tg.sh

#!/bin/sh
# TopGit - A different patch queue manager
# Copyright (C) 2008 Petr Baudis <pasky@suse.cz>
# Copyright (C) 2014-2017 Kyle J. McKay <mackyle@gmail.com>
# All rights reserved.
# GPLv2

TG_VERSION=0.19.8

# Update in Makefile if you add any code that requires a newer version of git
GIT_MINIMUM_VERSION="@mingitver@"

## SHA-1 pattern

octet='[0-9a-f][0-9a-f]'
octet4="$octet$octet$octet$octet"
octet19="$octet4$octet4$octet4$octet4$octet$octet$octet"
octet20="$octet4$octet4$octet4$octet4$octet4"
nullsha="0000000000000000000000000000000000000000" # :|git mktree|tr 0-9a-f 0
mtblob="e69de29bb2d1d6434b8b29ae775ad8c2e48c5391" # :|git hash-object --stdin -w
tab='	'
lf='
'

## Auxiliary functions

# some ridiculous sh implementations require 'trap ... EXIT' to be executed
# OUTSIDE ALL FUNCTIONS to work in a sane fashion.  Always trap it and eval
# "${TRAPEXIT_:-exit}" as a substitute.
trapexit_()
{
	EXITCODE_=${1:-$?}
	trap - EXIT
	eval "${TRAPEXIT_:-exit $EXITCODE_}"
	exit $EXITCODE_
}
trap 'trapexit_ $?' EXIT

# unset that ignores error code that shouldn't be produced according to POSIX
unset_()
{
	{ unset "$@"; } >/dev/null 2>&1 || :
}

# Preserves current $? value while triggering a non-zero set -e exit if active
# This works even for shells that sometimes fail to correctly trigger a -e exit
check_exit_code()
{
	return $?
}

# This is the POSIX equivalent of which
cmd_path()
(
	{ "unset" -f command unset unalias "$1"; } >/dev/null 2>&1 || :
	{ "unalias" -a || unalias -m "*"; } >/dev/null 2>&1 || :
	command -v "$1"
)

# helper for wrappers
# note deliberate use of '(' ... ')' rather than '{' ... '}'
exec_lc_all_c()
(
	{ "unset" -f "$1" || :; } >/dev/null 2>&1 &&
	shift &&
	LC_ALL="C" &&
	export LC_ALL &&
	exec "$@"
)

# These tools work better for us with LC_ALL=C and by using these little
# convenience functions LC_ALL=C does not have to appear in the code but
# any Git translations will still appear for Git commands
awk()	{ exec_lc_all_c awk @AWK_PATH@	"$@"; }
cat()	{ exec_lc_all_c cat cat		"$@"; }
cut()	{ exec_lc_all_c cut cut		"$@"; }
find()	{ exec_lc_all_c find find	"$@"; }
grep()	{ exec_lc_all_c grep grep	"$@"; }
join()	{ exec_lc_all_c join join	"$@"; }
paste()	{ exec_lc_all_c paste paste	"$@"; }
sed()	{ exec_lc_all_c sed sed		"$@"; }
sort()	{ exec_lc_all_c sort sort	"$@"; }
tr()	{ exec_lc_all_c tr tr		"$@"; }
wc()	{ exec_lc_all_c wc wc		"$@"; }
xargs()	{ exec_lc_all_c xargs xargs	"$@"; }

# Output arguments without any possible interpretation
# (Avoid misinterpretation of '\' characters or leading "-n", "-E" or "-e")
echol()
{
	printf '%s\n' "$*"
}

info()
{
	echol "${TG_RECURSIVE}${tgname:-tg}: $*"
}

warn()
{
	info "warning: $*" >&2
}

err()
{
	info "error: $*" >&2
}

fatal()
{
	info "fatal: $*" >&2
}

die()
{
	fatal "$@"
	exit 1
}

# shift off first arg then return "$*" properly quoted in single-quotes
# if $1 was '' output goes to stdout otherwise it's assigned to $1
# the final \n, if any, is omitted from the result but any others are included
v_quotearg()
{
	_quotearg_v="$1"
	shift
	set -- "$_quotearg_v" \
	"sed \"s/'/'\\\\\\''/g;1s/^/'/;\\\$s/\\\$/'/;s/'''/'/g;1s/^''\\(.\\)/\\1/\"" "$*"
	unset_ _quotearg_v
	if [ -z "$3" ]; then
		if [ -z "$1" ]; then
			echo "''"
		else
			eval "$1=\"''\""
		fi
	else
		if [ -z "$1" ]; then
			printf "%s$4" "$3" | eval "$2"
		else
			eval "$1="'"$(printf "%s$4" "$3" | eval "$2")"'
		fi
	fi
}

# same as v_quotearg except there's no extra $1 so output always goes to stdout
quotearg()
{
	v_quotearg '' "$@"
}

vcmp()
{
	# Compare $1 to $3 each of which must match ^[^0-9]*\d*(\.\d*)*.*$
	# where only the "\d*" parts in the regex participate in the comparison
	# Since EVERY string matches that regex this function is easy to use
	# An empty string ('') for $1 or $3 or any "\d*" part is treated as 0
	# $2 is a compare op '<', '<=', '=', '==', '!=', '>=', '>'
	# Return code is 0 for true, 1 for false (or unknown compare op)
	# There is NO difference in behavior between '=' and '=='
	# Note that "vcmp 1.8 == 1.8.0.0.0.0" correctly returns 0
	set -- "$1" "$2" "$3" "${1%%[0-9]*}" "${3%%[0-9]*}"
	set -- "${1#"$4"}" "$2" "${3#"$5"}"
	set -- "${1%%[!0-9.]*}" "$2" "${3%%[!0-9.]*}"
	while
		vcmp_a_="${1%%.*}"
		vcmp_b_="${3%%.*}"
		[ "z$vcmp_a_" != "z" -o "z$vcmp_b_" != "z" ]
	do
		if [ "${vcmp_a_:-0}" -lt "${vcmp_b_:-0}" ]; then
			unset_ vcmp_a_ vcmp_b_
			case "$2" in "<"|"<="|"!=") return 0; esac
			return 1
		elif [ "${vcmp_a_:-0}" -gt "${vcmp_b_:-0}" ]; then
			unset_ vcmp_a_ vcmp_b_
			case "$2" in ">"|">="|"!=") return 0; esac
			return 1;
		fi
		vcmp_a_="${1#$vcmp_a_}"
		vcmp_b_="${3#$vcmp_b_}"
		set -- "${vcmp_a_#.}" "$2" "${vcmp_b_#.}"
	done
	unset_ vcmp_a_ vcmp_b_
	case "$2" in "="|"=="|"<="|">=") return 0; esac
	return 1
}

# true if "$1" is an existing dir and is empty except for
# any additional files given as extra arguments.  If "$2"
# is the single character "." then all ".*" files will be
# ignored for the test (plus any further args, if any)
is_empty_dir() {
	test -n "$1" && test -d "$1" || return 1
	iedd_="$1"
	shift
	ieddnok_='\.?$'
	if [ z"$1" = z"." ]; then
		ieddnok_=
		shift
		while ! case "$1" in "."*) ! :; esac; do shift; done
	fi
	if [ $# -eq 0 ]; then
		! \ls -a1 "$iedd_" | grep -q -E -v '^\.'"$ieddnok_"
	else
		# we only handle ".git" right now for efficiency
		[ z"$*" = z".git" ] || {
			fatal "[BUG] is_empty_dir not implemented for arguments: $*"
			exit 70
		}
		! \ls -a1 "$iedd_" | grep -q -E -v -i -e '^\.\.?$' -e '^\.git$'
	fi
}

precheck() {
	if ! git_version="$(git version)"; then
		die "'git version' failed"
	fi
	case "$git_version" in [Gg]"it version "*);;*)
		die "'git version' output does not start with 'git version '"
	esac

	vcmp "$git_version" '>=' "$GIT_MINIMUM_VERSION" ||
		die "git version >= $GIT_MINIMUM_VERSION required but found $git_version instead"
}

case "$1" in version|--version|-V)
	echo "TopGit version $TG_VERSION"
	exit 0
esac

[ $# -eq 1 ] && [ "$1" = "--make-empty-blob" ] || precheck
[ $# -ne 1 ] || [ "$1" != "precheck" ] || exit 0

cat_depsmsg_internal()
{
	_rev="$(ref_exists_rev "refs/heads/$1")" || return 0
	if [ -s "$tg_cache_dir/refs/heads/$1/.$2" ]; then
		if read _rev_match && [ "$_rev" = "$_rev_match" ]; then
			_line=
			while IFS= read -r _line || [ -n "$_line" ]; do
				printf '%s\n' "$_line"
			done
			return 0
		fi <"$tg_cache_dir/refs/heads/$1/.$2"
	fi
	[ -d "$tg_cache_dir/refs/heads/$1" ] || mkdir -p "$tg_cache_dir/refs/heads/$1" 2>/dev/null || :
	if [ -d "$tg_cache_dir/refs/heads/$1" ]; then
		printf '%s\n' "$_rev" >"$tg_cache_dir/refs/heads/$1/.$2"
		_line=
		git cat-file blob "$_rev:.$2" 2>/dev/null |
		while IFS= read -r _line || [ -n "$_line" ]; do
			printf '%s\n' "$_line" >&3
			printf '%s\n' "$_line"
		done 3>>"$tg_cache_dir/refs/heads/$1/.$2"
	else
		git cat-file blob "$_rev:.$2" 2>/dev/null
	fi
}

# cat_deps BRANCHNAME
# Caches result
cat_deps()
{
	cat_depsmsg_internal "$1" topdeps
}

# cat_msg BRANCHNAME
# Caches result
cat_msg()
{
	cat_depsmsg_internal "$1" topmsg
}

# cat_file TOPIC:PATH [FROM]
# cat the file PATH from branch TOPIC when FROM is empty.
# FROM can be -i or -w, than the file will be from the index or worktree,
# respectively. The caller should than ensure that HEAD is TOPIC, to make sense.
cat_file()
{
	path="$1"
	case "$2" in
	-w)
		cat "$root_dir/${path#*:}"
		;;
	-i)
		# ':file' means cat from index
		git cat-file blob ":${path#*:}" 2>/dev/null
		;;
	'')
		case "$path" in
		refs/heads/*:.topdeps)
			_temp="${path%:.topdeps}"
			cat_deps "${_temp#refs/heads/}"
			;;
		refs/heads/*:.topmsg)
			_temp="${path%:.topmsg}"
			cat_msg "${_temp#refs/heads/}"
			;;
		*)
			git cat-file blob "$path" 2>/dev/null
			;;
		esac
		;;
	*)
		die "Wrong argument to cat_file: '$2'"
		;;
	esac
}

# if use_alt_temp_odb and tg_use_alt_odb are true try to write the object(s)
# into the temporary alt odb area instead of the usual location
git_temp_alt_odb_cmd()
{
	if [ -n "$use_alt_temp_odb" ] && [ -n "$tg_use_alt_odb" ] &&
	   [ -n "$TG_OBJECT_DIRECTORY" ] &&
	   [ -f "$TG_OBJECT_DIRECTORY/info/alternates" ]; then
		(
			GIT_ALTERNATE_OBJECT_DIRECTORIES="$TG_PRESERVED_ALTERNATES"
			GIT_OBJECT_DIRECTORY="$TG_OBJECT_DIRECTORY"
			unset_ TG_OBJECT_DIRECTORY TG_PRESERVED_ALTERNATES
			export GIT_ALTERNATE_OBJECT_DIRECTORIES GIT_OBJECT_DIRECTORY
			git "$@"
		)
	else
		git "$@"
	fi
}

git_write_tree() { git_temp_alt_odb_cmd write-tree "$@"; }
git_mktree() { git_temp_alt_odb_cmd mktree "$@"; }

make_mtblob() {
	use_alt_temp_odb=1
	tg_use_alt_odb=1
	git_temp_alt_odb_cmd hash-object -t blob -w --stdin </dev/null >/dev/null 2>&1
}
# short-circuit this for speed
[ $# -eq 1 ] && [ "$1" = "--make-empty-blob" ] && { make_mtblob || :; exit 0; }

# get tree for the committed topic
get_tree_()
{
	echo "refs/heads/$1"
}

# get tree for the base
get_tree_b()
{
	echo "refs/$topbases/$1"
}

# get tree for the index
get_tree_i()
{
	git_write_tree
}

# get tree for the worktree
get_tree_w()
{
	i_tree=$(git_write_tree)
	(
		# the file for --index-output needs to sit next to the
		# current index file
		cd "$root_dir"
		: ${GIT_INDEX_FILE:="$git_dir/index"}
		TMP_INDEX="$(mktemp "${GIT_INDEX_FILE}-tg.XXXXXX")"
		git read-tree -m $i_tree --index-output="$TMP_INDEX" &&
		GIT_INDEX_FILE="$TMP_INDEX" &&
		export GIT_INDEX_FILE &&
		git diff --name-only -z HEAD |
			git update-index -z --add --remove --stdin &&
		git_write_tree &&
		rm -f "$TMP_INDEX"
	)
}

# get tree for arbitrary ref
get_tree_r()
{
	echo "$1"
}

# strip_ref "$(git symbolic-ref HEAD)"
# Output will have a leading refs/heads/ or refs/$topbases/ stripped if present
strip_ref()
{
	case "$1" in
		refs/"$topbases"/*)
			echol "${1#refs/$topbases/}"
			;;
		refs/heads/*)
			echol "${1#refs/heads/}"
			;;
		*)
			echol "$1"
	esac
}

# pretty_tree [-t] NAME [-b | -i | -w | -r]
# Output tree ID of a cleaned-up tree without tg's artifacts.
# NAME will be ignored for -i and -w, but needs to be present
# With -r NAME must be a full ref name to a treeish (it's used as-is)
# If -t is used the tree is written into the alternate temporary objects area
pretty_tree()
{
	use_alt_temp_odb=
	[ "$1" != "-t" ] || { shift; use_alt_temp_odb=1; }
	name="$1"
	source="${2#?}"
	git ls-tree --full-tree "$(get_tree_$source "$name")" |
		sed -ne '/	\.top.*$/!p' |
		git_mktree
}

# return an empty-tree root commit -- date is either passed in or current
# If passed in "$*" must be epochsecs followed by optional hhmm offset (+0000 default)
# An invalid secs causes the current date to be used, an invalid zone offset
# causes +0000 to be used
make_empty_commit()
(
	# the empty tree is guaranteed to always be there even in a repo with
	# zero objects, but for completeness we force it to exist as a real object
	SECS=
	read -r SECS ZONE JUNK <<-EOT || :
		$*
		EOT
	case "$SECS" in *[!0-9]*) SECS=; esac
	if [ -z "$SECS" ]; then
		MTDATE="$(date '+%s %z')"
	else
		case "$ZONE" in
			-[01][0-9][0-5][0-9]|+[01][0-9][0-5][0-9])
				;;
			[01][0-9][0-5][0-9])
				ZONE="+$ZONE"
				;;
			*)
				ZONE="+0000"
		esac
		MTDATE="$SECS $ZONE"
	fi
	EMPTYID="- <-> $MTDATE"
	EMPTYTREE="$(git hash-object -t tree -w --stdin < /dev/null)"
	printf '%s\n' "tree $EMPTYTREE" "author $EMPTYID" "committer $EMPTYID" '' |
	git hash-object -t commit -w --stdin
)

# standard input is a diff
# standard output is the "+" lines with leading "+ " removed
# beware that old lines followed by the dreaded '\ No newline at end of file'
# will appear to be new lines if lines are added after them
# the git diff --ignore-space-at-eol option can be used to prevent this
diff_added_lines()
{
	awk '
BEGIN      { in_hunk = 0; }
/^@@ /     { in_hunk = 1; }
/^\+/      { if (in_hunk == 1) printf("%s\n", substr($0, 2)); }
!/^\\ No newline at end of file/ &&
/^[^@ +-]/ { in_hunk = 0; }
'
}

# $1 is name of new branch to create locally if all of these are true:
#   a) exists as a remote TopGit branch for "$base_remote"
#   b) the branch "name" does not have any invalid characters in it
#   c) neither of the two branch refs (branch or base) exist locally
# returns success only if a new local branch was created (and dumps message)
auto_create_local_remote()
{
	case "$1" in ""|*[" $tab$lf~^:\\*?["]*|.*|*/.*|*.|*./|/*|*/|*//*) return 1; esac
	[ -n "$base_remote" ] &&
	git update-ref --stdin <<-EOT >/dev/null 2>&1 &&
		verify refs/remotes/$base_remote/${topbases#heads/}/$1 refs/remotes/$base_remote/${topbases#heads/}/$1
		verify refs/remotes/$base_remote/$1 refs/remotes/$base_remote/$1
		create refs/$topbases/$1 refs/remotes/$base_remote/${topbases#heads/}/$1^0
		create refs/heads/$1 refs/remotes/$base_remote/$1^0
	EOT
	{ init_reflog "refs/$topbases/$1" || :; } &&
	info "topic branch '$1' automatically set up from remote '$base_remote'"
}

# setup_hook NAME
setup_hook()
{
	setup_git_dir_is_bare
	[ -z "$git_dir_is_bare" ] || return 0
	tgname="${0##*/}"
	hook_call="\"\$(\"$tgname\" --hooks-path)\"/$1 \"\$@\""
	if [ -f "$git_hooks_dir/$1" ] && grep -Fq "$hook_call" "$git_hooks_dir/$1"; then
		# Another job well done!
		return
	fi
	# Prepare incantation
	hook_chain=
	if [ -s "$git_hooks_dir/$1" -a -x "$git_hooks_dir/$1" ]; then
		hook_call="$hook_call"' || exit $?'
		if [ -L "$git_hooks_dir/$1" ] || ! sed -n 1p <"$git_hooks_dir/$1" | grep -Fqx "#!@SHELL_PATH@"; then
			chain_num=
			while [ -e "$git_hooks_dir/$1-chain$chain_num" ]; do
				chain_num=$(( $chain_num + 1 ))
			done
			mv -f "$git_hooks_dir/$1" "$git_hooks_dir/$1-chain$chain_num"
			hook_chain=1
		fi
	else
		hook_call="exec $hook_call"
		[ -d "$git_hooks_dir" ] || mkdir -p "$git_hooks_dir" || :
	fi
	# Don't call hook if tg is not installed
	hook_call="if command -v \"$tgname\" >/dev/null 2>&1; then $hook_call; fi"
	# Insert call into the hook
	{
		echol "#!@SHELL_PATH@"
		echol "$hook_call"
		if [ -n "$hook_chain" ]; then
			echol "exec \"\$0-chain$chain_num\" \"\$@\""
		else
			[ ! -s "$git_hooks_dir/$1" ] || cat "$git_hooks_dir/$1"
		fi
	} >"$git_hooks_dir/$1+"
	chmod a+x "$git_hooks_dir/$1+"
	mv "$git_hooks_dir/$1+" "$git_hooks_dir/$1"
}

# setup_ours (no arguments)
setup_ours()
{
	setup_git_dir_is_bare
	[ -z "$git_dir_is_bare" ] || return 0
	if [ ! -s "$git_common_dir/info/attributes" ] || ! grep -q topmsg "$git_common_dir/info/attributes"; then
		[ -d "$git_common_dir/info" ] || mkdir "$git_common_dir/info"
		{
			echo ".topmsg	merge=ours"
			echo ".topdeps	merge=ours"
		} >>"$git_common_dir/info/attributes"
	fi
	if ! git config merge.ours.driver >/dev/null; then
		git config merge.ours.name '"always keep ours" merge driver'
		git config merge.ours.driver 'touch %A'
	fi
}

# measure_branch NAME [BASE] [EXTRAHEAD...]
measure_branch()
{
	_bname="$1"; _base="$2"
	shift; shift
	[ -n "$_base" ] || _base="refs/$topbases/$(strip_ref "$_bname")"
	# The caller should've verified $name is valid
	_commits="$(git rev-list --count "$_bname" "$@" ^"$_base" --)"
	_nmcommits="$(git rev-list --count --no-merges "$_bname" "$@" ^"$_base" --)"
	if [ $_commits -ne 1 ]; then
		_suffix="commits"
	else
		_suffix="commit"
	fi
	echo "$_commits/$_nmcommits $_suffix"
}

# true if $1 is contained by (or the same as) $2
# this is never slower than merge-base --is-ancestor and is often slightly faster
contained_by()
{
        [ "$(git rev-list --count --max-count=1 "$1" --not "$2" --)" = "0" ]
}

# branch_contains B1 B2
# Whether B1 is a superset of B2.
branch_contains()
{
	_revb1="$(ref_exists_rev "$1")" || return 0
	_revb2="$(ref_exists_rev "$2")" || return 0
	if [ -s "$tg_cache_dir/$1/.bc/$2/.d" ]; then
		if read _result _rev_matchb1 _rev_matchb2 &&
			[ "$_revb1" = "$_rev_matchb1" -a "$_revb2" = "$_rev_matchb2" ]; then
			return $_result
		fi <"$tg_cache_dir/$1/.bc/$2/.d"
	fi
	[ -d "$tg_cache_dir/$1/.bc/$2" ] || mkdir -p "$tg_cache_dir/$1/.bc/$2" 2>/dev/null || :
	_result=0
	contained_by "$_revb2" "$_revb1" || _result=1
	if [ -d "$tg_cache_dir/$1/.bc/$2" ]; then
		echo "$_result" "$_revb1" "$_revb2" >"$tg_cache_dir/$1/.bc/$2/.d"
	fi
	return $_result
}

create_ref_dirs()
{
	[ ! -s "$tg_tmp_dir/tg~ref-dirs-created" -a -s "$tg_ref_cache" ] || return 0
	mkdir -p "$tg_tmp_dir/cached/refs"
	awk '{x = $1; sub(/^refs\//, "", x); if (x != "") print x}' <"$tg_ref_cache" | tr '\n' '\0' | {
		cd "$tg_tmp_dir/cached/refs" &&
		xargs -0 mkdir -p
	}
	awk -v p="$tg_tmp_dir/cached/" '
		NF == 2 &&
		$1 ~ /^refs\/./ &&
		$2 ~ /^[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]+$/ {
			fn = p $1 "/.ref"
			print "0 " $2 >fn
			close(fn)
		}
	' <"$tg_ref_cache"
	echo 1 >"$tg_tmp_dir/tg~ref-dirs-created"
}

# If the first argument is non-empty, stores "1" there if this call created the cache
v_create_ref_cache()
{
	[ -n "$tg_ref_cache" -a ! -s "$tg_ref_cache" ] || return 0
	_remotespec=
	[ -z "$base_remote" ] || _remotespec="refs/remotes/$base_remote"
	[ -z "$1" ] || eval "$1=1"
	git for-each-ref --format='%(refname) %(objectname)' \
		refs/heads "refs/$topbases" $_remotespec >"$tg_ref_cache"
	create_ref_dirs
}

remove_ref_cache()
{
	[ -n "$tg_ref_cache" -a -s "$tg_ref_cache" ] || return 0
	>"$tg_ref_cache"
	>"$tg_ref_cache_br"
	>"$tg_ref_cache_rbr"
	>"$tg_ref_cache_ann"
	>"$tg_ref_cache_dep"
}

# setting tg_ref_cache_only to non-empty will force non-$tg_ref_cache lookups to fail
rev_parse()
{
	rev_parse_code_=1
	if [ -n "$tg_ref_cache" -a -s "$tg_ref_cache" ]; then
		rev_parse_code_=0
		awk -v r="$1" 'BEGIN {e=1}; $1 == r {print $2; e=0; exit}; END {exit e}' <"$tg_ref_cache" ||
		rev_parse_code_=$?
	fi
	[ $rev_parse_code_ -ne 0 ] && [ -z "$tg_ref_cache_only" ] || return $rev_parse_code_
	git rev-parse --quiet --verify "$1^0" -- 2>/dev/null
}

# ref_exists_rev REF
# Whether REF is a valid ref name
# REF must be fully qualified and start with refs/heads/, refs/$topbases/
# or, if $base_remote is set, refs/remotes/$base_remote/
# Caches result if $tg_read_only and outputs HASH on success
ref_exists_rev()
{
	case "$1" in
		refs/*)
			;;
		$octet20)
			printf '%s' "$1"
			return;;
		*)
			die "ref_exists_rev requires fully-qualified ref name (given: $1)"
	esac
	[ -n "$tg_read_only" ] || { git rev-parse --quiet --verify "$1^0" -- 2>/dev/null; return; }
	_result=
	_result_rev=
	{ read -r _result _result_rev <"$tg_tmp_dir/cached/$1/.ref"; } 2>/dev/null || :
	[ -z "$_result" ] || { printf '%s' "$_result_rev"; return $_result; }
	_result=0
	_result_rev="$(rev_parse "$1")" || _result=$?
	[ -d "$tg_tmp_dir/cached/$1" ] || mkdir -p "$tg_tmp_dir/cached/$1" 2>/dev/null
	[ ! -d "$tg_tmp_dir/cached/$1" ] ||
	echo $_result $_result_rev >"$tg_tmp_dir/cached/$1/.ref" 2>/dev/null || :
	printf '%s' "$_result_rev"
	return $_result
}

# Same as ref_exists_rev but output is abbreviated hash
# Optional second argument defaults to --short but may be any --short=.../--no-short option
ref_exists_rev_short()
{
	case "$1" in
		refs/*)
			;;
		$octet20)
			;;
		*)
			die "ref_exists_rev_short requires fully-qualified ref name"
	esac
	[ -n "$tg_read_only" ] || { git rev-parse --quiet --verify ${2:---short} "$1^0" -- 2>/dev/null; return; }
	_result=
	_result_rev=
	{ read -r _result _result_rev <"$tg_tmp_dir/cached/$1/.rfs"; } 2>/dev/null || :
	[ -z "$_result" ] || { printf '%s' "$_result_rev"; return $_result; }
	_result=0
	_result_rev="$(rev_parse "$1")" || _result=$?
	if [ $_result -eq 0 ]; then
		_result_rev="$(git rev-parse --verify ${2:---short} --quiet "$_result_rev^0" --)"
		_result=$?
	fi
	[ -d "$tg_tmp_dir/cached/$1" ] || mkdir -p "$tg_tmp_dir/cached/$1" 2>/dev/null
	[ ! -d "$tg_tmp_dir/cached/$1" ] ||
	echo $_result $_result_rev >"$tg_tmp_dir/cached/$1/.rfs" 2>/dev/null || :
	printf '%s' "$_result_rev"
	return $_result
}

# ref_exists REF
# Whether REF is a valid ref name
# REF must be fully qualified and start with refs/heads/, refs/$topbases/
# or, if $base_remote is set, refs/remotes/$base_remote/
# Caches result
ref_exists()
{
	ref_exists_rev "$1" >/dev/null
}

# rev_parse_tree REF
# Runs git rev-parse REF^{tree}
# Caches result if $tg_read_only
rev_parse_tree()
{
	[ -n "$tg_read_only" ] || { git rev-parse --verify "$1^{tree}" -- 2>/dev/null; return; }
	if [ -f "$tg_tmp_dir/cached/$1/.rpt" ]; then
		if IFS= read -r _result <"$tg_tmp_dir/cached/$1/.rpt"; then
			printf '%s\n' "$_result"
			return 0
		fi
		return 1
	fi
	[ -d "$tg_tmp_dir/cached/$1" ] || mkdir -p "$tg_tmp_dir/cached/$1" 2>/dev/null || :
	if [ -d "$tg_tmp_dir/cached/$1" ]; then
		git rev-parse --verify "$1^{tree}" -- >"$tg_tmp_dir/cached/$1/.rpt" 2>/dev/null || :
		if IFS= read -r _result <"$tg_tmp_dir/cached/$1/.rpt"; then
			printf '%s\n' "$_result"
			return 0
		fi
		return 1
	fi
	git rev-parse --verify "$1^{tree}" -- 2>/dev/null
}

# has_remote BRANCH
# Whether BRANCH has a remote equivalent (accepts ${topbases#heads/}/ too)
has_remote()
{
	[ -n "$base_remote" ] && ref_exists "refs/remotes/$base_remote/$1"
}

# Return the verified TopGit branch name for "$2" in "$1" or die with an error.
# If -z "$1" still set return code but do not return result
# As a convenience, if HEAD or @ is given and HEAD is a symbolic ref to
# refs/heads/... then ... will be verified instead.
# if "$3" = "-f" (for fail) then return an error rather than dying.
v_verify_topgit_branch()
{
	if [ "$2" = "HEAD" ] || [ "$2" = "@" ]; then
		_verifyname="$(git symbolic-ref HEAD 2>/dev/null)" || :
		[ -n "$_verifyname" -o "$3" = "-f" ] || die "HEAD is not a symbolic ref"
		case "$_verifyname" in refs/"$topbases"/*|refs/heads/*);;*)
			[ "$3" != "-f" ] || return 1
			die "HEAD is not a symbolic ref to the refs/heads namespace"
		esac
		set -- "$1" "$_verifyname" "$3"
	fi
	case "$2" in
		refs/"$topbases"/*)
			_verifyname="${2#refs/$topbases/}"
			;;
		refs/heads/*)
			_verifyname="${2#refs/heads/}"
			;;
		*)
			_verifyname="$2"
			;;
	esac
	if ! ref_exists "refs/heads/$_verifyname"; then
		[ "$3" != "-f" ] || return 1
		die "no such branch: $_verifyname"
	fi
	if ! ref_exists "refs/$topbases/$_verifyname"; then
		[ "$3" != "-f" ] || return 1
		die "not a TopGit-controlled branch: $_verifyname"
	fi
	[ -z "$1" ] || eval "$1="'"$_verifyname"'
}

# Return the verified TopGit branch name or die with an error.
# As a convenience, if HEAD or @ is given and HEAD is a symbolic ref to
# refs/heads/... then ... will be verified instead.
# if "$2" = "-f" (for fail) then return an error rather than dying.
verify_topgit_branch()
{
	v_verify_topgit_branch _verifyname "$@" || return
	printf '%s' "$_verifyname"
}

# Caches result
# $1 = branch name (i.e. "t/foo/bar")
# $2 = optional result of rev-parse "refs/heads/$1"
# $3 = optional result of rev-parse "refs/$topbases/$1"
branch_annihilated()
{
	_branch_name="$1"
	_rev="${2:-$(ref_exists_rev "refs/heads/$_branch_name")}"
	_rev_base="${3:-$(ref_exists_rev "refs/$topbases/$_branch_name")}"

	_result=
	_result_rev=
	_result_rev_base=
	{ read -r _result _result_rev _result_rev_base <"$tg_cache_dir/refs/heads/$_branch_name/.ann"; } 2>/dev/null || :
	[ -z "$_result" -o "$_result_rev" != "$_rev" -o "$_result_rev_base" != "$_rev_base" ] || return $_result

	# use the merge base in case the base is ahead.
	mb="$(git merge-base "$_rev_base" "$_rev" 2>/dev/null)"

	test -z "$mb" || test "$(rev_parse_tree "$mb")" = "$(rev_parse_tree "$_rev")"
	_result=$?
	[ -d "$tg_cache_dir/refs/heads/$_branch_name" ] || mkdir -p "$tg_cache_dir/refs/heads/$_branch_name" 2>/dev/null
	[ ! -d "$tg_cache_dir/refs/heads/$_branch_name" ] ||
	echo $_result $_rev $_rev_base >"$tg_cache_dir/refs/heads/$_branch_name/.ann" 2>/dev/null || :
	return $_result
}

non_annihilated_branches()
{
	refscacheopt="${TG_DEBUG:+-p=\"\$tg_ref_cache.pre\" }"
	if [ -n "$tg_read_only" ] && [ -n "$tg_ref_cache" ] && [ -s "$tg_ref_cache" ]; then
		refscacheopt="$refscacheopt"'-r="$tg_ref_cache" "refs/$topbases"'
	fi
	eval run_awk_topgit_branches -n "$refscacheopt" '"refs/$topbases" "$@"'
}

# Make sure our tree is clean
# if optional "$1" given also verify that a checkout to "$1" would succeed
ensure_clean_tree()
{
	check_status
	[ -z "$tg_state$git_state" ] || { do_status; exit 1; }
	git update-index --ignore-submodules --refresh ||
		die "the working directory has uncommitted changes (see above) - first commit or reset them"
	[ -z "$(git diff-index --cached --name-status -r --ignore-submodules HEAD --)" ] ||
		die "the index has uncommited changes"
	[ -z "$1" ] || git read-tree -n -u -m "$1" ||
		die "git checkout \"$1\" would fail"
}

# Make sure .topdeps and .topmsg are "clean"
# They are considered "clean" if each is identical in worktree, index and HEAD
# With "-u" as the argument skip the HEAD check (-u => unborn)
# untracked .topdeps and/or .topmsg files are always considered "dirty" as well
# with -u them just existing constitutes "dirty"
ensure_clean_topfiles()
{
	_dirtw=0
	_dirti=0
	_dirtu=0
	_check="$(git diff-files --ignore-submodules --name-only -- :/.topdeps :/.topmsg)" &&
	[ -z "$_check" ] || _dirtw=1
	if [ "$1" != "-u" ]; then
		_check="$(git diff-index --cached --ignore-submodules --name-only HEAD -- :/.topdeps :/.topmsg)" &&
		[ -z "$_check" ] || _dirti=1
	fi
	if [ "$_dirti$_dirtw" = "00" ]; then
		v_get_show_cdup
		if [ -e "${git_cdup_result}.topdeps" ] || [ -e "${git_cdup_result}.topmsg" ]; then
			[ "$1" != "-u" ] &&
			_check="$(git status --porcelain --ignored --untracked-files --ignore-submodules -- :/.topdeps :/.topmsg)" &&
			[ -z "$_check" ] || _dirtu=1
		fi
	fi
	if [ "$_dirtu$_dirti$_dirtw" != "000" ]; then
		git status --ignored --untracked-files --ignore-submodules -- :/.topdeps :/.topmsg || :
		case "$_dirtu$_dirti$_dirtw" in
		001) die "the working directory has uncommitted changes (see above) - first commit or reset them";;
		010) die "the index has uncommited changes (see above)";;
		011) die "the working directory and index have uncommitted changes (see above) - first commit or reset them";;
		100) die "the working directory has untracked files that would be overwritten (see above)";;
		esac
	fi
}

# is_sha1 REF
# Whether REF is a SHA1 (compared to a symbolic name).
is_sha1()
{
	case "$1" in $octet20) return 0;; esac
	return 1
}

# navigate_deps <run_awk_topgit_navigate options and arguments>
# all options and arguments are passed through to run_awk_topgit_navigate
# except for a leading -td= option, if any, which is picked off for deps
# after arranging to feed it a suitable deps list
navigate_deps()
{
	dogfer=
	dorad=1
	userc=
	tmpdep=
	ratd_opts="${TG_DEBUG:+-p=\"\$tg_ref_cache.pre\" }"
	ratn_opts=
	if [ -n "$tg_read_only" ] && [ -n "$tg_ref_cache" ]; then
		userc=1
		tmprfs="$tg_ref_cache"
		tmptgbr="$tg_ref_cache_br"
		tmpann="$tg_ref_cache_ann"
		tmpdep="$tg_ref_cache_dep"
		[ -s "$tg_ref_cache" ] || dogfer=1
		[ -n "$dogfer" ] || ! [ -s "$tmptgbr" ] || ! [ -f "$tmpann" ] || ! [ -s "$tmpdep" ] || dorad=
	else
		ratd_opts="${ratd_opts}-rmr"
		ratn_opts="-rma -rmb"
		tmprfs="$tg_tmp_dir/refs.$$"
		tmpann="$tg_tmp_dir/ann.$$"
		tmptgbr="$tg_tmp_dir/tgbr.$$"
		dogfer=1
	fi
	refpats="\"refs/heads\" \"refs/\$topbases\""
	[ -z "$base_remote" ] || refpats="$refpats \"refs/remotes/\$base_remote\""
	[ -z "$dogfer" ] ||
	eval git for-each-ref '--format="%(refname) %(objectname)"' "$refpats" >"$tmprfs"
	depscmd="run_awk_topgit_deps $ratd_opts"
	case "$1" in -td=*)
		userc=
		depscmd="$depscmd $1"
		shift
	esac
	depscmd="$depscmd"' -a="$tmpann" -b="$tmptgbr" -r="$tmprfs" -s "refs/$topbases"'
	if [ -n "$userc" ]; then
		if [ -n "$dorad" ]; then
			eval "$depscmd" >"$tmpdep"
		fi
		depscmd='<"$tmpdep" '
	else
		depscmd="$depscmd |"
	fi
	eval "$depscmd" run_awk_topgit_navigate '-a="$tmpann" -b="$tmptgbr"' "$ratn_opts" '"$@"'
}

# recurse_deps_internal NAME [BRANCHPATH...]
# get recursive list of dependencies with leading 0 if branch exists 1 if missing
# followed by a 1 if the branch is "tgish" (2 if it also has a remote); 0 if not
# followed by a 0 for a non-leaf, 1 for a leaf or 2 for annihilated tgish
# (but missing and remotes are always "0")
# followed by a 0 for no excess visits or a positive number of excess visits
# then the branch name followed by its depedency chain (which might be empty)
# An output line might look like this:
#   0 1 1 0 t/foo/leaf t/foo/int t/stage
# If no_remotes is non-empty, exclude remotes
# If recurse_preorder is non-empty, do a preorder rather than postorder traversal
# If with_top_level is non-empty, include the top-level that's normally omitted
# any branch names in the space-separated recurse_deps_exclude variable
# are skipped (along with their dependencies)
recurse_deps_internal()
{
	case " $recurse_deps_exclude " in *" $1 "*) return 0; esac
	ratr_opts="${recurse_preorder:+-f} ${with_top_level:+-s}"
	dogfer=
	dorad=1
	userc=
	tmpdep=
	if [ -n "$tg_read_only" ] && [ -n "$tg_ref_cache" ]; then
		userc=1
		tmprfs="$tg_ref_cache"
		tmptgbr="$tg_ref_cache_br"
		tmpann="$tg_ref_cache_ann"
		tmpdep="$tg_ref_cache_dep"
		[ -s "$tg_ref_cache" ] || dogfer=1
		[ -n "$dogfer" ] || ! [ -s "$tmptgbr" ] || ! [ -f "$tmpann" ] || ! [ -s "$tmpdep" ] || dorad=
	else
		ratr_opts="$ratr_opts -rmh -rma -rmb"
		tmprfs="$tg_tmp_dir/refs.$$"
		tmpann="$tg_tmp_dir/ann.$$"
		tmptgbr="$tg_tmp_dir/tgbr.$$"
		dogfer=1
	fi
	refpats="\"refs/heads\" \"refs/\$topbases\""
	[ -z "$base_remote" ] || refpats="$refpats \"refs/remotes/\$base_remote\""
	tmptgrmtbr=
	dorab=1
	if [ -z "$no_remotes" ] && [ -n "$base_remote" ]; then
		if [ -n "$userc" ]; then
			tmptgrmtbr="$tg_ref_cache_rbr"
			[ -n "$dogfer" ] || ! [ -s "$tmptgrmtbr" ] || dorab=
		else
			tmptgrmtbr="$tg_tmp_dir/tgrmtbr.$$"
			ratr_opts="$ratr_opts -rmr"
		fi
		ratr_opts="$ratr_opts -r=\"\$tmptgrmtbr\" -u=\":refs/remotes/\$base_remote/\${topbases#heads/}\""
	fi
	[ -z "$dogfer" ] ||
	eval git for-each-ref '--format="%(refname) %(objectname)"' "$refpats" >"$tmprfs"
	if [ -n "$tmptgrmtbr" ] && [ -n "$dorab" ]; then
		run_awk_topgit_branches -n -h="refs/remotes/$base_remote" -r="$tmprfs" \
			"refs/remotes/$base_remote/${topbases#heads/}" >"$tmptgrmtbr"
	fi
	depscmd="run_awk_topgit_deps -s${TG_DEBUG:+ -p=\"\$tg_ref_cache.pre\"}"
	depscmd="$depscmd"' -a="$tmpann" -b="$tmptgbr" -r="$tmprfs" "refs/$topbases"'
	if [ -n "$userc" ]; then
		if [ -n "$dorad" ]; then
			eval "$depscmd" >"$tmpdep"
		fi
		depscmd='<"$tmpdep" '
	else
		depscmd="$depscmd |"
	fi
	eval "$depscmd" run_awk_topgit_recurse '-a="$tmpann" -b="$tmptgbr"' \
		'-c=1 -h="$tmprfs"' "$ratr_opts" '-x="$recurse_deps_exclude"' '"$@"'
}

# do_eval CMD
# helper for recurse_deps so that a return statement executed inside CMD
# does not return from recurse_deps.  This shouldn't be necessary, but it
# seems that it actually is.
do_eval()
{
	eval "$@"
}

# becomes read-only for caching purposes
# assigns new value to tg_read_only
# become_cacheable/undo_become_cacheable calls may be nested
become_cacheable()
{
	_old_tg_read_only="$tg_read_only"
	if [ -z "$tg_read_only" ]; then
		! [ -e "$tg_tmp_dir/cached" ] && ! [ -e "$tg_tmp_dir/tg~ref-dirs-created" ] ||
		rm -rf "$tg_tmp_dir/cached" "$tg_tmp_dir/tg~ref-dirs-created"
		tg_read_only=1
	fi
	_my_ref_cache=
	v_create_ref_cache _my_ref_cache
	_my_ref_cache="${_my_ref_cache:+1}"
	tg_read_only="undo${_my_ref_cache:-0}-$_old_tg_read_only"
}

# restores tg_read_only and ref_cache to state before become_cacheable call
# become_cacheable/undo_bocome_cacheable calls may be nested
undo_become_cacheable()
{
	case "$tg_read_only" in
		"undo"[01]"-"*)
			_suffix="${tg_read_only#undo?-}"
			[ "${tg_read_only%$_suffix}" = "undo0-" ] || remove_ref_cache
			tg_read_only="$_suffix"
	esac
}

# just call this, no undo, sets tg_read_only= and removes ref cache and cached results
become_non_cacheable()
{
	remove_ref_cache
	tg_read_only=
	! [ -e "$tg_tmp_dir/cached" ] && ! [ -e "$tg_tmp_dir/tg~ref-dirs-created" ] ||
	rm -rf "$tg_tmp_dir/cached" "$tg_tmp_dir/tg~ref-dirs-created"
}

# call this to make sure the current Git repository has an associated work tree
# also make sure we are not in wayback mode
ensure_work_tree()
{
	[ -z "$wayback" ] ||
	die "the wayback machine cannot be used with the specified options"
	setup_git_dir_is_bare
	[ -n "$git_dir_is_bare" ] || return 0
	die "This operation must be run in a work tree"
}

# call this to make sure Git will not complain about a missing user/email
# result is cached in TG_IDENT_CHECKED and a non-empty value suppresses the check
ensure_ident_available()
{
	[ -z "$TG_IDENT_CHECKED" ] || return 0
	git var GIT_AUTHOR_IDENT >/dev/null &&
	git var GIT_COMMITTER_IDENT >/dev/null || exit
	TG_IDENT_CHECKED=1
	export TG_IDENT_CHECKED
	return 0
}

# recurse_deps [-o=<options string>] CMD NAME [BRANCHPATH...]
# Recursively eval CMD on all dependencies of NAME.
# Dependencies are visited in topological order.
# If <options string> is given, it's eval'd into the recurse_deps_internal
# call just before the "--" that's passed just before NAME
# CMD can refer to the following variables:
#
#   _ret              starts as 0; CMD can change; will be final return result
#   _dep              bare branch name or ":refs/remotes/..." for a remote
#   _name             has $_dep in its .topdeps ("" for top and $with_top_level)
#   _depchain         0+ space-sep branch names (_name first) form a path to top
#   _dep_missing      boolean "1" if no such $_dep ref; "" if ref present
#   _dep_is_leaf      boolean "1" if leaf; "" if not
#   _dep_is_tgish     boolean "1" if tgish; "" if not (which implies no remote)
#   _dep_has_remote   boolean "1" if $_dep has_remote; "" if not
#   _dep_annihilated  boolean "1" if $_dep annihilated; "" if not
#   _dep_xvisits      non-negative integer number of excess visits (often 0)
#
# CMD may use a "return" statement without issue; its return value is ignored,
# but if CMD sets _ret to a negative value, e.g. "-0" or "-1" the enumeration
# will stop immediately and the value with the leading "-" stripped off will
# be the final result code
#
# CMD can refer to $_name for queried branch name,
# $_dep for dependency name,
# $_depchain for space-seperated branch backtrace,
# $_dep_missing boolean to check whether $_dep is present
# and the $_dep_is_tgish and $_dep_annihilated booleans.
# If recurse_preorder is NOT set then the $_dep_is_leaf boolean is also valid.
# It can modify $_ret to affect the return value
# of the whole function.
# If recurse_deps() hits missing dependencies, it will append
# them to space-separated $missing_deps list and skip them
# after calling CMD with _dep_missing set.
# remote dependencies are processed if no_remotes is unset.
# any branch names in the space-separated recurse_deps_exclude variable
# are skipped (along with their dependencies)
#
# If no_remotes is non-empty, exclude remotes
# If recurse_preorder is non-empty, do a preorder rather than postorder traversal
# If with_top_level is non-empty, include the top-level that's normally omitted
# any branch names in the space-separated recurse_deps_exclude variable
# are skipped (along with their dependencies)
recurse_deps()
{
	_opts=
	case "$1" in -o=*) _opts="${1#-o=}"; shift; esac
	_cmd="$1"; shift

	_depsfile="$(get_temp tg-depsfile)"
	eval recurse_deps_internal "$_opts" -- '"$@"' >"$_depsfile" || :

	_ret=0
	while read _ismissing _istgish _isleaf _dep_xvisits _dep _name _deppath; do
		_depchain="$_name${_deppath:+ $_deppath}"
		_dep_is_tgish=
		[ "$_istgish" = "0" ] || _dep_is_tgish=1
		_dep_has_remote=
		[ "$_istgish" != "2" ] || _dep_has_remote=1
		_dep_missing=
		if [ "$_ismissing" != "0" ]; then
			_dep_missing=1
			case " $missing_deps " in *" $_dep "*);;*)
				missing_deps="${missing_deps:+$missing_deps }$_dep"
			esac
		fi
		_dep_annihilated=
		_dep_is_leaf=
		if [ "$_isleaf" = "1" ]; then
			_dep_is_leaf=1
		elif [ "$_isleaf" = "2" ]; then
			_dep_annihilated=1
		fi
		do_eval "$_cmd" || :
		if [ "${_ret#-}" != "$_ret" ]; then
			_ret="${_ret#-}"
			break
		fi
	done <"$_depsfile"
	rm -f "$_depsfile"
	return ${_ret:-0}
}

# find_leaves NAME
# output (one per line) the unique leaves of NAME
# a leaf is either
#   1) a non-tgish dependency
#   2) the base of a tgish dependency with no non-annihilated dependencies
# duplicates are suppressed (by commit rev) and remotes are always ignored
# if a leaf has an exact tag match that will be output
# note that recurse_deps_exclude IS honored for this operation
find_leaves()
{
	no_remotes=1
	with_top_level=1
	recurse_preorder=
	seen_leaf_refs=
	seen_leaf_revs=
	while read _ismissing _istgish _isleaf _dep _name _deppath; do
		[ "$_isleaf" = "1" ] && [ "$_ismissing" = "0" ] || continue
		if [ "$_istgish" != "0" ]; then
			fulldep="refs/$topbases/$_dep"
		else
			fulldep="refs/heads/$_dep"
		fi
		case " $seen_leaf_refs " in *" $fulldep "*);;*)
			seen_leaf_refs="${seen_leaf_refs:+$seen_leaf_refs }$fulldep"
			if fullrev="$(ref_exists_rev "$fulldep")"; then
				case " $seen_leaf_revs " in *" $fullrev "*);;*)
					seen_leaf_revs="${seen_leaf_revs:+$seen_leaf_revs }$fullrev"
					# See if Git knows it by another name
					if tagname="$(git describe --exact-match "$fullrev" 2>/dev/null)" && [ -n "$tagname" ]; then
						echo "refs/tags/$tagname"
					else
						echo "$fulldep"
					fi
				esac
			fi
		esac
	done <<-EOT
	$(recurse_deps_internal -l -o=1 -- "$1")
	EOT
	with_top_level=
}

# branch_needs_update
# This is a helper function for determining whether given branch
# is up-to-date wrt. its dependencies. It expects input as if it
# is called as a recurse_deps() helper.
# In case the branch does need update, it will echo it together
# with the branch backtrace on the output (see needs_update()
# description for details) and set $_ret to non-zero.
branch_needs_update()
{
	if [ -n "$_dep_missing" ]; then
		echo "! $_dep $_depchain"
		return 0
	fi

	if [ -n "$_dep_is_tgish" ]; then
		[ -z "$_dep_annihilated" ] || return 0

		if [ -n "$_dep_has_remote" ]; then
			branch_contains "refs/heads/$_dep" "refs/remotes/$base_remote/$_dep" || {
				echo ":refs/remotes/$base_remote/$_dep $_dep $_depchain"
				_ret=1
			}
		fi
		# We want to sync with our base first and should output this before
		# the remote branch, but the order does not actually matter to tg-update
		# as it just recurses regardless, but it does matter for tg-info (which
		# treats out-of-date bases as though they were already merged in) so
		# we output the remote before the base.
		branch_contains "refs/heads/$_dep" "refs/$topbases/$_dep" || {
			echo ": $_dep $_depchain"
			_ret=1
			return
		}
	fi

	if [ -n "$_name" ]; then
		case "$_dep" in :*) _fulldep="${_dep#:}";; *) _fulldep="refs/heads/$_dep";; esac
		if ! branch_contains "refs/$topbases/$_name" "$_fulldep"; then
			# Some new commits in _dep
			echo "$_dep $_depchain"
			_ret=1
		fi
	fi
}

# needs_update NAME
# This function is recursive; it outputs reverse path from NAME
# to the branch (e.g. B_DIRTY B1 B2 NAME), one path per line,
# inner paths first. Innermost name can be :refs/remotes/<remote>/<name>
# if the head is not in sync with the <remote> branch <name>, ':' if
# the head is not in sync with the base (in this order of priority)
# or '!' if dependency is missing.  Note that the remote branch, base
# order is reversed from the order they will actually be updated in
# order to accomodate tg info which treats out-of-date items that are
# only in the base as already being in the head for status purposes.
# It will also return non-zero status if NAME needs update (seems backwards
# but think of it as non-zero status if any non-missing output lines produced)
# If needs_update() hits missing dependencies, it will append
# them to space-separated $missing_deps list and skip them.
needs_update()
{
	recurse_deps branch_needs_update "$1"
}

# append second arg to first arg variable gluing with space if first already set
vplus()
{
	eval "$1=\"\${$1:+\$$1 }\$2\""
}

# true if whitespace separated first var name list contains second arg
# use `vcontains 3 "value" "some list"` for a literal list
vcontains()
{
	eval case "\" \${$1} \"" in '*" $2 "*) return 0; esac; return 1'
}

# if the $1 var does not already contain $2 it's appended
vsetadd()
{
	vcontains "$1" "$2" || vplus "$1" "$2"
}

# reset needs_update_check results to empty
needs_update_check_clear()
{
	unset_ needs_update_processed needs_update_behind needs_update_ahead needs_update_partial
}

# needs_update_check NAME...
#
# A faster version of needs_update that always succeeds
# No output and unsuitable for actually performing updates themselves
# If any of NAME... are NOT up-to-date AND they were not already processed
# return status always will be zero however a simple check of
# needs_update_behind after the call will answer the:
#   "are any out of date?": test -n "$needs_update_behind"
#   "is <x> out of date?":  vcontains needs_update_behind "<x>"
#
# Note that results are cumulative and "no_remotes" is honored as well as other
# variables that modify recurse_deps_internal behavior.  See the preceding
# function to reset the results to empty when accumulation should start over.
#
# Unlike needs_update, the branch names are themselves also checked to see if
# they are out-of-date with respect to their bases or remote branches (not just
# their remote bases).  However, this can muddy some status results so this
# can be disabled by setting needs_update_check_no_self to a non-empty value.
#
# Unlike needs_update, here the remote base check is handled together with the
# remote head check so if one is modified the other is too in the same way.
#
# Dependencies are normally considered "behind" if they need an update from
# their base or remote but this can be suppressed by setting the
# needs_update_check_no_same to a non-empty value.  This will NOT prevent
# parents of those dependencies from still being considered behind in such a
# case even though the dependency itself will not be.  Note that setting
# needs_update_check_no_same also implies needs_update_check_no_self.
#
# The following whitespace-separated lists are updated with the results:
#
# The "no_remotes" setting is obeyed but remote names themselves will never
# appear in any of the lists
#
#   needs_update_processed
#       The branch names in here have been processed and will be skipped
#
#   needs_update_behind
#       Any branch named in here needs an update from one or more of its
#       direct or indirect dependencies (i.e. it's "out-of-date")
#
#   needs_update_ahead
#       Any branch named in here is NOT fully contained by at least one of
#       its dependents (i.e. it's a source of "out-of-date (aka dirty)"ness
#
#   needs_update_partial
#       Any branch names in here are either missing themselves or have one
#       or more detected missing dependencies (a completely missing remote
#       branch is never "detected")
needs_update_check()
{
	# each head must be processed independently or else there will be
	# confusion about who's missing what and which branches actually are
	# out of date
	tmptgrdi="$tg_tmp_dir/tgrdi.$$"
	for nucname in "$@"; do
		! vcontains needs_update_processed "$nucname" || continue
		# no need to fuss with recurse_deps, just use
		# recurse_deps_internal directly
		recurse_deps_internal -s -o=-1 "$nucname" >"$tmptgrdi"
		while read -r _rdi_m _rdi_t _rdi_l _rdi_v _rdi_node _rdi_parent _rdi_chain; do
			case "$_rdi_node" in ""|:*) continue; esac # empty or checked with remote
			vsetadd needs_update_processed "$_rdi_node"
			if [ "$_rdi_m" != "0" ]; then # missing
				vsetadd needs_update_partial "$_rdi_node"
				[ -z "$_rdi_parent" ] || vsetadd needs_update_partial "$_rdi_parent"
				continue
			fi
			[ "$_rdi_t$_rdi_l" != "12" ] || continue # always skip annihilated
			_rdi_dertee= # :)
			if [ -n "$_rdi_parent" ]; then # not a "self" line
				! vcontains needs_update_partial "$_rdi_node" || vsetadd needs_update_partial "$_rdi_parent"
				! vcontains needs_update_behind "$_rdi_node" || _rdi_dertee=2
			else
				[ -z "$needs_update_check_no_self$needs_update_check_no_same" ] || continue # skip self
			fi
			if [ -z "$_rdi_dertee" ]; then
				if [ "$_rdi_t" != "0" ]; then # tgish
					if branch_contains "refs/heads/$_rdi_node" "refs/$topbases/$_rdi_node"; then
						if [ "$_rdi_t" = "2" ]; then # will never be "2" when no_remotes is set
							branch_contains "refs/heads/$_rdi_node" "refs/remotes/$base_remote/$_rdi_node" &&
							branch_contains "refs/$topbases/$_rdi_node" "refs/remotes/$base_remote/${topbases#heads/}/$_rdi_node" ||
							_rdi_dertee=3
						fi
					else
						_rdi_dertee=3
					fi
					[ -z "$_rdi_dertee" ] || [ -n "$needs_update_check_no_same" ] || _rdi_dertee=1
				fi
			fi
			[ z"$_rdi_dertee" != z"1" ] || vsetadd needs_update_behind "$_rdi_node"
			[ -n "$_rdi_parent" ] || continue # self line
			if ! branch_contains "refs/$topbases/$_rdi_parent" "refs/heads/$_rdi_node"; then
				_rdi_dertee=1
				vsetadd needs_update_ahead "$_rdi_node"
			fi
			[ -z "$_rdi_dertee" ] || vsetadd needs_update_behind "$_rdi_parent"
		done <"$tmptgrdi"
	done
}

# branch_empty NAME [-i | -w]
branch_empty()
{
	if [ -z "$2" ]; then
		_rev="$(ref_exists_rev "refs/heads/$1")" || return 0
		_result=
		_result_rev=
		{ read -r _result _result_rev <"$tg_cache_dir/refs/heads/$1/.mt"; } 2>/dev/null || :
		[ -z "$_result" -o "$_result_rev" != "$_rev" ] || return $_result
		_result=0
		[ "$(pretty_tree -t "$1" -b)" = "$(pretty_tree -t "$1" $2)" ] || _result=$?
		[ -d "$tg_cache_dir/refs/heads/$1" ] || mkdir -p "$tg_cache_dir/refs/heads/$1" 2>/dev/null
		[ ! -d "$tg_cache_dir/refs/heads/$1" ] || echo $_result $_rev >"$tg_cache_dir/refs/heads/$1/.mt"
		return $_result
	else
		[ "$(pretty_tree -t "$1" -b)" = "$(pretty_tree -t "$1" $2)" ]
	fi
}

v_get_tdmopt_internal()
{
	[ -n "$1" ] && [ -n "$3" ] || return 0
	[ "$2" = "-i" ] || [ "$2" = "-w" ] || return 0
	ensure_work_tree
	_optval=
	if v_verify_topgit_branch _tghead "HEAD" -f; then
		if [ "$2" = "-w" ] && [ -f "$root_dir/$3" ] && [ -r "$root_dir/$3" ]; then
			_opthash=
			if _opthash="$(git hash-object -w -t blob --stdin <"$root_dir/$3")" && [ -n "$_opthash" ]; then
				_optval="$4\"$_tghead:$_opthash\""
			fi
		elif [ "$2" = "-i" ]; then
			if _opthash="$(git rev-parse --quiet --verify ":0:$3" --)" && [ -n "$_opthash" ]; then
				_optval="$4\"$_tghead:$_opthash\""
			fi
		fi
	fi
	eval "$1="'"$_optval"'
}

# set var $1 to the correct -td= option for use in an eval for $2 -i or -w mode
v_get_tdopt() { v_get_tdmopt_internal "$1" "$2" ".topdeps" "-td="; }

# set var $1 to the correct -tm= option for use in an eval for $2 -i or -w mode
v_get_tmopt() { v_get_tdmopt_internal "$1" "$2" ".topmsg" "-tm="; }

# checkout_symref_full [-f] FULLREF [SEED]
# Just like git checkout $iowopt -b FULLREF [SEED] except that FULLREF MUST start with
# refs/ and HEAD is ALWAYS set to a symref to it and [SEED] (default is FULLREF)
# MUST be a committish which if present will be used instead of current FULLREF
# (and FULLREF will be updated to it as well in that case)
# Any merge state is always cleared by this function
# With -f it's like git checkout $iowopt -f -b FULLREF (uses read-tree --reset
# instead of -m) but it will clear out any unmerged entries
# As an extension, FULLREF may also be a full hash to create a detached HEAD instead
checkout_symref_full()
{
	_mode=-m
	_head="HEAD"
	if [ "$1" = "-f" ]; then
		_mode="--reset"
		_head=
		shift
	fi
	_ishash=
	case "$1" in
		refs/?*)
			;;
		$octet20)
			_ishash=1
			[ -z "$2" ] || [ "$1" = "$2" ] ||
				die "programmer error: invalid checkout_symref_full \"$1\" \"$2\""
			set -- HEAD "$1"
			;;
		*)
			die "programmer error: invalid checkout_symref_full \"$1\""
			;;
	esac
	_seedrev="$(git rev-parse --quiet --verify "${2:-$1}^0" --)" ||
		die "invalid committish: \"${2:-$1}\""
	# Clear out any MERGE_HEAD kruft
	rm -f "$git_dir/MERGE_HEAD" || :
	# We have to do all the hard work ourselves :/
	# This is like git checkout -b "$1" "$2"
	# (or just git checkout "$1"),
	# but never creates a detached HEAD (unless $1 is a hash)
	git read-tree -u $_mode $_head "$_seedrev" &&
	{
		[ -z "$2" ] && [ "$(git cat-file -t "$1")" = "commit" ] ||
		git update-ref ${_ishash:+--no-deref} "$1" "$_seedrev"
	} && {
		[ -n "$_ishash" ] || git symbolic-ref HEAD "$1"
	}
}

# switch_to_base NAME [SEED]
switch_to_base()
{
	checkout_symref_full "refs/$topbases/$1" "$2"
}

# run editor with arguments
# the editor setting will be cached in $tg_editor (which is eval'd)
# result non-zero if editor fails or GIT_EDITOR cannot be determined
# just in case, noalt_setup will be in effect while the editor is running
run_editor()
{
	tg_editor="$GIT_EDITOR"
	[ -n "$tg_editor" ] || tg_editor="$(git var GIT_EDITOR)" || return $?
	(
		noalt_setup
		eval "$tg_editor" '"$@"'
	)
}

# Show the help messages.
do_help()
{
	_www=
	if [ "$1" = "-w" ]; then
		_www=1
		shift
	fi
	if [ -z "$1" ] ; then
		# This is currently invoked in all kinds of circumstances,
		# including when the user made a usage error. Should we end up
		# providing more than a short help message, then we should
		# differentiate.
		# Petr's comment: http://marc.info/?l=git&m=122718711327376&w=2

		## Build available commands list for help output

		cmds=
		sep=
		for cmd in "$TG_INST_CMDDIR"/tg-[!-]*; do
			! [ -r "$cmd" ] && continue
			# strip directory part and "tg-" prefix
			cmd="${cmd##*/}"
			cmd="${cmd#tg-}"
			[ "$cmd" != "migrate-bases" ] || continue
			[ "$cmd" != "summary" ] || cmd="st[atus]|$cmd"
			cmds="$cmds$sep$cmd"
			sep="|"
		done

		echo "TopGit version $TG_VERSION - A different patch queue manager"
		echo "Usage: $tgname [-C <dir>] [-r <remote> | -u]" \
			"[-c <name>=<val>] [--[no-]pager|-p] [-w [:]<tgtag>] ($cmds) ..."
		echo "   Or: $tgname help [-w] [<command>]"
		echo "Use \"$tgdisplaydir$tgname help tg\" for overview of TopGit"
	elif [ -r "$TG_INST_CMDDIR"/tg-$1 -o -r "$TG_INST_SHAREDIR/tg-$1.txt" ] ; then
		if [ -n "$_www" ]; then
			nohtml=
			if ! [ -r "$TG_INST_SHAREDIR/topgit.html" ]; then
				echo "${0##*/}: missing html help file:" \
					"$TG_INST_SHAREDIR/topgit.html" 1>&2
				nohtml=1
			fi
			if ! [ -r "$TG_INST_SHAREDIR/tg-$1.html" ]; then
				echo "${0##*/}: missing html help file:" \
					"$TG_INST_SHAREDIR/tg-$1.html" 1>&2
				nohtml=1
			fi
			if [ -n "$nohtml" ]; then
				echo "${0##*/}: use" \
					"\"${0##*/} help $1\" instead" 1>&2
				exit 1
			fi
			git web--browse -c help.browser "$TG_INST_SHAREDIR/tg-$1.html"
			exit
		fi
		output()
		{
			if [ -r "$TG_INST_CMDDIR"/tg-$1 ] ; then
				"$TG_INST_CMDDIR"/tg-$1 -h 2>&1 || :
				echo
			elif [ "$1" = "help" ]; then
				echo "Usage: ${tgname:-tg} help [-w] [<command>]"
				echo
			elif [ "$1" = "status" ] || [ "$1" = "st" ]; then
				echo "Usage: ${tgname:-tg} @tgsthelpusage@"
				echo
			fi
			if [ -r "$TG_INST_SHAREDIR/tg-$1.txt" ] ; then
				cat "$TG_INST_SHAREDIR/tg-$1.txt"
			fi
		}
		page output "$1"
	else
		echo "${0##*/}: no help for $1" 1>&2
		do_help
		exit 1
	fi
}

check_status()
{
	git_state=
	git_remove=
	tg_state=
	tg_remove=
	tg_topmerge=
	setup_git_dir_is_bare
	[ -z "$git_dir_is_bare" ] || return 0

	if [ -e "$git_dir/MERGE_HEAD" ]; then
		git_state="merge"
	elif [ -e "$git_dir/rebase-apply/applying" ]; then
		git_state="am"
		git_remove="$git_dir/rebase-apply"
	elif [ -e "$git_dir/rebase-apply" ]; then
		git_state="rebase"
		git_remove="$git_dir/rebase-apply"
	elif [ -e "$git_dir/rebase-merge" ]; then
		git_state="rebase"
		git_remove="$git_dir/rebase-merge"
	elif [ -e "$git_dir/CHERRY_PICK_HEAD" ]; then
		git_state="cherry-pick"
	elif [ -e "$git_dir/BISECT_LOG" ]; then
		git_state="bisect"
	elif [ -e "$git_dir/REVERT_HEAD" ]; then
		git_state="revert"
	fi
	git_remove="${git_remove#./}"

	if [ -e "$git_dir/tg-update" ]; then
		tg_state="update"
		tg_remove="$git_dir/tg-update"
		! [ -s "$git_dir/tg-update/merging_topfiles" ] || tg_topmerge=1
	fi
	tg_remove="${tg_remove#./}"
}

# Show status information
do_status()
{
	do_status_result=0
	do_status_verbose=
	do_status_help=
	abbrev=refs
	pfx=
	while [ $# -gt 0 ] && case "$1" in
		--help|-h)
			do_status_help=1
			break;;
		-vv)
			# kludge in this common bundling option
			abbrev=
			do_status_verbose=1
			pfx="## "
			;;
		--verbose|-v)
			[ -z "$do_status_verbose" ] || abbrev=
			do_status_verbose=1
			pfx="## "
			;;
		--exit-code)
			do_status_result=2
			;;
		*)
			die "unknown status argument: $1"
			;;
	esac; do shift; done
	if [ -n "$do_status_help" ]; then
		echo "Usage: ${tgname:-tg} @tgsthelpusage@"
		return
	fi
	check_status
	symref="$(git symbolic-ref --quiet HEAD)" || :
	headrv="$(git rev-parse --quiet --verify ${abbrev:+--short} HEAD --)" || :
	if [ -n "$symref" ]; then
		uprefpart=
		if [ -n "$headrv" ]; then
			upref="$(git rev-parse --symbolic-full-name @{upstream} 2>/dev/null)" || :
			if [ -n "$upref" ]; then
				uprefpart=" ... ${upref#$abbrev/remotes/}"
				mbase="$(git merge-base HEAD "$upref")" || :
				ahead="$(git rev-list --count HEAD ${mbase:+--not $mbase})" || ahead=0
				behind="$(git rev-list --count "$upref" ${mbase:+--not $mbase})" || behind=0
				[ "$ahead$behind" = "00" ] || uprefpart="$uprefpart ["
				[ "$ahead" = "0" ] || uprefpart="${uprefpart}ahead $ahead"
				[ "$ahead" = "0" ] || [ "$behind" = "0" ] || uprefpart="$uprefpart, "
				[ "$behind" = "0" ] || uprefpart="${uprefpart}behind $behind"
				[ "$ahead$behind" = "00" ] || uprefpart="$uprefpart]"
			fi
		fi
		echol "${pfx}HEAD -> ${symref#$abbrev/heads/} [${headrv:-unborn}]$uprefpart"
	else
		echol "${pfx}HEAD -> ${headrv:-?}"
	fi
	if [ -n "$tg_state" ]; then
		extra=
		if [ "$tg_state" = "update" ]; then
			IFS= read -r uname <"$git_dir/tg-update/name" || :
			[ -z "$uname" ] ||
			extra="; currently updating branch '$uname'"
		fi
		echol "${pfx}tg $tg_state in progress$extra"
		if [ -s "$git_dir/tg-update/fullcmd" ] && [ -s "$git_dir/tg-update/names" ]; then
			printf "${pfx}You are currently updating as a result of:\n${pfx}  "
			cat "$git_dir/tg-update/fullcmd"
			bcnt="$(( $(wc -w < "$git_dir/tg-update/names") ))"
			if [ $bcnt -gt 1 ]; then
				pcnt=0
				! [ -s "$git_dir/tg-update/processed" ] ||
				pcnt="$(( $(wc -w < "$git_dir/tg-update/processed") ))"
				echo "${pfx}$pcnt of $bcnt branches updated so far"
			fi
		fi
		if [ "$tg_state" = "update" ]; then
			echol "${pfx}  (use \"$tgdisplayac update --continue\" to continue)"
			echol "${pfx}  (use \"$tgdisplayac update --skip\" to skip this branch and continue)"
			echol "${pfx}  (use \"$tgdisplayac update --stop\" to stop and retain changes so far)"
			echol "${pfx}  (use \"$tgdisplayac update --abort\" to restore pre-update state)"
		fi
	fi
	[ -z "$git_state" ] || echo "${pfx}git $git_state in progress"
	if [ "$git_state" = "merge" ]; then
		ucnt="$(( $(git ls-files --unmerged --full-name --abbrev :/ | wc -l) ))"
		if [ $ucnt -gt 0 ]; then
			echo "${pfx}"'fix conflicts and then "git commit" the result'
		else
			echo "${pfx}"'all conflicts fixed; run "git commit" to record result'
		fi
	fi
	if [ -z "$git_state" ]; then
		setup_git_dir_is_bare
		[ -z "$git_dir_is_bare" ] || return 0
		gsp="$(git status --porcelain 2>/dev/null)" || return 0 # bare repository???
		gspcnt=0
		[ -z "$gsp" ] ||
		gspcnt="$(( $(printf '%s\n' "$gsp" | sed -n '/^??/!p' | wc -l) ))"
		untr=
		if [ "$gspcnt" -eq 0 ]; then
			[ -z "$gsp" ] || untr="; non-ignored, untracked files present"
			echo "${pfx}working directory is clean$untr"
			[ -n "$tg_state" ] || do_status_result=0
		else
			echo "${pfx}working directory is DIRTY"
			[ -z "$do_status_verbose" ] || git status --short --untracked-files=no
		fi
	fi
}

## Pager stuff

# isatty FD
isatty()
{
	test -t $1
}

# pass "diff" to get pager.diff
# if pager.$1 is a boolean false returns cat
# if set to true or unset fails
# otherwise succeeds and returns the value
get_pager()
{
	if _x="$(git config --bool "pager.$1" 2>/dev/null)"; then
		[ "$_x" != "true" ] || return 1
		echo "cat"
		return 0
	fi
	if _x="$(git config "pager.$1" 2>/dev/null)"; then
		echol "$_x"
		return 0
	fi
	return 1
}

# setup_pager
# Set TG_PAGER to a valid executable
# After calling, code to be paged should be surrounded with {...} | eval "$TG_PAGER"
# See also the following "page" function for ease of use
# emptypager will be set to 1 (otherwise empty) if TG_PAGER was set to "cat" to not be empty
# Preference is (same as Git):
#   1. GIT_PAGER
#   2. pager.$USE_PAGER_TYPE (but only if USE_PAGER_TYPE is set and so is pager.$USE_PAGER_TYPE)
#   3. core.pager (only if set)
#   4. PAGER
#   5. git var GIT_PAGER
#   6. less
setup_pager()
{
	isatty 1 || { emptypager=1; TG_PAGER=cat; return 0; }

	emptypager=
	if [ -z "$TG_PAGER_IN_USE" ]; then
		# TG_PAGER = GIT_PAGER | PAGER | less
		# NOTE: GIT_PAGER='' is significant
		if [ -n "${GIT_PAGER+set}" ]; then
			TG_PAGER="$GIT_PAGER"
		elif [ -n "$USE_PAGER_TYPE" ] && _dp="$(get_pager "$USE_PAGER_TYPE")"; then
			TG_PAGER="$_dp"
		elif _cp="$(git config core.pager 2>/dev/null)"; then
			TG_PAGER="$_cp"
		elif [ -n "${PAGER+set}" ]; then
			TG_PAGER="$PAGER"
		else
			_gp="$(git var GIT_PAGER 2>/dev/null)" || :
			[ "$_gp" != ":" ] || _gp=
			TG_PAGER="${_gp:-less}"
		fi
		if [ -z "$TG_PAGER" ]; then
			emptypager=1
			TG_PAGER=cat
		fi
	else
		emptypager=1
		TG_PAGER=cat
	fi

	# Set pager default environment variables
	# see pager.c:setup_pager
	if [ -z "${LESS+set}" ]; then
		LESS="-FRX"
		export LESS
	fi
	if [ -z "${LV+set}" ]; then
		LV="-c"
		export LV
	fi

	# this is needed so e.g. $(git diff) will still colorize it's output if
	# requested in ~/.gitconfig with color.diff=auto
	GIT_PAGER_IN_USE=1
	export GIT_PAGER_IN_USE

	# this is needed so we don't get nested pagers
	TG_PAGER_IN_USE=1
	export TG_PAGER_IN_USE
}

# page eval_arg [arg ...]
#
# Calls setup_pager then evals the first argument passing it all the rest
# where the output is piped through eval "$TG_PAGER" unless emptypager is set
# by setup_pager (in which case the output is left as-is).
#
# To handle arbitrary paging duties, collect lines to be paged into a
# function and then call page with the function name or perhaps func_name "$@".
#
# If no arguments at all are passed in do nothing (return with success).
page()
{
	[ $# -gt 0 ] || return 0
	setup_pager
	_evalarg="$1"; shift
	if [ -n "$emptypager" ]; then
		eval "$_evalarg" '"$@"'
	else
		{ eval "$_evalarg" '"$@"';} | eval "$TG_PAGER"
	fi
}

# get_temp NAME [-d]
# creates a new temporary file (or directory with -d) in the global
# temporary directory $tg_tmp_dir with pattern prefix NAME
get_temp()
{
	mktemp $2 "$tg_tmp_dir/$1.XXXXXX"
}

# automatically called by strftime
# does nothing if already setup
# may be called explicitly if the first call would otherwise be in a subshell
# so that the setup is only done once before subshells start being spawned
setup_strftime()
{
	[ -z "$strftime_is_setup" ] || return 0

	# date option to format raw epoch seconds values
	daterawopt=
	_testes='951807788'
	_testdt='2000-02-29 07:03:08 UTC'
	_testfm='%Y-%m-%d %H:%M:%S %Z'
	if [ "$(TZ=UTC date "-d@$_testes" "+$_testfm" 2>/dev/null)" = "$_testdt" ]; then
		daterawopt='-d@'
	elif [ "$(TZ=UTC date "-r$_testes" "+$_testfm" 2>/dev/null)" = "$_testdt" ]; then
		daterawopt='-r'
	fi
	strftime_is_setup=1
}

# $1 => strftime format string to use
# $2 => raw timestamp as seconds since epoch
# $3 => optional time zone string (empty/absent for local time zone)
strftime()
{
	setup_strftime
	if [ -n "$daterawopt" ]; then
		if [ -n "$3" ]; then
			TZ="$3" date "$daterawopt$2" "+$1"
		else
			date "$daterawopt$2" "+$1"
		fi
	else
		if [ -n "$3" ]; then
			TZ="$3" perl -MPOSIX=strftime -le 'print strftime($ARGV[0],localtime($ARGV[1]))' "$1" "$2"
		else
			perl -MPOSIX=strftime -le 'print strftime($ARGV[0],localtime($ARGV[1]))' "$1" "$2"
		fi
	fi
}

got_cdup_result=
git_cdup_result=
v_get_show_cdup()
{
	if [ -z "$got_cdup_result" ]; then
		git_cdup_result="$(git rev-parse --show-cdup)"
		got_cdup_result=1
	fi
	[ -z "$1" ] || eval "$1="'"$git_cdup_result"'
}

setup_git_dir_is_bare()
{
	if [ -z "$git_dir_is_bare_setup" ]; then
		git_dir_is_bare="$(git rev-parse --is-bare-repository)"
		[ z"$git_dir_is_bare" = z"true" ] || git_dir_is_bare=
		git_dir_is_bare_setup=1
	fi
}

setup_git_dirs()
{
	[ -n "$git_dir" ] || git_dir="$(git rev-parse --git-dir)"
	if [ -n "$git_dir" ] && [ -d "$git_dir" ]; then
		git_dir="$(cd "$git_dir" && pwd)"
	fi
	if [ -z "$git_common_dir" ]; then
		if vcmp "$git_version" '>=' "2.5"; then
			# rev-parse --git-common-dir is broken and may give
			# an incorrect result unless the current directory is
			# already set to the top level directory
			v_get_show_cdup
			git_common_dir="$(cd "./$git_cdup_result" && cd "$(git rev-parse --git-common-dir)" && pwd)"
		else
			git_common_dir="$git_dir"
		fi
	fi
	[ -n "$git_dir" ] && [ -n "$git_common_dir" ] &&
	[ -d "$git_dir" ] && [ -d "$git_common_dir" ] || die "Not a git repository"
	git_hooks_dir="$git_common_dir/hooks"
	if vcmp "$git_version" '>=' "2.9" && gchp="$(git config --path --get core.hooksPath 2>/dev/null)" && [ -n "$gchp" ]; then
		case "$gchp" in
			/[!/]*)
				git_hooks_dir="$gchp"
				;;
			*)
				[ -n "$1" ] || warn "ignoring non-absolute core.hooksPath: $gchp"
				;;
		esac
		unset_ gchp
	fi
}

basic_setup_remote()
{
	if [ -z "$base_remote" ]; then
		if [ "${TG_EXPLICIT_REMOTE+set}" = "set" ]; then
			base_remote="$TG_EXPLICIT_REMOTE"
		else
			base_remote="$(git config topgit.remote 2>/dev/null)" || :
		fi
	fi
}

basic_setup()
{
	setup_git_dirs $1
	basic_setup_remote
	tgsequester="$(git config --bool topgit.sequester 2>/dev/null)" || :
	tgnosequester=
	[ "$tgsequester" != "false" ] || tgnosequester=1
	unset_ tgsequester

	# catch errors if topbases is used without being set
	unset_ tg_topbases_set
	topbases="programmer*:error"
	topbasesrx="programmer*:error}"
	oldbases="$topbases"
}

tmpdir_setup()
{
	[ -z "$tg_tmp_dir" ] || return 0
	if [ -n "$TG_TMPDIR" ] && [ -d "$TG_TMPDIR" ] && [ -w "$TG_TMPDIR" ] &&
	   { >"$TG_TMPDIR/.check"; } >/dev/null 2>&1; then
		tg_tmp_dir="$TG_TMPDIR"
	else
		tg_tmp_dir=
		TRAPEXIT_='${TG_DEBUG:+echo} rm -rf "$tg_tmp_dir" >&2'
		trap 'trapexit_ 129' HUP
		trap 'trapexit_ 130' INT
		trap 'trapexit_ 131' QUIT
		trap 'trapexit_ 134' ABRT
		trap 'trapexit_ 141' PIPE
		trap 'trapexit_ 143' TERM
		tg_tmp_dir="$(mktemp -d "$git_dir/tg-tmp.XXXXXX" 2>/dev/null)" || tg_tmp_dir=
		[ -n "$tg_tmp_dir" ] || tg_tmp_dir="$(mktemp -d "${TMPDIR:-/tmp}/tg-tmp.XXXXXX" 2>/dev/null)" || tg_tmp_dir=
		[ -n "$tg_tmp_dir" ] || [ -z "$TMPDIR" ] || tg_tmp_dir="$(mktemp -d "/tmp/tg-tmp.XXXXXX" 2>/dev/null)" || tg_tmp_dir=
		[ -z "$tg_tmp_dir" ] || tg_tmp_dir="$(cd "$tg_tmp_dir" && pwd -P)"
	fi
	[ -n "$tg_tmp_dir" ] && [ -w "$tg_tmp_dir" ] && { >"$tg_tmp_dir/.check"; } >/dev/null 2>&1 ||
		die "could not create a writable temporary directory"

	# whenever tg_tmp_dir is != "" these must always be set
	tg_ref_cache="$tg_tmp_dir/tg~ref-cache"
	tg_ref_cache_br="$tg_ref_cache.br"
	tg_ref_cache_rbr="$tg_ref_cache.rbr"
	tg_ref_cache_ann="$tg_ref_cache.ann"
	tg_ref_cache_dep="$tg_ref_cache.dep"
}

cachedir_setup()
{
	[ -z "$tg_cache_dir" ] || return 0
	user_id_no="$(id -u)" || :
	: "${user_id_no:=_99_}"
	tg_cache_dir="$git_common_dir/tg-cache"
	[ -d "$tg_cache_dir" ] || mkdir "$tg_cache_dir" >/dev/null 2>&1 || tg_cache_dir=
	[ -z "$tg_cache_dir" ] || tg_cache_dir="$tg_cache_dir/$user_id_no"
	[ -z "$tg_cache_dir" ] || [ -d "$tg_cache_dir" ] || mkdir "$tg_cache_dir" >/dev/null 2>&1 || tg_cache_dir=
	[ -z "$tg_cache_dir" ] || { >"$tg_cache_dir/.tgcache"; } >/dev/null 2>&1 || tg_cache_dir=
	if [ -z "$tg_cache_dir" ]; then
		tg_cache_dir="$tg_tmp_dir/tg-cache"
		[ -d "$tg_cache_dir" ] || mkdir "$tg_cache_dir" >/dev/null 2>&1 || tg_cache_dir=
		[ -z "$tg_cache_dir" ] || { >"$tg_cache_dir/.tgcache"; } >/dev/null 2>&1 || tg_cache_dir=
	fi
	[ -n "$tg_cache_dir" ] ||
		die "could not create a writable tg-cache directory (even a temporary one)"

	if [ -n "$2" ]; then
		# allow the wayback machine to share a separate cache
		[ -d "$tg_cache_dir/wayback" ] || mkdir "$tg_cache_dir/wayback" >/dev/null 2>&1 || :
		! [ -d "$tg_cache_dir/wayback" ] || ! { >"$tg_cache_dir/wayback/.tgcache"; } >/dev/null 2>&1 ||
		tg_cache_dir="$tg_cache_dir/wayback"
	fi
}

# set up alternate deb dirs
altodb_setup()
{
	# GIT_ALTERNATE_OBJECT_DIRECTORIES can contain double-quoted entries
	# since Git v2.11.1; however, it's only necessary for : (or perhaps ;)
	# so we avoid it if possible and require v2.11.1 to do it at all
	# otherwise just don't make an alternates temporary store in that case;
	# it's okay to not have one; everything will still work; the nicety of
	# making the temporary tree objects vanish when tg exits just won't
	# happen in that case but nothing will break also be sure to reuse
	# the parent's if we've been recursively invoked and it's for the
	# same repository we were invoked on

	tg_use_alt_odb=1
	_fullodbdir=
	_odbdir="${GIT_OBJECT_DIRECTORY:-$git_common_dir/objects}"
	[ -n "$_odbdir" ] && [ -d "$_odbdir" ] && _fullodbdir="$(cd "$_odbdir" && pwd -P)" ||
		die "could not find objects directory"
	if [ -n "$TG_OBJECT_DIRECTORY" ] && [ -d "$TG_OBJECT_DIRECTORY/info" ] &&
	   [ -f "$TG_OBJECT_DIRECTORY/info/alternates" ] && [ -r "$TG_OBJECT_DIRECTORY/info/alternates" ]; then
		if IFS= read -r _otherodbdir <"$TG_OBJECT_DIRECTORY/info/alternates" &&
		   [ -n "$_otherodbdir" ] && [ "$_otherodbdir" = "$_fullodbdir" ]; then
			tg_use_alt_odb=2
		fi
	fi
	_fulltmpdir="$(cd "$tg_tmp_dir" && pwd -P)"
	if [ "$tg_use_alt_odb" = "1" ]; then
		# create an alternate objects database to keep the ephemeral objects in
		mkdir -p "$tg_tmp_dir/objects/info"
		TG_OBJECT_DIRECTORY="$_fulltmpdir/objects"
		[ "$_fullodbdir" = "$TG_OBJECT_DIRECTORY" ] ||
		echol "$_fullodbdir" >"$tg_tmp_dir/objects/info/alternates"
	fi
	case "$_fulltmpdir" in *[";:"]*|'"'*) vcmp "$git_version" '>=' "2.11.1" || tg_use_alt_odb=; esac
	if [ "$tg_use_alt_odb" = "1" ]; then
		case "$TG_OBJECT_DIRECTORY" in
			*[";:"]*|'"'*)
				# surround in "..." and backslash-escape internal '"' and '\\'
				_altodbdq="\"$(printf '%s\n' "$TG_OBJECT_DIRECTORY" |
					sed 's/\([""\\]\)/\\\1/g')\""
				;;
			*)
				_altodbdq="$TG_OBJECT_DIRECTORY"
				;;
		esac
		TG_PRESERVED_ALTERNATES="$GIT_ALTERNATE_OBJECT_DIRECTORIES"
		if [ -n "$GIT_ALTERNATE_OBJECT_DIRECTORIES" ]; then
			GIT_ALTERNATE_OBJECT_DIRECTORIES="$_altodbdq:$GIT_ALTERNATE_OBJECT_DIRECTORIES"
		else
			GIT_ALTERNATE_OBJECT_DIRECTORIES="$_altodbdq"
		fi
		export TG_PRESERVED_ALTERNATES TG_OBJECT_DIRECTORY GIT_ALTERNATE_OBJECT_DIRECTORIES
		if [ -n "$GIT_OBJECT_DIRECTORY" ]; then
			export GIT_OBJECT_DIRECTORY
		else
			unset_ GIT_OBJECT_DIRECTORY
		fi
	fi
}

noalt_setup()
{
	if [ "${TG_PRESERVED_ALTERNATES+set}" = "set" ]; then
		GIT_ALTERNATE_OBJECT_DIRECTORIES="$TG_PRESERVED_ALTERNATES"
		if [ -n "$GIT_ALTERNATE_OBJECT_DIRECTORIES" ]; then
			export GIT_ALTERNATE_OBJECT_DIRECTORIES
		else
			unset_ GIT_ALTERNATE_OBJECT_DIRECTORIES
		fi
	fi
	unset_ TG_TMPDIR TG_OBJECT_DIRECTORY TG_PRESERVED_ALTERNATES tg_use_alt_odb
}

## Initial setup
initial_setup()
{
	# suppress the merge log editor feature since git 1.7.10

	GIT_MERGE_AUTOEDIT=no
	export GIT_MERGE_AUTOEDIT

	basic_setup $1
	iowopt=
	! vcmp "$git_version" '>=' "2.5" || iowopt="--ignore-other-worktrees"
	gcfbopt=
	! vcmp "$git_version" '>=' "2.6" || gcfbopt="--buffer"
	auhopt=
	! vcmp "$git_version" '>=' "2.9" || auhopt="--allow-unrelated-histories"
	v_get_show_cdup root_dir
	root_dir="${root_dir:-.}"
	logrefupdates="$(git config --bool core.logallrefupdates 2>/dev/null)" || :
	[ "$logrefupdates" = "true" ] || logrefupdates=

	# make sure root_dir doesn't end with a trailing slash.

	root_dir="${root_dir%/}"

	# create global temporary and cache directories, usually inside GIT_DIR

	tmpdir_setup
	unset_ TG_TMPDIR
	cachedir_setup

	# the wayback machine directory serves as its own "altodb"
	[ -n "$wayback" ] || altodb_setup
}

activate_wayback_machine()
{
	[ -n "${1#:}" ] || [ -n "$2" ] || { wayback=; return 0; }
	setup_git_dirs
	tmpdir_setup
	altodb_setup
	tgwbr=
	tgwbr2=
	if [ -n "${1#:}" ]; then
		tgwbr="$(get_temp wbinfo)"
		tgwbr2="${tgwbr}2"
		tg revert --list --no-short "${1#:}" >"$tgwbr" && test -s "$tgwbr" || return 1
		# tg revert will likely leave a revert-tag-only cache which is not what we want
		remove_ref_cache
	fi
	cachedir_setup "" 1 # use a separate wayback cache dir
	# but don't step on the normal one if the separate one could not be set up
	case "$tg_cache_dir" in */wayback);;*) tg_cache_dir=; esac
	altodb="$TG_OBJECT_DIRECTORY"
	if [ -n "$3" ] && [ -n "$2" ]; then
		[ -d "$3" ] || { mkdir -p "$3" && [ -d "$3" ]; } ||
			die "could not create wayback directory: $3"
		tg_wayback_dir="$(cd "$3" && pwd -P)" || die "could not get wayback directory full path"
		[ -d "$tg_wayback_dir/.git" ] || { mkdir -p "$tg_wayback_dir/.git" && [ -d "$tg_wayback_dir/.git" ]; } ||
			die "could not initialize wayback directory: $3"
		is_empty_dir "$tg_wayback_dir" ".git" && is_empty_dir "$tg_wayback_dir/.git" "." ||
			die "wayback directory is not empty: $3"
		mkdir "$tg_wayback_dir/.git/objects"
		mkdir "$tg_wayback_dir/.git/objects/info"
		cat "$altodb/info/alternates" >"$tg_wayback_dir/.git/objects/info/alternates"
	else
		tg_wayback_dir="$tg_tmp_dir/wayback"
		mkdir "$tg_wayback_dir"
		mkdir "$tg_wayback_dir/.git"
		ln -s "$altodb" "$tg_wayback_dir/.git/objects"
	fi
	mkdir "$tg_wayback_dir/.git/refs"
	printf '0 Wayback Machine' >"$tg_wayback_dir/.git/gc.pid"
	qpesc="$(printf '%s\n' "$git_common_dir" | sed -e 's/\([\\""]\)/\\\1/g' -e '$!s/$/\\n/' | tr -d '\n')"
	laru="false"
	[ -z "$2" ] || laru="true"
	printf '%s' "\
[include]
	path = \"$qpesc/config\"
[core]
	bare = false
	logAllRefUpdates = $laru
	repositoryFormatVersion = 0
[extensions]
	preciousObjects = true
[gc]
	auto = 0
	autoDetach = false
	autoPackLimit = 0
	packRefs = false
[remote \"wayback\"]
	url = \"$qpesc\"
[push]
	default = nothing
	followTags = true
[alias]
	wayback-updates = fetch --force --no-tags --dry-run wayback refs/*:refs/*
" >"$tg_wayback_dir/.git/config"
	cat "$git_dir/HEAD" >"$tg_wayback_dir/.git/HEAD"
	case "$1" in ":"?*);;*)
		git show-ref >"$tg_wayback_dir/.git/packed-refs"
		git --git-dir="$tg_wayback_dir/.git" pack-refs --all
	esac
	noalt_setup
	TG_OBJECT_DIRECTORY="$altodb" && export TG_OBJECT_DIRECTORY
	if [ -n "${1#:}" ]; then
		<"$tgwbr" sed 's/^\([^ ][^ ]*\) \([^ ][^ ]*\)$/update \2 \1/' |
		git --git-dir="$tg_wayback_dir/.git" update-ref -m "wayback to $1" ${2:+--create-reflog} --stdin
	fi
	if test -n "$2"; then
		# extra setup for potential shell
		qpesc2="$(printf '%s\n' "$git_common_dir" | sed -e 's/\([\\""]\)/\\\\\1/g' -e '$!s/$/\\n/' | tr -d '\n')"
		printf '\twayback-repository = "!printf '\''%%s\\\\n'\'' \\"%s\\""\n' "$qpesc2" >>"$tg_wayback_dir/.git/config"
		qtesc="$(printf '%s\n' "${1:-:}" | sed 's/\([""]\)/\\\1/g')"
		printf '\twayback-tag = "!printf '\''%%s\\\\n'\'' \\"%s\\""\n' "$qtesc" >>"$tg_wayback_dir/.git/config"
		if [ -d "$git_common_dir/rr-cache" ]; then
			ln -s "$git_common_dir/rr-cache" "$tg_wayback_dir/.git/rr-cache"
			printf "[rerere]\n\tenabled = true\n" >>"$tg_wayback_dir/.git/config"
		fi
		if [ z"$2" != z"2" ]; then
			wbauth=
			wbprnt=
			if [ -n "${1#:}" ]; then
				[ -n "$tgwbr2" ] || tgwbr2="$(get_temp wbtag)"
				git --git-dir="$git_common_dir" cat-file tag "${1#:}" >"$tgwbr2" || return 1
				wbprnt="${lf}parent $(git --git-dir="$git_common_dir" rev-parse --verify --quiet "${1#:}"^0 -- 2>/dev/null)" || wbprnt=
				wbauth="$(<"$tgwbr2" awk '{if(!$0)exit;if($1=="tagger")print "author" substr($0,7)}')"
			fi
			wbcmtr="committer Wayback Machine <-> $(date "+%s %z")"
			[ -n "$wbauth" ] || wbauth="author${wbcmtr#committer}"
			wbtree="$(git --git-dir="$tg_wayback_dir/.git" mktree </dev/null)"
			wbcmt="$({
				printf '%s\n' "tree $wbtree$wbprnt" "$wbauth" "$wbcmtr" ""
				if [ -n "$tgwbr2" ]; then
					<"$tgwbr2" sed -e '1,/^$/d' -e '/^-----BEGIN/,$d' | git stripspace
				else
					echo "Wayback Machine"
				fi
			} | git --git-dir="$tg_wayback_dir/.git" hash-object -t commit -w --stdin)"
			test -n "$wbcmt" || return 1
			echo "$wbcmt" >"$tg_wayback_dir/.git/HEAD"
		fi
	fi
	cd "$tg_wayback_dir"
	unset git_dir git_common_dir
}

set_topbases()
{
	# refer to "top-bases" in a refname with $topbases

	[ -z "$tg_topbases_set" ] || return 0

	topbases_implicit_default=1
	# See if topgit.top-bases is set to heads or refs
	tgtb="$(git config "topgit.top-bases" 2>/dev/null)" || :
	if [ -n "$tgtb" ] && [ "$tgtb" != "heads" ] && [ "$tgtb" != "refs" ]; then
		if [ -n "$1" ]; then
			# never die on the hook script
			unset_ tgtb
		else
			die "invalid \"topgit.top-bases\" setting (must be \"heads\" or \"refs\")"
		fi
	fi
	if [ -n "$tgtb" ]; then
		case "$tgtb" in
		heads)
			topbases="heads/{top-bases}"
			topbasesrx="heads/[{]top-bases[}]"
			oldbases="top-bases";;
		refs)
			topbases="top-bases"
			topbasesrx="top-bases"
			oldbases="heads/{top-bases}";;
		esac
		# MUST NOT be exported
		unset_ tgtb tg_topbases_set topbases_implicit_default
		tg_topbases_set=1
		return 0
	fi
	unset_ tgtb

	# check heads and top-bases and see what state the current
	# repository is in.  remotes are ignored.

	rc=0 activebases=
	activebases="$(
		git for-each-ref --format='%(refname)' "refs/heads" "refs/top-bases" 2>/dev/null |
		run_awk_ref_prefixes ${1:+-e} -n -- "refs/heads/{top-bases}" "refs/top-bases" "refs/heads")" ||
		rc=$?
	if [ "$rc" = "65" ]; then
		# Complain and die
		err "repository contains existing TopGit branches"
		err "but some use refs/top-bases/... for the base"
		err "and some use refs/heads/{top-bases}/... for the base"
		err "with the latter being the new, preferred location"
		err "set \"topgit.top-bases\" to either \"heads\" to use"
		err "the new heads/{top-bases} location or \"refs\" to use"
		err "the old top-bases location."
		err "(the tg migrate-bases command can also resolve this issue)"
		die "schizophrenic repository requires topgit.top-bases setting"
	fi
	[ -z "$activebases" ] || unset_ topbases_implicit_default
	if [ "$activebases" = "refs/heads/{top-bases}" ]; then
		topbases="heads/{top-bases}"
		topbasesrx="heads/[{]top-bases[}]"
		oldbases="top-bases"
	else
		# default is still top-bases for now
		topbases="top-bases"
		topbasesrx="top-bases"
		oldbases="heads/{top-bases}"
	fi
	# MUST NOT be exported
	unset_ rc activebases tg_topases_set
	tg_topbases_set=1
	return 0
}

# $1 is remote name to check
# $2 is optional variable name to set to result of check
# $3 is optional command name to use in message (defaults to $cmd)
# Fatal error if remote has schizophrenic top-bases
# No error (and $2, if provided, will be set to empty) if remote has no top-bases at all
check_remote_topbases()
{
	[ -n "$1" ] || die "programmer error: check_remote_topbases called with no remote argument"
	_crrc=0 _crremotebases=
	_crremotebases="$(
		git for-each-ref --format='%(refname)' "refs/remotes/$1" 2>/dev/null |
		run_awk_ref_prefixes -n -- "refs/remotes/$1/{top-bases}" "refs/remotes/$1/top-bases" "refs/remotes/$1")" ||
		_crrc=$?
	if [ "$_crrc" = "65" ]; then
		err "remote \"$1\" has top-bases in both locations:"
		err "  refs/remotes/$1/{top-bases}/..."
		err "  refs/remotes/$1/top-bases/..."
		err "set \"topgit.top-bases\" to \"heads\" for the first, preferred location"
		err "or set \"topgit.top-bases\" to \"refs\" for the second, old location"
		err "(the \"-c topgit.top-bases=<val>\" option can be used for this)"
		err "then re-run the tg ${3:-$cmd} command"
		err "(the tg migrate-bases command can also help with this problem)"
		die "schizophrenic remote \"$1\" requires topgit.top-bases setting"
	fi
	[ "$_crrc" != "66" ] || _crremotebases= # just to be sure
	[ -z "$2" ] || eval "$2="'"$_crremotebases"'
	unset _crrc _crremotebases
	return 0
}

# init_reflog "ref"
# if "$logrefupdates" is set and ref is not under refs/heads/ then force
# an empty log file to exist so that ref changes will be logged
# "$1" must be a fully-qualified refname (i.e. start with "refs/")
# However, if "$1" is "refs/tgstash" then always make the reflog
# The only ref not under refs/ that Git will write a reflog for is HEAD;
# no matter what, it will NOT update a reflog for any other bare refs so
# just quietly succeed when passed TG_STASH without doing anything.
init_reflog()
{
	[ -n "$1" ] && [ "$1" != "TG_STASH" ] || return 0
	[ -n "$logrefupdates" ] || [ "$1" = "refs/tgstash" ] || return 0
	case "$1" in refs/heads/*|HEAD) return 0;; refs/*[!/]);; *) return 1; esac
	mkdir -p "$git_common_dir/logs/${1%/*}" 2>/dev/null || :
	{ >>"$git_common_dir/logs/$1" || :; } 2>/dev/null
 }

# store the "realpath" for "$2" in "$1" except the leaf is not resolved if it's
# a symbolic link.  The directory part must exist, but the basename need not.
v_get_abs_path()
{
	[ -n "$1" ] && [ -n "$2" ] || return 1
	set -- "$1" "$2" "${2%/}"
	case "$3" in
		*/*) set -- "$1" "$2" "${3%/*}";;
		*  ) set -- "$1" "$2" ".";;
	esac
	case "$2" in */)
		set -- "$1" "${2%/}" "$3" "/"
	esac
	[ -d "$3" ] || return 1
	eval "$1="'"$(cd "$3" && pwd -P)/${2##*/}$4"'
}

## Startup

: "${TG_INST_CMDDIR:=@cmddir@}"
: "${TG_INST_SHAREDIR:=@sharedir@}"
: "${TG_INST_HOOKSDIR:=@hooksdir@}"

[ -d "$TG_INST_CMDDIR" ] ||
	die "No command directory: '$TG_INST_CMDDIR'"

## Include awk scripts and their utility functions (separated for easier debugging)

[ -f "$TG_INST_CMDDIR/tg--awksome" ] && [ -r "$TG_INST_CMDDIR/tg--awksome" ] ||
	die "Missing awk scripts: '$TG_INST_CMDDIR/tg--awksome'"
. "$TG_INST_CMDDIR/tg--awksome"

if [ -n "$tg__include" ]; then

	# We were sourced from another script for our utility functions;
	# this is set by hooks.  Skip the rest of the file.  A simple return doesn't
	# work as expected in every shell.  See http://bugs.debian.org/516188

	# ensure setup happens

	initial_setup 1
	set_topbases 1
	noalt_setup

else

	set -e

	tgbin="$0"
	tgdir="${tgbin%/}"
	case "$tgdir" in */*);;*) tgdir="./$tgdir"; esac
	tgdir="${tgdir%/*}/"
	tgname="${tgbin##*/}"
	[ "$0" != "$tgname" ] || tgdir=""

	# If tg contains a '/' but does not start with one then replace it with an absolute path

	case "$0" in /*) ;; */*)
		tgdir="$(cd "${0%/*}" && pwd -P)/"
		tgbin="$tgdir$tgname"
	esac

	# tgdisplay will include any explicit -C <dir> etc. options whereas tgname will not
	# tgdisplayac is the same as tgdisplay but without any -r or -u options (ac => abort/continue)

	tgdisplaydir="$tgdir"
	tgdisplay="$tgbin"
	tgdisplayac="$tgdisplay"
	if
	    v_get_abs_path _tgnameabs "$(cmd_path "$tgname")" &&
	    _tgabs="$_tgnameabs" &&
	    { [ "$tgbin" = "$tgname" ] || v_get_abs_path _tgabs "$tgbin"; } &&
	    [ "$_tgabs" = "$_tgnameabs" ]
	then
		tgdisplaydir=""
		tgdisplay="$tgname"
		tgdisplayac="$tgdisplay"
	fi
	[ -z "$_tgabs" ] || tgbin="$_tgabs"
	unset_ _tgabs _tgnameabs

	tg() (
		TG_TMPDIR="$tg_tmp_dir" && export TG_TMPDIR &&
		exec "$tgbin" "$@"
	)

	explicit_remote=
	explicit_dir=
	gitcdopt=
	noremote=
	forcepager=
	wayback=

	cmd=
	while :; do case "$1" in

		help|--help|-h)
			cmd=help
			shift
			break;;

		status|--status)
			cmd=status
			shift
			break;;

		--hooks-path)
			cmd=hooks-path
			shift
			break;;

		--exec-path)
			cmd=exec-path
			shift
			break;;

		--awk-path)
			cmd=awk-path
			shift
			break;;

		--top-bases)
			cmd=top-bases
			shift
			break;;

		--no-pager)
			forcepager=0
			shift;;

		--pager|-p)
			forcepager=1
			shift;;

		-r)
			shift
			if [ -z "$1" ]; then
				echo "Option -r requires an argument." >&2
				do_help
				exit 1
			fi
			unset_ noremote
			base_remote="$1"
			explicit_remote="$base_remote"
			tgdisplay="$tgdisplaydir$tgname$gitcdopt -r $explicit_remote"
			TG_EXPLICIT_REMOTE="$base_remote" && export TG_EXPLICIT_REMOTE
			shift;;

		-u)
			unset_ base_remote explicit_remote
			noremote=1
			tgdisplay="$tgdisplaydir$tgname$gitcdopt -u"
			TG_EXPLICIT_REMOTE= && export TG_EXPLICIT_REMOTE
			shift;;

		-C)
			shift
			if [ -z "$1" ]; then
				echo "Option -C requires an argument." >&2
				do_help
				exit 1
			fi
			cd "$1"
			unset_ GIT_DIR GIT_COMMON_DIR
			if [ -z "$explicit_dir" ]; then
				explicit_dir="$1"
			else
				explicit_dir="$PWD"
			fi
			gitcdopt=" -C \"$explicit_dir\""
			[ "$explicit_dir" != "." ] || explicit_dir="." gitcdopt=" -C ."
			tgdisplay="$tgdisplaydir$tgname$gitcdopt"
			tgdisplayac="$tgdisplay"
			[ -z "$explicit_remote" ] || tgdisplay="$tgdisplay -r $explicit_remote"
			[ -z "$noremote" ] || tgdisplay="$tgdisplay -u"
			shift;;

		-c)
			shift
			if [ -z "$1" ]; then
				echo "Option -c requires an argument." >&2
				do_help
				exit 1
			fi
			param="'$(printf '%s\n' "$1" | sed "s/[']/'\\\\''/g")'"
			GIT_CONFIG_PARAMETERS="${GIT_CONFIG_PARAMETERS:+$GIT_CONFIG_PARAMETERS }$param"
			export GIT_CONFIG_PARAMETERS
			shift;;

		-w)
			if [ -n "$wayback" ]; then
				echo "Option -w may be used at most once." >&2
				do_help
				exit 1
			fi
			shift
			if [ -z "$1" ]; then
				echo "Option -w requires an argument." >&2
				do_help
				exit 1
			fi
			wayback="$1"
			shift;;

		--)
			shift
			break;;

		-*)
			echo "Invalid option $1 (subcommand options must appear AFTER the subcommand)." >&2
			do_help
			exit 1;;

		*)
			break;;

	esac; done
	if [ z"$forcepager" = z"0" ]; then
		GIT_PAGER_IN_USE=1 TG_PAGER_IN_USE=1 &&
		export GIT_PAGER_IN_USE TG_PAGER_IN_USE
	fi

	[ -n "$cmd" -o $# -lt 1 ] || { cmd="$1"; shift; }

	## Dispatch

	[ -n "$cmd" ] || { do_help; exit 1; }

	case "$cmd" in

		help)
			do_help "$@"
			exit 0;;

		status|st)
			unset_ base_remote
			basic_setup
			set_topbases
			do_status "$@"
			exit ${do_status_result:-0};;

		hooks-path)
			# Internal command
			echol "$TG_INST_HOOKSDIR";;

		exec-path)
			# Internal command
			echol "$TG_INST_CMDDIR";;

		awk-path)
			# Internal command
			echol "$TG_INST_CMDDIR/awk";;

		top-bases)
			# Maintenance command
			do_topbases_help=
			show_remote_topbases=
			case "$1" in
				--help|-h)
					do_topbases_help=0;;
				-r|--remote)
					if [ $# -eq 2 ] && [ -n "$2" ]; then
						# unadvertised, but make it work
						base_remote="$2"
						shift
					fi
					show_remote_topbases=1;;
				*)
					[ $# -eq 0 ] || do_topbases_help=1;;
			esac
			[ $# -le 1 ] || do_topbases_help=1
			if [ -n "$do_topbases_help" ]; then
				helpcmd='echo "Usage: ${tgname:-tg} [-r <remote>] --top-bases [-r]"'
				[ $do_topbases_help -eq 0 ] || helpcmd="$helpcmd >&2"
				eval "$helpcmd"
				exit $do_topbases_help
			fi
			git_dir=
			if git_dir="$(git rev-parse --git-dir 2>&1)"; then
				[ -z "$wayback" ] || activate_wayback_machine "$wayback"
				setup_git_dirs
			fi
			set_topbases
			if [ -n "$show_remote_topbases" ]; then
				basic_setup_remote
				[ -n "$base_remote" ] ||
				die "no remote location given. Either use -r <remote> option or set topgit.remote"
				rbases=
				[ -z "$topbases_implicit_default" ] ||
				check_remote_topbases "$base_remote" rbases "--top-bases"
				if [ -n "$rbases" ]; then
					echol "$rbases"
				else
					echol "refs/remotes/$base_remote/${topbases#heads/}"
				fi
			else
				echol "refs/$topbases"
			fi;;

		*)
			isutil=
			case "$cmd" in index-merge-one-file)
				isutil="-"
			esac
			[ -r "$TG_INST_CMDDIR"/tg-$isutil$cmd ] || {
				looplevel="$TG_ALIAS_DEPTH"
				[ "${looplevel#[1-9]}" != "$looplevel" ] &&
				[ "${looplevel%%[!0-9]*}" = "$looplevel" ] ||
				looplevel=0
				tgalias="$(git config "topgit.alias.$cmd" 2>/dev/null)" || :
				[ -n "$tgalias" ] || {
					echo "Unknown subcommand: $cmd" >&2
					do_help
					exit 1
				}
				looplevel=$(( $looplevel + 1 ))
				[ $looplevel -le 10 ] || die "topgit.alias nesting level 10 exceeded"
				TG_ALIAS_DEPTH="$looplevel"
				export TG_ALIAS_DEPTH
				if [ "!${tgalias#?}" = "$tgalias" ]; then
					[ -z "$wayback" ] ||
					die "-w is not allowed before an '!' alias command"
					unset_ GIT_PREFIX
					if pfx="$(git rev-parse --show-prefix 2>/dev/null)"; then
						GIT_PREFIX="$pfx"
						export GIT_PREFIX
					fi
					cd "./$(git rev-parse --show-cdup 2>/dev/null)"
					exec @SHELL_PATH@ -c "${tgalias#?} \"\$@\"" @SHELL_PATH@ "$@"
				else
					eval 'exec "$tgbin"' "${wayback:+-w \"\$wayback\"}" "$tgalias" '"$@"'
				fi
				die "alias execution failed for: $tgalias"
			}
			unset_ TG_ALIAS_DEPTH

			showing_help=
			if [ "$*" = "-h" ] || [ "$*" = "--help" ]; then
				showing_help=1
			fi

			nomergesetup="$showing_help"
			case "$cmd" in base|contains|export|files|info|log|mail|next|patch|prev|rebase|revert|shell|summary|tag)
				# avoid merge setup where not necessary

				nomergesetup=1
			esac

			if [ -n "$wayback" ] && [ -z "$showing_help" ]; then
				[ -n "$nomergesetup" ] ||
				die "the wayback machine cannot be used with the \"$cmd\" subcommand"
				if [ "$cmd" = "shell" ]; then
					# this is ugly; `tg shell` should handle this but it's too
					# late there so we have to do it here
					wayback_dir=
					case "$1" in
						"--directory="?*)
							wayback_dir="${1#--directory=}" && shift;;
						"--directory=")
							die "--directory requires an argument";;
						"--directory")
							[ $# -ge 2 ] || die "--directory requires an argument"
							wayback_dir="$2" && shift 2;;
					esac
					activate_wayback_machine "$wayback" 1 "$wayback_dir"
				else
					_fullwb=
					# export might drop out into a shell for conflict resolution
					[ "$cmd" != "export" ] || _fullwb=2
					activate_wayback_machine "$wayback" "$_fullwb"
				fi ||
				die "failed to set the wayback machine to target \"$wayback\""
			fi

			[ -n "$showing_help" ] || initial_setup
			[ -z "$noremote" ] || unset_ base_remote

			if [ -z "$nomergesetup" ]; then
				# make sure merging the .top* files will always behave sanely

				setup_ours
				setup_hook "pre-commit"
			fi

			# everything but rebase needs topbases set
			carefully="$showing_help"
			[ "$cmd" != "migrate-bases" ] || carefully=1
			[ "$cmd" = "rebase" ] || set_topbases $carefully

			_use_ref_cache=
			tg_read_only=1
			_suppress_alt=
			case "$cmd$showing_help" in
				contains|info|summary|tag)
					_use_ref_cache=1;;
				"export")
					_use_ref_cache=1
					_suppress_alt=1;;
				annihilate|create|delete|depend|import|update)
					tg_read_only=
					_suppress_alt=1;;
			esac
			[ -z "$_suppress_alt" ] || noalt_setup
			[ -z "$_use_ref_cache" ] || v_create_ref_cache

			fullcmd="${tgname:-tg} $cmd $*"
			if [ z"$forcepager" = z"1" ]; then
				page '. "$TG_INST_CMDDIR"/tg-$isutil$cmd' "$@"
			else
				. "$TG_INST_CMDDIR"/tg-$isutil$cmd
			fi;;
	esac

fi