trivialfs_gen

#! /bin/sh
HDR_KEY=TrivialFS
HDR_VAL=80a29844-f5e3-11e3-b1c1-b827eb896db5

# Generates a new trivial file system recursively from the contents of the
# current directory. Symbolic links will automatically be transformed into
# hard links within the generated file system. The generated file system will
# either be written to the file or block device given as the only argument, or
# to standard output if invoked without arguments.
#
# trivialfs_gen version 2016.118
#
# Copyright (c) 2014-2016 Guenther Brunthaler. All rights reserved.
# 
# This script is free software.
# Distribution is permitted under the terms of the GPLv3.

cleanup() {
	local rc=$?
	for t in "$T" "$T2" "$T3"
	do
		test -n "$t" && rm -- "$t"
	done
	test $rc = 0 || echo "${0##*/} failed!" >& 2
}

set -e
T=; T2=; T3=
trap cleanup 0
FSUUID=
FSLABEL=
VERBOSE=
OUT=
DUMP=
while getopts L:l:dvtru: OPT
do
	case $OPT in
		v) VERBOSE=y;;
		u) FSUUID=$OPTARG;;
		L | l) FSLABEL=$OPTARG;;
		r | t) FSUUID=`uuidgen -$OPT`;;
		d) DUMP=y;;
		*) fail
	esac
done
shift `expr $OPTIND - 1`
test -n "$1" && { OUT=$1; shift; }
test $# = 0
if test -n "$DUMP"
then
	# Perform a hex dump with decimal offsets for stdin or file argument.
	set -- hexdump -e '"%10_ad" 16/1 " %02x"' -e '" |" 16 "%_p" "|\n"'
	test -n "$OUT" && set -- "$@" "$OUT"
	exec "$@"
fi
test -z "$FSUUID" && FSUUID=`uuidgen -r`
tempfile() {
	mktemp -- "${TMPDIR:-/tmp}/${0##*/}".XXXXXXXXXX
}
T=`tempfile`; T2=`tempfile`; T3=`tempfile`
find -type f -o -type l | cut -d / -f2- | LC_ALL=C sort \
| while IFS= read -r fn
do
	stat -Lc "%i |%n" -- "$fn"
done | sort -sn -k2 | {
	cat <<- .
	$HDR_KEY=$HDR_VAL
	COMPATIBLE_VERSION=3
	UUID=$FSUUID
	LABEL=$FSLABEL
	ACTUAL_VERSION=3
	CREATED=`date -u +%s`
.
	start=0
	li=
	while read -r i fn
	do
		if test x"$li" != x"$i"
		then
			fn=${fn#?}
			test -f "$fn"
			off=$start
			size=`stat -c %s -- "$fn"`
			test $size = 0 && off=0
			echo "@$off+$size=$fn"
			cat "$fn" >> "$T"
			start=`expr $start + $size`
			li=$i
		else
			echo "$fn"
		fi
	done
	echo EOF
} > "$T2"
lsize=0
its=0
while
	size=`stat -c %s -- "$T2"`
	test $lsize != $size
do
	test $lsize -lt $size
	# Add increment of $size relative to $lsize to all offsets in $T2.
	inc=`expr $size - $lsize`
	cat "$T2" > "$T3"
	while read -r LINE
	do
		case $LINE in
			"@"*)
				rest="+${LINE#*+}"
				case $rest in
					"+0="*) ;;
					*)
						start=${LINE%"$rest"}
						start=${start#?}
						start=`expr $start + $inc`
						LINE="@"$start$rest
				esac
		esac
		echo "$LINE"
	done < "$T3" > "$T2"
	lsize=$size
	its=`expr $its + 1`
done
cat "$T" >> "$T2"
if test -n "$OUT"
then
	cat "$T2" > "$OUT"
else
	cat "$T2"
	tty -s <& 1 && echo "================" >& 2
fi
echo "Trivial FS creation successful." >& 2
test -n "$VERBOSE" && echo \
	"$its iterations for offset correction were required." >& 2