/*
 * Builtin "git log" and related commands (show, whatchanged)
 *
 * (C) Copyright 2006 Linus Torvalds
 *		 2006 Junio Hamano
 */
#include "cache.h"
#include "color.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "log-tree.h"
#include "builtin.h"
#include "tag.h"
#include "reflog-walk.h"
#include "patch-ids.h"
#include "run-command.h"
#include "shortlog.h"
#include "remote.h"
#include "string-list.h"
#include "parse-options.h"

/* Set a default date-time format for git log ("log.date" config variable) */
static const char *default_date_mode = NULL;

static int default_show_root = 1;
static int decoration_style;
static const char *fmt_patch_subject_prefix = "PATCH";
static const char *fmt_pretty;

static const char * const builtin_log_usage =
	"git log [<options>] [<since>..<until>] [[--] <path>...]\n"
	"   or: git show [options] <object>...";

static int parse_decoration_style(const char *var, const char *value)
{
	switch (git_config_maybe_bool(var, value)) {
	case 1:
		return DECORATE_SHORT_REFS;
	case 0:
		return 0;
	default:
		break;
	}
	if (!strcmp(value, "full"))
		return DECORATE_FULL_REFS;
	else if (!strcmp(value, "short"))
		return DECORATE_SHORT_REFS;
	return -1;
}

static void cmd_log_init(int argc, const char **argv, const char *prefix,
			 struct rev_info *rev, struct setup_revision_opt *opt)
{
	int i;
	int decoration_given = 0;
	struct userformat_want w;

	rev->abbrev = DEFAULT_ABBREV;
	rev->commit_format = CMIT_FMT_DEFAULT;
	if (fmt_pretty)
		get_commit_format(fmt_pretty, rev);
	rev->verbose_header = 1;
	DIFF_OPT_SET(&rev->diffopt, RECURSIVE);
	rev->show_root_diff = default_show_root;
	rev->subject_prefix = fmt_patch_subject_prefix;
	DIFF_OPT_SET(&rev->diffopt, ALLOW_TEXTCONV);

	if (default_date_mode)
		rev->date_mode = parse_date_format(default_date_mode);

	/*
	 * Check for -h before setup_revisions(), or "git log -h" will
	 * fail when run without a git directory.
	 */
	if (argc == 2 && !strcmp(argv[1], "-h"))
		usage(builtin_log_usage);
	argc = setup_revisions(argc, argv, rev, opt);

	memset(&w, 0, sizeof(w));
	userformat_find_requirements(NULL, &w);

	if (!rev->show_notes_given && (!rev->pretty_given || w.notes))
		rev->show_notes = 1;
	if (rev->show_notes)
		init_display_notes(&rev->notes_opt);

	if (rev->diffopt.pickaxe || rev->diffopt.filter)
		rev->always_show_header = 0;
	if (DIFF_OPT_TST(&rev->diffopt, FOLLOW_RENAMES)) {
		rev->always_show_header = 0;
		if (rev->diffopt.nr_paths != 1)
			usage("git logs can only follow renames on one pathname at a time");
	}
	for (i = 1; i < argc; i++) {
		const char *arg = argv[i];
		if (!strcmp(arg, "--decorate")) {
			decoration_style = DECORATE_SHORT_REFS;
			decoration_given = 1;
		} else if (!prefixcmp(arg, "--decorate=")) {
			const char *v = skip_prefix(arg, "--decorate=");
			decoration_style = parse_decoration_style(arg, v);
			if (decoration_style < 0)
				die("invalid --decorate option: %s", arg);
			decoration_given = 1;
		} else if (!strcmp(arg, "--no-decorate")) {
			decoration_style = 0;
		} else if (!strcmp(arg, "--source")) {
			rev->show_source = 1;
		} else if (!strcmp(arg, "-h")) {
			usage(builtin_log_usage);
		} else
			die("unrecognized argument: %s", arg);
	}

	/*
	 * defeat log.decorate configuration interacting with --pretty=raw
	 * from the command line.
	 */
	if (!decoration_given && rev->pretty_given
	    && rev->commit_format == CMIT_FMT_RAW)
		decoration_style = 0;

	if (decoration_style) {
		rev->show_decorations = 1;
		load_ref_decorations(decoration_style);
	}
	setup_pager();
}

/*
 * This gives a rough estimate for how many commits we
 * will print out in the list.
 */
static int estimate_commit_count(struct rev_info *rev, struct commit_list *list)
{
	int n = 0;

	while (list) {
		struct commit *commit = list->item;
		unsigned int flags = commit->object.flags;
		list = list->next;
		if (!(flags & (TREESAME | UNINTERESTING)))
			n++;
	}
	return n;
}

static void show_early_header(struct rev_info *rev, const char *stage, int nr)
{
	if (rev->shown_one) {
		rev->shown_one = 0;
		if (rev->commit_format != CMIT_FMT_ONELINE)
			putchar(rev->diffopt.line_termination);
	}
	printf("Final output: %d %s\n", nr, stage);
}

static struct itimerval early_output_timer;

static void log_show_early(struct rev_info *revs, struct commit_list *list)
{
	int i = revs->early_output;
	int show_header = 1;

	sort_in_topological_order(&list, revs->lifo);
	while (list && i) {
		struct commit *commit = list->item;
		switch (simplify_commit(revs, commit)) {
		case commit_show:
			if (show_header) {
				int n = estimate_commit_count(revs, list);
				show_early_header(revs, "incomplete", n);
				show_header = 0;
			}
			log_tree_commit(revs, commit);
			i--;
			break;
		case commit_ignore:
			break;
		case commit_error:
			return;
		}
		list = list->next;
	}

	/* Did we already get enough commits for the early output? */
	if (!i)
		return;

	/*
	 * ..if no, then repeat it twice a second until we
	 * do.
	 *
	 * NOTE! We don't use "it_interval", because if the
	 * reader isn't listening, we want our output to be
	 * throttled by the writing, and not have the timer
	 * trigger every second even if we're blocked on a
	 * reader!
	 */
	early_output_timer.it_value.tv_sec = 0;
	early_output_timer.it_value.tv_usec = 500000;
	setitimer(ITIMER_REAL, &early_output_timer, NULL);
}

static void early_output(int signal)
{
	show_early_output = log_show_early;
}

static void setup_early_output(struct rev_info *rev)
{
	struct sigaction sa;

	/*
	 * Set up the signal handler, minimally intrusively:
	 * we only set a single volatile integer word (not
	 * using sigatomic_t - trying to avoid unnecessary
	 * system dependencies and headers), and using
	 * SA_RESTART.
	 */
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = early_output;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_RESTART;
	sigaction(SIGALRM, &sa, NULL);

	/*
	 * If we can get the whole output in less than a
	 * tenth of a second, don't even bother doing the
	 * early-output thing..
	 *
	 * This is a one-time-only trigger.
	 */
	early_output_timer.it_value.tv_sec = 0;
	early_output_timer.it_value.tv_usec = 100000;
	setitimer(ITIMER_REAL, &early_output_timer, NULL);
}

static void finish_early_output(struct rev_info *rev)
{
	int n = estimate_commit_count(rev, rev->commits);
	signal(SIGALRM, SIG_IGN);
	show_early_header(rev, "done", n);
}

static int cmd_log_walk(struct rev_info *rev)
{
	struct commit *commit;

	if (rev->early_output)
		setup_early_output(rev);

	if (prepare_revision_walk(rev))
		die("revision walk setup failed");

	if (rev->early_output)
		finish_early_output(rev);

	/*
	 * For --check and --exit-code, the exit code is based on CHECK_FAILED
	 * and HAS_CHANGES being accumulated in rev->diffopt, so be careful to
	 * retain that state information if replacing rev->diffopt in this loop
	 */
	while ((commit = get_revision(rev)) != NULL) {
		log_tree_commit(rev, commit);
		if (!rev->reflog_info) {
			/* we allow cycles in reflog ancestry */
			free(commit->buffer);
			commit->buffer = NULL;
		}
		free_commit_list(commit->parents);
		commit->parents = NULL;
	}
	if (rev->diffopt.output_format & DIFF_FORMAT_CHECKDIFF &&
	    DIFF_OPT_TST(&rev->diffopt, CHECK_FAILED)) {
		return 02;
	}
	return diff_result_code(&rev->diffopt, 0);
}

static int git_log_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "format.pretty"))
		return git_config_string(&fmt_pretty, var, value);
	if (!strcmp(var, "format.subjectprefix"))
		return git_config_string(&fmt_patch_subject_prefix, var, value);
	if (!strcmp(var, "log.date"))
		return git_config_string(&default_date_mode, var, value);
	if (!strcmp(var, "log.decorate")) {
		decoration_style = parse_decoration_style(var, value);
		if (decoration_style < 0)
			decoration_style = 0; /* maybe warn? */
		return 0;
	}
	if (!strcmp(var, "log.showroot")) {
		default_show_root = git_config_bool(var, value);
		return 0;
	}
	if (!prefixcmp(var, "color.decorate."))
		return parse_decorate_color_config(var, 15, value);

	return git_diff_ui_config(var, value, cb);
}

int cmd_whatchanged(int argc, const char **argv, const char *prefix)
{
	struct rev_info rev;
	struct setup_revision_opt opt;

	git_config(git_log_config, NULL);

	if (diff_use_color_default == -1)
		diff_use_color_default = git_use_color_default;

	init_revisions(&rev, prefix);
	rev.diff = 1;
	rev.simplify_history = 0;
	memset(&opt, 0, sizeof(opt));
	opt.def = "HEAD";
	cmd_log_init(argc, argv, prefix, &rev, &opt);
	if (!rev.diffopt.output_format)
		rev.diffopt.output_format = DIFF_FORMAT_RAW;
	return cmd_log_walk(&rev);
}

static void show_tagger(char *buf, int len, struct rev_info *rev)
{
	struct strbuf out = STRBUF_INIT;

	pp_user_info("Tagger", rev->commit_format, &out, buf, rev->date_mode,
		git_log_output_encoding ?
		git_log_output_encoding: git_commit_encoding);
	printf("%s", out.buf);
	strbuf_release(&out);
}

static int show_object(const unsigned char *sha1, int show_tag_object,
	struct rev_info *rev)
{
	unsigned long size;
	enum object_type type;
	char *buf = read_sha1_file(sha1, &type, &size);
	int offset = 0;

	if (!buf)
		return error("Could not read object %s", sha1_to_hex(sha1));

	if (show_tag_object)
		while (offset < size && buf[offset] != '\n') {
			int new_offset = offset + 1;
			while (new_offset < size && buf[new_offset++] != '\n')
				; /* do nothing */
			if (!prefixcmp(buf + offset, "tagger "))
				show_tagger(buf + offset + 7,
					    new_offset - offset - 7, rev);
			offset = new_offset;
		}

	if (offset < size)
		fwrite(buf + offset, size - offset, 1, stdout);
	free(buf);
	return 0;
}

static int show_tree_object(const unsigned char *sha1,
		const char *base, int baselen,
		const char *pathname, unsigned mode, int stage, void *context)
{
	printf("%s%s\n", pathname, S_ISDIR(mode) ? "/" : "");
	return 0;
}

static void show_rev_tweak_rev(struct rev_info *rev, struct setup_revision_opt *opt)
{
	if (rev->ignore_merges) {
		/* There was no "-m" on the command line */
		rev->ignore_merges = 0;
		if (!rev->first_parent_only && !rev->combine_merges) {
			/* No "--first-parent", "-c", nor "--cc" */
			rev->combine_merges = 1;
			rev->dense_combined_merges = 1;
		}
	}
	if (!rev->diffopt.output_format)
		rev->diffopt.output_format = DIFF_FORMAT_PATCH;
}

int cmd_show(int argc, const char **argv, const char *prefix)
{
	struct rev_info rev;
	struct object_array_entry *objects;
	struct setup_revision_opt opt;
	int i, count, ret = 0;

	git_config(git_log_config, NULL);

	if (diff_use_color_default == -1)
		diff_use_color_default = git_use_color_default;

	init_revisions(&rev, prefix);
	rev.diff = 1;
	rev.always_show_header = 1;
	rev.no_walk = 1;
	memset(&opt, 0, sizeof(opt));
	opt.def = "HEAD";
	opt.tweak = show_rev_tweak_rev;
	cmd_log_init(argc, argv, prefix, &rev, &opt);

	count = rev.pending.nr;
	objects = rev.pending.objects;
	for (i = 0; i < count && !ret; i++) {
		struct object *o = objects[i].item;
		const char *name = objects[i].name;
		switch (o->type) {
		case OBJ_BLOB:
			ret = show_object(o->sha1, 0, NULL);
			break;
		case OBJ_TAG: {
			struct tag *t = (struct tag *)o;

			if (rev.shown_one)
				putchar('\n');
			printf("%stag %s%s\n",
					diff_get_color_opt(&rev.diffopt, DIFF_COMMIT),
					t->tag,
					diff_get_color_opt(&rev.diffopt, DIFF_RESET));
			ret = show_object(o->sha1, 1, &rev);
			rev.shown_one = 1;
			if (ret)
				break;
			o = parse_object(t->tagged->sha1);
			if (!o)
				ret = error("Could not read object %s",
					    sha1_to_hex(t->tagged->sha1));
			objects[i].item = o;
			i--;
			break;
		}
		case OBJ_TREE:
			if (rev.shown_one)
				putchar('\n');
			printf("%stree %s%s\n\n",
					diff_get_color_opt(&rev.diffopt, DIFF_COMMIT),
					name,
					diff_get_color_opt(&rev.diffopt, DIFF_RESET));
			read_tree_recursive((struct tree *)o, "", 0, 0, NULL,
					show_tree_object, NULL);
			rev.shown_one = 1;
			break;
		case OBJ_COMMIT:
			rev.pending.nr = rev.pending.alloc = 0;
			rev.pending.objects = NULL;
			add_object_array(o, name, &rev.pending);
			ret = cmd_log_walk(&rev);
			break;
		default:
			ret = error("Unknown type: %d", o->type);
		}
	}
	free(objects);
	return ret;
}

/*
 * This is equivalent to "git log -g --abbrev-commit --pretty=oneline"
 */
int cmd_log_reflog(int argc, const char **argv, const char *prefix)
{
	struct rev_info rev;
	struct setup_revision_opt opt;

	git_config(git_log_config, NULL);

	if (diff_use_color_default == -1)
		diff_use_color_default = git_use_color_default;

	init_revisions(&rev, prefix);
	init_reflog_walk(&rev.reflog_info);
	rev.abbrev_commit = 1;
	rev.verbose_header = 1;
	memset(&opt, 0, sizeof(opt));
	opt.def = "HEAD";
	cmd_log_init(argc, argv, prefix, &rev, &opt);

	/*
	 * This means that we override whatever commit format the user gave
	 * on the cmd line.  Sad, but cmd_log_init() currently doesn't
	 * allow us to set a different default.
	 */
	rev.commit_format = CMIT_FMT_ONELINE;
	rev.use_terminator = 1;
	rev.always_show_header = 1;

	return cmd_log_walk(&rev);
}

int cmd_log(int argc, const char **argv, const char *prefix)
{
	struct rev_info rev;
	struct setup_revision_opt opt;

	git_config(git_log_config, NULL);

	if (diff_use_color_default == -1)
		diff_use_color_default = git_use_color_default;

	init_revisions(&rev, prefix);
	rev.always_show_header = 1;
	memset(&opt, 0, sizeof(opt));
	opt.def = "HEAD";
	cmd_log_init(argc, argv, prefix, &rev, &opt);
	return cmd_log_walk(&rev);
}

/* format-patch */

static const char *fmt_patch_suffix = ".patch";
static int numbered = 0;
static int auto_number = 1;

static char *default_attach = NULL;

static struct string_list extra_hdr;
static struct string_list extra_to;
static struct string_list extra_cc;

static void add_header(const char *value)
{
	struct string_list_item *item;
	int len = strlen(value);
	while (len && value[len - 1] == '\n')
		len--;

	if (!strncasecmp(value, "to: ", 4)) {
		item = string_list_append(&extra_to, value + 4);
		len -= 4;
	} else if (!strncasecmp(value, "cc: ", 4)) {
		item = string_list_append(&extra_cc, value + 4);
		len -= 4;
	} else {
		item = string_list_append(&extra_hdr, value);
	}

	item->string[len] = '\0';
}

#define THREAD_SHALLOW 1
#define THREAD_DEEP 2
static int thread;
static int do_signoff;
static const char *signature = git_version_string;

static int git_format_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "format.headers")) {
		if (!value)
			die("format.headers without value");
		add_header(value);
		return 0;
	}
	if (!strcmp(var, "format.suffix"))
		return git_config_string(&fmt_patch_suffix, var, value);
	if (!strcmp(var, "format.to")) {
		if (!value)
			return config_error_nonbool(var);
		string_list_append(&extra_to, value);
		return 0;
	}
	if (!strcmp(var, "format.cc")) {
		if (!value)
			return config_error_nonbool(var);
		string_list_append(&extra_cc, value);
		return 0;
	}
	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
		return 0;
	}
	if (!strcmp(var, "format.numbered")) {
		if (value && !strcasecmp(value, "auto")) {
			auto_number = 1;
			return 0;
		}
		numbered = git_config_bool(var, value);
		auto_number = auto_number && numbered;
		return 0;
	}
	if (!strcmp(var, "format.attach")) {
		if (value && *value)
			default_attach = xstrdup(value);
		else
			default_attach = xstrdup(git_version_string);
		return 0;
	}
	if (!strcmp(var, "format.thread")) {
		if (value && !strcasecmp(value, "deep")) {
			thread = THREAD_DEEP;
			return 0;
		}
		if (value && !strcasecmp(value, "shallow")) {
			thread = THREAD_SHALLOW;
			return 0;
		}
		thread = git_config_bool(var, value) && THREAD_SHALLOW;
		return 0;
	}
	if (!strcmp(var, "format.signoff")) {
		do_signoff = git_config_bool(var, value);
		return 0;
	}
	if (!strcmp(var, "format.signature"))
		return git_config_string(&signature, var, value);

	return git_log_config(var, value, cb);
}

static FILE *realstdout = NULL;
static const char *output_directory = NULL;
static int outdir_offset;

static int reopen_stdout(struct commit *commit, struct rev_info *rev)
{
	struct strbuf filename = STRBUF_INIT;
	int suffix_len = strlen(fmt_patch_suffix) + 1;

	if (output_directory) {
		strbuf_addstr(&filename, output_directory);
		if (filename.len >=
		    PATH_MAX - FORMAT_PATCH_NAME_MAX - suffix_len)
			return error("name of output directory is too long");
		if (filename.buf[filename.len - 1] != '/')
			strbuf_addch(&filename, '/');
	}

	get_patch_filename(commit, rev->nr, fmt_patch_suffix, &filename);

	if (!DIFF_OPT_TST(&rev->diffopt, QUICK))
		fprintf(realstdout, "%s\n", filename.buf + outdir_offset);

	if (freopen(filename.buf, "w", stdout) == NULL)
		return error("Cannot open patch file %s", filename.buf);

	strbuf_release(&filename);
	return 0;
}

static void get_patch_ids(struct rev_info *rev, struct patch_ids *ids, const char *prefix)
{
	struct rev_info check_rev;
	struct commit *commit;
	struct object *o1, *o2;
	unsigned flags1, flags2;

	if (rev->pending.nr != 2)
		die("Need exactly one range.");

	o1 = rev->pending.objects[0].item;
	flags1 = o1->flags;
	o2 = rev->pending.objects[1].item;
	flags2 = o2->flags;

	if ((flags1 & UNINTERESTING) == (flags2 & UNINTERESTING))
		die("Not a range.");

	init_patch_ids(ids);

	/* given a range a..b get all patch ids for b..a */
	init_revisions(&check_rev, prefix);
	o1->flags ^= UNINTERESTING;
	o2->flags ^= UNINTERESTING;
	add_pending_object(&check_rev, o1, "o1");
	add_pending_object(&check_rev, o2, "o2");
	if (prepare_revision_walk(&check_rev))
		die("revision walk setup failed");

	while ((commit = get_revision(&check_rev)) != NULL) {
		/* ignore merges */
		if (commit->parents && commit->parents->next)
			continue;

		add_commit_patch_id(commit, ids);
	}

	/* reset for next revision walk */
	clear_commit_marks((struct commit *)o1,
			SEEN | UNINTERESTING | SHOWN | ADDED);
	clear_commit_marks((struct commit *)o2,
			SEEN | UNINTERESTING | SHOWN | ADDED);
	o1->flags = flags1;
	o2->flags = flags2;
}

static void gen_message_id(struct rev_info *info, char *base)
{
	const char *committer = git_committer_info(IDENT_WARN_ON_NO_NAME);
	const char *email_start = strrchr(committer, '<');
	const char *email_end = strrchr(committer, '>');
	struct strbuf buf = STRBUF_INIT;
	if (!email_start || !email_end || email_start > email_end - 1)
		die("Could not extract email from committer identity.");
	strbuf_addf(&buf, "%s.%lu.git.%.*s", base,
		    (unsigned long) time(NULL),
		    (int)(email_end - email_start - 1), email_start + 1);
	info->message_id = strbuf_detach(&buf, NULL);
}

static void print_signature(void)
{
	if (signature && *signature)
		printf("-- \n%s\n\n", signature);
}

static void make_cover_letter(struct rev_info *rev, int use_stdout,
			      int numbered, int numbered_files,
			      struct commit *origin,
			      int nr, struct commit **list, struct commit *head)
{
	const char *committer;
	const char *subject_start = NULL;
	const char *body = "*** SUBJECT HERE ***\n\n*** BLURB HERE ***\n";
	const char *msg;
	const char *extra_headers = rev->extra_headers;
	struct shortlog log;
	struct strbuf sb = STRBUF_INIT;
	int i;
	const char *encoding = "UTF-8";
	struct diff_options opts;
	int need_8bit_cte = 0;
	struct commit *commit = NULL;

	if (rev->commit_format != CMIT_FMT_EMAIL)
		die("Cover letter needs email format");

	committer = git_committer_info(0);

	if (!numbered_files) {
		/*
		 * We fake a commit for the cover letter so we get the filename
		 * desired.
		 */
		commit = xcalloc(1, sizeof(*commit));
		commit->buffer = xmalloc(400);
		snprintf(commit->buffer, 400,
			"tree 0000000000000000000000000000000000000000\n"
			"parent %s\n"
			"author %s\n"
			"committer %s\n\n"
			"cover letter\n",
			sha1_to_hex(head->object.sha1), committer, committer);
	}

	if (!use_stdout && reopen_stdout(commit, rev))
		return;

	if (commit) {

		free(commit->buffer);
		free(commit);
	}

	log_write_email_headers(rev, head, &subject_start, &extra_headers,
				&need_8bit_cte);

	for (i = 0; !need_8bit_cte && i < nr; i++)
		if (has_non_ascii(list[i]->buffer))
			need_8bit_cte = 1;

	msg = body;
	pp_user_info(NULL, CMIT_FMT_EMAIL, &sb, committer, DATE_RFC2822,
		     encoding);
	pp_title_line(CMIT_FMT_EMAIL, &msg, &sb, subject_start, extra_headers,
		      encoding, need_8bit_cte);
	pp_remainder(CMIT_FMT_EMAIL, &msg, &sb, 0);
	printf("%s\n", sb.buf);

	strbuf_release(&sb);

	shortlog_init(&log);
	log.wrap_lines = 1;
	log.wrap = 72;
	log.in1 = 2;
	log.in2 = 4;
	for (i = 0; i < nr; i++)
		shortlog_add_commit(&log, list[i]);

	shortlog_output(&log);

	/*
	 * We can only do diffstat with a unique reference point
	 */
	if (!origin)
		return;

	memcpy(&opts, &rev->diffopt, sizeof(opts));
	opts.output_format = DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;

	diff_setup_done(&opts);

	diff_tree_sha1(origin->tree->object.sha1,
		       head->tree->object.sha1,
		       "", &opts);
	diffcore_std(&opts);
	diff_flush(&opts);

	printf("\n");
	print_signature();
}

static const char *clean_message_id(const char *msg_id)
{
	char ch;
	const char *a, *z, *m;

	m = msg_id;
	while ((ch = *m) && (isspace(ch) || (ch == '<')))
		m++;
	a = m;
	z = NULL;
	while ((ch = *m)) {
		if (!isspace(ch) && (ch != '>'))
			z = m;
		m++;
	}
	if (!z)
		die("insane in-reply-to: %s", msg_id);
	if (++z == m)
		return a;
	return xmemdupz(a, z - a);
}

static const char *set_outdir(const char *prefix, const char *output_directory)
{
	if (output_directory && is_absolute_path(output_directory))
		return output_directory;

	if (!prefix || !*prefix) {
		if (output_directory)
			return output_directory;
		/* The user did not explicitly ask for "./" */
		outdir_offset = 2;
		return "./";
	}

	outdir_offset = strlen(prefix);
	if (!output_directory)
		return prefix;

	return xstrdup(prefix_filename(prefix, outdir_offset,
				       output_directory));
}

static const char * const builtin_format_patch_usage[] = {
	"git format-patch [options] [<since> | <revision range>]",
	NULL
};

static int keep_subject = 0;

static int keep_callback(const struct option *opt, const char *arg, int unset)
{
	((struct rev_info *)opt->value)->total = -1;
	keep_subject = 1;
	return 0;
}

static int subject_prefix = 0;

static int subject_prefix_callback(const struct option *opt, const char *arg,
			    int unset)
{
	subject_prefix = 1;
	((struct rev_info *)opt->value)->subject_prefix = arg;
	return 0;
}

static int numbered_cmdline_opt = 0;

static int numbered_callback(const struct option *opt, const char *arg,
			     int unset)
{
	*(int *)opt->value = numbered_cmdline_opt = unset ? 0 : 1;
	if (unset)
		auto_number =  0;
	return 0;
}

static int no_numbered_callback(const struct option *opt, const char *arg,
				int unset)
{
	return numbered_callback(opt, arg, 1);
}

static int output_directory_callback(const struct option *opt, const char *arg,
			      int unset)
{
	const char **dir = (const char **)opt->value;
	if (*dir)
		die("Two output directories?");
	*dir = arg;
	return 0;
}

static int thread_callback(const struct option *opt, const char *arg, int unset)
{
	int *thread = (int *)opt->value;
	if (unset)
		*thread = 0;
	else if (!arg || !strcmp(arg, "shallow"))
		*thread = THREAD_SHALLOW;
	else if (!strcmp(arg, "deep"))
		*thread = THREAD_DEEP;
	else
		return 1;
	return 0;
}

static int attach_callback(const struct option *opt, const char *arg, int unset)
{
	struct rev_info *rev = (struct rev_info *)opt->value;
	if (unset)
		rev->mime_boundary = NULL;
	else if (arg)
		rev->mime_boundary = arg;
	else
		rev->mime_boundary = git_version_string;
	rev->no_inline = unset ? 0 : 1;
	return 0;
}

static int inline_callback(const struct option *opt, const char *arg, int unset)
{
	struct rev_info *rev = (struct rev_info *)opt->value;
	if (unset)
		rev->mime_boundary = NULL;
	else if (arg)
		rev->mime_boundary = arg;
	else
		rev->mime_boundary = git_version_string;
	rev->no_inline = 0;
	return 0;
}

static int header_callback(const struct option *opt, const char *arg, int unset)
{
	if (unset) {
		string_list_clear(&extra_hdr, 0);
		string_list_clear(&extra_to, 0);
		string_list_clear(&extra_cc, 0);
	} else {
	    add_header(arg);
	}
	return 0;
}

static int to_callback(const struct option *opt, const char *arg, int unset)
{
	if (unset)
		string_list_clear(&extra_to, 0);
	else
		string_list_append(&extra_to, arg);
	return 0;
}

static int cc_callback(const struct option *opt, const char *arg, int unset)
{
	if (unset)
		string_list_clear(&extra_cc, 0);
	else
		string_list_append(&extra_cc, arg);
	return 0;
}

int cmd_format_patch(int argc, const char **argv, const char *prefix)
{
	struct commit *commit;
	struct commit **list = NULL;
	struct rev_info rev;
	struct setup_revision_opt s_r_opt;
	int nr = 0, total, i;
	int use_stdout = 0;
	int start_number = -1;
	int numbered_files = 0;		/* _just_ numbers */
	int ignore_if_in_upstream = 0;
	int cover_letter = 0;
	int boundary_count = 0;
	int no_binary_diff = 0;
	struct commit *origin = NULL, *head = NULL;
	const char *in_reply_to = NULL;
	struct patch_ids ids;
	char *add_signoff = NULL;
	struct strbuf buf = STRBUF_INIT;
	int use_patch_format = 0;
	const struct option builtin_format_patch_options[] = {
		{ OPTION_CALLBACK, 'n', "numbered", &numbered, NULL,
			    "use [PATCH n/m] even with a single patch",
			    PARSE_OPT_NOARG, numbered_callback },
		{ OPTION_CALLBACK, 'N', "no-numbered", &numbered, NULL,
			    "use [PATCH] even with multiple patches",
			    PARSE_OPT_NOARG, no_numbered_callback },
		OPT_BOOLEAN('s', "signoff", &do_signoff, "add Signed-off-by:"),
		OPT_BOOLEAN(0, "stdout", &use_stdout,
			    "print patches to standard out"),
		OPT_BOOLEAN(0, "cover-letter", &cover_letter,
			    "generate a cover letter"),
		OPT_BOOLEAN(0, "numbered-files", &numbered_files,
			    "use simple number sequence for output file names"),
		OPT_STRING(0, "suffix", &fmt_patch_suffix, "sfx",
			    "use <sfx> instead of '.patch'"),
		OPT_INTEGER(0, "start-number", &start_number,
			    "start numbering patches at <n> instead of 1"),
		{ OPTION_CALLBACK, 0, "subject-prefix", &rev, "prefix",
			    "Use [<prefix>] instead of [PATCH]",
			    PARSE_OPT_NONEG, subject_prefix_callback },
		{ OPTION_CALLBACK, 'o', "output-directory", &output_directory,
			    "dir", "store resulting files in <dir>",
			    PARSE_OPT_NONEG, output_directory_callback },
		{ OPTION_CALLBACK, 'k', "keep-subject", &rev, NULL,
			    "don't strip/add [PATCH]",
			    PARSE_OPT_NOARG | PARSE_OPT_NONEG, keep_callback },
		OPT_BOOLEAN(0, "no-binary", &no_binary_diff,
			    "don't output binary diffs"),
		OPT_BOOLEAN(0, "ignore-if-in-upstream", &ignore_if_in_upstream,
			    "don't include a patch matching a commit upstream"),
		{ OPTION_BOOLEAN, 'p', "no-stat", &use_patch_format, NULL,
		  "show patch format instead of default (patch + stat)",
		  PARSE_OPT_NONEG | PARSE_OPT_NOARG },
		OPT_GROUP("Messaging"),
		{ OPTION_CALLBACK, 0, "add-header", NULL, "header",
			    "add email header", 0, header_callback },
		{ OPTION_CALLBACK, 0, "to", NULL, "email", "add To: header",
			    0, to_callback },
		{ OPTION_CALLBACK, 0, "cc", NULL, "email", "add Cc: header",
			    0, cc_callback },
		OPT_STRING(0, "in-reply-to", &in_reply_to, "message-id",
			    "make first mail a reply to <message-id>"),
		{ OPTION_CALLBACK, 0, "attach", &rev, "boundary",
			    "attach the patch", PARSE_OPT_OPTARG,
			    attach_callback },
		{ OPTION_CALLBACK, 0, "inline", &rev, "boundary",
			    "inline the patch",
			    PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
			    inline_callback },
		{ OPTION_CALLBACK, 0, "thread", &thread, "style",
			    "enable message threading, styles: shallow, deep",
			    PARSE_OPT_OPTARG, thread_callback },
		OPT_STRING(0, "signature", &signature, "signature",
			    "add a signature"),
		OPT_END()
	};

	extra_hdr.strdup_strings = 1;
	extra_to.strdup_strings = 1;
	extra_cc.strdup_strings = 1;
	git_config(git_format_config, NULL);
	init_revisions(&rev, prefix);
	rev.commit_format = CMIT_FMT_EMAIL;
	rev.verbose_header = 1;
	rev.diff = 1;
	rev.combine_merges = 0;
	rev.ignore_merges = 1;
	DIFF_OPT_SET(&rev.diffopt, RECURSIVE);
	rev.subject_prefix = fmt_patch_subject_prefix;
	memset(&s_r_opt, 0, sizeof(s_r_opt));
	s_r_opt.def = "HEAD";

	if (default_attach) {
		rev.mime_boundary = default_attach;
		rev.no_inline = 1;
	}

	/*
	 * Parse the arguments before setup_revisions(), or something
	 * like "git format-patch -o a123 HEAD^.." may fail; a123 is
	 * possibly a valid SHA1.
	 */
	argc = parse_options(argc, argv, prefix, builtin_format_patch_options,
			     builtin_format_patch_usage,
			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN |
			     PARSE_OPT_KEEP_DASHDASH);

	if (do_signoff) {
		const char *committer;
		const char *endpos;
		committer = git_committer_info(IDENT_ERROR_ON_NO_NAME);
		endpos = strchr(committer, '>');
		if (!endpos)
			die("bogus committer info %s", committer);
		add_signoff = xmemdupz(committer, endpos - committer + 1);
	}

	for (i = 0; i < extra_hdr.nr; i++) {
		strbuf_addstr(&buf, extra_hdr.items[i].string);
		strbuf_addch(&buf, '\n');
	}

	if (extra_to.nr)
		strbuf_addstr(&buf, "To: ");
	for (i = 0; i < extra_to.nr; i++) {
		if (i)
			strbuf_addstr(&buf, "    ");
		strbuf_addstr(&buf, extra_to.items[i].string);
		if (i + 1 < extra_to.nr)
			strbuf_addch(&buf, ',');
		strbuf_addch(&buf, '\n');
	}

	if (extra_cc.nr)
		strbuf_addstr(&buf, "Cc: ");
	for (i = 0; i < extra_cc.nr; i++) {
		if (i)
			strbuf_addstr(&buf, "    ");
		strbuf_addstr(&buf, extra_cc.items[i].string);
		if (i + 1 < extra_cc.nr)
			strbuf_addch(&buf, ',');
		strbuf_addch(&buf, '\n');
	}

	rev.extra_headers = strbuf_detach(&buf, NULL);

	if (start_number < 0)
		start_number = 1;

	/*
	 * If numbered is set solely due to format.numbered in config,
	 * and it would conflict with --keep-subject (-k) from the
	 * command line, reset "numbered".
	 */
	if (numbered && keep_subject && !numbered_cmdline_opt)
		numbered = 0;

	if (numbered && keep_subject)
		die ("-n and -k are mutually exclusive.");
	if (keep_subject && subject_prefix)
		die ("--subject-prefix and -k are mutually exclusive.");

	argc = setup_revisions(argc, argv, &rev, &s_r_opt);
	if (argc > 1)
		die ("unrecognized argument: %s", argv[1]);

	if (rev.diffopt.output_format & DIFF_FORMAT_NAME)
		die("--name-only does not make sense");
	if (rev.diffopt.output_format & DIFF_FORMAT_NAME_STATUS)
		die("--name-status does not make sense");
	if (rev.diffopt.output_format & DIFF_FORMAT_CHECKDIFF)
		die("--check does not make sense");

	if (!use_patch_format &&
		(!rev.diffopt.output_format ||
		 rev.diffopt.output_format == DIFF_FORMAT_PATCH))
		rev.diffopt.output_format = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_SUMMARY;

	/* Always generate a patch */
	rev.diffopt.output_format |= DIFF_FORMAT_PATCH;

	if (!DIFF_OPT_TST(&rev.diffopt, TEXT) && !no_binary_diff)
		DIFF_OPT_SET(&rev.diffopt, BINARY);

	if (rev.show_notes)
		init_display_notes(&rev.notes_opt);

	if (!use_stdout)
		output_directory = set_outdir(prefix, output_directory);

	if (output_directory) {
		if (use_stdout)
			die("standard output, or directory, which one?");
		if (mkdir(output_directory, 0777) < 0 && errno != EEXIST)
			die_errno("Could not create directory '%s'",
				  output_directory);
	}

	if (rev.pending.nr == 1) {
		if (rev.max_count < 0 && !rev.show_root_diff) {
			/*
			 * This is traditional behaviour of "git format-patch
			 * origin" that prepares what the origin side still
			 * does not have.
			 */
			rev.pending.objects[0].item->flags |= UNINTERESTING;
			add_head_to_pending(&rev);
		}
		/*
		 * Otherwise, it is "format-patch -22 HEAD", and/or
		 * "format-patch --root HEAD".  The user wants
		 * get_revision() to do the usual traversal.
		 */
	}

	/*
	 * We cannot move this anywhere earlier because we do want to
	 * know if --root was given explicitly from the command line.
	 */
	rev.show_root_diff = 1;

	if (cover_letter) {
		/* remember the range */
		int i;
		for (i = 0; i < rev.pending.nr; i++) {
			struct object *o = rev.pending.objects[i].item;
			if (!(o->flags & UNINTERESTING))
				head = (struct commit *)o;
		}
		/* We can't generate a cover letter without any patches */
		if (!head)
			return 0;
	}

	if (ignore_if_in_upstream) {
		/* Don't say anything if head and upstream are the same. */
		if (rev.pending.nr == 2) {
			struct object_array_entry *o = rev.pending.objects;
			if (hashcmp(o[0].item->sha1, o[1].item->sha1) == 0)
				return 0;
		}
		get_patch_ids(&rev, &ids, prefix);
	}

	if (!use_stdout)
		realstdout = xfdopen(xdup(1), "w");

	if (prepare_revision_walk(&rev))
		die("revision walk setup failed");
	rev.boundary = 1;
	while ((commit = get_revision(&rev)) != NULL) {
		if (commit->object.flags & BOUNDARY) {
			boundary_count++;
			origin = (boundary_count == 1) ? commit : NULL;
			continue;
		}

		/* ignore merges */
		if (commit->parents && commit->parents->next)
			continue;

		if (ignore_if_in_upstream &&
				has_commit_patch_id(commit, &ids))
			continue;

		nr++;
		list = xrealloc(list, nr * sizeof(list[0]));
		list[nr - 1] = commit;
	}
	total = nr;
	if (!keep_subject && auto_number && total > 1)
		numbered = 1;
	if (numbered)
		rev.total = total + start_number - 1;
	if (in_reply_to || thread || cover_letter)
		rev.ref_message_ids = xcalloc(1, sizeof(struct string_list));
	if (in_reply_to) {
		const char *msgid = clean_message_id(in_reply_to);
		string_list_append(rev.ref_message_ids, msgid);
	}
	rev.numbered_files = numbered_files;
	rev.patch_suffix = fmt_patch_suffix;
	if (cover_letter) {
		if (thread)
			gen_message_id(&rev, "cover");
		make_cover_letter(&rev, use_stdout, numbered, numbered_files,
				  origin, nr, list, head);
		total++;
		start_number--;
	}
	rev.add_signoff = add_signoff;
	while (0 <= --nr) {
		int shown;
		commit = list[nr];
		rev.nr = total - nr + (start_number - 1);
		/* Make the second and subsequent mails replies to the first */
		if (thread) {
			/* Have we already had a message ID? */
			if (rev.message_id) {
				/*
				 * For deep threading: make every mail
				 * a reply to the previous one, no
				 * matter what other options are set.
				 *
				 * For shallow threading:
				 *
				 * Without --cover-letter and
				 * --in-reply-to, make every mail a
				 * reply to the one before.
				 *
				 * With --in-reply-to but no
				 * --cover-letter, make every mail a
				 * reply to the <reply-to>.
				 *
				 * With --cover-letter, make every
				 * mail but the cover letter a reply
				 * to the cover letter.  The cover
				 * letter is a reply to the
				 * --in-reply-to, if specified.
				 */
				if (thread == THREAD_SHALLOW
				    && rev.ref_message_ids->nr > 0
				    && (!cover_letter || rev.nr > 1))
					free(rev.message_id);
				else
					string_list_append(rev.ref_message_ids,
							   rev.message_id);
			}
			gen_message_id(&rev, sha1_to_hex(commit->object.sha1));
		}

		if (!use_stdout && reopen_stdout(numbered_files ? NULL : commit,
						 &rev))
			die("Failed to create output files");
		shown = log_tree_commit(&rev, commit);
		free(commit->buffer);
		commit->buffer = NULL;

		/* We put one extra blank line between formatted
		 * patches and this flag is used by log-tree code
		 * to see if it needs to emit a LF before showing
		 * the log; when using one file per patch, we do
		 * not want the extra blank line.
		 */
		if (!use_stdout)
			rev.shown_one = 0;
		if (shown) {
			if (rev.mime_boundary)
				printf("\n--%s%s--\n\n\n",
				       mime_boundary_leader,
				       rev.mime_boundary);
			else
				print_signature();
		}
		if (!use_stdout)
			fclose(stdout);
	}
	free(list);
	string_list_clear(&extra_to, 0);
	string_list_clear(&extra_cc, 0);
	string_list_clear(&extra_hdr, 0);
	if (ignore_if_in_upstream)
		free_patch_ids(&ids);
	return 0;
}

static int add_pending_commit(const char *arg, struct rev_info *revs, int flags)
{
	unsigned char sha1[20];
	if (get_sha1(arg, sha1) == 0) {
		struct commit *commit = lookup_commit_reference(sha1);
		if (commit) {
			commit->object.flags |= flags;
			add_pending_object(revs, &commit->object, arg);
			return 0;
		}
	}
	return -1;
}

static const char * const cherry_usage[] = {
	"git cherry [-v] [<upstream> [<head> [<limit>]]]",
	NULL
};

int cmd_cherry(int argc, const char **argv, const char *prefix)
{
	struct rev_info revs;
	struct patch_ids ids;
	struct commit *commit;
	struct commit_list *list = NULL;
	struct branch *current_branch;
	const char *upstream;
	const char *head = "HEAD";
	const char *limit = NULL;
	int verbose = 0, abbrev = 0;

	struct option options[] = {
		OPT__ABBREV(&abbrev),
		OPT__VERBOSE(&verbose),
		OPT_END()
	};

	argc = parse_options(argc, argv, prefix, options, cherry_usage, 0);

	switch (argc) {
	case 3:
		limit = argv[2];
		/* FALLTHROUGH */
	case 2:
		head = argv[1];
		/* FALLTHROUGH */
	case 1:
		upstream = argv[0];
		break;
	default:
		current_branch = branch_get(NULL);
		if (!current_branch || !current_branch->merge
					|| !current_branch->merge[0]
					|| !current_branch->merge[0]->dst) {
			fprintf(stderr, "Could not find a tracked"
					" remote branch, please"
					" specify <upstream> manually.\n");
			usage_with_options(cherry_usage, options);
		}

		upstream = current_branch->merge[0]->dst;
	}

	init_revisions(&revs, prefix);
	revs.diff = 1;
	revs.combine_merges = 0;
	revs.ignore_merges = 1;
	DIFF_OPT_SET(&revs.diffopt, RECURSIVE);

	if (add_pending_commit(head, &revs, 0))
		die("Unknown commit %s", head);
	if (add_pending_commit(upstream, &revs, UNINTERESTING))
		die("Unknown commit %s", upstream);

	/* Don't say anything if head and upstream are the same. */
	if (revs.pending.nr == 2) {
		struct object_array_entry *o = revs.pending.objects;
		if (hashcmp(o[0].item->sha1, o[1].item->sha1) == 0)
			return 0;
	}

	get_patch_ids(&revs, &ids, prefix);

	if (limit && add_pending_commit(limit, &revs, UNINTERESTING))
		die("Unknown commit %s", limit);

	/* reverse the list of commits */
	if (prepare_revision_walk(&revs))
		die("revision walk setup failed");
	while ((commit = get_revision(&revs)) != NULL) {
		/* ignore merges */
		if (commit->parents && commit->parents->next)
			continue;

		commit_list_insert(commit, &list);
	}

	while (list) {
		char sign = '+';

		commit = list->item;
		if (has_commit_patch_id(commit, &ids))
			sign = '-';

		if (verbose) {
			struct strbuf buf = STRBUF_INIT;
			struct pretty_print_context ctx = {0};
			pretty_print_commit(CMIT_FMT_ONELINE, commit,
					    &buf, &ctx);
			printf("%c %s %s\n", sign,
			       find_unique_abbrev(commit->object.sha1, abbrev),
			       buf.buf);
			strbuf_release(&buf);
		}
		else {
			printf("%c %s\n", sign,
			       find_unique_abbrev(commit->object.sha1, abbrev));
		}

		list = list->next;
	}

	free_patch_ids(&ids);
	return 0;
}