From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 29 Mar 2010 04:52:28 +0000 (-0700)
Subject: Merge branch 'cc/cherry-pick-ff'
X-Git-Tag: v1.7.1-rc0~36
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=99f5b0845ac53f9f6e845fe4401e68fcef154690;p=git.git

Merge branch 'cc/cherry-pick-ff'

* cc/cherry-pick-ff:
  revert: fix tiny memory leak in cherry-pick --ff
  rebase -i: use new --ff cherry-pick option
  Documentation: describe new cherry-pick --ff option
  cherry-pick: add tests for new --ff option
  revert: add --ff option to allow fast forward when cherry-picking
  builtin/merge: make checkout_fast_forward() non static
  parse-options: add parse_options_concat() to concat options
---

99f5b0845ac53f9f6e845fe4401e68fcef154690
diff --cc builtin/merge.c
index 3aaec7bed,000000000..c04306684
mode 100644,000000..100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@@ -1,1292 -1,0 +1,1292 @@@
 +/*
 + * 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"
 +#include "help.h"
 +#include "merge-recursive.h"
 +#include "resolve-undo.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 fast_forward_only;
 +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 **xopts;
 +static size_t xopts_nr, xopts_alloc;
 +static const char *branch;
 +static int verbosity;
 +static int allow_rerere_auto;
 +
 +static struct strategy all_strategy[] = {
 +	{ "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
 +	{ "octopus",    DEFAULT_OCTOPUS },
 +	{ "resolve",    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 if (arg) {
 +		strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
 +		have_message = 1;
 +	} else
 +		return error("switch `m' requires a value");
 +	return 0;
 +}
 +
 +static struct strategy *get_strategy(const char *name)
 +{
 +	int i;
 +	struct strategy *ret;
 +	static struct cmdnames main_cmds, other_cmds;
 +	static int loaded;
 +
 +	if (!name)
 +		return NULL;
 +
 +	for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 +		if (!strcmp(name, all_strategy[i].name))
 +			return &all_strategy[i];
 +
 +	if (!loaded) {
 +		struct cmdnames not_strategies;
 +		loaded = 1;
 +
 +		memset(&not_strategies, 0, sizeof(struct cmdnames));
 +		load_command_list("git-merge-", &main_cmds, &other_cmds);
 +		for (i = 0; i < main_cmds.cnt; i++) {
 +			int j, found = 0;
 +			struct cmdname *ent = main_cmds.names[i];
 +			for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 +				if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 +						&& !all_strategy[j].name[ent->len])
 +					found = 1;
 +			if (!found)
 +				add_cmdname(&not_strategies, ent->name, ent->len);
 +		}
 +		exclude_cmds(&main_cmds, &not_strategies);
 +	}
 +	if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 +		fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
 +		fprintf(stderr, "Available strategies are:");
 +		for (i = 0; i < main_cmds.cnt; i++)
 +			fprintf(stderr, " %s", main_cmds.names[i]->name);
 +		fprintf(stderr, ".\n");
 +		if (other_cmds.cnt) {
 +			fprintf(stderr, "Available custom strategies are:");
 +			for (i = 0; i < other_cmds.cnt; i++)
 +				fprintf(stderr, " %s", other_cmds.names[i]->name);
 +			fprintf(stderr, ".\n");
 +		}
 +		exit(1);
 +	}
 +
 +	ret = xcalloc(1, sizeof(struct strategy));
 +	ret->name = xstrdup(name);
 +	return ret;
 +}
 +
 +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)
 +{
 +	if (unset)
 +		return 0;
 +
 +	append_strategy(get_strategy(name));
 +	return 0;
 +}
 +
 +static int option_parse_x(const struct option *opt,
 +			  const char *arg, int unset)
 +{
 +	if (unset)
 +		return 0;
 +
 +	ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 +	xopts[xopts_nr++] = xstrdup(arg);
 +	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_BOOLEAN(0, "ff-only", &fast_forward_only,
 +		"abort if fast-forward is not possible"),
 +	OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 +	OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 +		"merge strategy to use", option_parse_strategy),
 +	OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
 +		"option for selected merge strategy", option_parse_x),
 +	OPT_CALLBACK('m', "message", &merge_msg, "message",
 +		"message to be used for the merge commit (if any)",
 +		option_parse_message),
 +	OPT__VERBOSITY(&verbosity),
 +	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"));
 +	unlink(git_path("MERGE_MODE"));
 +}
 +
 +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 = STRBUF_INIT;
 +	const char *args[] = { "stash", "apply", NULL, NULL };
 +
 +	if (is_null_sha1(stash))
 +		return;
 +
 +	reset_hard(head, 1);
 +
 +	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)
 +{
 +	if (verbosity >= 0)
 +		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 = STRBUF_INIT;
 +	struct commit_list *j;
 +	int fd;
 +	struct pretty_print_context ctx = {0};
 +
 +	printf("Squash commit -- not updating HEAD\n");
 +	fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
 +	if (fd < 0)
 +		die_errno("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");
 +
 +	ctx.abbrev = rev.abbrev;
 +	ctx.date_mode = rev.date_mode;
 +
 +	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, &ctx);
 +	}
 +	if (write(fd, out.buf, out.len) < 0)
 +		die_errno("Writing SQUASH_MSG");
 +	if (close(fd))
 +		die_errno("Finishing SQUASH_MSG");
 +	strbuf_release(&out);
 +}
 +
 +static void finish(const unsigned char *new_head, const char *msg)
 +{
 +	struct strbuf reflog_message = STRBUF_INIT;
 +
 +	if (!msg)
 +		strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 +	else {
 +		if (verbosity >= 0)
 +			printf("%s\n", msg);
 +		strbuf_addf(&reflog_message, "%s: %s",
 +			getenv("GIT_REFLOG_ACTION"), msg);
 +	}
 +	if (squash) {
 +		squash_message();
 +	} else {
 +		if (verbosity >= 0 && !merge_msg.len)
 +			printf("No merge message -- not updating HEAD\n");
 +		else {
 +			const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 +			update_ref(reflog_message.buf, "HEAD",
 +				new_head, head, 0,
 +				DIE_ON_ERR);
 +			/*
 +			 * We ignore errors in 'gc --auto', since the
 +			 * user should see them.
 +			 */
 +			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 +		}
 +	}
 +	if (new_head && show_diffstat) {
 +		struct diff_options opts;
 +		diff_setup(&opts);
 +		opts.output_format |=
 +			DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 +		opts.detect_rename = DIFF_DETECT_RENAME;
 +		if (diff_use_color_default > 0)
 +			DIFF_OPT_SET(&opts, COLOR_DIFF);
 +		if (diff_setup_done(&opts) < 0)
 +			die("diff_setup_done failed");
 +		diff_tree_sha1(head, new_head, "", &opts);
 +		diffcore_std(&opts);
 +		diff_flush(&opts);
 +	}
 +
 +	/* Run a post-merge hook */
 +	run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
 +
 +	strbuf_release(&reflog_message);
 +}
 +
 +/* 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 = 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 = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
 +	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/remotes/")) {
 +			strbuf_addf(msg, "%s\t\tremote 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 (resolve_ref(truname.buf, buf_sha, 0, NULL)) {
 +			strbuf_addf(msg,
 +				    "%s\t\tbranch '%s'%s of .\n",
 +				    sha1_to_hex(remote_head->sha1),
 +				    truname.buf + 11,
 +				    (early ? " (early part)" : ""));
 +			strbuf_release(&truname);
 +			goto cleanup;
 +		}
 +	}
 +
 +	if (!strcmp(remote, "FETCH_HEAD") &&
 +			!access(git_path("FETCH_HEAD"), R_OK)) {
 +		FILE *fp;
 +		struct strbuf line = STRBUF_INIT;
 +		char *ptr;
 +
 +		fp = fopen(git_path("FETCH_HEAD"), "r");
 +		if (!fp)
 +			die_errno("could not open '%s' for reading",
 +				  git_path("FETCH_HEAD"));
 +		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;
 +	}
 +	strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 +		sha1_to_hex(remote_head->sha1), remote);
 +cleanup:
 +	strbuf_release(&buf);
 +	strbuf_release(&bname);
 +}
 +
 +static 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);
 +		if (argc < 0)
 +			die("Bad branch.%s.mergeoptions string", branch);
 +		argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 +		memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 +		argc++;
 +		parse_options(argc, argv, NULL, 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, x = 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_shift = "";
 +
 +		for (x = 0; x < xopts_nr; x++) {
 +			if (!strcmp(xopts[x], "ours"))
 +				o.recursive_variant = MERGE_RECURSIVE_OURS;
 +			else if (!strcmp(xopts[x], "theirs"))
 +				o.recursive_variant = MERGE_RECURSIVE_THEIRS;
 +			else if (!strcmp(xopts[x], "subtree"))
 +				o.subtree_shift = "";
 +			else if (!prefixcmp(xopts[x], "subtree="))
 +				o.subtree_shift = xopts[x]+8;
 +			else
 +				die("Unknown option for merge-recursive: -X%s", xopts[x]);
 +		}
 +
 +		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 + xopts_nr + commit_list_count(common) +
 +					commit_list_count(remoteheads)) * 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 = 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 (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 = remoteheads; 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 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)
 +{
 +	int i, ret = 0;
 +
 +	for (i = 0; i < active_nr; i++)
 +		if (ce_stage(active_cache[i]))
 +			ret++;
 +
 +	return ret;
 +}
 +
- static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
++int checkout_fast_forward(const unsigned char *head, const 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));
 +
 +	refresh_cache(REFRESH_QUIET);
 +
 +	fd = hold_locked_index(lock_file, 1);
 +
 +	memset(&trees, 0, sizeof(trees));
 +	memset(&opts, 0, sizeof(opts));
 +	memset(&t, 0, sizeof(t));
 +	memset(&dir, 0, sizeof(dir));
 +	dir.flags |= DIR_SHOW_IGNORED;
 +	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;
 +	opts.msgs = get_porcelain_error_msgs();
 +
 +	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) {
 +		for (i = 0; i < list_nr; i++)
 +			append_strategy(get_strategy(list[i].name));
 +		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 = xmalloc(sizeof(*parent));
 +
 +	write_tree_trivial(result_tree);
 +	printf("Wonderful.\n");
 +	parent->item = lookup_commit(head);
 +	parent->next = xmalloc(sizeof(*parent->next));
 +	parent->next->item = remoteheads->item;
 +	parent->next->next = NULL;
 +	commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
 +	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, NULL);
 +	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_errno("Could not 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(allow_rerere_auto);
 +	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 > 2) {
 +		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;
 +
 +	/* 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 = 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 (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).");
 +	}
 +
 +	resolve_undo_clear();
 +	/*
 +	 * 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();
 +}
diff --cc builtin/revert.c
index eff52687a,000000000..9a3c14c32
mode 100644,000000..100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@@ -1,460 -1,0 +1,498 @@@
 +#include "cache.h"
 +#include "builtin.h"
 +#include "object.h"
 +#include "commit.h"
 +#include "tag.h"
 +#include "wt-status.h"
 +#include "run-command.h"
 +#include "exec_cmd.h"
 +#include "utf8.h"
 +#include "parse-options.h"
 +#include "cache-tree.h"
 +#include "diff.h"
 +#include "revision.h"
 +#include "rerere.h"
 +#include "merge-recursive.h"
++#include "refs.h"
 +
 +/*
 + * This implements the builtins revert and cherry-pick.
 + *
 + * Copyright (c) 2007 Johannes E. Schindelin
 + *
 + * Based on git-revert.sh, which is
 + *
 + * Copyright (c) 2005 Linus Torvalds
 + * Copyright (c) 2005 Junio C Hamano
 + */
 +
 +static const char * const revert_usage[] = {
 +	"git revert [options] <commit-ish>",
 +	NULL
 +};
 +
 +static const char * const cherry_pick_usage[] = {
 +	"git cherry-pick [options] <commit-ish>",
 +	NULL
 +};
 +
- static int edit, no_replay, no_commit, mainline, signoff;
++static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
 +static enum { REVERT, CHERRY_PICK } action;
 +static struct commit *commit;
 +static const char *commit_name;
 +static int allow_rerere_auto;
 +
 +static const char *me;
 +
 +#define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 +
 +static void parse_args(int argc, const char **argv)
 +{
 +	const char * const * usage_str =
 +		action == REVERT ?  revert_usage : cherry_pick_usage;
 +	unsigned char sha1[20];
 +	int noop;
 +	struct option options[] = {
 +		OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
 +		OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
 +		OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
 +		OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
 +		OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
 +		OPT_INTEGER('m', "mainline", &mainline, "parent number"),
 +		OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 +		OPT_END(),
++		OPT_END(),
++		OPT_END(),
 +	};
 +
++	if (action == CHERRY_PICK) {
++		struct option cp_extra[] = {
++			OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
++			OPT_END(),
++		};
++		if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
++			die("program error");
++	}
++
 +	if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
 +		usage_with_options(usage_str, options);
 +
 +	commit_name = argv[0];
 +	if (get_sha1(commit_name, sha1))
 +		die ("Cannot find '%s'", commit_name);
 +	commit = lookup_commit_reference(sha1);
 +	if (!commit)
 +		exit(1);
 +}
 +
 +static char *get_oneline(const char *message)
 +{
 +	char *result;
 +	const char *p = message, *abbrev, *eol;
 +	int abbrev_len, oneline_len;
 +
 +	if (!p)
 +		die ("Could not read commit message of %s",
 +				sha1_to_hex(commit->object.sha1));
 +	while (*p && (*p != '\n' || p[1] != '\n'))
 +		p++;
 +
 +	if (*p) {
 +		p += 2;
 +		for (eol = p + 1; *eol && *eol != '\n'; eol++)
 +			; /* do nothing */
 +	} else
 +		eol = p;
 +	abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 +	abbrev_len = strlen(abbrev);
 +	oneline_len = eol - p;
 +	result = xmalloc(abbrev_len + 5 + oneline_len);
 +	memcpy(result, abbrev, abbrev_len);
 +	memcpy(result + abbrev_len, "... ", 4);
 +	memcpy(result + abbrev_len + 4, p, oneline_len);
 +	result[abbrev_len + 4 + oneline_len] = '\0';
 +	return result;
 +}
 +
 +static char *get_encoding(const char *message)
 +{
 +	const char *p = message, *eol;
 +
 +	if (!p)
 +		die ("Could not read commit message of %s",
 +				sha1_to_hex(commit->object.sha1));
 +	while (*p && *p != '\n') {
 +		for (eol = p + 1; *eol && *eol != '\n'; eol++)
 +			; /* do nothing */
 +		if (!prefixcmp(p, "encoding ")) {
 +			char *result = xmalloc(eol - 8 - p);
 +			strlcpy(result, p + 9, eol - 8 - p);
 +			return result;
 +		}
 +		p = eol;
 +		if (*p == '\n')
 +			p++;
 +	}
 +	return NULL;
 +}
 +
 +static struct lock_file msg_file;
 +static int msg_fd;
 +
 +static void add_to_msg(const char *string)
 +{
 +	int len = strlen(string);
 +	if (write_in_full(msg_fd, string, len) < 0)
 +		die_errno ("Could not write to MERGE_MSG");
 +}
 +
 +static void add_message_to_msg(const char *message)
 +{
 +	const char *p = message;
 +	while (*p && (*p != '\n' || p[1] != '\n'))
 +		p++;
 +
 +	if (!*p)
 +		add_to_msg(sha1_to_hex(commit->object.sha1));
 +
 +	p += 2;
 +	add_to_msg(p);
 +	return;
 +}
 +
 +static void set_author_ident_env(const char *message)
 +{
 +	const char *p = message;
 +	if (!p)
 +		die ("Could not read commit message of %s",
 +				sha1_to_hex(commit->object.sha1));
 +	while (*p && *p != '\n') {
 +		const char *eol;
 +
 +		for (eol = p; *eol && *eol != '\n'; eol++)
 +			; /* do nothing */
 +		if (!prefixcmp(p, "author ")) {
 +			char *line, *pend, *email, *timestamp;
 +
 +			p += 7;
 +			line = xmemdupz(p, eol - p);
 +			email = strchr(line, '<');
 +			if (!email)
 +				die ("Could not extract author email from %s",
 +					sha1_to_hex(commit->object.sha1));
 +			if (email == line)
 +				pend = line;
 +			else
 +				for (pend = email; pend != line + 1 &&
 +						isspace(pend[-1]); pend--);
 +					; /* do nothing */
 +			*pend = '\0';
 +			email++;
 +			timestamp = strchr(email, '>');
 +			if (!timestamp)
 +				die ("Could not extract author time from %s",
 +					sha1_to_hex(commit->object.sha1));
 +			*timestamp = '\0';
 +			for (timestamp++; *timestamp && isspace(*timestamp);
 +					timestamp++)
 +				; /* do nothing */
 +			setenv("GIT_AUTHOR_NAME", line, 1);
 +			setenv("GIT_AUTHOR_EMAIL", email, 1);
 +			setenv("GIT_AUTHOR_DATE", timestamp, 1);
 +			free(line);
 +			return;
 +		}
 +		p = eol;
 +		if (*p == '\n')
 +			p++;
 +	}
 +	die ("No author information found in %s",
 +			sha1_to_hex(commit->object.sha1));
 +}
 +
 +static char *help_msg(const char *name)
 +{
 +	struct strbuf helpbuf = STRBUF_INIT;
 +	char *msg = getenv("GIT_CHERRY_PICK_HELP");
 +
 +	if (msg)
 +		return msg;
 +
 +	strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 +		"mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 +		"and commit the result");
 +
 +	if (action == CHERRY_PICK) {
 +		strbuf_addf(&helpbuf, " with: \n"
 +			"\n"
 +			"        git commit -c %s\n",
 +			name);
 +	}
 +	else
 +		strbuf_addch(&helpbuf, '.');
 +	return strbuf_detach(&helpbuf, NULL);
 +}
 +
 +static struct tree *empty_tree(void)
 +{
 +	struct tree *tree = xcalloc(1, sizeof(struct tree));
 +
 +	tree->object.parsed = 1;
 +	tree->object.type = OBJ_TREE;
 +	pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 +	return tree;
 +}
 +
 +static NORETURN void die_dirty_index(const char *me)
 +{
 +	if (read_cache_unmerged()) {
 +		die_resolve_conflict(me);
 +	} else {
 +		if (advice_commit_before_merge)
 +			die("Your local changes would be overwritten by %s.\n"
 +			    "Please, commit your changes or stash them to proceed.", me);
 +		else
 +			die("Your local changes would be overwritten by %s.\n", me);
 +	}
 +}
 +
++static int fast_forward_to(const unsigned char *to, const unsigned char *from)
++{
++	struct ref_lock *ref_lock;
++
++	read_cache();
++	if (checkout_fast_forward(from, to))
++		exit(1); /* the callee should have complained already */
++	ref_lock = lock_any_ref_for_update("HEAD", from, 0);
++	return write_ref_sha1(ref_lock, to, "cherry-pick");
++}
++
 +static int revert_or_cherry_pick(int argc, const char **argv)
 +{
 +	unsigned char head[20];
 +	struct commit *base, *next, *parent;
 +	int i, index_fd, clean;
 +	char *oneline, *reencoded_message = NULL;
 +	const char *message, *encoding;
- 	char *defmsg = git_pathdup("MERGE_MSG");
++	char *defmsg = NULL;
 +	struct merge_options o;
 +	struct tree *result, *next_tree, *base_tree, *head_tree;
 +	static struct lock_file index_lock;
 +
 +	git_config(git_default_config, NULL);
 +	me = action == REVERT ? "revert" : "cherry-pick";
 +	setenv(GIT_REFLOG_ACTION, me, 0);
 +	parse_args(argc, argv);
 +
 +	/* this is copied from the shell script, but it's never triggered... */
 +	if (action == REVERT && !no_replay)
 +		die("revert is incompatible with replay");
 +
++	if (allow_ff) {
++		if (signoff)
++			die("cherry-pick --ff cannot be used with --signoff");
++		if (no_commit)
++			die("cherry-pick --ff cannot be used with --no-commit");
++		if (no_replay)
++			die("cherry-pick --ff cannot be used with -x");
++		if (edit)
++			die("cherry-pick --ff cannot be used with --edit");
++	}
++
 +	if (read_cache() < 0)
 +		die("git %s: failed to read the index", me);
 +	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();
 +
- 	index_fd = hold_locked_index(&index_lock, 1);
- 
 +	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 (!(message = commit->buffer))
 +		die ("Cannot get commit message for %s",
 +				sha1_to_hex(commit->object.sha1));
 +
 +	if (parent && parse_commit(parent) < 0)
 +		die("%s: cannot parse parent commit %s",
 +		    me, sha1_to_hex(parent->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");
 +	msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
 +					   LOCK_DIE_ON_ERROR);
 +
 +	encoding = get_encoding(message);
 +	if (!encoding)
 +		encoding = "UTF-8";
 +	if (!git_commit_encoding)
 +		git_commit_encoding = "UTF-8";
 +	if ((reencoded_message = reencode_string(message,
 +					git_commit_encoding, encoding)))
 +		message = reencoded_message;
 +
 +	oneline = get_oneline(message);
 +
++	index_fd = hold_locked_index(&index_lock, 1);
++
 +	if (action == REVERT) {
 +		char *oneline_body = strchr(oneline, ' ');
 +
 +		base = commit;
 +		next = parent;
 +		add_to_msg("Revert \"");
 +		add_to_msg(oneline_body + 1);
 +		add_to_msg("\"\n\nThis reverts commit ");
 +		add_to_msg(sha1_to_hex(commit->object.sha1));
 +
 +		if (commit->parents->next) {
 +			add_to_msg(", reversing\nchanges made to ");
 +			add_to_msg(sha1_to_hex(parent->object.sha1));
 +		}
 +		add_to_msg(".\n");
 +	} else {
 +		base = parent;
 +		next = commit;
 +		set_author_ident_env(message);
 +		add_message_to_msg(message);
 +		if (no_replay) {
 +			add_to_msg("(cherry picked from commit ");
 +			add_to_msg(sha1_to_hex(commit->object.sha1));
 +			add_to_msg(")\n");
 +		}
 +	}
 +
 +	read_cache();
 +	init_merge_options(&o);
 +	o.branch1 = "HEAD";
 +	o.branch2 = oneline;
 +
 +	head_tree = parse_tree_indirect(head);
 +	next_tree = next ? next->tree : empty_tree();
 +	base_tree = base ? base->tree : empty_tree();
 +
 +	clean = merge_trees(&o,
 +			    head_tree,
 +			    next_tree, base_tree, &result);
 +
 +	if (active_cache_changed &&
 +	    (write_cache(index_fd, active_cache, active_nr) ||
 +	     commit_locked_index(&index_lock)))
 +		die("%s: Unable to write new index file", me);
 +	rollback_lock_file(&index_lock);
 +
 +	if (!clean) {
 +		add_to_msg("\nConflicts:\n\n");
 +		for (i = 0; i < active_nr;) {
 +			struct cache_entry *ce = active_cache[i++];
 +			if (ce_stage(ce)) {
 +				add_to_msg("\t");
 +				add_to_msg(ce->name);
 +				add_to_msg("\n");
 +				while (i < active_nr && !strcmp(ce->name,
 +						active_cache[i]->name))
 +					i++;
 +			}
 +		}
 +		if (commit_lock_file(&msg_file) < 0)
 +			die ("Error wrapping up %s", defmsg);
 +		fprintf(stderr, "Automatic %s failed.%s\n",
 +			me, help_msg(commit_name));
 +		rerere(allow_rerere_auto);
 +		exit(1);
 +	}
 +	if (commit_lock_file(&msg_file) < 0)
 +		die ("Error wrapping up %s", defmsg);
 +	fprintf(stderr, "Finished one %s.\n", me);
 +
 +	/*
 +	 *
 +	 * If we are cherry-pick, and if the merge did not result in
 +	 * hand-editing, we will hit this commit and inherit the original
 +	 * author date and name.
 +	 * If we are revert, or if our cherry-pick results in a hand merge,
 +	 * we had better say that the current user is responsible for that.
 +	 */
 +
 +	if (!no_commit) {
 +		/* 6 is max possible length of our args array including NULL */
 +		const char *args[6];
 +		int i = 0;
 +		args[i++] = "commit";
 +		args[i++] = "-n";
 +		if (signoff)
 +			args[i++] = "-s";
 +		if (!edit) {
 +			args[i++] = "-F";
 +			args[i++] = defmsg;
 +		}
 +		args[i] = NULL;
 +		return execv_git_cmd(args);
 +	}
 +	free(reencoded_message);
 +	free(defmsg);
 +
 +	return 0;
 +}
 +
 +int cmd_revert(int argc, const char **argv, const char *prefix)
 +{
 +	if (isatty(0))
 +		edit = 1;
 +	no_replay = 1;
 +	action = REVERT;
 +	return revert_or_cherry_pick(argc, argv);
 +}
 +
 +int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 +{
 +	no_replay = 0;
 +	action = CHERRY_PICK;
 +	return revert_or_cherry_pick(argc, argv);
 +}