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

 #!/bin/sh

 USAGE='[help|start|bad|good|skip|next|reset|visualize|replay|log|run]'
 LONG_USAGE='git bisect help
         print this long help message.
 git bisect start [<bad> [<good>...]] [--] [<pathspec>...]
         reset bisect state and start bisection.
 git bisect bad [<rev>]
         mark <rev> a known-bad revision.
 git bisect good [<rev>...]
         mark <rev>... known-good revisions.
 git bisect skip [(<rev>|<range>)...]
         mark <rev>... untestable revisions.
 git bisect next
         find next bisection to test and check it out.
 git bisect reset [<branch>]
         finish bisection search and go back to branch.
 git bisect visualize
         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
 require_work_tree

 _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"

 sq() {
 	@@PERL@@ -e '
 		for (@ARGV) {
 			s/'\''/'\'\\\\\'\''/g;
 			print " '\''$_'\''";
 		}
 		print "\n";
 	' "$@"
 }

 bisect_autostart() {
 	test -s "$GIT_DIR/BISECT_START" || {
 		echo >&2 'You need to start by "git bisect start"'
 		if test -t 0
 		then
 			echo >&2 -n 'Do you want me to do it for you [Y/n]? '
 			read yesno
 			case "$yesno" in
 			[Nn]*)
 				exit ;;
 			esac
 			bisect_start
 		else
 			exit 1
 		fi
 	}
 }

 bisect_start() {
 	#
 	# Verify HEAD.
 	#
 	head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) ||
 	head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
 	die "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 "$GIT_DIR/BISECT_START")
 		git checkout "$start_head" -- || exit
 	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 "$GIT_DIR/head-name" ] &&
 				die "won't bisect on seeked tree"
 			start_head="${head#refs/heads/}"
 			;;
 		*)
 			die "Bad HEAD - strange symbolic ref"
 			;;
 		esac
 	fi

 	#
 	# Get rid of any old bisect state.
 	#
 	bisect_clean_state || exit

 	#
 	# Check for one bad and then some good revisions.
 	#
 	has_double_dash=0
 	for arg; do
 	    case "$arg" in --) has_double_dash=1; break ;; esac
 	done
 	orig_args=$(sq "$@")
 	bad_seen=0
 	eval=''
 	while [ $# -gt 0 ]; do
 	    arg="$1"
 	    case "$arg" in
 	    --)
 		shift
 		break
 		;;
 	    *)
 		rev=$(git rev-parse -q --verify "$arg^{commit}") || {
 		    test $has_double_dash -eq 1 &&
 		        die "'$arg' does not appear to be a valid revision"
 		    break
 		}
 		case $bad_seen in
 		0) state='bad' ; bad_seen=1 ;;
 		*) state='good' ;;
 		esac
 		eval="$eval bisect_write '$state' '$rev' 'nolog'; "
 		shift
 		;;
 	    esac
 	done

 	#
 	# 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 'bisect_clean_state' 0
 	trap 'exit 255' 1 2 3 15

 	#
 	# Write new start state.
 	#
 	echo "$start_head" >"$GIT_DIR/BISECT_START" &&
 	sq "$@" >"$GIT_DIR/BISECT_NAMES" &&
 	eval "$eval" &&
 	echo "git bisect start$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
 		bad)		tag="$state" ;;
 		good|skip)	tag="$state"-"$rev" ;;
 		*)		die "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"
 }

 is_expected_rev() {
 	test -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
 	test "$1" = $(cat "$GIT_DIR/BISECT_EXPECTED_REV")
 }

 mark_expected_rev() {
 	echo "$1" > "$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 "$@"
 	do
 	    case "$arg" in
             *..*)
                 revs=$(git rev-list "$arg") || die "Bad rev input: $arg" ;;
             *)
                 revs=$(sq "$arg") ;;
 	    esac
             all="$all $revs"
         done
         eval bisect_state 'skip' $all
 }

 bisect_state() {
 	bisect_autostart
 	state=$1
 	case "$#,$state" in
 	0,*)
 		die "Please call 'bisect_state' with at least one argument." ;;
 	1,bad|1,good|1,skip)
 		rev=$(git rev-parse --verify HEAD) ||
 			die "Bad rev input: HEAD"
 		bisect_write "$state" "$rev"
 		check_expected_revs "$rev" ;;
 	2,bad|*,good|*,skip)
 		shift
 		eval=''
 		for rev in "$@"
 		do
 			sha=$(git rev-parse --verify "$rev^{commit}") ||
 				die "Bad rev input: $rev"
 			eval="$eval bisect_write '$state' '$sha'; "
 		done
 		eval "$eval"
 		check_expected_revs "$@" ;;
 	*,bad)
 		die "'git bisect 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/bad || missing_bad=t
 	test -n "$(git for-each-ref "refs/bisect/good-*")" || missing_good=t

 	case "$missing_good,$missing_bad,$1" in
 	,,*)
 		: have both good and bad - ok
 		;;
 	*,)
 		# do not have both but not asked to fail - just report.
 		false
 		;;
 	t,,good)
 		# have bad but not good.  we could bisect although
 		# this is less optimum.
 		echo >&2 'Warning: bisecting only with a bad commit.'
 		if test -t 0
 		then
 			printf >&2 'Are you sure [Y/n]? '
 			read yesno
 			case "$yesno" in [Nn]*) exit 1 ;; esac
 		fi
 		: bisect without good...
 		;;
 	*)
 		THEN=''
 		test -s "$GIT_DIR/BISECT_START" || {
 			echo >&2 'You need to start by "git bisect start".'
 			THEN='then '
 		}
 		echo >&2 'You '$THEN'need to give me at least one good' \
 			'and one bad revisions.'
 		echo >&2 '(You can use "git bisect bad" and' \
 			'"git bisect good" for that.)'
 		exit 1 ;;
 	esac
 }

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

 exit_if_skipped_commits () {
 	_tried=$1
 	_bad=$2
 	if test -n "$_tried" ; then
 		echo "There are only 'skip'ped commit left to test."
 		echo "The first bad commit could be any of:"
 		echo "$_tried" | tr '[|]' '[\012]'
 		test -n "$_bad" && echo "$_bad"
 		echo "We cannot bisect more!"
 		exit 2
 	fi
 }

 bisect_checkout() {
 	_rev="$1"
 	_msg="$2"
 	echo "Bisecting: $_msg"
 	mark_expected_rev "$_rev"
 	git checkout -q "$_rev" -- || exit
 	git show-branch "$_rev"
 }

 is_among() {
 	_rev="$1"
 	_list="$2"
 	case "$_list" in *$_rev*) return 0 ;; esac
 	return 1
 }

 handle_bad_merge_base() {
 	_badmb="$1"
 	_good="$2"
 	if is_expected_rev "$_badmb"; then
 		cat >&2 <<EOF
 The merge base $_badmb is bad.
 This means the bug has been fixed between $_badmb and [$_good].
 EOF
 		exit 3
 	else
 		cat >&2 <<EOF
 Some good revs are not ancestor of the bad rev.
 git bisect cannot work properly in this case.
 Maybe you mistake good and bad revs?
 EOF
 		exit 1
 	fi
 }

 handle_skipped_merge_base() {
 	_mb="$1"
 	_bad="$2"
 	_good="$3"
 	cat >&2 <<EOF
 Warning: the merge base between $_bad and [$_good] must be skipped.
 So we cannot be sure the first bad commit is between $_mb and $_bad.
 We continue anyway.
 EOF
 }

 #
 # "check_merge_bases" checks that merge bases are not "bad".
 #
 # - If one is "good", that's good, we have nothing to do.
 # - If one is "bad", it means the user assumed something wrong
 # and we must exit.
 # - If one is "skipped", we can't know but we should warn.
 # - If we don't know, we should check it out and ask the user to test.
 #
 # In the last case we will return 1, and otherwise 0.
 #
 check_merge_bases() {
 	_bad="$1"
 	_good="$2"
 	_skip="$3"
 	for _mb in $(git merge-base --all $_bad $_good)
 	do
 		if is_among "$_mb" "$_good"; then
 			continue
 		elif test "$_mb" = "$_bad"; then
 			handle_bad_merge_base "$_bad" "$_good"
 		elif is_among "$_mb" "$_skip"; then
 			handle_skipped_merge_base "$_mb" "$_bad" "$_good"
 		else
 			bisect_checkout "$_mb" "a merge base must be tested"
 			return 1
 		fi
 	done
 	return 0
 }

 #
 # "check_good_are_ancestors_of_bad" checks that all "good" revs are
 # ancestor of the "bad" rev.
 #
 # If that's not the case, we need to check the merge bases.
 # If a merge base must be tested by the user we return 1 and
 # otherwise 0.
 #
 check_good_are_ancestors_of_bad() {
 	test -f "$GIT_DIR/BISECT_ANCESTORS_OK" &&
 		return

 	_bad="$1"
 	_good=$(echo $2 | sed -e 's/\^//g')
 	_skip="$3"

 	# Bisecting with no good rev is ok
 	test -z "$_good" && return

 	_side=$(git rev-list $_good ^$_bad)
 	if test -n "$_side"; then
 		# Return if a checkout was done
 		check_merge_bases "$_bad" "$_good" "$_skip" || return
 	fi

 	: > "$GIT_DIR/BISECT_ANCESTORS_OK"

 	return 0
 }

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

 	# Get bad, good and skipped revs
 	bad=$(git rev-parse --verify refs/bisect/bad) &&
 	good=$(git for-each-ref --format='^%(objectname)' \
 		"refs/bisect/good-*" | tr '\012' ' ') &&
 	skip=$(git for-each-ref --format='%(objectname)' \
 		"refs/bisect/skip-*" | tr '\012' ' ') || exit

 	# Maybe some merge bases must be tested first
 	check_good_are_ancestors_of_bad "$bad" "$good" "$skip"
 	# Return now if a checkout has already been done
 	test "$?" -eq "1" && return

 	# Get bisection information
 	eval=$(eval "git bisect--helper --next-vars") &&
 	eval "$eval" || exit

 	if [ -z "$bisect_rev" ]; then
 		# We should exit here only if the "bad"
 		# commit is also a "skip" commit (see above).
 		exit_if_skipped_commits "$bisect_tried"
 		echo "$bad was both good and bad"
 		exit 1
 	fi
 	if [ "$bisect_rev" = "$bad" ]; then
 		exit_if_skipped_commits "$bisect_tried" "$bad"
 		echo "$bisect_rev is first bad commit"
 		git diff-tree --pretty $bisect_rev
 		exit 0
 	fi

 	bisect_checkout "$bisect_rev" "$bisect_nr revisions left to test after this (roughly $bisect_steps steps)"
 }

 bisect_visualize() {
 	bisect_next_check fail

 	if test $# = 0
 	then
 		case "${DISPLAY+set}${SESSIONNAME+set}${MSYSTEM+set}${SECURITYSESSIONID+set}" in
 		'')	set git log ;;
 		set*)	set gitk ;;
 		esac
 	else
 		case "$1" in
 		git*|tig) ;;
 		-*)	set git log "$@" ;;
 		*)	set git "$@" ;;
 		esac
 	fi

 	not=$(git for-each-ref --format='%(refname)' "refs/bisect/good-*")
 	eval '"$@"' refs/bisect/bad --not $not -- $(cat "$GIT_DIR/BISECT_NAMES")
 }

 bisect_reset() {
 	test -s "$GIT_DIR/BISECT_START" || {
 		echo "We are not bisecting."
 		return
 	}
 	case "$#" in
 	0) branch=$(cat "$GIT_DIR/BISECT_START") ;;
 	1) git show-ref --verify --quiet -- "refs/heads/$1" ||
 	       die "$1 does not seem to be a valid branch"
 	   branch="$1" ;;
 	*)
 	    usage ;;
 	esac
 	git checkout "$branch" -- && 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" &&
 	# Cleanup head-name if it got left by an old version of git-bisect
 	rm -f "$GIT_DIR/head-name" &&

 	rm -f "$GIT_DIR/BISECT_START"
 }

 bisect_replay () {
 	test -r "$1" || die "cannot read $1 for replaying"
 	bisect_reset
 	while read git bisect command rev
 	do
 		test "$git $bisect" = "git bisect" -o "$git" = "git-bisect" || continue
 		if test "$git" = "git-bisect"; then
 			rev="$command"
 			command="$bisect"
 		fi
 		case "$command" in
 		start)
 			cmd="bisect_start $rev"
 			eval "$cmd" ;;
 		good|bad|skip)
 			bisect_write "$command" "$rev" ;;
 		*)
 			die "?? what are you talking about?" ;;
 		esac
 	done <"$1"
 	bisect_auto_next
 }

 bisect_run () {
     bisect_next_check fail

     while true
     do
       echo "running $@"
       "$@"
       res=$?

       # Check for really bad run error.
       if [ $res -lt 0 -o $res -ge 128 ]; then
 	  echo >&2 "bisect run failed:"
 	  echo >&2 "exit code $res from '$@' is < 0 or >= 128"
 	  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='bad'
       else
 	  state='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 grep "first bad commit could be any of" "$GIT_DIR/BISECT_RUN" \
 		> /dev/null; then
 	  echo >&2 "bisect run cannot continue any more"
 	  exit $res
       fi

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

       if grep "is first bad commit" "$GIT_DIR/BISECT_RUN" > /dev/null; then
 	  echo "bisect run success"
 	  exit 0;
       fi

     done
 }


 case "$#" in
 0)
     usage ;;
 *)
     cmd="$1"
     shift
     case "$cmd" in
     help)
         git bisect -h ;;
     start)
         bisect_start "$@" ;;
     bad|good)
         bisect_state "$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)
 	cat "$GIT_DIR/BISECT_LOG" ;;
     run)
         bisect_run "$@" ;;
     *)
         usage ;;
     esac
 esac
	#!/bin/sh

	USAGE='[help\|start\|bad\|good\|skip\|next\|reset\|visualize\|replay\|log\|run]'
	LONG_USAGE='git bisect help
	print this long help message.
	git bisect start [<bad> [<good>...]] [--] [<pathspec>...]
	reset bisect state and start bisection.
	git bisect bad [<rev>]
	mark <rev> a known-bad revision.
	git bisect good [<rev>...]
	mark <rev>... known-good revisions.
	git bisect skip [(<rev>\|<range>)...]
	mark <rev>... untestable revisions.
	git bisect next
	find next bisection to test and check it out.
	git bisect reset [<branch>]
	finish bisection search and go back to branch.
	git bisect visualize
	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
	require_work_tree

	_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"

	sq() {
	@@PERL@@ -e '
	for (@ARGV) {
	s/'\''/'\'\\\\\'\''/g;
	print " '\''$_'\''";
	}
	print "\n";
	' "$@"
	}

	bisect_autostart() {
	test -s "$GIT_DIR/BISECT_START" \|\| {
	echo >&2 'You need to start by "git bisect start"'
	if test -t 0
	then
	echo >&2 -n 'Do you want me to do it for you [Y/n]? '
	read yesno
	case "$yesno" in
	[Nn]*)
	exit ;;
	esac
	bisect_start
	else
	exit 1
	fi
	}
	}

	bisect_start() {
	#
	# Verify HEAD.
	#
	head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) \|\|
	head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) \|\|
	die "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 "$GIT_DIR/BISECT_START")
	git checkout "$start_head" -- \|\| exit
	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 "$GIT_DIR/head-name" ] &&
	die "won't bisect on seeked tree"
	start_head="${head#refs/heads/}"
	;;
	*)
	die "Bad HEAD - strange symbolic ref"
	;;
	esac
	fi

	#
	# Get rid of any old bisect state.
	#
	bisect_clean_state \|\| exit

	#
	# Check for one bad and then some good revisions.
	#
	has_double_dash=0
	for arg; do
	case "$arg" in --) has_double_dash=1; break ;; esac
	done
	orig_args=$(sq "$@")
	bad_seen=0
	eval=''
	while [ $# -gt 0 ]; do
	arg="$1"
	case "$arg" in
	--)
	shift
	break
	;;
	*)
	rev=$(git rev-parse -q --verify "$arg^{commit}") \|\| {
	test $has_double_dash -eq 1 &&
	die "'$arg' does not appear to be a valid revision"
	break
	}
	case $bad_seen in
	0) state='bad' ; bad_seen=1 ;;
	*) state='good' ;;
	esac
	eval="$eval bisect_write '$state' '$rev' 'nolog'; "
	shift
	;;
	esac
	done

	#
	# 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 'bisect_clean_state' 0
	trap 'exit 255' 1 2 3 15

	#
	# Write new start state.
	#
	echo "$start_head" >"$GIT_DIR/BISECT_START" &&
	sq "$@" >"$GIT_DIR/BISECT_NAMES" &&
	eval "$eval" &&
	echo "git bisect start$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
	bad) tag="$state" ;;
	good\|skip) tag="$state"-"$rev" ;;
	*) die "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"
	}

	is_expected_rev() {
	test -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
	test "$1" = $(cat "$GIT_DIR/BISECT_EXPECTED_REV")
	}

	mark_expected_rev() {
	echo "$1" > "$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 "$@"
	do
	case "$arg" in
	..)
	revs=$(git rev-list "$arg") \|\| die "Bad rev input: $arg" ;;
	*)
	revs=$(sq "$arg") ;;
	esac
	all="$all $revs"
	done
	eval bisect_state 'skip' $all
	}

	bisect_state() {
	bisect_autostart
	state=$1
	case "$#,$state" in
	0,*)
	die "Please call 'bisect_state' with at least one argument." ;;
	1,bad\|1,good\|1,skip)
	rev=$(git rev-parse --verify HEAD) \|\|
	die "Bad rev input: HEAD"
	bisect_write "$state" "$rev"
	check_expected_revs "$rev" ;;
	2,bad\|,good\|,skip)
	shift
	eval=''
	for rev in "$@"
	do
	sha=$(git rev-parse --verify "$rev^{commit}") \|\|
	die "Bad rev input: $rev"
	eval="$eval bisect_write '$state' '$sha'; "
	done
	eval "$eval"
	check_expected_revs "$@" ;;
	*,bad)
	die "'git bisect 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/bad \|\| missing_bad=t
	test -n "$(git for-each-ref "refs/bisect/good-*")" \|\| missing_good=t

	case "$missing_good,$missing_bad,$1" in
	,,*)
	: have both good and bad - ok
	;;
	*,)
	# do not have both but not asked to fail - just report.
	false
	;;
	t,,good)
	# have bad but not good. we could bisect although
	# this is less optimum.
	echo >&2 'Warning: bisecting only with a bad commit.'
	if test -t 0
	then
	printf >&2 'Are you sure [Y/n]? '
	read yesno
	case "$yesno" in [Nn]*) exit 1 ;; esac
	fi
	: bisect without good...
	;;
	*)
	THEN=''
	test -s "$GIT_DIR/BISECT_START" \|\| {
	echo >&2 'You need to start by "git bisect start".'
	THEN='then '
	}
	echo >&2 'You '$THEN'need to give me at least one good' \
	'and one bad revisions.'
	echo >&2 '(You can use "git bisect bad" and' \
	'"git bisect good" for that.)'
	exit 1 ;;
	esac
	}

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

	exit_if_skipped_commits () {
	_tried=$1
	_bad=$2
	if test -n "$_tried" ; then
	echo "There are only 'skip'ped commit left to test."
	echo "The first bad commit could be any of:"
	echo "$_tried" \| tr '[\|]' '[\012]'
	test -n "$_bad" && echo "$_bad"
	echo "We cannot bisect more!"
	exit 2
	fi
	}

	bisect_checkout() {
	_rev="$1"
	_msg="$2"
	echo "Bisecting: $_msg"
	mark_expected_rev "$_rev"
	git checkout -q "$_rev" -- \|\| exit
	git show-branch "$_rev"
	}

	is_among() {
	_rev="$1"
	_list="$2"
	case "$_list" in $_rev) return 0 ;; esac
	return 1
	}

	handle_bad_merge_base() {
	_badmb="$1"
	_good="$2"
	if is_expected_rev "$_badmb"; then
	cat >&2 <<EOF
	The merge base $_badmb is bad.
	This means the bug has been fixed between $_badmb and [$_good].
	EOF
	exit 3
	else
	cat >&2 <<EOF
	Some good revs are not ancestor of the bad rev.
	git bisect cannot work properly in this case.
	Maybe you mistake good and bad revs?
	EOF
	exit 1
	fi
	}

	handle_skipped_merge_base() {
	_mb="$1"
	_bad="$2"
	_good="$3"
	cat >&2 <<EOF
	Warning: the merge base between $_bad and [$_good] must be skipped.
	So we cannot be sure the first bad commit is between $_mb and $_bad.
	We continue anyway.
	EOF
	}

	#
	# "check_merge_bases" checks that merge bases are not "bad".
	#
	# - If one is "good", that's good, we have nothing to do.
	# - If one is "bad", it means the user assumed something wrong
	# and we must exit.
	# - If one is "skipped", we can't know but we should warn.
	# - If we don't know, we should check it out and ask the user to test.
	#
	# In the last case we will return 1, and otherwise 0.
	#
	check_merge_bases() {
	_bad="$1"
	_good="$2"
	_skip="$3"
	for _mb in $(git merge-base --all $_bad $_good)
	do
	if is_among "$_mb" "$_good"; then
	continue
	elif test "$_mb" = "$_bad"; then
	handle_bad_merge_base "$_bad" "$_good"
	elif is_among "$_mb" "$_skip"; then
	handle_skipped_merge_base "$_mb" "$_bad" "$_good"
	else
	bisect_checkout "$_mb" "a merge base must be tested"
	return 1
	fi
	done
	return 0
	}

	#
	# "check_good_are_ancestors_of_bad" checks that all "good" revs are
	# ancestor of the "bad" rev.
	#
	# If that's not the case, we need to check the merge bases.
	# If a merge base must be tested by the user we return 1 and
	# otherwise 0.
	#
	check_good_are_ancestors_of_bad() {
	test -f "$GIT_DIR/BISECT_ANCESTORS_OK" &&
	return

	_bad="$1"
	_good=$(echo $2 \| sed -e 's/\^//g')
	_skip="$3"

	# Bisecting with no good rev is ok
	test -z "$_good" && return

	_side=$(git rev-list $_good ^$_bad)
	if test -n "$_side"; then
	# Return if a checkout was done
	check_merge_bases "$_bad" "$_good" "$_skip" \|\| return
	fi

	: > "$GIT_DIR/BISECT_ANCESTORS_OK"

	return 0
	}

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

	# Get bad, good and skipped revs
	bad=$(git rev-parse --verify refs/bisect/bad) &&
	good=$(git for-each-ref --format='^%(objectname)' \
	"refs/bisect/good-*" \| tr '\012' ' ') &&
	skip=$(git for-each-ref --format='%(objectname)' \
	"refs/bisect/skip-*" \| tr '\012' ' ') \|\| exit

	# Maybe some merge bases must be tested first
	check_good_are_ancestors_of_bad "$bad" "$good" "$skip"
	# Return now if a checkout has already been done
	test "$?" -eq "1" && return

	# Get bisection information
	eval=$(eval "git bisect--helper --next-vars") &&
	eval "$eval" \|\| exit

	if [ -z "$bisect_rev" ]; then
	# We should exit here only if the "bad"
	# commit is also a "skip" commit (see above).
	exit_if_skipped_commits "$bisect_tried"
	echo "$bad was both good and bad"
	exit 1
	fi
	if [ "$bisect_rev" = "$bad" ]; then
	exit_if_skipped_commits "$bisect_tried" "$bad"
	echo "$bisect_rev is first bad commit"
	git diff-tree --pretty $bisect_rev
	exit 0
	fi

	bisect_checkout "$bisect_rev" "$bisect_nr revisions left to test after this (roughly $bisect_steps steps)"
	}

	bisect_visualize() {
	bisect_next_check fail

	if test $# = 0
	then
	case "${DISPLAY+set}${SESSIONNAME+set}${MSYSTEM+set}${SECURITYSESSIONID+set}" in
	'') set git log ;;
	set*) set gitk ;;
	esac
	else
	case "$1" in
	git*\|tig) ;;
	-*) set git log "$@" ;;
	*) set git "$@" ;;
	esac
	fi

	not=$(git for-each-ref --format='%(refname)' "refs/bisect/good-*")
	eval '"$@"' refs/bisect/bad --not $not -- $(cat "$GIT_DIR/BISECT_NAMES")
	}

	bisect_reset() {
	test -s "$GIT_DIR/BISECT_START" \|\| {
	echo "We are not bisecting."
	return
	}
	case "$#" in
	0) branch=$(cat "$GIT_DIR/BISECT_START") ;;
	1) git show-ref --verify --quiet -- "refs/heads/$1" \|\|
	die "$1 does not seem to be a valid branch"
	branch="$1" ;;
	*)
	usage ;;
	esac
	git checkout "$branch" -- && 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" &&
	# Cleanup head-name if it got left by an old version of git-bisect
	rm -f "$GIT_DIR/head-name" &&

	rm -f "$GIT_DIR/BISECT_START"
	}

	bisect_replay () {
	test -r "$1" \|\| die "cannot read $1 for replaying"
	bisect_reset
	while read git bisect command rev
	do
	test "$git $bisect" = "git bisect" -o "$git" = "git-bisect" \|\| continue
	if test "$git" = "git-bisect"; then
	rev="$command"
	command="$bisect"
	fi
	case "$command" in
	start)
	cmd="bisect_start $rev"
	eval "$cmd" ;;
	good\|bad\|skip)
	bisect_write "$command" "$rev" ;;
	*)
	die "?? what are you talking about?" ;;
	esac
	done <"$1"
	bisect_auto_next
	}

	bisect_run () {
	bisect_next_check fail

	while true
	do
	echo "running $@"
	"$@"
	res=$?

	# Check for really bad run error.
	if [ $res -lt 0 -o $res -ge 128 ]; then
	echo >&2 "bisect run failed:"
	echo >&2 "exit code $res from '$@' is < 0 or >= 128"
	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='bad'
	else
	state='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 grep "first bad commit could be any of" "$GIT_DIR/BISECT_RUN" \
	> /dev/null; then
	echo >&2 "bisect run cannot continue any more"
	exit $res
	fi

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

	if grep "is first bad commit" "$GIT_DIR/BISECT_RUN" > /dev/null; then
	echo "bisect run success"
	exit 0;
	fi

	done
	}


	case "$#" in
	0)
	usage ;;
	*)
	cmd="$1"
	shift
	case "$cmd" in
	help)
	git bisect -h ;;
	start)
	bisect_start "$@" ;;
	bad\|good)
	bisect_state "$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)
	cat "$GIT_DIR/BISECT_LOG" ;;
	run)
	bisect_run "$@" ;;
	*)
	usage ;;
	esac
	esac