git-bisect.sh - jrn/git - Git at Google

 #!/bin/sh

 USAGE='[help|start|bad|good|new|old|terms|skip|next|reset|visualize|view|replay|log|run]'
 LONG_USAGE='git bisect help
 	print this long help message.
 git bisect start [--term-{old,good}=<term> --term-{new,bad}=<term>]
 		 [--no-checkout] [<bad> [<good>...]] [--] [<pathspec>...]
 	reset bisect state and start bisection.
 git bisect (bad|new) [<rev>]
 	mark <rev> a known-bad revision/
 		a revision after change in a given property.
 git bisect (good|old) [<rev>...]
 	mark <rev>... known-good revisions/
 		revisions before change in a given property.
 git bisect terms [--term-good | --term-bad]
 	show the terms used for old and new commits (default: bad, good)
 git bisect skip [(<rev>|<range>)...]
 	mark <rev>... untestable revisions.
 git bisect next
 	find next bisection to test and check it out.
 git bisect reset [<commit>]
 	finish bisection search and go back to commit.
 git bisect (visualize|view)
 	show bisect status in gitk.
 git bisect replay <logfile>
 	replay bisection log.
 git bisect log
 	show bisect log.
 git bisect run <cmd>...
 	use <cmd>... to automatically bisect.

 Please use "git help bisect" to get the full man page.'

 OPTIONS_SPEC=
 . git-sh-setup

 _x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
 _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 TERM_BAD=bad
 TERM_GOOD=good

 bisect_head()
 {
 	if test -f "$GIT_DIR/BISECT_HEAD"
 	then
 		echo BISECT_HEAD
 	else
 		echo HEAD
 	fi
 }

 bisect_autostart() {
 	test -s "$GIT_DIR/BISECT_START" || {
 		gettextln "You need to start by \"git bisect start\"" >&2
 		if test -t 0
 		then
 			# TRANSLATORS: Make sure to include [Y] and [n] in your
 			# translation. The program will only accept English input
 			# at this point.
 			gettext "Do you want me to do it for you [Y/n]? " >&2
 			read yesno
 			case "$yesno" in
 			[Nn]*)
 				exit ;;
 			esac
 			bisect_start
 		else
 			exit 1
 		fi
 	}
 }

 bisect_start() {
 	#
 	# Check for one bad and then some good revisions.
 	#
 	has_double_dash=0
 	for arg; do
 		case "$arg" in --) has_double_dash=1; break ;; esac
 	done
 	orig_args=$(git rev-parse --sq-quote "$@")
 	bad_seen=0
 	eval=''
 	must_write_terms=0
 	revs=''
 	if test "z$(git rev-parse --is-bare-repository)" != zfalse
 	then
 		mode=--no-checkout
 	else
 		mode=''
 	fi
 	while [ $# -gt 0 ]; do
 		arg="$1"
 		case "$arg" in
 		--)
 			shift
 			break
 		;;
 		--no-checkout)
 			mode=--no-checkout
 			shift ;;
 		--term-good|--term-old)
 			shift
 			must_write_terms=1
 			TERM_GOOD=$1
 			shift ;;
 		--term-good=*|--term-old=*)
 			must_write_terms=1
 			TERM_GOOD=${1#*=}
 			shift ;;
 		--term-bad|--term-new)
 			shift
 			must_write_terms=1
 			TERM_BAD=$1
 			shift ;;
 		--term-bad=*|--term-new=*)
 			must_write_terms=1
 			TERM_BAD=${1#*=}
 			shift ;;
 		--*)
 			die "$(eval_gettext "unrecognised option: '\$arg'")" ;;
 		*)
 			rev=$(git rev-parse -q --verify "$arg^{commit}") || {
 				test $has_double_dash -eq 1 &&
 				die "$(eval_gettext "'\$arg' does not appear to be a valid revision")"
 				break
 			}
 			revs="$revs $rev"
 			shift
 			;;
 		esac
 	done

 	for rev in $revs
 	do
 		# 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.
 		must_write_terms=1

 		case $bad_seen in
 		0) state=$TERM_BAD ; bad_seen=1 ;;
 		*) state=$TERM_GOOD ;;
 		esac
 		eval="$eval bisect_write '$state' '$rev' 'nolog' &&"
 	done
 	#
 	# Verify HEAD.
 	#
 	head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) ||
 	head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
 	die "$(gettext "Bad HEAD - I need a HEAD")"

 	#
 	# Check if we are bisecting.
 	#
 	start_head=''
 	if test -s "$GIT_DIR/BISECT_START"
 	then
 		# Reset to the rev from where we started.
 		start_head=$(cat "$GIT_DIR/BISECT_START")
 		if test "z$mode" != "z--no-checkout"
 		then
 			git checkout "$start_head" -- ||
 			die "$(eval_gettext "Checking out '\$start_head' failed. Try 'git bisect reset <valid-branch>'.")"
 		fi
 	else
 		# Get rev from where we start.
 		case "$head" in
 		refs/heads/*|$_x40)
 			# This error message should only be triggered by
 			# cogito usage, and cogito users should understand
 			# it relates to cg-seek.
 			[ -s "$GIT_DIR/head-name" ] &&
 				die "$(gettext "won't bisect on cg-seek'ed tree")"
 			start_head="${head#refs/heads/}"
 			;;
 		*)
 			die "$(gettext "Bad HEAD - strange symbolic ref")"
 			;;
 		esac
 	fi

 	#
 	# Get rid of any old bisect state.
 	#
 	git bisect--helper --bisect-clean-state || exit

 	#
 	# Change state.
 	# In case of mistaken revs or checkout error, or signals received,
 	# "bisect_auto_next" below may exit or misbehave.
 	# We have to trap this to be able to clean up using
 	# "bisect_clean_state".
 	#
 	trap 'git bisect--helper --bisect-clean-state' 0
 	trap 'exit 255' 1 2 3 15

 	#
 	# Write new start state.
 	#
 	echo "$start_head" >"$GIT_DIR/BISECT_START" && {
 		test "z$mode" != "z--no-checkout" ||
 		git update-ref --no-deref BISECT_HEAD "$start_head"
 	} &&
 	git rev-parse --sq-quote "$@" >"$GIT_DIR/BISECT_NAMES" &&
 	eval "$eval true" &&
 	if test $must_write_terms -eq 1
 	then
 		git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" || exit
 	fi &&
 	echo "git bisect start$orig_args" >>"$GIT_DIR/BISECT_LOG" || exit
 	#
 	# Check if we can proceed to the next bisect state.
 	#
 	bisect_auto_next

 	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 "$@"
 	do
 		case "$arg" in
 		*..*)
 			revs=$(git rev-list "$arg") || die "$(eval_gettext "Bad rev input: \$arg")" ;;
 		*)
 			revs=$(git rev-parse --sq-quote "$arg") ;;
 		esac
 		all="$all $revs"
 	done
 	eval bisect_state 'skip' $all
 }

 bisect_state() {
 	bisect_autostart
 	state=$1
 	check_and_set_terms $state
 	case "$#,$state" in
 	0,*)
 		die "Please call 'bisect_state' with at least one argument." ;;
 	1,"$TERM_BAD"|1,"$TERM_GOOD"|1,skip)
 		bisected_head=$(bisect_head)
 		rev=$(git rev-parse --verify "$bisected_head") ||
 			die "$(eval_gettext "Bad rev input: \$bisected_head")"
 		bisect_write "$state" "$rev"
 		git bisect--helper --check-expected-revs "$rev" ;;
 	2,"$TERM_BAD"|*,"$TERM_GOOD"|*,skip)
 		shift
 		hash_list=''
 		for rev in "$@"
 		do
 			sha=$(git rev-parse --verify "$rev^{commit}") ||
 				die "$(eval_gettext "Bad rev input: \$rev")"
 			hash_list="$hash_list $sha"
 		done
 		for rev in $hash_list
 		do
 			bisect_write "$state" "$rev"
 		done
 		git bisect--helper --check-expected-revs $hash_list ;;
 	*,"$TERM_BAD")
 		die "$(eval_gettext "'git bisect \$TERM_BAD' can take only one argument.")" ;;
 	*)
 		usage ;;
 	esac
 	bisect_auto_next
 }

 bisect_next_check() {
 	missing_good= missing_bad=
 	git show-ref -q --verify refs/bisect/$TERM_BAD || missing_bad=t
 	test -n "$(git for-each-ref "refs/bisect/$TERM_GOOD-*")" || missing_good=t

 	case "$missing_good,$missing_bad,$1" in
 	,,*)
 		: have both $TERM_GOOD and $TERM_BAD - ok
 		;;
 	*,)
 		# do not have both but not asked to fail - just report.
 		false
 		;;
 	t,,"$TERM_GOOD")
 		# have bad (or new) but not good (or old).  we could bisect although
 		# this is less optimum.
 		eval_gettextln "Warning: bisecting only with a \$TERM_BAD commit." >&2
 		if test -t 0
 		then
 			# TRANSLATORS: Make sure to include [Y] and [n] in your
 			# translation. The program will only accept English input
 			# at this point.
 			gettext "Are you sure [Y/n]? " >&2
 			read yesno
 			case "$yesno" in [Nn]*) exit 1 ;; esac
 		fi
 		: bisect without $TERM_GOOD...
 		;;
 	*)
 		bad_syn=$(bisect_voc bad)
 		good_syn=$(bisect_voc good)
 		if test -s "$GIT_DIR/BISECT_START"
 		then

 			eval_gettextln "You need to give me at least one \$bad_syn and one \$good_syn revision.
 (You can use \"git bisect \$bad_syn\" and \"git bisect \$good_syn\" for that.)" >&2
 		else
 			eval_gettextln "You need to start by \"git bisect start\".
 You then need to give me at least one \$good_syn and one \$bad_syn revision.
 (You can use \"git bisect \$bad_syn\" and \"git bisect \$good_syn\" for that.)" >&2
 		fi
 		exit 1 ;;
 	esac
 }

 bisect_auto_next() {
 	bisect_next_check && bisect_next || :
 }

 bisect_next() {
 	case "$#" in 0) ;; *) usage ;; esac
 	bisect_autostart
 	bisect_next_check $TERM_GOOD

 	# Perform all bisection computation, display and checkout
 	git bisect--helper --next-all $(test -f "$GIT_DIR/BISECT_HEAD" && echo --no-checkout)
 	res=$?

 	# Check if we should exit because bisection is finished
 	if test $res -eq 10
 	then
 		bad_rev=$(git show-ref --hash --verify refs/bisect/$TERM_BAD)
 		bad_commit=$(git show-branch $bad_rev)
 		echo "# first $TERM_BAD commit: $bad_commit" >>"$GIT_DIR/BISECT_LOG"
 		exit 0
 	elif test $res -eq 2
 	then
 		echo "# only skipped commits left to test" >>"$GIT_DIR/BISECT_LOG"
 		good_revs=$(git for-each-ref --format="%(objectname)" "refs/bisect/$TERM_GOOD-*")
 		for skipped in $(git rev-list refs/bisect/$TERM_BAD --not $good_revs)
 		do
 			skipped_commit=$(git show-branch $skipped)
 			echo "# possible first $TERM_BAD commit: $skipped_commit" >>"$GIT_DIR/BISECT_LOG"
 		done
 		exit $res
 	fi

 	# Check for an error in the bisection process
 	test $res -ne 0 && exit $res

 	return 0
 }

 bisect_visualize() {
 	bisect_next_check fail

 	if test $# = 0
 	then
 		if test -n "${DISPLAY+set}${SESSIONNAME+set}${MSYSTEM+set}${SECURITYSESSIONID+set}" &&
 			type gitk >/dev/null 2>&1
 		then
 			set gitk
 		else
 			set git log
 		fi
 	else
 		case "$1" in
 		git*|tig) ;;
 		-*)	set git log "$@" ;;
 		*)	set git "$@" ;;
 		esac
 	fi

 	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 "$(eval_gettext "cannot read \$file for replaying")"
 	bisect_reset
 	while read git bisect command rev
 	do
 		test "$git $bisect" = "git bisect" || test "$git" = "git-bisect" || continue
 		if test "$git" = "git-bisect"
 		then
 			rev="$command"
 			command="$bisect"
 		fi
 		get_terms
 		check_and_set_terms "$command"
 		case "$command" in
 		start)
 			cmd="bisect_start $rev"
 			eval "$cmd" ;;
 		"$TERM_GOOD"|"$TERM_BAD"|skip)
 			bisect_write "$command" "$rev" ;;
 		terms)
 			bisect_terms $rev ;;
 		*)
 			die "$(gettext "?? what are you talking about?")" ;;
 		esac
 	done <"$file"
 	bisect_auto_next
 }

 bisect_run () {
 	bisect_next_check fail

 	test -n "$*" || die "$(gettext "bisect run failed: no command provided.")"

 	while true
 	do
 		command="$@"
 		eval_gettextln "running \$command"
 		"$@"
 		res=$?

 		# Check for really bad run error.
 		if [ $res -lt 0 -o $res -ge 128 ]
 		then
 			eval_gettextln "bisect run failed:
 exit code \$res from '\$command' is < 0 or >= 128" >&2
 			exit $res
 		fi

 		# Find current state depending on run success or failure.
 		# A special exit code of 125 means cannot test.
 		if [ $res -eq 125 ]
 		then
 			state='skip'
 		elif [ $res -gt 0 ]
 		then
 			state="$TERM_BAD"
 		else
 			state="$TERM_GOOD"
 		fi

 		# We have to use a subshell because "bisect_state" can exit.
 		( bisect_state $state >"$GIT_DIR/BISECT_RUN" )
 		res=$?

 		cat "$GIT_DIR/BISECT_RUN"

 		if sane_grep "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN" \
 			>/dev/null
 		then
 			gettextln "bisect run cannot continue any more" >&2
 			exit $res
 		fi

 		if [ $res -ne 0 ]
 		then
 			eval_gettextln "bisect run failed:
 'bisect_state \$state' exited with error code \$res" >&2
 			exit $res
 		fi

 		if sane_grep "is the first $TERM_BAD commit" "$GIT_DIR/BISECT_RUN" >/dev/null
 		then
 			gettextln "bisect run success"
 			exit 0;
 		fi

 	done
 }

 bisect_log () {
 	test -s "$GIT_DIR/BISECT_LOG" || die "$(gettext "We are not bisecting.")"
 	cat "$GIT_DIR/BISECT_LOG"
 }

 get_terms () {
 	if test -s "$GIT_DIR/BISECT_TERMS"
 	then
 		{
 		read TERM_BAD
 		read TERM_GOOD
 		} <"$GIT_DIR/BISECT_TERMS"
 	fi
 }

 check_and_set_terms () {
 	cmd="$1"
 	case "$cmd" in
 	skip|start|terms) ;;
 	*)
 		if test -s "$GIT_DIR/BISECT_TERMS" && test "$cmd" != "$TERM_BAD" && test "$cmd" != "$TERM_GOOD"
 		then
 			die "$(eval_gettext "Invalid command: you're currently in a \$TERM_BAD/\$TERM_GOOD bisect.")"
 		fi
 		case "$cmd" in
 		bad|good)
 			if ! test -s "$GIT_DIR/BISECT_TERMS"
 			then
 				TERM_BAD=bad
 				TERM_GOOD=good
 				git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" || exit
 			fi
 			;;
 		new|old)
 			if ! test -s "$GIT_DIR/BISECT_TERMS"
 			then
 				TERM_BAD=new
 				TERM_GOOD=old
 				git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" || exit
 			fi
 			;;
 		esac ;;
 	esac
 }

 bisect_voc () {
 	case "$1" in
 	bad) echo "bad|new" ;;
 	good) echo "good|old" ;;
 	esac
 }

 bisect_terms () {
 	get_terms
 	if ! test -s "$GIT_DIR/BISECT_TERMS"
 	then
 		die "$(gettext "no terms defined")"
 	fi
 	case "$#" in
 	0)
 		gettextln "Your current terms are $TERM_GOOD for the old state
 and $TERM_BAD for the new state."
 		;;
 	1)
 		arg=$1
 		case "$arg" in
 			--term-good|--term-old)
 				printf '%s\n' "$TERM_GOOD"
 				;;
 			--term-bad|--term-new)
 				printf '%s\n' "$TERM_BAD"
 				;;
 			*)
 				die "$(eval_gettext "invalid argument \$arg for 'git bisect terms'.
 Supported options are: --term-good|--term-old and --term-bad|--term-new.")"
 				;;
 		esac
 		;;
 	*)
 		usage ;;
 	esac
 }

 case "$#" in
 0)
 	usage ;;
 *)
 	cmd="$1"
 	get_terms
 	shift
 	case "$cmd" in
 	help)
 		git bisect -h ;;
 	start)
 		bisect_start "$@" ;;
 	bad|good|new|old|"$TERM_BAD"|"$TERM_GOOD")
 		bisect_state "$cmd" "$@" ;;
 	skip)
 		bisect_skip "$@" ;;
 	next)
 		# Not sure we want "next" at the UI level anymore.
 		bisect_next "$@" ;;
 	visualize|view)
 		bisect_visualize "$@" ;;
 	reset)
 		bisect_reset "$@" ;;
 	replay)
 		bisect_replay "$@" ;;
 	log)
 		bisect_log ;;
 	run)
 		bisect_run "$@" ;;
 	terms)
 		bisect_terms "$@" ;;
 	*)
 		usage ;;
 	esac
 esac
	#!/bin/sh

	USAGE='[help\|start\|bad\|good\|new\|old\|terms\|skip\|next\|reset\|visualize\|view\|replay\|log\|run]'
	LONG_USAGE='git bisect help
	print this long help message.
	git bisect start [--term-{old,good}=<term> --term-{new,bad}=<term>]
	[--no-checkout] [<bad> [<good>...]] [--] [<pathspec>...]
	reset bisect state and start bisection.
	git bisect (bad\|new) [<rev>]
	mark <rev> a known-bad revision/
	a revision after change in a given property.
	git bisect (good\|old) [<rev>...]
	mark <rev>... known-good revisions/
	revisions before change in a given property.
	git bisect terms [--term-good \| --term-bad]
	show the terms used for old and new commits (default: bad, good)
	git bisect skip [(<rev>\|<range>)...]
	mark <rev>... untestable revisions.
	git bisect next
	find next bisection to test and check it out.
	git bisect reset [<commit>]
	finish bisection search and go back to commit.
	git bisect (visualize\|view)
	show bisect status in gitk.
	git bisect replay <logfile>
	replay bisection log.
	git bisect log
	show bisect log.
	git bisect run <cmd>...
	use <cmd>... to automatically bisect.

	Please use "git help bisect" to get the full man page.'

	OPTIONS_SPEC=
	. git-sh-setup

	_x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
	_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
	TERM_BAD=bad
	TERM_GOOD=good

	bisect_head()
	{
	if test -f "$GIT_DIR/BISECT_HEAD"
	then
	echo BISECT_HEAD
	else
	echo HEAD
	fi
	}

	bisect_autostart() {
	test -s "$GIT_DIR/BISECT_START" \|\| {
	gettextln "You need to start by \"git bisect start\"" >&2
	if test -t 0
	then
	# TRANSLATORS: Make sure to include [Y] and [n] in your
	# translation. The program will only accept English input
	# at this point.
	gettext "Do you want me to do it for you [Y/n]? " >&2
	read yesno
	case "$yesno" in
	[Nn]*)
	exit ;;
	esac
	bisect_start
	else
	exit 1
	fi
	}
	}

	bisect_start() {
	#
	# Check for one bad and then some good revisions.
	#
	has_double_dash=0
	for arg; do
	case "$arg" in --) has_double_dash=1; break ;; esac
	done
	orig_args=$(git rev-parse --sq-quote "$@")
	bad_seen=0
	eval=''
	must_write_terms=0
	revs=''
	if test "z$(git rev-parse --is-bare-repository)" != zfalse
	then
	mode=--no-checkout
	else
	mode=''
	fi
	while [ $# -gt 0 ]; do
	arg="$1"
	case "$arg" in
	--)
	shift
	break
	;;
	--no-checkout)
	mode=--no-checkout
	shift ;;
	--term-good\|--term-old)
	shift
	must_write_terms=1
	TERM_GOOD=$1
	shift ;;
	--term-good=\|--term-old=)
	must_write_terms=1
	TERM_GOOD=${1#*=}
	shift ;;
	--term-bad\|--term-new)
	shift
	must_write_terms=1
	TERM_BAD=$1
	shift ;;
	--term-bad=\|--term-new=)
	must_write_terms=1
	TERM_BAD=${1#*=}
	shift ;;
	--*)
	die "$(eval_gettext "unrecognised option: '\$arg'")" ;;
	*)
	rev=$(git rev-parse -q --verify "$arg^{commit}") \|\| {
	test $has_double_dash -eq 1 &&
	die "$(eval_gettext "'\$arg' does not appear to be a valid revision")"
	break
	}
	revs="$revs $rev"
	shift
	;;
	esac
	done

	for rev in $revs
	do
	# 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.
	must_write_terms=1

	case $bad_seen in
	0) state=$TERM_BAD ; bad_seen=1 ;;
	*) state=$TERM_GOOD ;;
	esac
	eval="$eval bisect_write '$state' '$rev' 'nolog' &&"
	done
	#
	# Verify HEAD.
	#
	head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) \|\|
	head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) \|\|
	die "$(gettext "Bad HEAD - I need a HEAD")"

	#
	# Check if we are bisecting.
	#
	start_head=''
	if test -s "$GIT_DIR/BISECT_START"
	then
	# Reset to the rev from where we started.
	start_head=$(cat "$GIT_DIR/BISECT_START")
	if test "z$mode" != "z--no-checkout"
	then
	git checkout "$start_head" -- \|\|
	die "$(eval_gettext "Checking out '\$start_head' failed. Try 'git bisect reset <valid-branch>'.")"
	fi
	else
	# Get rev from where we start.
	case "$head" in
	refs/heads/*\|$_x40)
	# This error message should only be triggered by
	# cogito usage, and cogito users should understand
	# it relates to cg-seek.
	[ -s "$GIT_DIR/head-name" ] &&
	die "$(gettext "won't bisect on cg-seek'ed tree")"
	start_head="${head#refs/heads/}"
	;;
	*)
	die "$(gettext "Bad HEAD - strange symbolic ref")"
	;;
	esac
	fi

	#
	# Get rid of any old bisect state.
	#
	git bisect--helper --bisect-clean-state \|\| exit

	#
	# Change state.
	# In case of mistaken revs or checkout error, or signals received,
	# "bisect_auto_next" below may exit or misbehave.
	# We have to trap this to be able to clean up using
	# "bisect_clean_state".
	#
	trap 'git bisect--helper --bisect-clean-state' 0
	trap 'exit 255' 1 2 3 15

	#
	# Write new start state.
	#
	echo "$start_head" >"$GIT_DIR/BISECT_START" && {
	test "z$mode" != "z--no-checkout" \|\|
	git update-ref --no-deref BISECT_HEAD "$start_head"
	} &&
	git rev-parse --sq-quote "$@" >"$GIT_DIR/BISECT_NAMES" &&
	eval "$eval true" &&
	if test $must_write_terms -eq 1
	then
	git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" \|\| exit
	fi &&
	echo "git bisect start$orig_args" >>"$GIT_DIR/BISECT_LOG" \|\| exit
	#
	# Check if we can proceed to the next bisect state.
	#
	bisect_auto_next

	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 "$@"
	do
	case "$arg" in
	..)
	revs=$(git rev-list "$arg") \|\| die "$(eval_gettext "Bad rev input: \$arg")" ;;
	*)
	revs=$(git rev-parse --sq-quote "$arg") ;;
	esac
	all="$all $revs"
	done
	eval bisect_state 'skip' $all
	}

	bisect_state() {
	bisect_autostart
	state=$1
	check_and_set_terms $state
	case "$#,$state" in
	0,*)
	die "Please call 'bisect_state' with at least one argument." ;;
	1,"$TERM_BAD"\|1,"$TERM_GOOD"\|1,skip)
	bisected_head=$(bisect_head)
	rev=$(git rev-parse --verify "$bisected_head") \|\|
	die "$(eval_gettext "Bad rev input: \$bisected_head")"
	bisect_write "$state" "$rev"
	git bisect--helper --check-expected-revs "$rev" ;;
	2,"$TERM_BAD"\|,"$TERM_GOOD"\|,skip)
	shift
	hash_list=''
	for rev in "$@"
	do
	sha=$(git rev-parse --verify "$rev^{commit}") \|\|
	die "$(eval_gettext "Bad rev input: \$rev")"
	hash_list="$hash_list $sha"
	done
	for rev in $hash_list
	do
	bisect_write "$state" "$rev"
	done
	git bisect--helper --check-expected-revs $hash_list ;;
	*,"$TERM_BAD")
	die "$(eval_gettext "'git bisect \$TERM_BAD' can take only one argument.")" ;;
	*)
	usage ;;
	esac
	bisect_auto_next
	}

	bisect_next_check() {
	missing_good= missing_bad=
	git show-ref -q --verify refs/bisect/$TERM_BAD \|\| missing_bad=t
	test -n "$(git for-each-ref "refs/bisect/$TERM_GOOD-*")" \|\| missing_good=t

	case "$missing_good,$missing_bad,$1" in
	,,*)
	: have both $TERM_GOOD and $TERM_BAD - ok
	;;
	*,)
	# do not have both but not asked to fail - just report.
	false
	;;
	t,,"$TERM_GOOD")
	# have bad (or new) but not good (or old). we could bisect although
	# this is less optimum.
	eval_gettextln "Warning: bisecting only with a \$TERM_BAD commit." >&2
	if test -t 0
	then
	# TRANSLATORS: Make sure to include [Y] and [n] in your
	# translation. The program will only accept English input
	# at this point.
	gettext "Are you sure [Y/n]? " >&2
	read yesno
	case "$yesno" in [Nn]*) exit 1 ;; esac
	fi
	: bisect without $TERM_GOOD...
	;;
	*)
	bad_syn=$(bisect_voc bad)
	good_syn=$(bisect_voc good)
	if test -s "$GIT_DIR/BISECT_START"
	then

	eval_gettextln "You need to give me at least one \$bad_syn and one \$good_syn revision.
	(You can use \"git bisect \$bad_syn\" and \"git bisect \$good_syn\" for that.)" >&2
	else
	eval_gettextln "You need to start by \"git bisect start\".
	You then need to give me at least one \$good_syn and one \$bad_syn revision.
	(You can use \"git bisect \$bad_syn\" and \"git bisect \$good_syn\" for that.)" >&2
	fi
	exit 1 ;;
	esac
	}

	bisect_auto_next() {
	bisect_next_check && bisect_next \|\| :
	}

	bisect_next() {
	case "$#" in 0) ;; *) usage ;; esac
	bisect_autostart
	bisect_next_check $TERM_GOOD

	# Perform all bisection computation, display and checkout
	git bisect--helper --next-all $(test -f "$GIT_DIR/BISECT_HEAD" && echo --no-checkout)
	res=$?

	# Check if we should exit because bisection is finished
	if test $res -eq 10
	then
	bad_rev=$(git show-ref --hash --verify refs/bisect/$TERM_BAD)
	bad_commit=$(git show-branch $bad_rev)
	echo "# first $TERM_BAD commit: $bad_commit" >>"$GIT_DIR/BISECT_LOG"
	exit 0
	elif test $res -eq 2
	then
	echo "# only skipped commits left to test" >>"$GIT_DIR/BISECT_LOG"
	good_revs=$(git for-each-ref --format="%(objectname)" "refs/bisect/$TERM_GOOD-*")
	for skipped in $(git rev-list refs/bisect/$TERM_BAD --not $good_revs)
	do
	skipped_commit=$(git show-branch $skipped)
	echo "# possible first $TERM_BAD commit: $skipped_commit" >>"$GIT_DIR/BISECT_LOG"
	done
	exit $res
	fi

	# Check for an error in the bisection process
	test $res -ne 0 && exit $res

	return 0
	}

	bisect_visualize() {
	bisect_next_check fail

	if test $# = 0
	then
	if test -n "${DISPLAY+set}${SESSIONNAME+set}${MSYSTEM+set}${SECURITYSESSIONID+set}" &&
	type gitk >/dev/null 2>&1
	then
	set gitk
	else
	set git log
	fi
	else
	case "$1" in
	git*\|tig) ;;
	-*) set git log "$@" ;;
	*) set git "$@" ;;
	esac
	fi

	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 "$(eval_gettext "cannot read \$file for replaying")"
	bisect_reset
	while read git bisect command rev
	do
	test "$git $bisect" = "git bisect" \|\| test "$git" = "git-bisect" \|\| continue
	if test "$git" = "git-bisect"
	then
	rev="$command"
	command="$bisect"
	fi
	get_terms
	check_and_set_terms "$command"
	case "$command" in
	start)
	cmd="bisect_start $rev"
	eval "$cmd" ;;
	"$TERM_GOOD"\|"$TERM_BAD"\|skip)
	bisect_write "$command" "$rev" ;;
	terms)
	bisect_terms $rev ;;
	*)
	die "$(gettext "?? what are you talking about?")" ;;
	esac
	done <"$file"
	bisect_auto_next
	}

	bisect_run () {
	bisect_next_check fail

	test -n "$*" \|\| die "$(gettext "bisect run failed: no command provided.")"

	while true
	do
	command="$@"
	eval_gettextln "running \$command"
	"$@"
	res=$?

	# Check for really bad run error.
	if [ $res -lt 0 -o $res -ge 128 ]
	then
	eval_gettextln "bisect run failed:
	exit code \$res from '\$command' is < 0 or >= 128" >&2
	exit $res
	fi

	# Find current state depending on run success or failure.
	# A special exit code of 125 means cannot test.
	if [ $res -eq 125 ]
	then
	state='skip'
	elif [ $res -gt 0 ]
	then
	state="$TERM_BAD"
	else
	state="$TERM_GOOD"
	fi

	# We have to use a subshell because "bisect_state" can exit.
	( bisect_state $state >"$GIT_DIR/BISECT_RUN" )
	res=$?

	cat "$GIT_DIR/BISECT_RUN"

	if sane_grep "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN" \
	>/dev/null
	then
	gettextln "bisect run cannot continue any more" >&2
	exit $res
	fi

	if [ $res -ne 0 ]
	then
	eval_gettextln "bisect run failed:
	'bisect_state \$state' exited with error code \$res" >&2
	exit $res
	fi

	if sane_grep "is the first $TERM_BAD commit" "$GIT_DIR/BISECT_RUN" >/dev/null
	then
	gettextln "bisect run success"
	exit 0;
	fi

	done
	}

	bisect_log () {
	test -s "$GIT_DIR/BISECT_LOG" \|\| die "$(gettext "We are not bisecting.")"
	cat "$GIT_DIR/BISECT_LOG"
	}

	get_terms () {
	if test -s "$GIT_DIR/BISECT_TERMS"
	then
	{
	read TERM_BAD
	read TERM_GOOD
	} <"$GIT_DIR/BISECT_TERMS"
	fi
	}

	check_and_set_terms () {
	cmd="$1"
	case "$cmd" in
	skip\|start\|terms) ;;
	*)
	if test -s "$GIT_DIR/BISECT_TERMS" && test "$cmd" != "$TERM_BAD" && test "$cmd" != "$TERM_GOOD"
	then
	die "$(eval_gettext "Invalid command: you're currently in a \$TERM_BAD/\$TERM_GOOD bisect.")"
	fi
	case "$cmd" in
	bad\|good)
	if ! test -s "$GIT_DIR/BISECT_TERMS"
	then
	TERM_BAD=bad
	TERM_GOOD=good
	git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" \|\| exit
	fi
	;;
	new\|old)
	if ! test -s "$GIT_DIR/BISECT_TERMS"
	then
	TERM_BAD=new
	TERM_GOOD=old
	git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" \|\| exit
	fi
	;;
	esac ;;
	esac
	}

	bisect_voc () {
	case "$1" in
	bad) echo "bad\|new" ;;
	good) echo "good\|old" ;;
	esac
	}

	bisect_terms () {
	get_terms
	if ! test -s "$GIT_DIR/BISECT_TERMS"
	then
	die "$(gettext "no terms defined")"
	fi
	case "$#" in
	0)
	gettextln "Your current terms are $TERM_GOOD for the old state
	and $TERM_BAD for the new state."
	;;
	1)
	arg=$1
	case "$arg" in
	--term-good\|--term-old)
	printf '%s\n' "$TERM_GOOD"
	;;
	--term-bad\|--term-new)
	printf '%s\n' "$TERM_BAD"
	;;
	*)
	die "$(eval_gettext "invalid argument \$arg for 'git bisect terms'.
	Supported options are: --term-good\|--term-old and --term-bad\|--term-new.")"
	;;
	esac
	;;
	*)
	usage ;;
	esac
	}

	case "$#" in
	0)
	usage ;;
	*)
	cmd="$1"
	get_terms
	shift
	case "$cmd" in
	help)
	git bisect -h ;;
	start)
	bisect_start "$@" ;;
	bad\|good\|new\|old\|"$TERM_BAD"\|"$TERM_GOOD")
	bisect_state "$cmd" "$@" ;;
	skip)
	bisect_skip "$@" ;;
	next)
	# Not sure we want "next" at the UI level anymore.
	bisect_next "$@" ;;
	visualize\|view)
	bisect_visualize "$@" ;;
	reset)
	bisect_reset "$@" ;;
	replay)
	bisect_replay "$@" ;;
	log)
	bisect_log ;;
	run)
	bisect_run "$@" ;;
	terms)
	bisect_terms "$@" ;;
	*)
	usage ;;
	esac
	esac