backup-rsync

#!/bin/bash

MV=${MV:=/bin/mv}
LN=${LN:=/bin/ln}
RM=${RM:=/bin/rm}
MKDIR=${MKDIR:=/bin/mkdir}
RSYNC=${RSYNC:=/usr/bin/rsync}
STAT=${STAT:=/usr/bin/stat}
DATE=${DATE:=/bin/date}
#DATE=${DATE:=/opt/local/bin/gdate}

# GNU date or BSD date
${DATE} --version > /dev/null 2>&1 && GNUDATE=yes

# GNU stat or BSD stat
${STAT} --version > /dev/null 2>&1 && GNUSTAT=yes

# Default
RSYNCOPTS=${RSYNCOPTS:=""}
DATEFMT=${DATEFMT:="%Y/%m/%d"}
DATEFMTDEPTH="$(echo $DATEFMT | tr -c -d / | wc -c)"

# now date
NOW=$(${DATE} +%s)

#
# backupdiff rsync://hostname/directory /backup-base-directory
#

usage() {
	echo "Usage: backupdiff SRC BASE [ -- append-rsync-options ]"
	echo "  -v                    verbose mode"
	echo "  -n                    don't actually run any commands"
	echo "  -d datestring         specify backup time"
	echo "  -f FORMAT             FORMAT controls relative-path \`date +FORMAT'"
	exit 1
}

opt_parse() {
	while getopts "nvf:s:d:h?o" flag; do
		case $flag in
		v)	verbose=yes
			RSYNCOPTS="$RSYNCOPTS -v"
			;;
		n)	dryrun=yes
			MV="echo mv"
			LN="echo ln"
			RM="echo rm"
			MKDIR="echo mkdir"
			RSYNC="echo rsync"
			;;
		f)	DATEFMT=$OPTARG;;
		d)	NOW=$OPTARG;;
		\?|h)	usage;;
	       *)	break;;
		esac
	done
	shift $(($OPTIND - 1))

	[ $# -lt 2 ] && usage
	srcdir=$1; basedir=$2; shift 2
	[ $srcdir == '--' -o $basedir == '--' ] && usage

	if [ $# -ge 1 ]; then
		[ "x$1" == 'x--' ] && shift || usage
		RSYNCOPTS="$RSYNCOPTS $*"
	fi
}

fromepoch() {
	secepoch=$1; fmt=$2

	if [ "${GNUDATE}" == "yes" ]; then
		echo $(${DATE} -d "@${secepoch}" "${fmt}")
	else
		echo $(${DATE} -j -f '%s' ${secepoch} "${fmt}")
	fi
}

inode() {
	file=$1

	if [ "${GNUSTAT}" == "yes" ]; then
		${STAT} -L -c %i $file 2> /dev/null
	else
		${STAT} -L -f %i $file 2> /dev/null
	fi
}

linkdatefmt() {
	datepoint=$1

	history=$basedir/history
	datepath=$history/$datepoint
	datelink=$basedir/$(fromepoch $datepoint +"$DATEFMT")

	pdir=$(dirname $datelink)
	[ ! -d $pdir ] && $MKDIR -p $pdir

	idatepath="$(inode $datepath)"

	i=0; link=$datelink
	while [ -d $link ]; do
		if [ "$idatepath" == "$(inode $link)" ]; then
			return
		fi
		link="${datelink}_$((++i))"
	done
	datelink=$link

	#$LN -s $datepath $datelink

	datepath=history/$datepoint
	for ((i=0;i<$DATEFMTDEPTH;i++)); do
		datepath="../$datepath"
	done

	$LN -s $datepath $datelink
}

backup_diff() {
	datepoint=$NOW

	last=$basedir/last
	history=$basedir/history
	datepath=$history/$datepoint
	progress=$history/progress-$datepoint

	[ ! -d $history ] && $MKDIR -p $history

	lastopts=""
	if [ -e $last ]; then
		if [ -h $last ]; then
			lastdatepath=$(readlink $last)
			if [ "${lastdatepath::1}" != "/" ]; then
				lastdatepath="$basedir/$lastdatepath"
			fi
			lastopts="--link-dest $lastdatepath"
		else
			echo "not symblic file \`$last'"
			return 1
		fi
	fi

	echo "Backup" $(fromepoch $datepoint +"$DATEFMT") "($datepoint)"
	$RSYNC -a --delete $RSYNCOPTS $lastopts $srcdir $progress
	if [ $? -ne 0 ]; then
		$RM -rf $progress
		return 2
	fi

	$MV $progress $datepath
	$RM $last
	$LN -s history/$datepoint $last

	linkdatefmt $datepoint
}

opt_parse "$@"
backup_diff