commit_list_insert(lookup_commit(head), &list);
		common = get_octopus_merge_bases(list);
		free(list);
	}

	update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
		DIE_ON_ERR);

	if (!common)
		; /* No common ancestors found. We need a real merge. */
	else if (!remoteheads->next && !common->next &&
			common->item == remoteheads->item) {
		/*
		 * If head can reach all the merge then we are up to date.
		 * but first the most common case of merging one remote.
		 */
		finish_up_to_date("Already up-to-date.");
		return 0;
	} else if (allow_fast_forward && !remoteheads->next &&
			!common->next &&
			!hashcmp(common->item->object.sha1, head)) {
		/* Again the most common case of merging one remote. */
		struct strbuf msg = STRBUF_INIT;
		struct object *o;
		char hex[41];

		strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));

		if (verbosity >= 0)
			printf("Updating %s..%s\n",
				hex,
				find_unique_abbrev(remoteheads->item->object.sha1,
				DEFAULT_ABBREV));
		strbuf_addstr(&msg, "Fast-forward");
		if (have_message)
			strbuf_addstr(&msg,
				" (no commit created; -m option ignored)");
		o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
			0, NULL, OBJ_COMMIT);
		if (!o)
			return 1;

		if (checkout_fast_forward(head, remoteheads->item->object.sha1))
			return 1;

		finish(o->sha1, msg.buf);
		drop_save();
		return 0;
	} else if (!remoteheads->next && common->next)
		;
		/*
		 * We are not doing octopus and not fast-forward.  Need
		 * a real merge.
		 */
	else if (!remoteheads->next && !common->next && option_commit) {
		/*
		 * We are not doing octopus, not fast-forward, and have
		 * only one common.
		 */
		refresh_cache(REFRESH_QUIET);
		if (allow_trivial && !fast_forward_only) {
			/* See if it is really trivial. */
			git_committer_info(IDENT_ERROR_ON_NO_NAME);
			printf("Trying really trivial in-index merge...\n");
			if (!read_tree_trivial(common->item->object.sha1,
					head, remoteheads->item->object.sha1))
				return merge_trivial();
			printf("Nope.\n");
		}
	} else {
		/*
		 * An octopus.  If we can reach all the remote we are up
		 * to date.
		 */
		int up_to_date = 1;
		struct commit_list *j;

		for (j = remoteheads; j; j = j->next) {
			struct commit_list *common_one;

			/*
			 * Here we *have* to calculate the individual
			 * merge_bases again, otherwise "git merge HEAD^
			 * HEAD^^" would be missed.
			 */
			common_one = get_merge_bases(lookup_commit(head),
				j->item, 1);
			if (hashcmp(common_one->item->object.sha1,
				j->item->object.sha1)) {
				up_to_date = 0;
				break;
			}
		}
		if (up_to_date) {
			finish_up_to_date("Already up-to-date. Yeeah!");
			return 0;
		}
	}

	if (fast_forward_only)
		die("Not possible to fast-forward, aborting.");

	/* We are going to make a new commit. */
	git_committer_info(IDENT_ERROR_ON_NO_NAME);

	/*
	 * At this point, we need a real merge.  No matter what strategy
	 * we use, it would operate on the index, possibly affecting the
	 * working tree, and when resolved cleanly, have the desired
	 * tree in the index -- this means that the index must be in
	 * sync with the head commit.  The strategies are responsible
	 * to ensure this.
	 */
	if (use_strategies_nr != 1) {
		/*
		 * Stash away the local changes so that we can try more
		 * than one.
		 */
		save_state();
	} else {
		memcpy(stash, null_sha1, 20);
	}

	for (i = 0; i < use_strategies_nr; i++) {
		int ret;
		if (i) {
			printf("Rewinding the tree to pristine...\n");
			restore_state();
		}
		if (use_strategies_nr != 1)
			printf("Trying merge strategy %s...\n",
				use_strategies[i]->name);
		/*
		 * Remember which strategy left the state in the working
		 * tree.
		 */
		wt_strategy = use_strategies[i]->name;

		ret = try_merge_strategy(use_strategies[i]->name,
			common, head_arg);
		if (!option_commit && !ret) {
			merge_was_ok = 1;
			/*
			 * This is necessary here just to avoid writing
			 * the tree, but later we will *not* exit with
			 * status code 1 because merge_was_ok is set.
			 */
			ret = 1;
		}

		if (ret) {
			/*
			 * The backend exits with 1 when conflicts are
			 * left to be resolved, with 2 when it does not
			 * handle the given merge at all.
			 */
			if (ret == 1) {
				int cnt = evaluate_result();

				if (best_cnt <= 0 || cnt <= best_cnt) {
					best_strategy = use_strategies[i]->name;
					best_cnt = cnt;
				}
			}
			if (merge_was_ok)
				break;
			else
				continue;
		}

		/* Automerge succeeded. */
		write_tree_trivial(result_tree);
		automerge_was_ok = 1;
		break;
	}

	/*
	 * If we have a resulting tree, that means the strategy module
	 * auto resolved the merge cleanly.
	 */
	if (automerge_was_ok)
		return finish_automerge(common, result_tree, wt_strategy);

	/*
	 * Pick the result from the best strategy and have the user fix
	 * it up.
	 */
	if (!best_strategy) {
		restore_state();
		if (use_strategies_nr > 1)
			fprintf(stderr,
				"No merge strategy handled the merge.\n");
		else
			fprintf(stderr, "Merge with strategy %s failed.\n",
				use_strategies[0]->name);
		return 2;
	} else if (best_strategy == wt_strategy)
		; /* We already have its result in the working tree. */
	else {
		printf("Rewinding the tree to pristine...\n");
		restore_state();
		printf("Using the %s to prepare resolving by hand.\n",
			best_strategy);
		try_merge_strategy(best_strategy, common, head_arg);
	}

	if (squash)
		finish(NULL, NULL);
	else {
		int fd;
		struct commit_list *j;

		for (j = remoteheads; j; j = j->next)
			strbuf_addf(&buf, "%s\n",
				sha1_to_hex(j->item->object.sha1));
		fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
		if (fd < 0)
			die_errno("Could not open '%s' for writing",
				  git_path("MERGE_HEAD"));
		if (write_in_full(fd, buf.buf, buf.len) != buf.len)
			die_errno("Could not write to '%s'", git_path("MERGE_HEAD"));
		close(fd);
		strbuf_addch(&merge_msg, '\n');
		fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
		if (fd < 0)
			die_errno("Could not open '%s' for writing",
				  git_path("MERGE_MSG"));
		if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
			merge_msg.len)
			die_errno("Could not write to '%s'", git_path("MERGE_MSG"));
		close(fd);
		fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
		if (fd < 0)
			die_errno("Could not open '%s' for writing",
				  git_path("MERGE_MODE"));
		strbuf_reset(&buf);
		if (!allow_fast_forward)
			strbuf_addf(&buf, "no-ff");
		if (write_in_full(fd, buf.buf, buf.len) != buf.len)
			die_errno("Could not write to '%s'", git_path("MERGE_MODE"));
		close(fd);
	}

	if (merge_was_ok) {
		fprintf(stderr, "Automatic merge went well; "
			"stopped before committing as requested\n");
		return 0;
	} else
		return suggest_conflicts();
}