From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 16 Jul 2008 02:09:46 +0000 (-0700)
Subject: Merge branch 'mv/merge-in-c'
X-Git-Tag: v1.6.0-rc0~51
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=fcab40a389e99786a8276108cdbc1cda8caf502f;p=git.git

Merge branch 'mv/merge-in-c'

* mv/merge-in-c:
  reduce_heads(): protect from duplicate input
  reduce_heads(): thinkofix
  Add a new test for git-merge-resolve
  t6021: add a new test for git-merge-resolve
  Teach merge.log to "git-merge" again
  Build in merge
  Fix t7601-merge-pull-config.sh on AIX
  git-commit-tree: make it usable from other builtins
  Add new test case to ensure git-merge prepends the custom merge message
  Add new test case to ensure git-merge reduces octopus parents when possible
  Introduce reduce_heads()
  Introduce get_merge_bases_many()
  Add new test to ensure git-merge handles more than 25 refs.
  Introduce get_octopus_merge_bases() in commit.c
  git-fmt-merge-msg: make it usable from other builtins
  Move read_cache_unmerged() to read-cache.c
  Add new test to ensure git-merge handles pull.twohead and pull.octopus
  Move parse-options's skip_prefix() to git-compat-util.h
  Move commit_list_count() to commit.c
  Move split_cmdline() to alias.c

Conflicts:
	Makefile
	parse-options.c
---

fcab40a389e99786a8276108cdbc1cda8caf502f
diff --cc Makefile
index de151638b,fbc53e9cb..9b52071b7
--- a/Makefile
+++ b/Makefile
@@@ -240,7 -240,7 +240,6 @@@ SCRIPT_SH += git-lost-found.s
  SCRIPT_SH += git-merge-octopus.sh
  SCRIPT_SH += git-merge-one-file.sh
  SCRIPT_SH += git-merge-resolve.sh
- SCRIPT_SH += git-merge.sh
 -SCRIPT_SH += git-merge-stupid.sh
  SCRIPT_SH += git-mergetool.sh
  SCRIPT_SH += git-parse-remote.sh
  SCRIPT_SH += git-pull.sh
diff --cc builtin-merge.c
index 000000000,2ee167469..129b4e62d
mode 000000,100644..100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@@ -1,0 -1,1155 +1,1156 @@@
+ /*
+  * Builtin "git merge"
+  *
+  * Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
+  *
+  * Based on git-merge.sh by Junio C Hamano.
+  */
+ 
+ #include "cache.h"
+ #include "parse-options.h"
+ #include "builtin.h"
+ #include "run-command.h"
+ #include "diff.h"
+ #include "refs.h"
+ #include "commit.h"
+ #include "diffcore.h"
+ #include "revision.h"
+ #include "unpack-trees.h"
+ #include "cache-tree.h"
+ #include "dir.h"
+ #include "utf8.h"
+ #include "log-tree.h"
+ #include "color.h"
++#include "rerere.h"
+ 
+ #define DEFAULT_TWOHEAD (1<<0)
+ #define DEFAULT_OCTOPUS (1<<1)
+ #define NO_FAST_FORWARD (1<<2)
+ #define NO_TRIVIAL      (1<<3)
+ 
+ struct strategy {
+ 	const char *name;
+ 	unsigned attr;
+ };
+ 
+ static const char * const builtin_merge_usage[] = {
+ 	"git-merge [options] <remote>...",
+ 	"git-merge [options] <msg> HEAD <remote>",
+ 	NULL
+ };
+ 
+ static int show_diffstat = 1, option_log, squash;
+ static int option_commit = 1, allow_fast_forward = 1;
+ static int allow_trivial = 1, have_message;
+ static struct strbuf merge_msg;
+ static struct commit_list *remoteheads;
+ static unsigned char head[20], stash[20];
+ static struct strategy **use_strategies;
+ static size_t use_strategies_nr, use_strategies_alloc;
+ static const char *branch;
+ 
+ static struct strategy all_strategy[] = {
+ 	{ "recur",      NO_TRIVIAL },
+ 	{ "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
+ 	{ "octopus",    DEFAULT_OCTOPUS },
+ 	{ "resolve",    0 },
+ 	{ "stupid",     0 },
+ 	{ "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
+ 	{ "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
+ };
+ 
+ static const char *pull_twohead, *pull_octopus;
+ 
+ static int option_parse_message(const struct option *opt,
+ 				const char *arg, int unset)
+ {
+ 	struct strbuf *buf = opt->value;
+ 
+ 	if (unset)
+ 		strbuf_setlen(buf, 0);
+ 	else {
+ 		strbuf_addf(buf, "%s\n\n", arg);
+ 		have_message = 1;
+ 	}
+ 	return 0;
+ }
+ 
+ static struct strategy *get_strategy(const char *name)
+ {
+ 	int i;
+ 
+ 	if (!name)
+ 		return NULL;
+ 
+ 	for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
+ 		if (!strcmp(name, all_strategy[i].name))
+ 			return &all_strategy[i];
+ 	return NULL;
+ }
+ 
+ static void append_strategy(struct strategy *s)
+ {
+ 	ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
+ 	use_strategies[use_strategies_nr++] = s;
+ }
+ 
+ static int option_parse_strategy(const struct option *opt,
+ 				 const char *name, int unset)
+ {
+ 	int i;
+ 	struct strategy *s;
+ 
+ 	if (unset)
+ 		return 0;
+ 
+ 	s = get_strategy(name);
+ 
+ 	if (s)
+ 		append_strategy(s);
+ 	else {
+ 		struct strbuf err;
+ 		strbuf_init(&err, 0);
+ 		for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
+ 			strbuf_addf(&err, " %s", all_strategy[i].name);
+ 		fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
+ 		fprintf(stderr, "Available strategies are:%s.\n", err.buf);
+ 		exit(1);
+ 	}
+ 	return 0;
+ }
+ 
+ static int option_parse_n(const struct option *opt,
+ 			  const char *arg, int unset)
+ {
+ 	show_diffstat = unset;
+ 	return 0;
+ }
+ 
+ static struct option builtin_merge_options[] = {
+ 	{ OPTION_CALLBACK, 'n', NULL, NULL, NULL,
+ 		"do not show a diffstat at the end of the merge",
+ 		PARSE_OPT_NOARG, option_parse_n },
+ 	OPT_BOOLEAN(0, "stat", &show_diffstat,
+ 		"show a diffstat at the end of the merge"),
+ 	OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
+ 	OPT_BOOLEAN(0, "log", &option_log,
+ 		"add list of one-line log to merge commit message"),
+ 	OPT_BOOLEAN(0, "squash", &squash,
+ 		"create a single commit instead of doing a merge"),
+ 	OPT_BOOLEAN(0, "commit", &option_commit,
+ 		"perform a commit if the merge succeeds (default)"),
+ 	OPT_BOOLEAN(0, "ff", &allow_fast_forward,
+ 		"allow fast forward (default)"),
+ 	OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
+ 		"merge strategy to use", option_parse_strategy),
+ 	OPT_CALLBACK('m', "message", &merge_msg, "message",
+ 		"message to be used for the merge commit (if any)",
+ 		option_parse_message),
+ 	OPT_END()
+ };
+ 
+ /* Cleans up metadata that is uninteresting after a succeeded merge. */
+ static void drop_save(void)
+ {
+ 	unlink(git_path("MERGE_HEAD"));
+ 	unlink(git_path("MERGE_MSG"));
+ }
+ 
+ static void save_state(void)
+ {
+ 	int len;
+ 	struct child_process cp;
+ 	struct strbuf buffer = STRBUF_INIT;
+ 	const char *argv[] = {"stash", "create", NULL};
+ 
+ 	memset(&cp, 0, sizeof(cp));
+ 	cp.argv = argv;
+ 	cp.out = -1;
+ 	cp.git_cmd = 1;
+ 
+ 	if (start_command(&cp))
+ 		die("could not run stash.");
+ 	len = strbuf_read(&buffer, cp.out, 1024);
+ 	close(cp.out);
+ 
+ 	if (finish_command(&cp) || len < 0)
+ 		die("stash failed");
+ 	else if (!len)
+ 		return;
+ 	strbuf_setlen(&buffer, buffer.len-1);
+ 	if (get_sha1(buffer.buf, stash))
+ 		die("not a valid object: %s", buffer.buf);
+ }
+ 
+ static void reset_hard(unsigned const char *sha1, int verbose)
+ {
+ 	int i = 0;
+ 	const char *args[6];
+ 
+ 	args[i++] = "read-tree";
+ 	if (verbose)
+ 		args[i++] = "-v";
+ 	args[i++] = "--reset";
+ 	args[i++] = "-u";
+ 	args[i++] = sha1_to_hex(sha1);
+ 	args[i] = NULL;
+ 
+ 	if (run_command_v_opt(args, RUN_GIT_CMD))
+ 		die("read-tree failed");
+ }
+ 
+ static void restore_state(void)
+ {
+ 	struct strbuf sb;
+ 	const char *args[] = { "stash", "apply", NULL, NULL };
+ 
+ 	if (is_null_sha1(stash))
+ 		return;
+ 
+ 	reset_hard(head, 1);
+ 
+ 	strbuf_init(&sb, 0);
+ 	args[2] = sha1_to_hex(stash);
+ 
+ 	/*
+ 	 * It is OK to ignore error here, for example when there was
+ 	 * nothing to restore.
+ 	 */
+ 	run_command_v_opt(args, RUN_GIT_CMD);
+ 
+ 	strbuf_release(&sb);
+ 	refresh_cache(REFRESH_QUIET);
+ }
+ 
+ /* This is called when no merge was necessary. */
+ static void finish_up_to_date(const char *msg)
+ {
+ 	printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
+ 	drop_save();
+ }
+ 
+ static void squash_message(void)
+ {
+ 	struct rev_info rev;
+ 	struct commit *commit;
+ 	struct strbuf out;
+ 	struct commit_list *j;
+ 	int fd;
+ 
+ 	printf("Squash commit -- not updating HEAD\n");
+ 	fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
+ 	if (fd < 0)
+ 		die("Could not write to %s", git_path("SQUASH_MSG"));
+ 
+ 	init_revisions(&rev, NULL);
+ 	rev.ignore_merges = 1;
+ 	rev.commit_format = CMIT_FMT_MEDIUM;
+ 
+ 	commit = lookup_commit(head);
+ 	commit->object.flags |= UNINTERESTING;
+ 	add_pending_object(&rev, &commit->object, NULL);
+ 
+ 	for (j = remoteheads; j; j = j->next)
+ 		add_pending_object(&rev, &j->item->object, NULL);
+ 
+ 	setup_revisions(0, NULL, &rev, NULL);
+ 	if (prepare_revision_walk(&rev))
+ 		die("revision walk setup failed");
+ 
+ 	strbuf_init(&out, 0);
+ 	strbuf_addstr(&out, "Squashed commit of the following:\n");
+ 	while ((commit = get_revision(&rev)) != NULL) {
+ 		strbuf_addch(&out, '\n');
+ 		strbuf_addf(&out, "commit %s\n",
+ 			sha1_to_hex(commit->object.sha1));
+ 		pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
+ 			NULL, NULL, rev.date_mode, 0);
+ 	}
+ 	write(fd, out.buf, out.len);
+ 	close(fd);
+ 	strbuf_release(&out);
+ }
+ 
+ static int run_hook(const char *name)
+ {
+ 	struct child_process hook;
+ 	const char *argv[3], *env[2];
+ 	char index[PATH_MAX];
+ 
+ 	argv[0] = git_path("hooks/%s", name);
+ 	if (access(argv[0], X_OK) < 0)
+ 		return 0;
+ 
+ 	snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
+ 	env[0] = index;
+ 	env[1] = NULL;
+ 
+ 	if (squash)
+ 		argv[1] = "1";
+ 	else
+ 		argv[1] = "0";
+ 	argv[2] = NULL;
+ 
+ 	memset(&hook, 0, sizeof(hook));
+ 	hook.argv = argv;
+ 	hook.no_stdin = 1;
+ 	hook.stdout_to_stderr = 1;
+ 	hook.env = env;
+ 
+ 	return run_command(&hook);
+ }
+ 
+ static void finish(const unsigned char *new_head, const char *msg)
+ {
+ 	struct strbuf reflog_message;
+ 
+ 	strbuf_init(&reflog_message, 0);
+ 	if (!msg)
+ 		strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
+ 	else {
+ 		printf("%s\n", msg);
+ 		strbuf_addf(&reflog_message, "%s: %s",
+ 			getenv("GIT_REFLOG_ACTION"), msg);
+ 	}
+ 	if (squash) {
+ 		squash_message();
+ 	} else {
+ 		if (!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("post-merge");
+ 
+ 	strbuf_release(&reflog_message);
+ }
+ 
+ /* Get the name for the merge commit's message. */
+ static void merge_name(const char *remote, struct strbuf *msg)
+ {
+ 	struct object *remote_head;
+ 	unsigned char branch_head[20], buf_sha[20];
+ 	struct strbuf buf;
+ 	const char *ptr;
+ 	int len, early;
+ 
+ 	memset(branch_head, 0, sizeof(branch_head));
+ 	remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
+ 	if (!remote_head)
+ 		die("'%s' does not point to a commit", remote);
+ 
+ 	strbuf_init(&buf, 0);
+ 	strbuf_addstr(&buf, "refs/heads/");
+ 	strbuf_addstr(&buf, remote);
+ 	resolve_ref(buf.buf, branch_head, 0, 0);
+ 
+ 	if (!hashcmp(remote_head->sha1, branch_head)) {
+ 		strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
+ 			sha1_to_hex(branch_head), remote);
+ 		return;
+ 	}
+ 
+ 	/* 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, len+11);
+ 		if (resolve_ref(truname.buf, buf_sha, 0, 0)) {
+ 			strbuf_addf(msg,
+ 				    "%s\t\tbranch '%s'%s of .\n",
+ 				    sha1_to_hex(remote_head->sha1),
+ 				    truname.buf,
+ 				    (early ? " (early part)" : ""));
+ 			return;
+ 		}
+ 	}
+ 
+ 	if (!strcmp(remote, "FETCH_HEAD") &&
+ 			!access(git_path("FETCH_HEAD"), R_OK)) {
+ 		FILE *fp;
+ 		struct strbuf line;
+ 		char *ptr;
+ 
+ 		strbuf_init(&line, 0);
+ 		fp = fopen(git_path("FETCH_HEAD"), "r");
+ 		if (!fp)
+ 			die("could not open %s for reading: %s",
+ 				git_path("FETCH_HEAD"), strerror(errno));
+ 		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);
+ 		return;
+ 	}
+ 	strbuf_addf(msg, "%s\t\tcommit '%s'\n",
+ 		sha1_to_hex(remote_head->sha1), remote);
+ }
+ 
+ int git_merge_config(const char *k, const char *v, void *cb)
+ {
+ 	if (branch && !prefixcmp(k, "branch.") &&
+ 		!prefixcmp(k + 7, branch) &&
+ 		!strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
+ 		const char **argv;
+ 		int argc;
+ 		char *buf;
+ 
+ 		buf = xstrdup(v);
+ 		argc = split_cmdline(buf, &argv);
+ 		argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
+ 		memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
+ 		argc++;
+ 		parse_options(argc, argv, builtin_merge_options,
+ 			      builtin_merge_usage, 0);
+ 		free(buf);
+ 	}
+ 
+ 	if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
+ 		show_diffstat = git_config_bool(k, v);
+ 	else if (!strcmp(k, "pull.twohead"))
+ 		return git_config_string(&pull_twohead, k, v);
+ 	else if (!strcmp(k, "pull.octopus"))
+ 		return git_config_string(&pull_octopus, k, v);
+ 	else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
+ 		option_log = git_config_bool(k, v);
+ 	return git_diff_ui_config(k, v, cb);
+ }
+ 
+ static int read_tree_trivial(unsigned char *common, unsigned char *head,
+ 			     unsigned char *one)
+ {
+ 	int i, nr_trees = 0;
+ 	struct tree *trees[MAX_UNPACK_TREES];
+ 	struct tree_desc t[MAX_UNPACK_TREES];
+ 	struct unpack_trees_options opts;
+ 
+ 	memset(&opts, 0, sizeof(opts));
+ 	opts.head_idx = 2;
+ 	opts.src_index = &the_index;
+ 	opts.dst_index = &the_index;
+ 	opts.update = 1;
+ 	opts.verbose_update = 1;
+ 	opts.trivial_merges_only = 1;
+ 	opts.merge = 1;
+ 	trees[nr_trees] = parse_tree_indirect(common);
+ 	if (!trees[nr_trees++])
+ 		return -1;
+ 	trees[nr_trees] = parse_tree_indirect(head);
+ 	if (!trees[nr_trees++])
+ 		return -1;
+ 	trees[nr_trees] = parse_tree_indirect(one);
+ 	if (!trees[nr_trees++])
+ 		return -1;
+ 	opts.fn = threeway_merge;
+ 	cache_tree_free(&active_cache_tree);
+ 	for (i = 0; i < nr_trees; i++) {
+ 		parse_tree(trees[i]);
+ 		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
+ 	}
+ 	if (unpack_trees(nr_trees, t, &opts))
+ 		return -1;
+ 	return 0;
+ }
+ 
+ static void write_tree_trivial(unsigned char *sha1)
+ {
+ 	if (write_cache_as_tree(sha1, 0, NULL))
+ 		die("git write-tree failed to write a tree");
+ }
+ 
+ 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;
+ 
+ 	args = xmalloc((4 + commit_list_count(common) +
+ 			commit_list_count(remoteheads)) * sizeof(char *));
+ 	strbuf_init(&buf, 0);
+ 	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);
+ 	return -ret;
+ }
+ 
+ static void count_diff_files(struct diff_queue_struct *q,
+ 			     struct diff_options *opt, void *data)
+ {
+ 	int *count = data;
+ 
+ 	(*count) += q->nr;
+ }
+ 
+ static int count_unmerged_entries(void)
+ {
+ 	const struct index_state *state = &the_index;
+ 	int i, ret = 0;
+ 
+ 	for (i = 0; i < state->cache_nr; i++)
+ 		if (ce_stage(state->cache[i]))
+ 			ret++;
+ 
+ 	return ret;
+ }
+ 
+ static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
+ {
+ 	struct tree *trees[MAX_UNPACK_TREES];
+ 	struct unpack_trees_options opts;
+ 	struct tree_desc t[MAX_UNPACK_TREES];
+ 	int i, fd, nr_trees = 0;
+ 	struct dir_struct dir;
+ 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+ 
+ 	if (read_cache_unmerged())
+ 		die("you need to resolve your current index first");
+ 
+ 	fd = hold_locked_index(lock_file, 1);
+ 
+ 	memset(&trees, 0, sizeof(trees));
+ 	memset(&opts, 0, sizeof(opts));
+ 	memset(&t, 0, sizeof(t));
+ 	dir.show_ignored = 1;
+ 	dir.exclude_per_dir = ".gitignore";
+ 	opts.dir = &dir;
+ 
+ 	opts.head_idx = 1;
+ 	opts.src_index = &the_index;
+ 	opts.dst_index = &the_index;
+ 	opts.update = 1;
+ 	opts.verbose_update = 1;
+ 	opts.merge = 1;
+ 	opts.fn = twoway_merge;
+ 
+ 	trees[nr_trees] = parse_tree_indirect(head);
+ 	if (!trees[nr_trees++])
+ 		return -1;
+ 	trees[nr_trees] = parse_tree_indirect(remote);
+ 	if (!trees[nr_trees++])
+ 		return -1;
+ 	for (i = 0; i < nr_trees; i++) {
+ 		parse_tree(trees[i]);
+ 		init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
+ 	}
+ 	if (unpack_trees(nr_trees, t, &opts))
+ 		return -1;
+ 	if (write_cache(fd, active_cache, active_nr) ||
+ 		commit_locked_index(lock_file))
+ 		die("unable to write new index file");
+ 	return 0;
+ }
+ 
+ static void split_merge_strategies(const char *string, struct strategy **list,
+ 				   int *nr, int *alloc)
+ {
+ 	char *p, *q, *buf;
+ 
+ 	if (!string)
+ 		return;
+ 
+ 	buf = xstrdup(string);
+ 	q = buf;
+ 	for (;;) {
+ 		p = strchr(q, ' ');
+ 		if (!p) {
+ 			ALLOC_GROW(*list, *nr + 1, *alloc);
+ 			(*list)[(*nr)++].name = xstrdup(q);
+ 			free(buf);
+ 			return;
+ 		} else {
+ 			*p = '\0';
+ 			ALLOC_GROW(*list, *nr + 1, *alloc);
+ 			(*list)[(*nr)++].name = xstrdup(q);
+ 			q = ++p;
+ 		}
+ 	}
+ }
+ 
+ static void add_strategies(const char *string, unsigned attr)
+ {
+ 	struct strategy *list = NULL;
+ 	int list_alloc = 0, list_nr = 0, i;
+ 
+ 	memset(&list, 0, sizeof(list));
+ 	split_merge_strategies(string, &list, &list_nr, &list_alloc);
+ 	if (list != NULL) {
+ 		for (i = 0; i < list_nr; i++) {
+ 			struct strategy *s;
+ 
+ 			s = get_strategy(list[i].name);
+ 			if (s)
+ 				append_strategy(s);
+ 		}
+ 		return;
+ 	}
+ 	for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
+ 		if (all_strategy[i].attr & attr)
+ 			append_strategy(&all_strategy[i]);
+ 
+ }
+ 
+ static int merge_trivial(void)
+ {
+ 	unsigned char result_tree[20], result_commit[20];
+ 	struct commit_list parent;
+ 
+ 	write_tree_trivial(result_tree);
+ 	printf("Wonderful.\n");
+ 	parent.item = remoteheads->item;
+ 	parent.next = NULL;
+ 	commit_tree(merge_msg.buf, result_tree, &parent, result_commit);
+ 	finish(result_commit, "In-index merge");
+ 	drop_save();
+ 	return 0;
+ }
+ 
+ static int finish_automerge(struct commit_list *common,
+ 			    unsigned char *result_tree,
+ 			    const char *wt_strategy)
+ {
+ 	struct commit_list *parents = NULL, *j;
+ 	struct strbuf buf = STRBUF_INIT;
+ 	unsigned char result_commit[20];
+ 
+ 	free_commit_list(common);
+ 	if (allow_fast_forward) {
+ 		parents = remoteheads;
+ 		commit_list_insert(lookup_commit(head), &parents);
+ 		parents = reduce_heads(parents);
+ 	} else {
+ 		struct commit_list **pptr = &parents;
+ 
+ 		pptr = &commit_list_insert(lookup_commit(head),
+ 				pptr)->next;
+ 		for (j = remoteheads; j; j = j->next)
+ 			pptr = &commit_list_insert(j->item, pptr)->next;
+ 	}
+ 	free_commit_list(remoteheads);
+ 	strbuf_addch(&merge_msg, '\n');
+ 	commit_tree(merge_msg.buf, result_tree, parents, result_commit);
+ 	strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
+ 	finish(result_commit, buf.buf);
+ 	strbuf_release(&buf);
+ 	drop_save();
+ 	return 0;
+ }
+ 
+ static int suggest_conflicts(void)
+ {
+ 	FILE *fp;
+ 	int pos;
+ 
+ 	fp = fopen(git_path("MERGE_MSG"), "a");
+ 	if (!fp)
+ 		die("Could open %s for writing", git_path("MERGE_MSG"));
+ 	fprintf(fp, "\nConflicts:\n");
+ 	for (pos = 0; pos < active_nr; pos++) {
+ 		struct cache_entry *ce = active_cache[pos];
+ 
+ 		if (ce_stage(ce)) {
+ 			fprintf(fp, "\t%s\n", ce->name);
+ 			while (pos + 1 < active_nr &&
+ 					!strcmp(ce->name,
+ 						active_cache[pos + 1]->name))
+ 				pos++;
+ 		}
+ 	}
+ 	fclose(fp);
+ 	rerere();
+ 	printf("Automatic merge failed; "
+ 			"fix conflicts and then commit the result.\n");
+ 	return 1;
+ }
+ 
+ static struct commit *is_old_style_invocation(int argc, const char **argv)
+ {
+ 	struct commit *second_token = NULL;
+ 	if (argc > 1) {
+ 		unsigned char second_sha1[20];
+ 
+ 		if (get_sha1(argv[1], second_sha1))
+ 			return NULL;
+ 		second_token = lookup_commit_reference_gently(second_sha1, 0);
+ 		if (!second_token)
+ 			die("'%s' is not a commit", argv[1]);
+ 		if (hashcmp(second_token->object.sha1, head))
+ 			return NULL;
+ 	}
+ 	return second_token;
+ }
+ 
+ static int evaluate_result(void)
+ {
+ 	int cnt = 0;
+ 	struct rev_info rev;
+ 
+ 	if (read_cache() < 0)
+ 		die("failed to read the cache");
+ 
+ 	/* Check how many files differ. */
+ 	init_revisions(&rev, "");
+ 	setup_revisions(0, NULL, &rev, NULL);
+ 	rev.diffopt.output_format |=
+ 		DIFF_FORMAT_CALLBACK;
+ 	rev.diffopt.format_callback = count_diff_files;
+ 	rev.diffopt.format_callback_data = &cnt;
+ 	run_diff_files(&rev, 0);
+ 
+ 	/*
+ 	 * Check how many unmerged entries are
+ 	 * there.
+ 	 */
+ 	cnt += count_unmerged_entries();
+ 
+ 	return cnt;
+ }
+ 
+ int cmd_merge(int argc, const char **argv, const char *prefix)
+ {
+ 	unsigned char result_tree[20];
+ 	struct strbuf buf;
+ 	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;
+ 
+ 	setup_work_tree();
+ 	if (unmerged_cache())
+ 		die("You are in the middle of a conflicted merge.");
+ 
+ 	/*
+ 	 * 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, builtin_merge_options,
+ 			builtin_merge_usage, 0);
+ 
+ 	if (squash) {
+ 		if (!allow_fast_forward)
+ 			die("You cannot combine --squash with --no-ff.");
+ 		option_commit = 0;
+ 	}
+ 
+ 	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.
+ 	 */
+ 	strbuf_init(&buf, 0);
+ 
+ 	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");
+ 		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;
+ 
+ 		/* 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.
+ 		 */
+ 		strbuf_init(&msg, 0);
+ 		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;
+ 
+ 		o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
+ 		if (!o)
+ 			die("%s - not something we can merge", argv[i]);
+ 		remotes = &commit_list_insert(lookup_commit(o->sha1),
+ 			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;
+ 		struct object *o;
+ 		char hex[41];
+ 
+ 		strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
+ 
+ 		printf("Updating %s..%s\n",
+ 			hex,
+ 			find_unique_abbrev(remoteheads->item->object.sha1,
+ 			DEFAULT_ABBREV));
+ 		refresh_cache(REFRESH_QUIET);
+ 		strbuf_init(&msg, 0);
+ 		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) {
+ 			/* 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;
+ 		}
+ 	}
+ 
+ 	/* 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("Could open %s for writing",
+ 				git_path("MERGE_HEAD"));
+ 		if (write_in_full(fd, buf.buf, buf.len) != buf.len)
+ 			die("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("Could open %s for writing", git_path("MERGE_MSG"));
+ 		if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
+ 			merge_msg.len)
+ 			die("Could not write to %s", git_path("MERGE_MSG"));
+ 		close(fd);
+ 	}
+ 
+ 	if (merge_was_ok) {
+ 		fprintf(stderr, "Automatic merge went well; "
+ 			"stopped before committing as requested\n");
+ 		return 0;
+ 	} else
+ 		return suggest_conflicts();
+ }
diff --cc git-compat-util.h
index 8c7e11473,31edc98f3..cf89cdf45
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@@ -155,8 -126,13 +155,14 @@@ extern void set_error_routine(void (*ro
  extern void set_warn_routine(void (*routine)(const char *warn, va_list params));
  
  extern int prefixcmp(const char *str, const char *prefix);
 +extern time_t tm_to_time_t(const struct tm *tm);
  
+ static inline const char *skip_prefix(const char *str, const char *prefix)
+ {
+ 	size_t len = strlen(prefix);
+ 	return strncmp(str, prefix, len) ? NULL : str + len;
+ }
+ 
  #ifdef NO_MMAP
  
  #ifndef PROT_READ
diff --cc parse-options.c
index ae88885d4,bbc3ca4a9..2fd5edbf5
--- a/parse-options.c
+++ b/parse-options.c
@@@ -5,12 -4,24 +5,6 @@@
  #define OPT_SHORT 1
  #define OPT_UNSET 2
  
- static inline const char *skip_prefix(const char *str, const char *prefix)
 -struct optparse_t {
 -	const char **argv;
 -	const char **out;
 -	int argc, cpidx;
 -	const char *opt;
 -};
 -
 -static inline const char *get_arg(struct optparse_t *p)
--{
- 	size_t len = strlen(prefix);
- 	return strncmp(str, prefix, len) ? NULL : str + len;
 -	if (p->opt) {
 -		const char *res = p->opt;
 -		p->opt = NULL;
 -		return res;
 -	}
 -	p->argc--;
 -	return *++p->argv;
--}
--
  static int opterror(const struct option *opt, const char *reason, int flags)
  {
  	if (flags & OPT_SHORT)