#!/bin/sh
#
# Helper script to run an nbd client and mount its device to the given
# mount point. This script is invoked by "mount" with
# $1 = source (here it's an nbd URL like nbd://server/export
# $2 = mount point
# $3 = -o
# $4 = client and mount options separated by comma
#   block-size=N => "-b N"
#   connections=N => "-C N"
#   timeout=N => "-t N"
#
# The script starts a nbd-client service client before mounting, and
# spawns a cleanup daemon that uses inotify to "discover" unmount to
# terminate the service client.

# Find a free /dev/nbd*
for ADM in /dev/nbd* ; do nbd-client -c $ADM > /dev/null || break ; done

if [ -z "$ADM" ] ; then
    echo "** No available /dev/nbd* device node" >&2
    exit 1
fi

if grep -qF " $ADM "  /proc/mounts ; then
    echo "*** $1 is already mounted" >&2
    exit 1
fi

# Split up options between partition and loop options
POPTS=""
LOPTS=""
for X in $(echo $4 | tr , ' ') ; do
    case $X in
	block-size=*) POPTS="$POPTS -b ${X#*=}" ;;
	connections=*) POPTS="$POPTS -C ${X#*=}" ;;
	timeout=*) POPTS="$POPTS -t ${X#*=}" ;;
	*) LOPTS="$LOPTS,$X" ;;
    esac
done

# Set up the device node service
# $1 = nbd://$host[:$port]/$export
read S P N <<EOF
$(echo "${1#nbd://}" | sed 's|/| |;s|[ :]| |')
EOF
[ -z "$N" ] && N=$P && P=
[ -z "$P" ] || P="-port $P"
POPTS="-persist $POPTS"
nbd-client $S $P -name $N $POPTS > /dev/null || exit 1

sleep 0.2
for i in 0 1 2 3 4 5 6 7 8 9 ; do
    # Loop-mount the nbdfuse "device" and spawn a cleanup daemon
    if mount -o$LOPTS $ADM "$2" 2> /dev/null ; then
	# Spawn a process to stop $ADM service when "$2" is umount-ed
	( (
	    inotifywait -e delete_self "$2" > /dev/null 2>&1
	    nbd-client -d $ADM
	) & ) &
	exit 0
    fi
    sleep 0.2
done

# Coming here if something wrong
nbd-client -d $ADM