[PATCH 0/9] Resend of gitster/pb/bisect

@@ -7,7 +7,7 @@
 #include "argv-array.h"
 #include "run-command.h"
 
-static GIT_PATH_FUNC(git_path_bisect_write_terms, "BISECT_TERMS")
+static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
 static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
 static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")

@@ -100,7 +100,7 @@ static int write_terms(const char *bad, const char *good)
 	if (check_term_format(bad, "bad") || check_term_format(good, "good"))
 		return -1;
 
-	fp = fopen(git_path_bisect_write_terms(), "w");
+	fp = fopen(git_path_bisect_terms(), "w");
 	if (!fp)
 		return error_errno(_("could not open the file BISECT_TERMS"));
 

@@ -134,7 +134,7 @@ static int bisect_clean_state(void)
 	remove_path(git_path_bisect_log());
 	remove_path(git_path_bisect_names());
 	remove_path(git_path_bisect_run());
-	remove_path(git_path_bisect_write_terms());
+	remove_path(git_path_bisect_terms());
 	/* Cleanup head-name if it got left by an old version of git-bisect */
 	remove_path(git_path_head_name());
 	/*

@@ -2,19 +2,72 @@
 #include "cache.h"
 #include "parse-options.h"
 #include "bisect.h"
+#include "refs.h"
 
 static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --next-all [--no-checkout]"),
+	N_("git bisect--helper --check-term-format <term> <orig_term>"),
 	NULL
 };
 
+/*
+ * Check whether the string `term` belongs to the set of strings
+ * included in the variable arguments.
+ */
+static int one_of(const char *term, ...)
+{
+	int res = 0;
+	va_list matches;
+	const char *match;
+
+	va_start(matches, term);
+	while (!res && (match = va_arg(matches, const char *)))
+		res = !strcmp(term, match);
+	va_end(matches);
+
+	return res;
+}
+
+static int check_term_format(const char *term, const char *orig_term)
+{
+	struct strbuf new_term = STRBUF_INIT;
+	strbuf_addf(&new_term, "refs/bisect/%s", term);
+
+	if (check_refname_format(new_term.buf, 0)) {
+		strbuf_release(&new_term);
+		return error(_("'%s' is not a valid term"), term);
+	}
+	strbuf_release(&new_term);
+
+	if (one_of(term, "help", "start", "skip", "next", "reset",
+			"visualize", "replay", "log", "run", NULL))
+		return error(_("can't use the builtin command '%s' as a term"), term);
+
+	/*
+	 * In theory, nothing prevents swapping completely good and bad,
+	 * but this situation could be confusing and hasn't been tested
+	 * enough. Forbid it for now.
+	 */
+
+	if ((strcmp(orig_term, "bad") && one_of(term, "bad", "new", NULL)) ||
+		 (strcmp(orig_term, "good") && one_of(term, "good", "old", NULL)))
+		return error(_("can't change the meaning of the term '%s'"), term);
+
+	return 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
-	enum { NEXT_ALL = 1 } cmdmode = 0;
+	enum {
+		NEXT_ALL = 1,
+		CHECK_TERM_FMT
+	} cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {
 		OPT_CMDMODE(0, "next-all", &cmdmode,
 			 N_("perform 'git bisect next'"), NEXT_ALL),
+		OPT_CMDMODE(0, "check-term-format", &cmdmode,
+			 N_("check format of the term"), CHECK_TERM_FMT),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()

@@ -29,6 +82,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 	switch (cmdmode) {
 	case NEXT_ALL:
 		return bisect_next_all(prefix, no_checkout);
+	case CHECK_TERM_FMT:
+		if (argc != 2)
+			die(_("--check-term-format requires two arguments"));
+		return check_term_format(argv[0], argv[1]);
 	default:
 		die("BUG: unknown subcommand '%d'", cmdmode);
 	}

@@ -564,38 +564,11 @@ write_terms () {
 	then
 		die "$(gettext "please use two different terms")"
 	fi
-	check_term_format "$TERM_BAD" bad
-	check_term_format "$TERM_GOOD" good
+	git bisect--helper --check-term-format "$TERM_BAD" bad || exit
+	git bisect--helper --check-term-format "$TERM_GOOD" good || exit
 	printf '%s\n%s\n' "$TERM_BAD" "$TERM_GOOD" >"$GIT_DIR/BISECT_TERMS"
 }
 
-check_term_format () {
-	term=$1
-	git check-ref-format refs/bisect/"$term" ||
-	die "$(eval_gettext "'\$term' is not a valid term")"
-	case "$term" in
-	help|start|terms|skip|next|reset|visualize|replay|log|run)
-		die "$(eval_gettext "can't use the builtin command '\$term' as a term")"
-		;;
-	bad|new)
-		if test "$2" != bad
-		then
-			# In theory, nothing prevents swapping
-			# completely good and bad, but this situation
-			# could be confusing and hasn't been tested
-			# enough. Forbid it for now.
-			die "$(eval_gettext "can't change the meaning of term '\$term'")"
-		fi
-		;;
-	good|old)
-		if test "$2" != good
-		then
-			die "$(eval_gettext "can't change the meaning of term '\$term'")"
-		fi
-		;;
-	esac
-}
-
 check_and_set_terms () {
 	cmd="$1"
 	case "$cmd" in

@@ -4,9 +4,11 @@
 #include "bisect.h"
 #include "refs.h"
 
+static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
+
 static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --next-all [--no-checkout]"),
-	N_("git bisect--helper --check-term-format <term> <orig_term>"),
+	N_("git bisect--helper --write-terms <bad_term> <good_term>"),
 	NULL
 };
 

@@ -56,18 +58,38 @@ static int check_term_format(const char *term, const char *orig_term)
 	return 0;
 }
 
+static int write_terms(const char *bad, const char *good)
+{
+	FILE *fp;
+	int res;
+
+	if (!strcmp(bad, good))
+		return error(_("please use two different terms"));
+
+	if (check_term_format(bad, "bad") || check_term_format(good, "good"))
+		return -1;
+
+	fp = fopen(git_path_bisect_terms(), "w");
+	if (!fp)
+		return error_errno(_("could not open the file BISECT_TERMS"));
+
+	res = fprintf(fp, "%s\n%s\n", bad, good);
+	fclose(fp);
+	return (res < 0) ? -1 : 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
 		NEXT_ALL = 1,
-		CHECK_TERM_FMT
+		WRITE_TERMS
 	} cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {
 		OPT_CMDMODE(0, "next-all", &cmdmode,
 			 N_("perform 'git bisect next'"), NEXT_ALL),
-		OPT_CMDMODE(0, "check-term-format", &cmdmode,
-			 N_("check format of the term"), CHECK_TERM_FMT),
+		OPT_CMDMODE(0, "write-terms", &cmdmode,
+			 N_("write the terms to .git/BISECT_TERMS"), WRITE_TERMS),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()

@@ -82,10 +104,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 	switch (cmdmode) {
 	case NEXT_ALL:
 		return bisect_next_all(prefix, no_checkout);
-	case CHECK_TERM_FMT:
+	case WRITE_TERMS:
 		if (argc != 2)
-			die(_("--check-term-format requires two arguments"));
-		return check_term_format(argv[0], argv[1]);
+			die(_("--write-terms requires two arguments"));
+		return write_terms(argv[0], argv[1]);
 	default:
 		die("BUG: unknown subcommand '%d'", cmdmode);
 	}

@@ -210,7 +210,7 @@ bisect_start() {
 	eval "$eval true" &&
 	if test $must_write_terms -eq 1
 	then
-		write_terms "$TERM_BAD" "$TERM_GOOD"
+		git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD"
 	fi &&
 	echo "git bisect start$orig_args" >>"$GIT_DIR/BISECT_LOG" || exit
 	#

@@ -557,18 +557,6 @@ get_terms () {
 	fi
 }
 
-write_terms () {
-	TERM_BAD=$1
-	TERM_GOOD=$2
-	if test "$TERM_BAD" = "$TERM_GOOD"
-	then
-		die "$(gettext "please use two different terms")"
-	fi
-	git bisect--helper --check-term-format "$TERM_BAD" bad || exit
-	git bisect--helper --check-term-format "$TERM_GOOD" good || exit
-	printf '%s\n%s\n' "$TERM_BAD" "$TERM_GOOD" >"$GIT_DIR/BISECT_TERMS"
-}
-
 check_and_set_terms () {
 	cmd="$1"
 	case "$cmd" in

@@ -582,13 +570,17 @@ check_and_set_terms () {
 		bad|good)
 			if ! test -s "$GIT_DIR/BISECT_TERMS"
 			then
-				write_terms bad good
+				TERM_BAD=bad
+				TERM_GOOD=good
+				git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" || exit
 			fi
 			;;
 		new|old)
 			if ! test -s "$GIT_DIR/BISECT_TERMS"
 			then
-				write_terms new old
+				TERM_BAD=new
+				TERM_GOOD=old
+				git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" || exit
 			fi
 			;;
 		esac ;;

@@ -10,11 +10,11 @@ static const char * const git_bisect_helper_usage[] = {
 
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
-	int next_all = 0;
+	enum { NEXT_ALL = 1 } cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {
-		OPT_BOOL(0, "next-all", &next_all,
-			 N_("perform 'git bisect next'")),
+		OPT_CMDMODE(0, "next-all", &cmdmode,
+			 N_("perform 'git bisect next'"), NEXT_ALL),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()

@@ -23,9 +23,14 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options,
 			     git_bisect_helper_usage, 0);
 
-	if (!next_all)
+	if (!cmdmode)
 		usage_with_options(git_bisect_helper_usage, options);
 
-	/* next-all */
-	return bisect_next_all(prefix, no_checkout);
+	switch (cmdmode) {
+	case NEXT_ALL:
+		return bisect_next_all(prefix, no_checkout);
+	default:
+		die("BUG: unknown subcommand '%d'", cmdmode);
+	}
+	return 0;
 }

@@ -30,22 +30,6 @@
 #include "mailinfo.h"
 
 /**
- * Returns 1 if the file is empty or does not exist, 0 otherwise.
- */
-static int is_empty_file(const char *filename)
-{
-	struct stat st;
-
-	if (stat(filename, &st) < 0) {
-		if (errno == ENOENT)
-			return 1;
-		die_errno(_("could not stat %s"), filename);
-	}
-
-	return !st.st_size;
-}
-
-/**
  * Returns the length of the first line of msg.
  */
 static int linelen(const char *msg)

@@ -1323,7 +1307,7 @@ static int parse_mail(struct am_state *state, const char *mail)
 		goto finish;
 	}
 
-	if (is_empty_file(am_path(state, "patch"))) {
+	if (is_empty_or_missing_file(am_path(state, "patch"))) {
 		printf_ln(_("Patch is empty. Was it split wrong?"));
 		die_user_resolve(state);
 	}

@@ -1911,7 +1895,7 @@ next:
 		resume = 0;
 	}
 
-	if (!is_empty_file(am_path(state, "rewritten"))) {
+	if (!is_empty_or_missing_file(am_path(state, "rewritten"))) {
 		assert(state->rebasing);
 		copy_notes_for_rebase(state);
 		run_post_rewrite_hook(state);

@@ -1870,4 +1870,7 @@ void sleep_millisec(int millisec);
  */
 void safe_create_dir(const char *dir, int share);
 
+/* Return 1 if the file is empty or does not exists, 0 otherwise. */
+extern int is_empty_or_missing_file(const char *filename);
+
 #endif /* CACHE_H */

@@ -696,3 +696,16 @@ void sleep_millisec(int millisec)
 {
 	poll(NULL, 0, millisec);
 }
+
+int is_empty_or_missing_file(const char *filename)
+{
+	struct stat st;
+
+	if (stat(filename, &st) < 0) {
+		if (errno == ENOENT)
+			return 1;
+		die_errno(_("could not stat %s"), filename);
+	}
+
+	return !st.st_size;
+}

@@ -3,12 +3,21 @@
 #include "parse-options.h"
 #include "bisect.h"
 #include "refs.h"
+#include "dir.h"
 
 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
+static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
+static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
+static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
+static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
+static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
+static GIT_PATH_FUNC(git_path_head_name, "head-name")
+static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
 
 static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --next-all [--no-checkout]"),
 	N_("git bisect--helper --write-terms <bad_term> <good_term>"),
+	N_("git bisect--helper --bisect-clean-state"),
 	NULL
 };
 

@@ -78,11 +87,49 @@ static int write_terms(const char *bad, const char *good)
 	return (res < 0) ? -1 : 0;
 }
 
+static int mark_for_removal(const char *refname, const struct object_id *oid,
+			    int flag, void *cb_data)
+{
+	struct string_list *refs = cb_data;
+	char *ref = xstrfmt("refs/bisect/%s", refname);
+	string_list_append(refs, ref);
+	return 0;
+}
+
+static int bisect_clean_state(void)
+{
+	int result = 0;
+
+	/* There may be some refs packed during bisection */
+	struct string_list refs_for_removal = STRING_LIST_INIT_NODUP;
+	for_each_ref_in("refs/bisect/", mark_for_removal, (void *) &refs_for_removal);
+	string_list_append(&refs_for_removal, xstrdup("BISECT_HEAD"));
+	result = delete_refs(&refs_for_removal);
+	refs_for_removal.strdup_strings = 1;
+	string_list_clear(&refs_for_removal, 0);
+	remove_path(git_path_bisect_expected_rev());
+	remove_path(git_path_bisect_ancestors_ok());
+	remove_path(git_path_bisect_log());
+	remove_path(git_path_bisect_names());
+	remove_path(git_path_bisect_run());
+	remove_path(git_path_bisect_terms());
+	/* Cleanup head-name if it got left by an old version of git-bisect */
+	remove_path(git_path_head_name());
+	/*
+	 * Cleanup BISECT_START last to support the --no-checkout option
+	 * introduced in the commit 4796e823a.
+	 */
+	remove_path(git_path_bisect_start());
+
+	return result;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
 		NEXT_ALL = 1,
-		WRITE_TERMS
+		WRITE_TERMS,
+		BISECT_CLEAN_STATE
 	} cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {

@@ -90,6 +137,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("perform 'git bisect next'"), NEXT_ALL),
 		OPT_CMDMODE(0, "write-terms", &cmdmode,
 			 N_("write the terms to .git/BISECT_TERMS"), WRITE_TERMS),
+		OPT_CMDMODE(0, "bisect-clean-state", &cmdmode,
+			 N_("cleanup the bisection state"), BISECT_CLEAN_STATE),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()

@@ -108,6 +157,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		if (argc != 2)
 			die(_("--write-terms requires two arguments"));
 		return write_terms(argv[0], argv[1]);
+	case BISECT_CLEAN_STATE:
+		if (argc != 0)
+			die(_("--bisect-clean-state requires no arguments"));
+		return bisect_clean_state();
 	default:
 		die("BUG: unknown subcommand '%d'", cmdmode);
 	}

@@ -187,7 +187,7 @@ bisect_start() {
 	#
 	# Get rid of any old bisect state.
 	#
-	bisect_clean_state || exit
+	git bisect--helper --bisect-clean-state || exit
 
 	#
 	# Change state.

@@ -196,7 +196,7 @@ bisect_start() {
 	# We have to trap this to be able to clean up using
 	# "bisect_clean_state".
 	#
-	trap 'bisect_clean_state' 0
+	trap 'git bisect--helper --bisect-clean-state' 0
 	trap 'exit 255' 1 2 3 15
 
 	#

@@ -430,27 +430,7 @@ bisect_reset() {
 		die "$(eval_gettext "Could not check out original HEAD '\$branch'.
 Try 'git bisect reset <commit>'.")"
 	fi
-	bisect_clean_state
-}
-
-bisect_clean_state() {
-	# There may be some refs packed during bisection.
-	git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* |
-	while read ref hash
-	do
-		git update-ref -d $ref $hash || exit
-	done
-	rm -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
-	rm -f "$GIT_DIR/BISECT_ANCESTORS_OK" &&
-	rm -f "$GIT_DIR/BISECT_LOG" &&
-	rm -f "$GIT_DIR/BISECT_NAMES" &&
-	rm -f "$GIT_DIR/BISECT_RUN" &&
-	rm -f "$GIT_DIR/BISECT_TERMS" &&
-	# Cleanup head-name if it got left by an old version of git-bisect
-	rm -f "$GIT_DIR/head-name" &&
-	git update-ref -d --no-deref BISECT_HEAD &&
-	# clean up BISECT_START last
-	rm -f "$GIT_DIR/BISECT_START"
+	git bisect--helper --bisect-clean-state || exit
 }
 
 bisect_replay () {

@@ -894,4 +894,21 @@ test_expect_success 'bisect start takes options and revs in any order' '
 	test_cmp expected actual
 '
 
+test_expect_success 'git bisect reset cleans bisection state properly' '
+	git bisect reset &&
+	git bisect start &&
+	git bisect good $HASH1 &&
+	git bisect bad $HASH4 &&
+	git bisect reset &&
+	test -z "$(git for-each-ref "refs/bisect/*")" &&
+	test_path_is_missing "$GIT_DIR/BISECT_EXPECTED_REV" &&
+	test_path_is_missing "$GIT_DIR/BISECT_ANCESTORS_OK" &&
+	test_path_is_missing "$GIT_DIR/BISECT_LOG" &&
+	test_path_is_missing "$GIT_DIR/BISECT_RUN" &&
+	test_path_is_missing "$GIT_DIR/BISECT_TERMS" &&
+	test_path_is_missing "$GIT_DIR/head-name" &&
+	test_path_is_missing "$GIT_DIR/BISECT_HEAD" &&
+	test_path_is_missing "$GIT_DIR/BISECT_START"
+'
+
 test_done

@@ -22,9 +22,27 @@ static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --write-terms <bad_term> <good_term>"),
 	N_("git bisect--helper --bisect-clean-state"),
 	N_("git bisect--helper --bisect-reset [<commit>]"),
+	N_("git bisect--helper --bisect-write <state> <revision> <TERM_GOOD> <TERM_BAD> [<nolog>]"),
 	NULL
 };
 
+struct bisect_terms {
+	struct strbuf term_good;
+	struct strbuf term_bad;
+};
+
+static void bisect_terms_init(struct bisect_terms *terms)
+{
+	strbuf_init(&terms->term_good, 0);
+	strbuf_init(&terms->term_bad, 0);
+}
+
+static void bisect_terms_release(struct bisect_terms *terms)
+{
+	strbuf_release(&terms->term_good);
+	strbuf_release(&terms->term_bad);
+}
+
 /*
  * Check whether the string `term` belongs to the set of strings
  * included in the variable arguments.

@@ -188,6 +206,52 @@ static int check_expected_revs(const char **revs, int rev_nr)
 	return 0;
 }
 
+static int bisect_write(const char *state, const char *rev,
+			const struct bisect_terms *terms, int nolog)
+{
+	struct strbuf tag = STRBUF_INIT;
+	struct strbuf commit_name = STRBUF_INIT;
+	struct object_id oid;
+	struct commit *commit;
+	struct pretty_print_context pp = {0};
+	FILE *fp;
+
+	if (!strcmp(state, terms->term_bad.buf))
+		strbuf_addf(&tag, "refs/bisect/%s", state);
+	else if(one_of(state, terms->term_good.buf, "skip", NULL))
+		strbuf_addf(&tag, "refs/bisect/%s-%s", state, rev);
+	else
+		return error(_("Bad bisect_write argument: %s"), state);
+
+	if (get_oid(rev, &oid)) {
+		strbuf_release(&tag);
+		return error(_("couldn't get the oid of the rev '%s'"), rev);
+	}
+
+	if (update_ref(NULL, tag.buf, oid.hash, NULL, 0,
+		       UPDATE_REFS_MSG_ON_ERR)) {
+		strbuf_release(&tag);
+		return -1;
+	}
+	strbuf_release(&tag);
+
+	fp = fopen(git_path_bisect_log(), "a");
+	if (!fp)
+		return error_errno(_("couldn't open the file '%s'"), git_path_bisect_log());
+
+	commit = lookup_commit_reference(oid.hash);
+	format_commit_message(commit, "%s", &commit_name, &pp);
+	fprintf(fp, "# %s: [%s] %s\n", state, sha1_to_hex(oid.hash),
+		commit_name.buf);
+	strbuf_release(&commit_name);
+
+	if (!nolog)
+		fprintf(fp, "git bisect %s %s\n", state, rev);
+
+	fclose(fp);
+	return 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {

@@ -195,9 +259,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		WRITE_TERMS,
 		BISECT_CLEAN_STATE,
 		BISECT_RESET,
-		CHECK_EXPECTED_REVS
+		CHECK_EXPECTED_REVS,
+		BISECT_WRITE
 	} cmdmode = 0;
-	int no_checkout = 0;
+	int no_checkout = 0, res = 0;
 	struct option options[] = {
 		OPT_CMDMODE(0, "next-all", &cmdmode,
 			 N_("perform 'git bisect next'"), NEXT_ALL),

@@ -209,10 +274,14 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("reset the bisection state"), BISECT_RESET),
 		OPT_CMDMODE(0, "check-expected-revs", &cmdmode,
 			 N_("check for expected revs"), CHECK_EXPECTED_REVS),
+		OPT_CMDMODE(0, "bisect-write", &cmdmode,
+			 N_("write out the bisection state in BISECT_LOG"), BISECT_WRITE),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()
 	};
+	struct bisect_terms terms;
+	bisect_terms_init(&terms);
 
 	argc = parse_options(argc, argv, prefix, options,
 			     git_bisect_helper_usage, 0);

@@ -221,24 +290,38 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		usage_with_options(git_bisect_helper_usage, options);
 
 	switch (cmdmode) {
+	int nolog;
 	case NEXT_ALL:
 		return bisect_next_all(prefix, no_checkout);
 	case WRITE_TERMS:
 		if (argc != 2)
 			die(_("--write-terms requires two arguments"));
-		return write_terms(argv[0], argv[1]);
+		res = write_terms(argv[0], argv[1]);
+		break;
 	case BISECT_CLEAN_STATE:
 		if (argc != 0)
 			die(_("--bisect-clean-state requires no arguments"));
-		return bisect_clean_state();
+		res = bisect_clean_state();
+		break;
 	case BISECT_RESET:
 		if (argc > 1)
 			die(_("--bisect-reset requires either zero or one arguments"));
-		return bisect_reset(argc ? argv[0] : NULL);
+		res = bisect_reset(argc ? argv[0] : NULL);
+		break;
 	case CHECK_EXPECTED_REVS:
-		return check_expected_revs(argv, argc);
+		res = check_expected_revs(argv, argc);
+		break;
+	case BISECT_WRITE:
+		if (argc != 4 && argc != 5)
+			die(_("--bisect-write requires either 4 or 5 arguments"));
+		nolog = (argc == 5) && !strcmp(argv[4], "nolog");
+		strbuf_addstr(&terms.term_good, argv[2]);
+		strbuf_addstr(&terms.term_bad, argv[3]);
+		res = bisect_write(argv[0], argv[1], &terms, nolog);
+		break;
 	default:
 		die("BUG: unknown subcommand '%d'", cmdmode);
 	}
-	return 0;
+	bisect_terms_release(&terms);
+	return res;
 }

@@ -145,7 +145,7 @@ bisect_start() {
 		0) state=$TERM_BAD ; bad_seen=1 ;;
 		*) state=$TERM_GOOD ;;
 		esac
-		eval="$eval bisect_write '$state' '$rev' 'nolog' &&"
+		eval="$eval git bisect--helper --bisect-write '$state' '$rev' '$TERM_GOOD' '$TERM_BAD' 'nolog' &&"
 	done
 	#
 	# Verify HEAD.

@@ -221,23 +221,6 @@ bisect_start() {
 	trap '-' 0
 }
 
-bisect_write() {
-	state="$1"
-	rev="$2"
-	nolog="$3"
-	case "$state" in
-		"$TERM_BAD")
-			tag="$state" ;;
-		"$TERM_GOOD"|skip)
-			tag="$state"-"$rev" ;;
-		*)
-			die "$(eval_gettext "Bad bisect_write argument: \$state")" ;;
-	esac
-	git update-ref "refs/bisect/$tag" "$rev" || exit
-	echo "# $state: $(git show-branch $rev)" >>"$GIT_DIR/BISECT_LOG"
-	test -n "$nolog" || echo "git bisect $state $rev" >>"$GIT_DIR/BISECT_LOG"
-}
-
 bisect_skip() {
 	all=''
 	for arg in "$@"

@@ -263,7 +246,7 @@ bisect_state() {
 	1,"$TERM_BAD"|1,"$TERM_GOOD"|1,skip)
 		rev=$(git rev-parse --verify $(bisect_head)) ||
 			die "$(gettext "Bad rev input: $(bisect_head)")"
-		bisect_write "$state" "$rev"
+		git bisect--helper --bisect-write "$state" "$rev" "$TERM_GOOD" "$TERM_BAD" || exit
 		git bisect--helper --check-expected-revs "$rev" ;;
 	2,"$TERM_BAD"|*,"$TERM_GOOD"|*,skip)
 		shift

@@ -276,7 +259,7 @@ bisect_state() {
 		done
 		for rev in $hash_list
 		do
-			bisect_write "$state" "$rev"
+			git bisect--helper --bisect-write "$state" "$rev" "$TERM_GOOD" "$TERM_BAD" || exit
 		done
 		git bisect--helper --check-expected-revs $hash_list ;;
 	*,"$TERM_BAD")

@@ -413,7 +396,7 @@ bisect_replay () {
 			cmd="bisect_start $rev"
 			eval "$cmd" ;;
 		"$TERM_GOOD"|"$TERM_BAD"|skip)
-			bisect_write "$command" "$rev" ;;
+			git bisect--helper --bisect-write "$command" "$rev" "$TERM_GOOD" "$TERM_BAD" || exit;;
 		terms)
 			bisect_terms $rev ;;
 		*)

@@ -4,6 +4,8 @@
 #include "bisect.h"
 #include "refs.h"
 #include "dir.h"
+#include "argv-array.h"
+#include "run-command.h"
 
 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")

@@ -13,11 +15,13 @@ static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
 static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
 static GIT_PATH_FUNC(git_path_head_name, "head-name")
 static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
+static GIT_PATH_FUNC(git_path_bisect_head, "BISECT_HEAD")
 
 static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --next-all [--no-checkout]"),
 	N_("git bisect--helper --write-terms <bad_term> <good_term>"),
 	N_("git bisect--helper --bisect-clean-state"),
+	N_("git bisect--helper --bisect-reset [<commit>]"),
 	NULL
 };
 

@@ -124,12 +128,47 @@ static int bisect_clean_state(void)
 	return result;
 }
 
+static int bisect_reset(const char *commit)
+{
+	struct strbuf branch = STRBUF_INIT;
+
+	if (!commit) {
+		if (strbuf_read_file(&branch, git_path_bisect_start(), 0) < 1) {
+			printf("We are not bisecting.\n");
+			return 0;
+		}
+		strbuf_rtrim(&branch);
+	} else {
+		struct object_id oid;
+		if (get_oid(commit, &oid))
+			return error(_("'%s' is not a valid commit"), commit);
+		strbuf_addstr(&branch, commit);
+	}
+
+	if (!file_exists(git_path_bisect_head())) {
+		struct argv_array argv = ARGV_ARRAY_INIT;
+		argv_array_pushl(&argv, "checkout", branch.buf, "--", NULL);
+		if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
+			error(_("Could not check out original HEAD '%s'. Try"
+				"'git bisect reset <commit>'."), branch.buf);
+			strbuf_release(&branch);
+			argv_array_clear(&argv);
+			return -1;
+		}
+		argv_array_clear(&argv);
+	}
+
+	strbuf_release(&branch);
+	return bisect_clean_state();
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
 		NEXT_ALL = 1,
 		WRITE_TERMS,
-		BISECT_CLEAN_STATE
+		BISECT_CLEAN_STATE,
+		BISECT_RESET
 	} cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {

@@ -139,6 +178,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("write the terms to .git/BISECT_TERMS"), WRITE_TERMS),
 		OPT_CMDMODE(0, "bisect-clean-state", &cmdmode,
 			 N_("cleanup the bisection state"), BISECT_CLEAN_STATE),
+		OPT_CMDMODE(0, "bisect-reset", &cmdmode,
+			 N_("reset the bisection state"), BISECT_RESET),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()

@@ -161,6 +202,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		if (argc != 0)
 			die(_("--bisect-clean-state requires no arguments"));
 		return bisect_clean_state();
+	case BISECT_RESET:
+		if (argc > 1)
+			die(_("--bisect-reset requires either zero or one arguments"));
+		return bisect_reset(argc ? argv[0] : NULL);
 	default:
 		die("BUG: unknown subcommand '%d'", cmdmode);
 	}

@@ -409,35 +409,11 @@ bisect_visualize() {
 	eval '"$@"' --bisect -- $(cat "$GIT_DIR/BISECT_NAMES")
 }
 
-bisect_reset() {
-	test -s "$GIT_DIR/BISECT_START" || {
-		gettextln "We are not bisecting."
-		return
-	}
-	case "$#" in
-	0) branch=$(cat "$GIT_DIR/BISECT_START") ;;
-	1) git rev-parse --quiet --verify "$1^{commit}" >/dev/null || {
-			invalid="$1"
-			die "$(eval_gettext "'\$invalid' is not a valid commit")"
-		}
-		branch="$1" ;;
-	*)
-		usage ;;
-	esac
-
-	if ! test -f "$GIT_DIR/BISECT_HEAD" && ! git checkout "$branch" --
-	then
-		die "$(eval_gettext "Could not check out original HEAD '\$branch'.
-Try 'git bisect reset <commit>'.")"
-	fi
-	git bisect--helper --bisect-clean-state || exit
-}
-
 bisect_replay () {
 	file="$1"
 	test "$#" -eq 1 || die "$(gettext "No logfile given")"
 	test -r "$file" || die "$(eval_gettext "cannot read \$file for replaying")"
-	bisect_reset
+	git bisect--helper --bisect-reset || exit
 	while read git bisect command rev
 	do
 		test "$git $bisect" = "git bisect" || test "$git" = "git-bisect" || continue

@@ -627,7 +603,7 @@ case "$#" in
 	visualize|view)
 		bisect_visualize "$@" ;;
 	reset)
-		bisect_reset "$@" ;;
+		git bisect--helper --bisect-reset "$@" ;;
 	replay)
 		bisect_replay "$@" ;;
 	log)

@@ -162,13 +162,40 @@ static int bisect_reset(const char *commit)
 	return bisect_clean_state();
 }
 
+static int is_expected_rev(const char *expected_hex)
+{
+	struct strbuf actual_hex = STRBUF_INIT;
+	int res = 0;
+	if (strbuf_read_file(&actual_hex, git_path_bisect_expected_rev(), 0) >= 0) {
+		strbuf_trim(&actual_hex);
+		res = !strcmp(actual_hex.buf, expected_hex);
+	}
+	strbuf_release(&actual_hex);
+	return res;
+}
+
+static int check_expected_revs(const char **revs, int rev_nr)
+{
+	int i;
+
+	for (i = 0; i < rev_nr; i++) {
+		if (!is_expected_rev(revs[i])) {
+			remove_path(git_path_bisect_ancestors_ok());
+			remove_path(git_path_bisect_expected_rev());
+			return 0;
+		}
+	}
+	return 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
 		NEXT_ALL = 1,
 		WRITE_TERMS,
 		BISECT_CLEAN_STATE,
-		BISECT_RESET
+		BISECT_RESET,
+		CHECK_EXPECTED_REVS
 	} cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {

@@ -180,6 +207,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("cleanup the bisection state"), BISECT_CLEAN_STATE),
 		OPT_CMDMODE(0, "bisect-reset", &cmdmode,
 			 N_("reset the bisection state"), BISECT_RESET),
+		OPT_CMDMODE(0, "check-expected-revs", &cmdmode,
+			 N_("check for expected revs"), CHECK_EXPECTED_REVS),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()

@@ -206,6 +235,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		if (argc > 1)
 			die(_("--bisect-reset requires either zero or one arguments"));
 		return bisect_reset(argc ? argv[0] : NULL);
+	case CHECK_EXPECTED_REVS:
+		return check_expected_revs(argv, argc);
 	default:
 		die("BUG: unknown subcommand '%d'", cmdmode);
 	}

@@ -238,22 +238,6 @@ bisect_write() {
 	test -n "$nolog" || echo "git bisect $state $rev" >>"$GIT_DIR/BISECT_LOG"
 }
 
-is_expected_rev() {
-	test -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
-	test "$1" = $(cat "$GIT_DIR/BISECT_EXPECTED_REV")
-}
-
-check_expected_revs() {
-	for _rev in "$@"; do
-		if ! is_expected_rev "$_rev"
-		then
-			rm -f "$GIT_DIR/BISECT_ANCESTORS_OK"
-			rm -f "$GIT_DIR/BISECT_EXPECTED_REV"
-			return
-		fi
-	done
-}
-
 bisect_skip() {
 	all=''
 	for arg in "$@"

@@ -280,7 +264,7 @@ bisect_state() {
 		rev=$(git rev-parse --verify $(bisect_head)) ||
 			die "$(gettext "Bad rev input: $(bisect_head)")"
 		bisect_write "$state" "$rev"
-		check_expected_revs "$rev" ;;
+		git bisect--helper --check-expected-revs "$rev" ;;
 	2,"$TERM_BAD"|*,"$TERM_GOOD"|*,skip)
 		shift
 		hash_list=''