1 files changed, 910 insertions, 50 deletions

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 4b5fadcbe1..709eb713a3 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -3,18 +3,67 @@
 #include "parse-options.h"
 #include "bisect.h"
 #include "refs.h"
+#include "dir.h"
+#include "strvec.h"
+#include "run-command.h"
+#include "prompt.h"
+#include "quote.h"
+#include "revision.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_start, "BISECT_START")
+static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
+static GIT_PATH_FUNC(git_path_head_name, "head-name")
+static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
+static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
 
 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>]"),
+	N_("git bisect--helper --bisect-write [--no-log] <state> <revision> <good_term> <bad_term>"),
+	N_("git bisect--helper --bisect-check-and-set-terms <command> <good_term> <bad_term>"),
+	N_("git bisect--helper --bisect-next-check <good_term> <bad_term> [<term>]"),
+	N_("git bisect--helper --bisect-terms [--term-good | --term-old | --term-bad | --term-new]"),
+	N_("git bisect--helper --bisect-start [--term-{new,bad}=<term> --term-{old,good}=<term>]"
+					    " [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<paths>...]"),
+	N_("git bisect--helper --bisect-next"),
+	N_("git bisect--helper --bisect-auto-next"),
+	N_("git bisect--helper --bisect-state (bad|new) [<rev>]"),
+	N_("git bisect--helper --bisect-state (good|old) [<rev>...]"),
 	NULL
 };
 
+struct add_bisect_ref_data {
+	struct rev_info *revs;
+	unsigned int object_flags;
+};
+
+struct bisect_terms {
+	char *term_good;
+	char *term_bad;
+};
+
+static void free_terms(struct bisect_terms *terms)
+{
+	FREE_AND_NULL(terms->term_good);
+	FREE_AND_NULL(terms->term_bad);
+}
+
+static void set_terms(struct bisect_terms *terms, const char *bad,
+		      const char *good)
+{
+	free((void *)terms->term_good);
+	terms->term_good = xstrdup(good);
+	free((void *)terms->term_bad);
+	terms->term_bad = xstrdup(bad);
+}
+
+static const char vocab_bad[] = "bad|new";
+static const char vocab_good[] = "good|old";
+
+static int bisect_autostart(struct bisect_terms *terms);
+
 /*
  * Check whether the string `term` belongs to the set of strings
  * included in the variable arguments.
@@ -34,6 +83,65 @@ static int one_of(const char *term, ...)
 	return res;
 }
 
+/*
+ * return code BISECT_INTERNAL_SUCCESS_MERGE_BASE
+ * and BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND are codes
+ * that indicate special success.
+ */
+
+static int is_bisect_success(enum bisect_error res)
+{
+	return !res ||
+		res == BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND ||
+		res == BISECT_INTERNAL_SUCCESS_MERGE_BASE;
+}
+
+static int write_in_file(const char *path, const char *mode, const char *format, va_list args)
+{
+	FILE *fp = NULL;
+	int res = 0;
+
+	if (strcmp(mode, "w") && strcmp(mode, "a"))
+		BUG("write-in-file does not support '%s' mode", mode);
+	fp = fopen(path, mode);
+	if (!fp)
+		return error_errno(_("cannot open file '%s' in mode '%s'"), path, mode);
+	res = vfprintf(fp, format, args);
+
+	if (res < 0) {
+		int saved_errno = errno;
+		fclose(fp);
+		errno = saved_errno;
+		return error_errno(_("could not write to file '%s'"), path);
+	}
+
+	return fclose(fp);
+}
+
+static int write_to_file(const char *path, const char *format, ...)
+{
+	int res;
+	va_list args;
+
+	va_start(args, format);
+	res = write_in_file(path, "w", format, args);
+	va_end(args);
+
+	return res;
+}
+
+static int append_to_file(const char *path, const char *format, ...)
+{
+	int res;
+	va_list args;
+
+	va_start(args, format);
+	res = write_in_file(path, "a", format, args);
+	va_end(args);
+
+	return res;
+}
+
 static int check_term_format(const char *term, const char *orig_term)
 {
 	int res;
@@ -64,7 +172,6 @@ static int check_term_format(const char *term, const char *orig_term)
 
 static int write_terms(const char *bad, const char *good)
 {
-	FILE *fp = NULL;
 	int res;
 
 	if (!strcmp(bad, good))
@@ -73,84 +180,837 @@ 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_terms(), "w");
+	res = write_to_file(git_path_bisect_terms(), "%s\n%s\n", bad, good);
+
+	return res;
+}
+
+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(commit, &oid))
+			return error(_("'%s' is not a valid commit"), commit);
+		strbuf_addstr(&branch, commit);
+	}
+
+	if (!ref_exists("BISECT_HEAD")) {
+		struct strvec argv = STRVEC_INIT;
+
+		strvec_pushl(&argv, "checkout", branch.buf, "--", NULL);
+		if (run_command_v_opt(argv.v, RUN_GIT_CMD)) {
+			error(_("could not check out original"
+				" HEAD '%s'. Try 'git bisect"
+				" reset <commit>'."), branch.buf);
+			strbuf_release(&branch);
+			strvec_clear(&argv);
+			return -1;
+		}
+		strvec_clear(&argv);
+	}
+
+	strbuf_release(&branch);
+	return bisect_clean_state();
+}
+
+static void log_commit(FILE *fp, char *fmt, const char *state,
+		       struct commit *commit)
+{
+	struct pretty_print_context pp = {0};
+	struct strbuf commit_msg = STRBUF_INIT;
+	char *label = xstrfmt(fmt, state);
+
+	format_commit_message(commit, "%s", &commit_msg, &pp);
+
+	fprintf(fp, "# %s: [%s] %s\n", label, oid_to_hex(&commit->object.oid),
+		commit_msg.buf);
+
+	strbuf_release(&commit_msg);
+	free(label);
+}
+
+static int bisect_write(const char *state, const char *rev,
+			const struct bisect_terms *terms, int nolog)
+{
+	struct strbuf tag = STRBUF_INIT;
+	struct object_id oid;
+	struct commit *commit;
+	FILE *fp = NULL;
+	int res = 0;
+
+	if (!strcmp(state, terms->term_bad)) {
+		strbuf_addf(&tag, "refs/bisect/%s", state);
+	} else if (one_of(state, terms->term_good, "skip", NULL)) {
+		strbuf_addf(&tag, "refs/bisect/%s-%s", state, rev);
+	} else {
+		res = error(_("Bad bisect_write argument: %s"), state);
+		goto finish;
+	}
+
+	if (get_oid(rev, &oid)) {
+		res = error(_("couldn't get the oid of the rev '%s'"), rev);
+		goto finish;
+	}
+
+	if (update_ref(NULL, tag.buf, &oid, NULL, 0,
+		       UPDATE_REFS_MSG_ON_ERR)) {
+		res = -1;
+		goto finish;
+	}
+
+	fp = fopen(git_path_bisect_log(), "a");
+	if (!fp) {
+		res = error_errno(_("couldn't open the file '%s'"), git_path_bisect_log());
+		goto finish;
+	}
+
+	commit = lookup_commit_reference(the_repository, &oid);
+	log_commit(fp, "%s", state, commit);
+
+	if (!nolog)
+		fprintf(fp, "git bisect %s %s\n", state, rev);
+
+finish:
+	if (fp)
+		fclose(fp);
+	strbuf_release(&tag);
+	return res;
+}
+
+static int check_and_set_terms(struct bisect_terms *terms, const char *cmd)
+{
+	int has_term_file = !is_empty_or_missing_file(git_path_bisect_terms());
+
+	if (one_of(cmd, "skip", "start", "terms", NULL))
+		return 0;
+
+	if (has_term_file && strcmp(cmd, terms->term_bad) &&
+	    strcmp(cmd, terms->term_good))
+		return error(_("Invalid command: you're currently in a "
+				"%s/%s bisect"), terms->term_bad,
+				terms->term_good);
+
+	if (!has_term_file) {
+		if (one_of(cmd, "bad", "good", NULL)) {
+			set_terms(terms, "bad", "good");
+			return write_terms(terms->term_bad, terms->term_good);
+		}
+		if (one_of(cmd, "new", "old", NULL)) {
+			set_terms(terms, "new", "old");
+			return write_terms(terms->term_bad, terms->term_good);
+		}
+	}
+
+	return 0;
+}
+
+static int mark_good(const char *refname, const struct object_id *oid,
+		     int flag, void *cb_data)
+{
+	int *m_good = (int *)cb_data;
+	*m_good = 0;
+	return 1;
+}
+
+static const char need_bad_and_good_revision_warning[] =
+	N_("You need to give me at least one %s and %s revision.\n"
+	   "You can use \"git bisect %s\" and \"git bisect %s\" for that.");
+
+static const char need_bisect_start_warning[] =
+	N_("You need to start by \"git bisect start\".\n"
+	   "You then need to give me at least one %s and %s revision.\n"
+	   "You can use \"git bisect %s\" and \"git bisect %s\" for that.");
+
+static int decide_next(const struct bisect_terms *terms,
+		       const char *current_term, int missing_good,
+		       int missing_bad)
+{
+	if (!missing_good && !missing_bad)
+		return 0;
+	if (!current_term)
+		return -1;
+
+	if (missing_good && !missing_bad &&
+	    !strcmp(current_term, terms->term_good)) {
+		char *yesno;
+		/*
+		 * have bad (or new) but not good (or old). We could bisect
+		 * although this is less optimum.
+		 */
+		warning(_("bisecting only with a %s commit"), terms->term_bad);
+		if (!isatty(0))
+			return 0;
+		/*
+		 * TRANSLATORS: Make sure to include [Y] and [n] in your
+		 * translation. The program will only accept English input
+		 * at this point.
+		 */
+		yesno = git_prompt(_("Are you sure [Y/n]? "), PROMPT_ECHO);
+		if (starts_with(yesno, "N") || starts_with(yesno, "n"))
+			return -1;
+		return 0;
+	}
+
+	if (!is_empty_or_missing_file(git_path_bisect_start()))
+		return error(_(need_bad_and_good_revision_warning),
+			     vocab_bad, vocab_good, vocab_bad, vocab_good);
+	else
+		return error(_(need_bisect_start_warning),
+			     vocab_good, vocab_bad, vocab_good, vocab_bad);
+}
+
+static int bisect_next_check(const struct bisect_terms *terms,
+			     const char *current_term)
+{
+	int missing_good = 1, missing_bad = 1;
+	char *bad_ref = xstrfmt("refs/bisect/%s", terms->term_bad);
+	char *good_glob = xstrfmt("%s-*", terms->term_good);
+
+	if (ref_exists(bad_ref))
+		missing_bad = 0;
+
+	for_each_glob_ref_in(mark_good, good_glob, "refs/bisect/",
+			     (void *) &missing_good);
+
+	free(good_glob);
+	free(bad_ref);
+
+	return decide_next(terms, current_term, missing_good, missing_bad);
+}
+
+static int get_terms(struct bisect_terms *terms)
+{
+	struct strbuf str = STRBUF_INIT;
+	FILE *fp = NULL;
+	int res = 0;
+
+	fp = fopen(git_path_bisect_terms(), "r");
+	if (!fp) {
+		res = -1;
+		goto finish;
+	}
+
+	free_terms(terms);
+	strbuf_getline_lf(&str, fp);
+	terms->term_bad = strbuf_detach(&str, NULL);
+	strbuf_getline_lf(&str, fp);
+	terms->term_good = strbuf_detach(&str, NULL);
+
+finish:
+	if (fp)
+		fclose(fp);
+	strbuf_release(&str);
+	return res;
+}
+
+static int bisect_terms(struct bisect_terms *terms, const char *option)
+{
+	if (get_terms(terms))
+		return error(_("no terms defined"));
+
+	if (option == NULL) {
+		printf(_("Your current terms are %s for the old state\n"
+			 "and %s for the new state.\n"),
+		       terms->term_good, terms->term_bad);
+		return 0;
+	}
+	if (one_of(option, "--term-good", "--term-old", NULL))
+		printf("%s\n", terms->term_good);
+	else if (one_of(option, "--term-bad", "--term-new", NULL))
+		printf("%s\n", terms->term_bad);
+	else
+		return error(_("invalid argument %s for 'git bisect terms'.\n"
+			       "Supported options are: "
+			       "--term-good|--term-old and "
+			       "--term-bad|--term-new."), option);
+
+	return 0;
+}
+
+static int bisect_append_log_quoted(const char **argv)
+{
+	int res = 0;
+	FILE *fp = fopen(git_path_bisect_log(), "a");
+	struct strbuf orig_args = STRBUF_INIT;
+
 	if (!fp)
-		return error_errno(_("could not open the file BISECT_TERMS"));
+		return -1;
+
+	if (fprintf(fp, "git bisect start") < 1) {
+		res = -1;
+		goto finish;
+	}
+
+	sq_quote_argv(&orig_args, argv);
+	if (fprintf(fp, "%s\n", orig_args.buf) < 1)
+		res = -1;
 
-	res = fprintf(fp, "%s\n%s\n", bad, good);
-	res |= fclose(fp);
-	return (res < 0) ? -1 : 0;
+finish:
+	fclose(fp);
+	strbuf_release(&orig_args);
+	return res;
 }
 
-static int is_expected_rev(const char *expected_hex)
+static int add_bisect_ref(const char *refname, const struct object_id *oid,
+			  int flags, void *cb)
+{
+	struct add_bisect_ref_data *data = cb;
+
+	add_pending_oid(data->revs, refname, oid, data->object_flags);
+
+	return 0;
+}
+
+static int prepare_revs(struct bisect_terms *terms, struct rev_info *revs)
 {
-	struct strbuf actual_hex = STRBUF_INIT;
 	int res = 0;
-	if (strbuf_read_file(&actual_hex, git_path_bisect_expected_rev(), 0) >= 40) {
-		strbuf_trim(&actual_hex);
-		res = !strcmp(actual_hex.buf, expected_hex);
+	struct add_bisect_ref_data cb = { revs };
+	char *good = xstrfmt("%s-*", terms->term_good);
+
+	/*
+	 * We cannot use terms->term_bad directly in
+	 * for_each_glob_ref_in() and we have to append a '*' to it,
+	 * otherwise for_each_glob_ref_in() will append '/' and '*'.
+	 */
+	char *bad = xstrfmt("%s*", terms->term_bad);
+
+	/*
+	 * It is important to reset the flags used by revision walks
+	 * as the previous call to bisect_next_all() in turn
+	 * sets up a revision walk.
+	 */
+	reset_revision_walk();
+	init_revisions(revs, NULL);
+	setup_revisions(0, NULL, revs, NULL);
+	for_each_glob_ref_in(add_bisect_ref, bad, "refs/bisect/", &cb);
+	cb.object_flags = UNINTERESTING;
+	for_each_glob_ref_in(add_bisect_ref, good, "refs/bisect/", &cb);
+	if (prepare_revision_walk(revs))
+		res = error(_("revision walk setup failed\n"));
+
+	free(good);
+	free(bad);
+	return res;
+}
+
+static int bisect_skipped_commits(struct bisect_terms *terms)
+{
+	int res;
+	FILE *fp = NULL;
+	struct rev_info revs;
+	struct commit *commit;
+	struct pretty_print_context pp = {0};
+	struct strbuf commit_name = STRBUF_INIT;
+
+	res = prepare_revs(terms, &revs);
+	if (res)
+		return res;
+
+	fp = fopen(git_path_bisect_log(), "a");
+	if (!fp)
+		return error_errno(_("could not open '%s' for appending"),
+				  git_path_bisect_log());
+
+	if (fprintf(fp, "# only skipped commits left to test\n") < 0)
+		return error_errno(_("failed to write to '%s'"), git_path_bisect_log());
+
+	while ((commit = get_revision(&revs)) != NULL) {
+		strbuf_reset(&commit_name);
+		format_commit_message(commit, "%s",
+				      &commit_name, &pp);
+		fprintf(fp, "# possible first %s commit: [%s] %s\n",
+			terms->term_bad, oid_to_hex(&commit->object.oid),
+			commit_name.buf);
 	}
-	strbuf_release(&actual_hex);
+
+	/*
+	 * Reset the flags used by revision walks in case
+	 * there is another revision walk after this one.
+	 */
+	reset_revision_walk();
+
+	strbuf_release(&commit_name);
+	fclose(fp);
+	return 0;
+}
+
+static int bisect_successful(struct bisect_terms *terms)
+{
+	struct object_id oid;
+	struct commit *commit;
+	struct pretty_print_context pp = {0};
+	struct strbuf commit_name = STRBUF_INIT;
+	char *bad_ref = xstrfmt("refs/bisect/%s",terms->term_bad);
+	int res;
+
+	read_ref(bad_ref, &oid);
+	commit = lookup_commit_reference_by_name(bad_ref);
+	format_commit_message(commit, "%s", &commit_name, &pp);
+
+	res = append_to_file(git_path_bisect_log(), "# first %s commit: [%s] %s\n",
+			    terms->term_bad, oid_to_hex(&commit->object.oid),
+			    commit_name.buf);
+
+	strbuf_release(&commit_name);
+	free(bad_ref);
 	return res;
 }
 
-static void check_expected_revs(const char **revs, int rev_nr)
+static enum bisect_error bisect_next(struct bisect_terms *terms, const char *prefix)
 {
-	int i;
+	enum bisect_error res;
 
-	for (i = 0; i < rev_nr; i++) {
-		if (!is_expected_rev(revs[i])) {
+	if (bisect_autostart(terms))
+		return BISECT_FAILED;
+
+	if (bisect_next_check(terms, terms->term_good))
+		return BISECT_FAILED;
+
+	/* Perform all bisection computation */
+	res = bisect_next_all(the_repository, prefix);
+
+	if (res == BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND) {
+		res = bisect_successful(terms);
+		return res ? res : BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
+	} else if (res == BISECT_ONLY_SKIPPED_LEFT) {
+		res = bisect_skipped_commits(terms);
+		return res ? res : BISECT_ONLY_SKIPPED_LEFT;
+	}
+	return res;
+}
+
+static enum bisect_error bisect_auto_next(struct bisect_terms *terms, const char *prefix)
+{
+	if (bisect_next_check(terms, NULL))
+		return BISECT_OK;
+
+	return bisect_next(terms, prefix);
+}
+
+static enum bisect_error bisect_start(struct bisect_terms *terms, const char **argv, int argc)
+{
+	int no_checkout = 0;
+	int first_parent_only = 0;
+	int i, has_double_dash = 0, must_write_terms = 0, bad_seen = 0;
+	int flags, pathspec_pos;
+	enum bisect_error res = BISECT_OK;
+	struct string_list revs = STRING_LIST_INIT_DUP;
+	struct string_list states = STRING_LIST_INIT_DUP;
+	struct strbuf start_head = STRBUF_INIT;
+	struct strbuf bisect_names = STRBUF_INIT;
+	struct object_id head_oid;
+	struct object_id oid;
+	const char *head;
+
+	if (is_bare_repository())
+		no_checkout = 1;
+
+	/*
+	 * Check for one bad and then some good revisions
+	 */
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--")) {
+			has_double_dash = 1;
+			break;
+		}
+	}
+
+	for (i = 0; i < argc; i++) {
+		const char *arg = argv[i];
+		if (!strcmp(argv[i], "--")) {
+			break;
+		} else if (!strcmp(arg, "--no-checkout")) {
+			no_checkout = 1;
+		} else if (!strcmp(arg, "--first-parent")) {
+			first_parent_only = 1;
+		} else if (!strcmp(arg, "--term-good") ||
+			 !strcmp(arg, "--term-old")) {
+			i++;
+			if (argc <= i)
+				return error(_("'' is not a valid term"));
+			must_write_terms = 1;
+			free((void *) terms->term_good);
+			terms->term_good = xstrdup(argv[i]);
+		} else if (skip_prefix(arg, "--term-good=", &arg) ||
+			   skip_prefix(arg, "--term-old=", &arg)) {
+			must_write_terms = 1;
+			free((void *) terms->term_good);
+			terms->term_good = xstrdup(arg);
+		} else if (!strcmp(arg, "--term-bad") ||
+			 !strcmp(arg, "--term-new")) {
+			i++;
+			if (argc <= i)
+				return error(_("'' is not a valid term"));
+			must_write_terms = 1;
+			free((void *) terms->term_bad);
+			terms->term_bad = xstrdup(argv[i]);
+		} else if (skip_prefix(arg, "--term-bad=", &arg) ||
+			   skip_prefix(arg, "--term-new=", &arg)) {
+			must_write_terms = 1;
+			free((void *) terms->term_bad);
+			terms->term_bad = xstrdup(arg);
+		} else if (starts_with(arg, "--")) {
+			return error(_("unrecognized option: '%s'"), arg);
+		} else if (!get_oidf(&oid, "%s^{commit}", arg)) {
+			string_list_append(&revs, oid_to_hex(&oid));
+		} else if (has_double_dash) {
+			die(_("'%s' does not appear to be a valid "
+			      "revision"), arg);
+		} else {
+			break;
+		}
+	}
+	pathspec_pos = i;
+
+	/*
+	 * The user ran "git bisect start <sha1> <sha1>", hence did not
+	 * explicitly specify the terms, but we are already starting to
+	 * set references named with the default terms, and won't be able
+	 * to change afterwards.
+	 */
+	if (revs.nr)
+		must_write_terms = 1;
+	for (i = 0; i < revs.nr; i++) {
+		if (bad_seen) {
+			string_list_append(&states, terms->term_good);
+		} else {
+			bad_seen = 1;
+			string_list_append(&states, terms->term_bad);
+		}
+	}
+
+	/*
+	 * Verify HEAD
+	 */
+	head = resolve_ref_unsafe("HEAD", 0, &head_oid, &flags);
+	if (!head)
+		if (get_oid("HEAD", &head_oid))
+			return error(_("bad HEAD - I need a HEAD"));
+
+	/*
+	 * Check if we are bisecting
+	 */
+	if (!is_empty_or_missing_file(git_path_bisect_start())) {
+		/* Reset to the rev from where we started */
+		strbuf_read_file(&start_head, git_path_bisect_start(), 0);
+		strbuf_trim(&start_head);
+		if (!no_checkout) {
+			struct strvec argv = STRVEC_INIT;
+
+			strvec_pushl(&argv, "checkout", start_head.buf,
+				     "--", NULL);
+			if (run_command_v_opt(argv.v, RUN_GIT_CMD)) {
+				res = error(_("checking out '%s' failed."
+						 " Try 'git bisect start "
+						 "<valid-branch>'."),
+					       start_head.buf);
+				goto finish;
+			}
+		}
+	} else {
+		/* Get the rev from where we start. */
+		if (!get_oid(head, &head_oid) &&
+		    !starts_with(head, "refs/heads/")) {
+			strbuf_reset(&start_head);
+			strbuf_addstr(&start_head, oid_to_hex(&head_oid));
+		} else if (!get_oid(head, &head_oid) &&
+			   skip_prefix(head, "refs/heads/", &head)) {
+			/*
+			 * This error message should only be triggered by
+			 * cogito usage, and cogito users should understand
+			 * it relates to cg-seek.
+			 */
+			if (!is_empty_or_missing_file(git_path_head_name()))
+				return error(_("won't bisect on cg-seek'ed tree"));
+			strbuf_addstr(&start_head, head);
+		} else {
+			return error(_("bad HEAD - strange symbolic ref"));
+		}
+	}
+
+	/*
+	 * Get rid of any old bisect state.
+	 */
+	if (bisect_clean_state())
+		return BISECT_FAILED;
+
+	/*
+	 * Write new start state
+	 */
+	write_file(git_path_bisect_start(), "%s\n", start_head.buf);
+
+	if (first_parent_only)
+		write_file(git_path_bisect_first_parent(), "\n");
+
+	if (no_checkout) {
+		if (get_oid(start_head.buf, &oid) < 0) {
+			res = error(_("invalid ref: '%s'"), start_head.buf);
+			goto finish;
+		}
+		if (update_ref(NULL, "BISECT_HEAD", &oid, NULL, 0,
+			       UPDATE_REFS_MSG_ON_ERR)) {
+			res = BISECT_FAILED;
+			goto finish;
+		}
+	}
+
+	if (pathspec_pos < argc - 1)
+		sq_quote_argv(&bisect_names, argv + pathspec_pos);
+	write_file(git_path_bisect_names(), "%s\n", bisect_names.buf);
+
+	for (i = 0; i < states.nr; i++)
+		if (bisect_write(states.items[i].string,
+				 revs.items[i].string, terms, 1)) {
+			res = BISECT_FAILED;
+			goto finish;
+		}
+
+	if (must_write_terms && write_terms(terms->term_bad,
+					    terms->term_good)) {
+		res = BISECT_FAILED;
+		goto finish;
+	}
+
+	res = bisect_append_log_quoted(argv);
+	if (res)
+		res = BISECT_FAILED;
+
+finish:
+	string_list_clear(&revs, 0);
+	string_list_clear(&states, 0);
+	strbuf_release(&start_head);
+	strbuf_release(&bisect_names);
+	if (res)
+		return res;
+
+	res = bisect_auto_next(terms, NULL);
+	if (!is_bisect_success(res))
+		bisect_clean_state();
+	return res;
+}
+
+static inline int file_is_not_empty(const char *path)
+{
+	return !is_empty_or_missing_file(path);
+}
+
+static int bisect_autostart(struct bisect_terms *terms)
+{
+	int res;
+	const char *yesno;
+
+	if (file_is_not_empty(git_path_bisect_start()))
+		return 0;
+
+	fprintf_ln(stderr, _("You need to start by \"git bisect "
+			  "start\"\n"));
+
+	if (!isatty(STDIN_FILENO))
+		return -1;
+
+	/*
+	 * TRANSLATORS: Make sure to include [Y] and [n] in your
+	 * translation. The program will only accept English input
+	 * at this point.
+	 */
+	yesno = git_prompt(_("Do you want me to do it for you "
+			     "[Y/n]? "), PROMPT_ECHO);
+	res = tolower(*yesno) == 'n' ?
+		-1 : bisect_start(terms, empty_strvec, 0);
+
+	return res;
+}
+
+static enum bisect_error bisect_state(struct bisect_terms *terms, const char **argv,
+				      int argc)
+{
+	const char *state;
+	int i, verify_expected = 1;
+	struct object_id oid, expected;
+	struct strbuf buf = STRBUF_INIT;
+	struct oid_array revs = OID_ARRAY_INIT;
+
+	if (!argc)
+		return error(_("Please call `--bisect-state` with at least one argument"));
+
+	if (bisect_autostart(terms))
+		return BISECT_FAILED;
+
+	state = argv[0];
+	if (check_and_set_terms(terms, state) ||
+	    !one_of(state, terms->term_good, terms->term_bad, "skip", NULL))
+		return BISECT_FAILED;
+
+	argv++;
+	argc--;
+	if (argc > 1 && !strcmp(state, terms->term_bad))
+		return error(_("'git bisect %s' can take only one argument."), terms->term_bad);
+
+	if (argc == 0) {
+		const char *head = "BISECT_HEAD";
+		enum get_oid_result res_head = get_oid(head, &oid);
+
+		if (res_head == MISSING_OBJECT) {
+			head = "HEAD";
+			res_head = get_oid(head, &oid);
+		}
+
+		if (res_head)
+			error(_("Bad rev input: %s"), head);
+		oid_array_append(&revs, &oid);
+	}
+
+	/*
+	 * All input revs must be checked before executing bisect_write()
+	 * to discard junk revs.
+	 */
+
+	for (; argc; argc--, argv++) {
+		if (get_oid(*argv, &oid)){
+			error(_("Bad rev input: %s"), *argv);
+			oid_array_clear(&revs);
+			return BISECT_FAILED;
+		}
+		oid_array_append(&revs, &oid);
+	}
+
+	if (strbuf_read_file(&buf, git_path_bisect_expected_rev(), 0) < the_hash_algo->hexsz ||
+	    get_oid_hex(buf.buf, &expected) < 0)
+		verify_expected = 0; /* Ignore invalid file contents */
+	strbuf_release(&buf);
+
+	for (i = 0; i < revs.nr; i++) {
+		if (bisect_write(state, oid_to_hex(&revs.oid[i]), terms, 0)) {
+			oid_array_clear(&revs);
+			return BISECT_FAILED;
+		}
+		if (verify_expected && !oideq(&revs.oid[i], &expected)) {
 			unlink_or_warn(git_path_bisect_ancestors_ok());
 			unlink_or_warn(git_path_bisect_expected_rev());
+			verify_expected = 0;
 		}
 	}
+
+	oid_array_clear(&revs);
+	return bisect_auto_next(terms, NULL);
 }
 
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
-		NEXT_ALL = 1,
-		WRITE_TERMS,
-		BISECT_CLEAN_STATE,
-		CHECK_EXPECTED_REVS
+		BISECT_RESET = 1,
+		BISECT_WRITE,
+		CHECK_AND_SET_TERMS,
+		BISECT_NEXT_CHECK,
+		BISECT_TERMS,
+		BISECT_START,
+		BISECT_AUTOSTART,
+		BISECT_NEXT,
+		BISECT_AUTO_NEXT,
+		BISECT_STATE
 	} cmdmode = 0;
-	int no_checkout = 0;
+	int res = 0, nolog = 0;
 	struct option options[] = {
-		OPT_CMDMODE(0, "next-all", &cmdmode,
-			 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_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_CMDMODE(0, "bisect-reset", &cmdmode,
+			 N_("reset the bisection state"), BISECT_RESET),
+		OPT_CMDMODE(0, "bisect-write", &cmdmode,
+			 N_("write out the bisection state in BISECT_LOG"), BISECT_WRITE),
+		OPT_CMDMODE(0, "check-and-set-terms", &cmdmode,
+			 N_("check and set terms in a bisection state"), CHECK_AND_SET_TERMS),
+		OPT_CMDMODE(0, "bisect-next-check", &cmdmode,
+			 N_("check whether bad or good terms exist"), BISECT_NEXT_CHECK),
+		OPT_CMDMODE(0, "bisect-terms", &cmdmode,
+			 N_("print out the bisect terms"), BISECT_TERMS),
+		OPT_CMDMODE(0, "bisect-start", &cmdmode,
+			 N_("start the bisect session"), BISECT_START),
+		OPT_CMDMODE(0, "bisect-next", &cmdmode,
+			 N_("find the next bisection commit"), BISECT_NEXT),
+		OPT_CMDMODE(0, "bisect-auto-next", &cmdmode,
+			 N_("verify the next bisection state then checkout the next bisection commit"), BISECT_AUTO_NEXT),
+		OPT_CMDMODE(0, "bisect-state", &cmdmode,
+			 N_("mark the state of ref (or refs)"), BISECT_STATE),
+		OPT_BOOL(0, "no-log", &nolog,
+			 N_("no log for BISECT_WRITE")),
 		OPT_END()
 	};
+	struct bisect_terms terms = { .term_good = NULL, .term_bad = NULL };
 
 	argc = parse_options(argc, argv, prefix, options,
-			     git_bisect_helper_usage, 0);
+			     git_bisect_helper_usage,
+			     PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_UNKNOWN);
 
 	if (!cmdmode)
 		usage_with_options(git_bisect_helper_usage, options);
 
 	switch (cmdmode) {
-	case NEXT_ALL:
-		return bisect_next_all(prefix, no_checkout);
-	case WRITE_TERMS:
-		if (argc != 2)
-			return error(_("--write-terms requires two arguments"));
-		return write_terms(argv[0], argv[1]);
-	case BISECT_CLEAN_STATE:
-		if (argc != 0)
-			return error(_("--bisect-clean-state requires no arguments"));
-		return bisect_clean_state();
-	case CHECK_EXPECTED_REVS:
-		check_expected_revs(argv, argc);
-		return 0;
+	case BISECT_RESET:
+		if (argc > 1)
+			return error(_("--bisect-reset requires either no argument or a commit"));
+		return !!bisect_reset(argc ? argv[0] : NULL);
+	case BISECT_WRITE:
+		if (argc != 4 && argc != 5)
+			return error(_("--bisect-write requires either 4 or 5 arguments"));
+		set_terms(&terms, argv[3], argv[2]);
+		res = bisect_write(argv[0], argv[1], &terms, nolog);
+		break;
+	case CHECK_AND_SET_TERMS:
+		if (argc != 3)
+			return error(_("--check-and-set-terms requires 3 arguments"));
+		set_terms(&terms, argv[2], argv[1]);
+		res = check_and_set_terms(&terms, argv[0]);
+		break;
+	case BISECT_NEXT_CHECK:
+		if (argc != 2 && argc != 3)
+			return error(_("--bisect-next-check requires 2 or 3 arguments"));
+		set_terms(&terms, argv[1], argv[0]);
+		res = bisect_next_check(&terms, argc == 3 ? argv[2] : NULL);
+		break;
+	case BISECT_TERMS:
+		if (argc > 1)
+			return error(_("--bisect-terms requires 0 or 1 argument"));
+		res = bisect_terms(&terms, argc == 1 ? argv[0] : NULL);
+		break;
+	case BISECT_START:
+		set_terms(&terms, "bad", "good");
+		res = bisect_start(&terms, argv, argc);
+		break;
+	case BISECT_NEXT:
+		if (argc)
+			return error(_("--bisect-next requires 0 arguments"));
+		get_terms(&terms);
+		res = bisect_next(&terms, prefix);
+		break;
+	case BISECT_AUTO_NEXT:
+		if (argc)
+			return error(_("--bisect-auto-next requires 0 arguments"));
+		get_terms(&terms);
+		res = bisect_auto_next(&terms, prefix);
+		break;
+	case BISECT_STATE:
+		set_terms(&terms, "bad", "good");
+		get_terms(&terms);
+		res = bisect_state(&terms, argv, argc);
+		break;
 	default:
-		return error("BUG: unknown subcommand '%d'", cmdmode);
+		BUG("unknown subcommand %d", cmdmode);
 	}
-	return 0;
+	free_terms(&terms);
+
+	/*
+	 * Handle early success
+	 * From check_merge_bases > check_good_are_ancestors_of_bad > bisect_next_all
+	 */
+	if ((res == BISECT_INTERNAL_SUCCESS_MERGE_BASE) || (res == BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND))
+		res = BISECT_OK;
+
+	return -res;
 }