git-mergetool--lib.sh - git - Git at Google

 # git-mergetool--lib is a shell library for common merge tool functions

 : ${MERGE_TOOLS_DIR=$(git --exec-path)/mergetools}

 IFS='
 '

 mode_ok () {
 	if diff_mode
 	then
 		can_diff
 	elif merge_mode
 	then
 		can_merge
 	else
 		false
 	fi
 }

 is_available () {
 	merge_tool_path=$(translate_merge_tool_path "$1") &&
 	type "$merge_tool_path" >/dev/null 2>&1
 }

 list_config_tools () {
 	section=$1
 	line_prefix=${2:-}

 	git config --get-regexp $section'\..*\.cmd' |
 	while read -r key value
 	do
 		toolname=${key#$section.}
 		toolname=${toolname%.cmd}

 		printf "%s%s\n" "$line_prefix" "$toolname"
 	done
 }

 show_tool_names () {
 	condition=${1:-true} per_line_prefix=${2:-} preamble=${3:-}
 	not_found_msg=${4:-}
 	extra_content=${5:-}

 	shown_any=
 	( cd "$MERGE_TOOLS_DIR" && ls ) | {
 		while read scriptname
 		do
 			setup_tool "$scriptname" 2>/dev/null
 			# We need an actual line feed here
 			variants="$variants
 $(list_tool_variants)"
 		done
 		variants="$(echo "$variants" | sort -u)"

 		for toolname in $variants
 		do
 			if setup_tool "$toolname" 2>/dev/null &&
 				(eval "$condition" "$toolname")
 			then
 				if test -n "$preamble"
 				then
 					printf "%s\n" "$preamble"
 					preamble=
 				fi
 				shown_any=yes
 				printf "%s%-15s  %s\n" "$per_line_prefix" "$toolname" $(diff_mode && diff_cmd_help "$toolname" || merge_cmd_help "$toolname")
 			fi
 		done

 		if test -n "$extra_content"
 		then
 			if test -n "$preamble"
 			then
 				# Note: no '\n' here since we don't want a
 				# blank line if there is no initial content.
 				printf "%s" "$preamble"
 				preamble=
 			fi
 			shown_any=yes
 			printf "\n%s\n" "$extra_content"
 		fi

 		if test -n "$preamble" && test -n "$not_found_msg"
 		then
 			printf "%s\n" "$not_found_msg"
 		fi

 		test -n "$shown_any"
 	}
 }

 diff_mode () {
 	test "$TOOL_MODE" = diff
 }

 merge_mode () {
 	test "$TOOL_MODE" = merge
 }

 get_gui_default () {
 	if diff_mode
 	then
 		GUI_DEFAULT_KEY="difftool.guiDefault"
 	else
 		GUI_DEFAULT_KEY="mergetool.guiDefault"
 	fi
 	GUI_DEFAULT_CONFIG_LCASE=$(git config --default false --get "$GUI_DEFAULT_KEY" | tr 'A-Z' 'a-z')
 	if test "$GUI_DEFAULT_CONFIG_LCASE" = "auto"
 	then
 		if test -n "$DISPLAY"
 		then
 			GUI_DEFAULT=true
 		else
 			GUI_DEFAULT=false
 		fi
 	else
 		GUI_DEFAULT=$(git config --default false --bool --get "$GUI_DEFAULT_KEY")
 		subshell_exit_status=$?
 		if test $subshell_exit_status -ne 0
 		then
 			exit $subshell_exit_status
 		fi
 	fi
 	echo $GUI_DEFAULT
 }

 gui_mode () {
 	if test -z "$GIT_MERGETOOL_GUI"
 	then
 		GIT_MERGETOOL_GUI=$(get_gui_default)
 		if test $? -ne 0
 		then
 			exit 2
 		fi
 	fi
 	test "$GIT_MERGETOOL_GUI" = true
 }

 translate_merge_tool_path () {
 	echo "$1"
 }

 check_unchanged () {
 	if test "$MERGED" -nt "$BACKUP"
 	then
 		return 0
 	else
 		while true
 		do
 			echo "$MERGED seems unchanged."
 			printf "Was the merge successful [y/n]? "
 			read answer || return 1
 			case "$answer" in
 			y*|Y*) return 0 ;;
 			n*|N*) return 1 ;;
 			esac
 		done
 	fi
 }

 valid_tool () {
 	setup_tool "$1" 2>/dev/null && return 0
 	cmd=$(get_merge_tool_cmd "$1")
 	test -n "$cmd"
 }

 setup_user_tool () {
 	merge_tool_cmd=$(get_merge_tool_cmd "$tool")
 	test -n "$merge_tool_cmd" || return 1

 	diff_cmd () {
 		( eval $merge_tool_cmd )
 	}

 	merge_cmd () {
 		( eval $merge_tool_cmd )
 	}

 	list_tool_variants () {
 		echo "$tool"
 	}
 }

 setup_tool () {
 	tool="$1"

 	# Fallback definitions, to be overridden by tools.
 	can_merge () {
 		return 0
 	}

 	can_diff () {
 		return 0
 	}

 	diff_cmd () {
 		return 1
 	}

 	diff_cmd_help () {
 		return 0
 	}

 	merge_cmd () {
 		return 1
 	}

 	merge_cmd_help () {
 		return 0
 	}

 	hide_resolved_enabled () {
 		return 0
 	}

 	translate_merge_tool_path () {
 		echo "$1"
 	}

 	list_tool_variants () {
 		echo "$tool"
 	}

 	# Most tools' exit codes cannot be trusted, so By default we ignore
 	# their exit code and check the merged file's modification time in
 	# check_unchanged() to determine whether or not the merge was
 	# successful.  The return value from run_merge_cmd, by default, is
 	# determined by check_unchanged().
 	#
 	# When a tool's exit code can be trusted then the return value from
 	# run_merge_cmd is simply the tool's exit code, and check_unchanged()
 	# is not called.
 	#
 	# The return value of exit_code_trustable() tells us whether or not we
 	# can trust the tool's exit code.
 	#
 	# User-defined and built-in tools default to false.
 	# Built-in tools advertise that their exit code is trustable by
 	# redefining exit_code_trustable() to true.

 	exit_code_trustable () {
 		false
 	}

 	if test -f "$MERGE_TOOLS_DIR/$tool"
 	then
 		. "$MERGE_TOOLS_DIR/$tool"
 	elif test -f "$MERGE_TOOLS_DIR/${tool%[0-9]}"
 	then
 		. "$MERGE_TOOLS_DIR/${tool%[0-9]}"
 	else
 		setup_user_tool
 		rc=$?
 		if test $rc -ne 0
 		then
 			echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
 		fi
 		return $rc
 	fi

 	# Now let the user override the default command for the tool.  If
 	# they have not done so then this will return 1 which we ignore.
 	setup_user_tool

 	if ! list_tool_variants | grep -q "^$tool$"
 	then
 		echo "error: unknown tool variant '$tool'" >&2
 		return 1
 	fi

 	if merge_mode && ! can_merge
 	then
 		echo "error: '$tool' can not be used to resolve merges" >&2
 		return 1
 	elif diff_mode && ! can_diff
 	then
 		echo "error: '$tool' can only be used to resolve merges" >&2
 		return 1
 	fi
 	return 0
 }

 get_merge_tool_cmd () {
 	merge_tool="$1"
 	if diff_mode
 	then
 		git config "difftool.$merge_tool.cmd" ||
 		git config "mergetool.$merge_tool.cmd"
 	else
 		git config "mergetool.$merge_tool.cmd"
 	fi
 }

 trust_exit_code () {
 	if git config --bool "mergetool.$1.trustExitCode"
 	then
 		:; # OK
 	elif exit_code_trustable
 	then
 		echo true
 	else
 		echo false
 	fi
 }

 initialize_merge_tool () {
 	# Bring tool-specific functions into scope
 	setup_tool "$1" || return 1
 }

 # Entry point for running tools
 run_merge_tool () {
 	# If GIT_PREFIX is empty then we cannot use it in tools
 	# that expect to be able to chdir() to its value.
 	GIT_PREFIX=${GIT_PREFIX:-.}
 	export GIT_PREFIX

 	merge_tool_path=$(get_merge_tool_path "$1") || exit
 	base_present="$2"

 	if merge_mode
 	then
 		run_merge_cmd "$1"
 	else
 		run_diff_cmd "$1"
 	fi
 }

 # Run a either a configured or built-in diff tool
 run_diff_cmd () {
 	diff_cmd "$1"
 }

 # Run a either a configured or built-in merge tool
 run_merge_cmd () {
 	mergetool_trust_exit_code=$(trust_exit_code "$1")
 	if test "$mergetool_trust_exit_code" = "true"
 	then
 		merge_cmd "$1"
 	else
 		touch "$BACKUP"
 		merge_cmd "$1"
 		check_unchanged
 	fi
 }

 list_merge_tool_candidates () {
 	if merge_mode
 	then
 		tools="tortoisemerge"
 	else
 		tools="kompare"
 	fi
 	if test -n "$DISPLAY"
 	then
 		if test -n "$GNOME_DESKTOP_SESSION_ID"
 		then
 			tools="meld opendiff kdiff3 tkdiff xxdiff $tools"
 		else
 			tools="opendiff kdiff3 tkdiff xxdiff meld $tools"
 		fi
 		tools="$tools gvimdiff diffuse diffmerge ecmerge"
 		tools="$tools p4merge araxis bc codecompare"
 		tools="$tools smerge"
 	fi
 	case "${VISUAL:-$EDITOR}" in
 	*nvim*)
 		tools="$tools nvimdiff vimdiff emerge"
 		;;
 	*vim*)
 		tools="$tools vimdiff nvimdiff emerge"
 		;;
 	*)
 		tools="$tools emerge vimdiff nvimdiff"
 		;;
 	esac
 }

 show_tool_help () {
 	tool_opt="'git ${TOOL_MODE}tool --tool=<tool>'"

 	tab='	'
 	LF='
 '
 	any_shown=no

 	cmd_name=${TOOL_MODE}tool
 	config_tools=$({
 		diff_mode && list_config_tools difftool "$tab$tab"
 		list_config_tools mergetool "$tab$tab"
 	} | sort)
 	extra_content=
 	if test -n "$config_tools"
 	then
 		extra_content="${tab}user-defined:${LF}$config_tools"
 	fi

 	show_tool_names 'mode_ok && is_available' "$tab$tab" \
 		"$tool_opt may be set to one of the following:" \
 		"No suitable tool for 'git $cmd_name --tool=<tool>' found." \
 		"$extra_content" &&
 		any_shown=yes

 	show_tool_names 'mode_ok && ! is_available' "$tab$tab" \
 		"${LF}The following tools are valid, but not currently available:" &&
 		any_shown=yes

 	if test "$any_shown" = yes
 	then
 		echo
 		echo "Some of the tools listed above only work in a windowed"
 		echo "environment. If run in a terminal-only session, they will fail."
 	fi
 	exit 0
 }

 guess_merge_tool () {
 	list_merge_tool_candidates
 	cat >&2 <<-EOF

 	This message is displayed because '$TOOL_MODE.tool' is not configured.
 	See 'git ${TOOL_MODE}tool --tool-help' or 'git help config' for more details.
 	'git ${TOOL_MODE}tool' will now attempt to use one of the following tools:
 	$tools
 	EOF

 	# Loop over each candidate and stop when a valid merge tool is found.
 	IFS=' '
 	for tool in $tools
 	do
 		is_available "$tool" && echo "$tool" && return 0
 	done

 	echo >&2 "No known ${TOOL_MODE} tool is available."
 	return 1
 }

 get_configured_merge_tool () {
 	keys=
 	if diff_mode
 	then
 		if gui_mode
 		then
 			keys="diff.guitool merge.guitool diff.tool merge.tool"
 		else
 			keys="diff.tool merge.tool"
 		fi
 	else
 		if gui_mode
 		then
 			keys="merge.guitool merge.tool"
 		else
 			keys="merge.tool"
 		fi
 	fi

 	merge_tool=$(
 		IFS=' '
 		for key in $keys
 		do
 			selected=$(git config $key)
 			if test -n "$selected"
 			then
 				echo "$selected"
 				return
 			fi
 		done)

 	if test -n "$merge_tool" && ! valid_tool "$merge_tool"
 	then
 		echo >&2 "git config option $TOOL_MODE.${gui_prefix}tool set to unknown tool: $merge_tool"
 		echo >&2 "Resetting to default..."
 		return 1
 	fi
 	echo "$merge_tool"
 }

 get_merge_tool_path () {
 	# A merge tool has been set, so verify that it's valid.
 	merge_tool="$1"
 	if ! valid_tool "$merge_tool"
 	then
 		echo >&2 "Unknown $TOOL_MODE tool $merge_tool"
 		exit 1
 	fi
 	if diff_mode
 	then
 		merge_tool_path=$(git config difftool."$merge_tool".path ||
 				  git config mergetool."$merge_tool".path)
 	else
 		merge_tool_path=$(git config mergetool."$merge_tool".path)
 	fi
 	if test -z "$merge_tool_path"
 	then
 		merge_tool_path=$(translate_merge_tool_path "$merge_tool")
 	fi
 	if test -z "$(get_merge_tool_cmd "$merge_tool")" &&
 		! type "$merge_tool_path" >/dev/null 2>&1
 	then
 		echo >&2 "The $TOOL_MODE tool $merge_tool is not available as"\
 			 "'$merge_tool_path'"
 		exit 1
 	fi
 	echo "$merge_tool_path"
 }

 get_merge_tool () {
 	is_guessed=false
 	# Check if a merge tool has been configured
 	merge_tool=$(get_configured_merge_tool)
 	subshell_exit_status=$?
 	if test $subshell_exit_status -gt "1"
 	then
 		exit $subshell_exit_status
 	fi
 	# Try to guess an appropriate merge tool if no tool has been set.
 	if test -z "$merge_tool"
 	then
 		merge_tool=$(guess_merge_tool) || exit
 		is_guessed=true
 	fi
 	echo "$merge_tool"
 	test "$is_guessed" = false
 }

 mergetool_find_win32_cmd () {
 	executable=$1
 	sub_directory=$2

 	# Use $executable if it exists in $PATH
 	if type -p "$executable" >/dev/null 2>&1
 	then
 		printf '%s' "$executable"
 		return
 	fi

 	# Look for executable in the typical locations
 	for directory in $(env | grep -Ei '^PROGRAM(FILES(\(X86\))?|W6432)=' |
 		cut -d '=' -f 2- | sort -u)
 	do
 		if test -n "$directory" && test -x "$directory/$sub_directory/$executable"
 		then
 			printf '%s' "$directory/$sub_directory/$executable"
 			return
 		fi
 	done

 	printf '%s' "$executable"
 }
	# git-mergetool--lib is a shell library for common merge tool functions

	: ${MERGE_TOOLS_DIR=$(git --exec-path)/mergetools}

	IFS='
	'

	mode_ok () {
	if diff_mode
	then
	can_diff
	elif merge_mode
	then
	can_merge
	else
	false
	fi
	}

	is_available () {
	merge_tool_path=$(translate_merge_tool_path "$1") &&
	type "$merge_tool_path" >/dev/null 2>&1
	}

	list_config_tools () {
	section=$1
	line_prefix=${2:-}

	git config --get-regexp $section'\..*\.cmd' \|
	while read -r key value
	do
	toolname=${key#$section.}
	toolname=${toolname%.cmd}

	printf "%s%s\n" "$line_prefix" "$toolname"
	done
	}

	show_tool_names () {
	condition=${1:-true} per_line_prefix=${2:-} preamble=${3:-}
	not_found_msg=${4:-}
	extra_content=${5:-}

	shown_any=
	( cd "$MERGE_TOOLS_DIR" && ls ) \| {
	while read scriptname
	do
	setup_tool "$scriptname" 2>/dev/null
	# We need an actual line feed here
	variants="$variants
	$(list_tool_variants)"
	done
	variants="$(echo "$variants" \| sort -u)"

	for toolname in $variants
	do
	if setup_tool "$toolname" 2>/dev/null &&
	(eval "$condition" "$toolname")
	then
	if test -n "$preamble"
	then
	printf "%s\n" "$preamble"
	preamble=
	fi
	shown_any=yes
	printf "%s%-15s %s\n" "$per_line_prefix" "$toolname" $(diff_mode && diff_cmd_help "$toolname" \|\| merge_cmd_help "$toolname")
	fi
	done

	if test -n "$extra_content"
	then
	if test -n "$preamble"
	then
	# Note: no '\n' here since we don't want a
	# blank line if there is no initial content.
	printf "%s" "$preamble"
	preamble=
	fi
	shown_any=yes
	printf "\n%s\n" "$extra_content"
	fi

	if test -n "$preamble" && test -n "$not_found_msg"
	then
	printf "%s\n" "$not_found_msg"
	fi

	test -n "$shown_any"
	}
	}

	diff_mode () {
	test "$TOOL_MODE" = diff
	}

	merge_mode () {
	test "$TOOL_MODE" = merge
	}

	get_gui_default () {
	if diff_mode
	then
	GUI_DEFAULT_KEY="difftool.guiDefault"
	else
	GUI_DEFAULT_KEY="mergetool.guiDefault"
	fi
	GUI_DEFAULT_CONFIG_LCASE=$(git config --default false --get "$GUI_DEFAULT_KEY" \| tr 'A-Z' 'a-z')
	if test "$GUI_DEFAULT_CONFIG_LCASE" = "auto"
	then
	if test -n "$DISPLAY"
	then
	GUI_DEFAULT=true
	else
	GUI_DEFAULT=false
	fi
	else
	GUI_DEFAULT=$(git config --default false --bool --get "$GUI_DEFAULT_KEY")
	subshell_exit_status=$?
	if test $subshell_exit_status -ne 0
	then
	exit $subshell_exit_status
	fi
	fi
	echo $GUI_DEFAULT
	}

	gui_mode () {
	if test -z "$GIT_MERGETOOL_GUI"
	then
	GIT_MERGETOOL_GUI=$(get_gui_default)
	if test $? -ne 0
	then
	exit 2
	fi
	fi
	test "$GIT_MERGETOOL_GUI" = true
	}

	translate_merge_tool_path () {
	echo "$1"
	}

	check_unchanged () {
	if test "$MERGED" -nt "$BACKUP"
	then
	return 0
	else
	while true
	do
	echo "$MERGED seems unchanged."
	printf "Was the merge successful [y/n]? "
	read answer \|\| return 1
	case "$answer" in
	y\|Y) return 0 ;;
	n\|N) return 1 ;;
	esac
	done
	fi
	}

	valid_tool () {
	setup_tool "$1" 2>/dev/null && return 0
	cmd=$(get_merge_tool_cmd "$1")
	test -n "$cmd"
	}

	setup_user_tool () {
	merge_tool_cmd=$(get_merge_tool_cmd "$tool")
	test -n "$merge_tool_cmd" \|\| return 1

	diff_cmd () {
	( eval $merge_tool_cmd )
	}

	merge_cmd () {
	( eval $merge_tool_cmd )
	}

	list_tool_variants () {
	echo "$tool"
	}
	}

	setup_tool () {
	tool="$1"

	# Fallback definitions, to be overridden by tools.
	can_merge () {
	return 0
	}

	can_diff () {
	return 0
	}

	diff_cmd () {
	return 1
	}

	diff_cmd_help () {
	return 0
	}

	merge_cmd () {
	return 1
	}

	merge_cmd_help () {
	return 0
	}

	hide_resolved_enabled () {
	return 0
	}

	translate_merge_tool_path () {
	echo "$1"
	}

	list_tool_variants () {
	echo "$tool"
	}

	# Most tools' exit codes cannot be trusted, so By default we ignore
	# their exit code and check the merged file's modification time in
	# check_unchanged() to determine whether or not the merge was
	# successful. The return value from run_merge_cmd, by default, is
	# determined by check_unchanged().
	#
	# When a tool's exit code can be trusted then the return value from
	# run_merge_cmd is simply the tool's exit code, and check_unchanged()
	# is not called.
	#
	# The return value of exit_code_trustable() tells us whether or not we
	# can trust the tool's exit code.
	#
	# User-defined and built-in tools default to false.
	# Built-in tools advertise that their exit code is trustable by
	# redefining exit_code_trustable() to true.

	exit_code_trustable () {
	false
	}

	if test -f "$MERGE_TOOLS_DIR/$tool"
	then
	. "$MERGE_TOOLS_DIR/$tool"
	elif test -f "$MERGE_TOOLS_DIR/${tool%[0-9]}"
	then
	. "$MERGE_TOOLS_DIR/${tool%[0-9]}"
	else
	setup_user_tool
	rc=$?
	if test $rc -ne 0
	then
	echo >&2 "error: ${TOOL_MODE}tool.$tool.cmd not set for tool '$tool'"
	fi
	return $rc
	fi

	# Now let the user override the default command for the tool. If
	# they have not done so then this will return 1 which we ignore.
	setup_user_tool

	if ! list_tool_variants \| grep -q "^$tool$"
	then
	echo "error: unknown tool variant '$tool'" >&2
	return 1
	fi

	if merge_mode && ! can_merge
	then
	echo "error: '$tool' can not be used to resolve merges" >&2
	return 1
	elif diff_mode && ! can_diff
	then
	echo "error: '$tool' can only be used to resolve merges" >&2
	return 1
	fi
	return 0
	}

	get_merge_tool_cmd () {
	merge_tool="$1"
	if diff_mode
	then
	git config "difftool.$merge_tool.cmd" \|\|
	git config "mergetool.$merge_tool.cmd"
	else
	git config "mergetool.$merge_tool.cmd"
	fi
	}

	trust_exit_code () {
	if git config --bool "mergetool.$1.trustExitCode"
	then
	:; # OK
	elif exit_code_trustable
	then
	echo true
	else
	echo false
	fi
	}

	initialize_merge_tool () {
	# Bring tool-specific functions into scope
	setup_tool "$1" \|\| return 1
	}

	# Entry point for running tools
	run_merge_tool () {
	# If GIT_PREFIX is empty then we cannot use it in tools
	# that expect to be able to chdir() to its value.
	GIT_PREFIX=${GIT_PREFIX:-.}
	export GIT_PREFIX

	merge_tool_path=$(get_merge_tool_path "$1") \|\| exit
	base_present="$2"

	if merge_mode
	then
	run_merge_cmd "$1"
	else
	run_diff_cmd "$1"
	fi
	}

	# Run a either a configured or built-in diff tool
	run_diff_cmd () {
	diff_cmd "$1"
	}

	# Run a either a configured or built-in merge tool
	run_merge_cmd () {
	mergetool_trust_exit_code=$(trust_exit_code "$1")
	if test "$mergetool_trust_exit_code" = "true"
	then
	merge_cmd "$1"
	else
	touch "$BACKUP"
	merge_cmd "$1"
	check_unchanged
	fi
	}

	list_merge_tool_candidates () {
	if merge_mode
	then
	tools="tortoisemerge"
	else
	tools="kompare"
	fi
	if test -n "$DISPLAY"
	then
	if test -n "$GNOME_DESKTOP_SESSION_ID"
	then
	tools="meld opendiff kdiff3 tkdiff xxdiff $tools"
	else
	tools="opendiff kdiff3 tkdiff xxdiff meld $tools"
	fi
	tools="$tools gvimdiff diffuse diffmerge ecmerge"
	tools="$tools p4merge araxis bc codecompare"
	tools="$tools smerge"
	fi
	case "${VISUAL:-$EDITOR}" in
	nvim)
	tools="$tools nvimdiff vimdiff emerge"
	;;
	vim)
	tools="$tools vimdiff nvimdiff emerge"
	;;
	*)
	tools="$tools emerge vimdiff nvimdiff"
	;;
	esac
	}

	show_tool_help () {
	tool_opt="'git ${TOOL_MODE}tool --tool=<tool>'"

	tab=' '
	LF='
	'
	any_shown=no

	cmd_name=${TOOL_MODE}tool
	config_tools=$({
	diff_mode && list_config_tools difftool "$tab$tab"
	list_config_tools mergetool "$tab$tab"
	} \| sort)
	extra_content=
	if test -n "$config_tools"
	then
	extra_content="${tab}user-defined:${LF}$config_tools"
	fi

	show_tool_names 'mode_ok && is_available' "$tab$tab" \
	"$tool_opt may be set to one of the following:" \
	"No suitable tool for 'git $cmd_name --tool=<tool>' found." \
	"$extra_content" &&
	any_shown=yes

	show_tool_names 'mode_ok && ! is_available' "$tab$tab" \
	"${LF}The following tools are valid, but not currently available:" &&
	any_shown=yes

	if test "$any_shown" = yes
	then
	echo
	echo "Some of the tools listed above only work in a windowed"
	echo "environment. If run in a terminal-only session, they will fail."
	fi
	exit 0
	}

	guess_merge_tool () {
	list_merge_tool_candidates
	cat >&2 <<-EOF

	This message is displayed because '$TOOL_MODE.tool' is not configured.
	See 'git ${TOOL_MODE}tool --tool-help' or 'git help config' for more details.
	'git ${TOOL_MODE}tool' will now attempt to use one of the following tools:
	$tools
	EOF

	# Loop over each candidate and stop when a valid merge tool is found.
	IFS=' '
	for tool in $tools
	do
	is_available "$tool" && echo "$tool" && return 0
	done

	echo >&2 "No known ${TOOL_MODE} tool is available."
	return 1
	}

	get_configured_merge_tool () {
	keys=
	if diff_mode
	then
	if gui_mode
	then
	keys="diff.guitool merge.guitool diff.tool merge.tool"
	else
	keys="diff.tool merge.tool"
	fi
	else
	if gui_mode
	then
	keys="merge.guitool merge.tool"
	else
	keys="merge.tool"
	fi
	fi

	merge_tool=$(
	IFS=' '
	for key in $keys
	do
	selected=$(git config $key)
	if test -n "$selected"
	then
	echo "$selected"
	return
	fi
	done)

	if test -n "$merge_tool" && ! valid_tool "$merge_tool"
	then
	echo >&2 "git config option $TOOL_MODE.${gui_prefix}tool set to unknown tool: $merge_tool"
	echo >&2 "Resetting to default..."
	return 1
	fi
	echo "$merge_tool"
	}

	get_merge_tool_path () {
	# A merge tool has been set, so verify that it's valid.
	merge_tool="$1"
	if ! valid_tool "$merge_tool"
	then
	echo >&2 "Unknown $TOOL_MODE tool $merge_tool"
	exit 1
	fi
	if diff_mode
	then
	merge_tool_path=$(git config difftool."$merge_tool".path \|\|
	git config mergetool."$merge_tool".path)
	else
	merge_tool_path=$(git config mergetool."$merge_tool".path)
	fi
	if test -z "$merge_tool_path"
	then
	merge_tool_path=$(translate_merge_tool_path "$merge_tool")
	fi
	if test -z "$(get_merge_tool_cmd "$merge_tool")" &&
	! type "$merge_tool_path" >/dev/null 2>&1
	then
	echo >&2 "The $TOOL_MODE tool $merge_tool is not available as"\
	"'$merge_tool_path'"
	exit 1
	fi
	echo "$merge_tool_path"
	}

	get_merge_tool () {
	is_guessed=false
	# Check if a merge tool has been configured
	merge_tool=$(get_configured_merge_tool)
	subshell_exit_status=$?
	if test $subshell_exit_status -gt "1"
	then
	exit $subshell_exit_status
	fi
	# Try to guess an appropriate merge tool if no tool has been set.
	if test -z "$merge_tool"
	then
	merge_tool=$(guess_merge_tool) \|\| exit
	is_guessed=true
	fi
	echo "$merge_tool"
	test "$is_guessed" = false
	}

	mergetool_find_win32_cmd () {
	executable=$1
	sub_directory=$2

	# Use $executable if it exists in $PATH
	if type -p "$executable" >/dev/null 2>&1
	then
	printf '%s' "$executable"
	return
	fi

	# Look for executable in the typical locations
	for directory in $(env \| grep -Ei '^PROGRAM(FILES(\(X86\))?\|W6432)=' \|
	cut -d '=' -f 2- \| sort -u)
	do
	if test -n "$directory" && test -x "$directory/$sub_directory/$executable"
	then
	printf '%s' "$directory/$sub_directory/$executable"
	return
	fi
	done

	printf '%s' "$executable"
	}