#!/bin/sh
#==============================================================================
# mount.vdi
#   Copyright (C) Elan Ruusamäe <glen@pld-linux.org>, 2008
#
#   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; either version 2 of
#   the License, or (at your option) any later version.
#
#   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.
#
#   You should have received a copy of the GNU General Public
#   License along with this program; if not, write to:
#   Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
#   Boston, MA  02110-1301  USA
#
#   -- For details, see the file named "LICENSE.GPLv2"
#==============================================================================

# Sanitize environment
export PATH=/bin:/sbin:/usr/bin:/usr/sbin

# Commands
LOSETUP=/sbin/losetup
MOUNT=/bin/mount

PROGRAM=${0##*/}
MOUNTARGS=
OPTIONS=
FSTYPE=

USAGE="VDI image mountpoint [-o options,...]

Options:
      partition=<number>              Specify partition to mount
      fstype=<fstype>                 Specify FS type instead of autodetecting
"

# This is braindead, two first args are dev and mountpoint if invoked from
# mount(1), but could be option if invoked from mount.vdi(1)
if [ -n "$1" ] && [[ "$1" != -* ]]; then
	DEVICE=$1
	shift
fi
if [ -n "$1" ] && [[ "$1" != -* ]]; then
	MOUNTPOINT=$1
	shift
fi

while :; do
	case "$1" in
	-h | "-?" )
		echo >&2 "Usage: $PROGRAM $USAGE"
		exit 0 ;;
	-o)
		OPTIONS="$2";
		shift ;;
	-n)
		MOUNTARGS="$MOUNTARGS $1"
		;;
	-?* )
		echo >&2 "$PROGRAM: unrecognized option: $1"
		exit 1 ;;
	*)
		break ;;
	esac
	shift
done

if [ -z "$DEVICE" ]; then
	echo >&2 "$PROGRAM: device to mount not specified"
	exit 1
fi

if [ -z "$MOUNTPOINT" ]; then
	echo >&2 "$PROGRAM: mount point not specified"
	exit 1
fi

if [ ! -f "$DEVICE" ]; then
	echo >&2 "$PROGRAM: $DEVICE is not a file"
	exit 1
fi

if [ ! -d "$MOUNTPOINT" ]; then
	echo >&2 "$PROGRAM: $MOUNTPOINT is not a directory"
	exit 1
fi

# check magic
magic=$(head -n 1 "$DEVICE")
if [ "$magic" != "<<< innotek VirtualBox Disk Image >>>" ]; then
	echo >&2 "$PROGRAM: $DEVICE: bad magic, not VDI image"
	exit 1
fi

MOUNTOPTIONS=
PARTITION=
OFFSET=
OLDIFS=$IFS
IFS=", "
for opt in $OPTIONS; do
    KEY=${opt%=*};
    VAL=${opt#*=};
	case "$KEY" in
	part|partition)
		PARTITION="$VAL"
		;;
	fstype)
		FSTYPE="$VAL"
		;;
	*)
		if [ -z "$MOUNTOPTIONS" ]; then
			MOUNTOPTIONS="$opt"
		else
			MOUNTOPTIONS="$MOUNTOPTIONS,$opt"
		fi
	;;
	esac
done
IFS="$OLDIFS"

if [ -z "$PARTITION" ]; then
	echo >&2 "$PROGRAM: missing partition option"
	exit 1
fi

# offset when disk starts
dskoff=8704

# find free loop device. XXX race possible
imgdev=$(losetup -f)
losetup $imgdev -o $dskoff "$DEVICE"
# http://vserver.13thfloor.at/Stuff/QEMU/hdloop.sh
sfd=$(/sbin/sfdisk -dump $imgdev 2>/dev/null | sed -n ' 
	/:/ s/[a-zA-Z]*=\ *\([0-9a-f]*\)\(,\|$\)/\1/g;
	T;  s/^.*:\ //; p' | tr ' ' '.')
losetup -d $imgdev

getoffset() {
	pstart=$1
	psize=$2

	blksize=512
	offset=$((pstart*blksize))
	size=$((psize*blksize))
	echo $((offset+dskoff))
}

p=1
for a in $sfd; do
	if [ "$p" = "$PARTITION" ]; then
		OFFSET=$(getoffset $(echo "$a" | tr '.' ' '))
	fi
	x=$((p++))
done

if [ -z "$OFFSET" ]; then
	echo >&2 "$PROGRAM: couldn't figure out offset, perhaps out of range?"
	exit 1
fi

if [ -z "$MOUNTOPTIONS" ]; then
	MOUNTOPTIONS="offset=$OFFSET"
else
	MOUNTOPTIONS="$MOUNTOPTIONS,offset=$OFFSET"
fi

# $MOUNTPOINT might not exist as mount can try to read it from /etc/fstab
"$MOUNT" $MOUNTARGS ${FSTYPE:+-t "$FSTYPE"} ${MOUNTOPTIONS:+-o "$MOUNTOPTIONS"} "$DEVICE" "$MOUNTPOINT"
if [ $? -ne 0 ]; then
    echo >&2 "$PROGRAM: error mounting $DEVICE"
fi