#!/usr/bin/bash
###########################################################################
#                                                                         #
#   Linux pktcdvd Module Control Script                                   #
#                                                                         #
#   Uses pktcdvd sysfs interface.                                         #
#                                                                         #
#   Copyright (C) 2006 Thomas Maier <balagi@justmail.de>                  #
#                                                                         #
#   May be copied or modified under the terms of the GNU General Public   #
#   License.                                                              #
#                                                                         #
#   This program is free software; you can redistribute it and/or modify  #
#   it under the terms of the GNU General Public License as published by  #
#   the Free Software Foundation;                                         #
#                                                                         #
#   This program is distributed in the hope that it will be useful,       #
#   but WITHOUT ANY WARRANTY; without even the implied warranty of        #
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         #
#   GNU General Public License for more details.                          #
###########################################################################


PKTCDVD_DIR="/sys/class/pktcdvd"
PKTDEV_DIR="/dev/pktcdvd"

usage()
{
	echo "pktcdvd control script   Version 1.0.0" >&2
	echo "Copyright (C) 2006 Thomas Maier <balagi@justmail.de>" >&2
	echo "usage:" >&2
	echo " # add new packet device for block device." >&2
	echo " # a device node is created: /dev/pktcdvd/<pktname>" >&2
	echo " pktcdvd -a pktname blkdev" >&2
	echo " # remove a packet device" >&2
	echo " pktcdvd -r pktname|pktmajor:pktminor" >&2
	echo " # show packet device stat infos" >&2
	echo " pktcdvd -i pktname|pktmajor:pktminor" >&2
	echo " # set write congestion marks for packet device" >&2
	echo " pktcdvd -C pktname|pktmajor:pktminor on [off]" >&2
	echo " # print write congestion marks for packet device" >&2
	echo " pktcdvd -c pktname|pktmajor:pktminor" >&2
	echo " # print device mapping" >&2
	echo " pktcdvd -m" >&2
}

exiterr()
{
	[ -n "$1" ] && echo "error: $1" >&2
	exit 1
}

usage_error()
{
	usage
	exiterr
}

# device file to device id (major:minor)
dev_to_id()
{
	if [[ "$1" == *:* ]] ; then
		echo "$1"
		return 0
	elif [ -b "$1" ] ; then
		/bin/ls -l "$1" \
		  | awk '{print $5 ":" $6}' | tr -d ','
		return 0
	fi
	return 1
}

# device file, device id or pktcdvd device name
# to packet device id (major:minor)
to_pktdev_id()
{
	typeset name="$1"
	typeset devid=""

	if [ -b "$PKTDEV_DIR/$name" ] ; then
		devid="$(dev_to_id "$PKTDEV_DIR/$name")"
	else
		devid="$(dev_to_id "$name")"
	fi
	[ -z "$devid" ] && exiterr "can not get device id for $name"
	echo "$devid"
}

to_pkt_name()
{
	typeset pktdev="$1"
	typeset pktdevid
	pktdevid="$(to_pktdev_id "$pktdev")" || exit 1
	typeset pktname="$(awk '$2=="'"$pktdevid"'" {print $1}' "$PKTCDVD_DIR/device_map" )"
	[ -z "$pktname" ] && exiterr "device $pktdev is not an active pktcdvd device"
	echo "$pktname"
}

to_pkt_sdir()
{
	typeset name
	name="$(to_pkt_name "$1")" || exit 1
	echo "$PKTCDVD_DIR/$name"
}

check_root()
{
	[ ! -w "$PKTCDVD_DIR/add" ] && exiterr "permission denied"
}


if [[ $# != 0 && ! -d "$PKTCDVD_DIR" ]] ; then
	exiterr "pktcdvd module not loaded or no sysfs available"
fi

case "$1" in

-a)
	(( "$#" != 3 )) && usage_error
	pktname="$2"
	blkdev="$3"
	blkdevid="$(dev_to_id "$blkdev")" || exiterr "not a block device: $blkdev"
	pktdev="$PKTDEV_DIR/$pktname"

	m="$(grep " $blkdevid\$" "$PKTCDVD_DIR/device_map")"
	[ -n "$m" ] && exiterr "device $blkdev already mapped to: $m"
	
	check_root
	echo "$blkdevid" >"$PKTCDVD_DIR/add" || exiterr "unable to add new pktcdvd device"
	pktdevid="$(awk '$3=="'"$blkdevid"'" {print $2}' "$PKTCDVD_DIR/device_map" )"
	[ -z "$pktdevid" ] && exiterr "can not add new pktcdvd device"
	pktsysn="$(awk '$3=="'"$blkdevid"'" {print $1}' "$PKTCDVD_DIR/device_map" )"
	
	rm -f "$pktdev" "$PKTDEV_DIR/$pktsysn"
	mkdir -p "$PKTDEV_DIR" || exiterr
	major="$(echo "$pktdevid" | cut -f 1 -d ':')"
	minor="$(echo "$pktdevid" | cut -f 2 -d ':')"
	mknod "$PKTDEV_DIR/$pktsysn" b "$major" "$minor" \
		|| exiterr "failed to make device node "$PKTDEV_DIR/$pktsysn" for $major:$minor"
	chmod 644 "$PKTDEV_DIR/$pktsysn"
	# create hard link, so dev_to_id() can resolve it!
	[[ "$pktsysn" != "$pktname" ]] && ln -f "$PKTDEV_DIR/$pktsysn" "$pktdev"
	
	echo "ok: $pktdev ($pktsysn [$pktdevid] -> $blkdev [$blkdevid])"
	;;
	
-r)
	(( "$#" != 2 )) && usage_error
	pktdev="$2"
	pktdevid="$(to_pktdev_id "$pktdev")" || exit 1

	pktsysn="$(awk '$2=="'"$pktdevid"'" {print $1}' "$PKTCDVD_DIR/device_map" )"
	[ -z "$pktsysn" ] && exiterr "device $pktdev is not an active pktcdvd device"

	check_root
	echo "$pktdevid" >"$PKTCDVD_DIR/remove" \
		|| exiterr "unable to remove pktcdvd device $pktdev ($pktdevid)"
	fgrep " $pktdevid " "$PKTCDVD_DIR/device_map" >/dev/null \
		&& exiterr "unable to remove pktcdvd device $pktdev ($pktdevid) or device busy"

	# use the inode number of $pktsysn to remove all names of the device
	inode="$(/bin/ls -i1 "$PKTDEV_DIR/$pktsysn" 2>/dev/null | awk '{print $1}')"
	[ -n "$inode" ] && find "$PKTDEV_DIR" -follow -inum "$inode" -exec rm {} \;
	;;
	
-i)
	(( "$#" != 2 )) && usage_error
	pktdev="$2"
	sdir="$(to_pkt_sdir "$pktdev")" || exit 1
	for i in stat write_queue ; do
		( cd "$sdir" && for f in "$i"/* ; do
			v="$(cat "$f" 2>/dev/null)"
			[ "$?" = 0 ] && echo "$f: $v"
		done )
	done
	exit "$?"
	;;
	
-C)
	(( "$#" < 3 )) && usage_error
	pktdev="$2"
	valon="$3"
	valoff="$4"
	sdir="$(to_pkt_sdir "$pktdev")/write_queue" || exit 1
	check_root
	echo "$valon" >"$sdir/congestion_on"
	[ -n "$valoff" ] && echo "$valoff" >"$sdir/congestion_off"
	echo "off=$(cat "$sdir/congestion_off") on=$(cat "$sdir/congestion_on")"
	;;
	
-c)
	(( "$#" != 2 )) && usage_error
	pktdev="$2"
	sdir="$(to_pkt_sdir "$pktdev")/write_queue" || exit 1
	echo "off=$(cat "$sdir/congestion_off") on=$(cat "$sdir/congestion_on")"
	;;
	
-m)
	(( "$#" != 1 )) && usage_error
	cat "$PKTCDVD_DIR/device_map"
	exit "$?"
	;;
	
*)
	usage_error
	;;
esac

exit 0