#!/bin/sh -e

# Rescp - secure copy with reget. Command line syntax is similar to scp.
# Copyright (c) 1997 by Solar Designer
# Modifications by Dmitry V. Levin <ldv@fandra.org>, 1998-2000

PROG="$(basename "$0")"

function usage() {
	RETVAL=$?
	echo "Usage: $PROG [options] [user@]host:file file"
	if [ -n "$1" ]; then
		exit "$1"
	else
		exit $RETVAL
	fi
}

VERBOSE=
while getopts "CP:c:i:o:vV" OPT; do
	[ "$OPT" != "?" ] || usage 0

	case "$OPT" in
		P)
			OPT="p"
			;;
		V)
			VERBOSE=1
			;;
		v)
			VERBOSE=1
			OPTS="$OPTS -$OPT"
			;;
		*)
			OPTS="$OPTS -$OPT"
			if [ -n "$OPTARG" ]; then
				OPTS="$OPTS $OPTARG"
			fi
			;;
	esac
done

[ $OPTIND -eq $[$#-1] ] || usage

shift $[$OPTIND-1]

USER="$(echo "$1" |sed -n "s/@.*//p")"
HOST="$(echo "$1" |sed -ne "s/[^@]*@//" -e "s/:.*//p")"
R_FILE="$(echo "$1" |sed -n "s/[^:]*://p")"

[ -n "$USER" ] || USER="$LOGNAME"

[ -n "$HOST" -a -n "$R_FILE" ] || usage

if [ -d "$2" ]; then
	L_FILE="$2/$(basename $R_FILE)"
else
	L_FILE="$2"
fi

if [ ! -f "$L_FILE" -o ! -r "$L_FILE" -o ! -w "$L_FILE" ]; then
	echo "$PROG: Destination file should exist and be both readable and writable"
	exit 1
fi

SIZE=$[$(wc -c "$L_FILE" |sed -e "s/[ ]*//" -e "s/ .*//") / 1024]

echo "$PROG: Restarting at $[$SIZE * 1024]"

: ${SSH:=ssh}
"$SSH" -a -x $OPTS -l "$USER" "$HOST" \
  "dd if=$R_FILE bs=1k count=$SIZE 2>>/dev/null |md5sum;" \
  "dd if=$R_FILE bs=1k skip=$SIZE count=1024k 2>>/dev/null" |
(
	if read; then
		L_SUM="$(dd if="$L_FILE" bs=1k count=$SIZE 2>>/dev/null |md5sum |sed -n "s/ .*//p")"
		R_SUM="$(echo "$REPLY" |sed -n "s/ .*//p")"

		if [ "$L_SUM" != "$R_SUM" ]; then
			echo "$PROG: Checksum doesn't match"
			exit 1
		fi
		if [ -n "$VERBOSE" ]; then
			echo "$PROG: Received checksum"
		fi
	else
		echo "$PROG: No checksum received"
		exit 1
	fi

	dd of="$L_FILE" bs=1k seek=$SIZE count=1024k 2>>/dev/null
)

RETVAL=$?

if [ -n "$VERBOSE" ]; then
	NEW_SIZE=$[$(wc -c "$L_FILE" |sed -e "s/[ ]*//" -e "s/ .*//") / 1024]
	echo "$PROG: Received $[NEW_SIZE-SIZE]k"
fi

exit $RETVAL