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155 lines
3.7 KiB
155 lines
3.7 KiB
#!/bin/sh
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#
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# mount qemu image file into a directory
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#
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prog=$(basename "$0")
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# use sudo for unprivileged users
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SUDO=
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[ "$(id -u)" -ne 0 ] && SUDO=sudo
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# print error message
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error() {
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echo "$prog:" "$@" 2>&1
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exit 1
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}
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# print usage
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usage() {
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if [ $# -ge 1 ]; then
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[ -n "$*" ] && echo "$prog:" "$@" 2>&1
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echo 2>&1
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fi
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cat << EOF >&2
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Mount the qemu image file into a directory.
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Usage: $prog [OPTIONS] qemu_image mount_point
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Options:
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-p partition_number select, which partition to mount, default #1
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-r mount read-only
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-t fstype set filesystem type
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-o mount_options additional mount options
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-u set owner to current user
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Without arguments it prints a list of mounted images.
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EOF
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exit 1
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}
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# Without arguments: print mounted images
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if [ $# -eq 0 ]; then
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for file in /tmp/nbd*.mount; do
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nbd=$(basename "$file" .mount)
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[ "$nbd" = "nbd*" ] && exit 0
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image=
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while read -r line; do
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if [ -z "$image" ]; then
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image="$line"
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else
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mdir="$line"
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echo "$nbd: $image -> $mdir"
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break
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fi
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done < "$file"
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done
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exit 0
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fi
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# parse command line
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partition=1
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read_only=
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fstype=
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mnt_options=
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set_uid=
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while getopts ":p:rt:o:u" opt; do
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case $opt in
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p) partition="$OPTARG"
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echo "$partition" | grep -q -x "[0-9][0-9]*" || \
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error "partition number must be numeric" ;;
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r) read_only=1 ;;
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t) fstype=$OPTARG ;;
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o) mnt_options="${mnt_options},${OPTARG}" ;;
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u) set_uid=1 ;;
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\?) usage "illegal option -- $OPTARG" ;;
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:) usage "option requires an argument -- $OPTARG" ;;
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esac
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done
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shift $((OPTIND-1)) # remove parsed options and args from $@ list
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mnt_options=${mnt_options#,}
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[ $# -ne 2 ] && usage "wrong number of arguments"
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image="$1"
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mdir="$2"
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# check file types
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[ -e "$image" ] || error "$image: no such file"
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[ -f "$image" ] || error "$image must be a regular file"
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[ -e "$mdir" ] || error "$mdir: no such directory"
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[ -d "$mdir" ] || error "$mdir must be a directory"
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full_image=$(readlink -f "$image")
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full_mdir=$(readlink -f "$mdir")
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img_fmt=$(qemu-img info "$image" | sed -n 's/^file format: \(.*\)/\1/p')
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[ -n "$img_fmt" ] || error "$image has unknown format"
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# load kernel module, check if sudo works
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$SUDO modprobe nbd nbds_max=16 max_part=31 || exit $?
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# load FAT filesystem module
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$SUDO modprobe vfat 2> /dev/null
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# lock
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umask=$(umask); umask 0
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(
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flock -w 5 9 || error "Can't get mount lock"
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umask "$umask"
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# already in use?
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grep -q -F -x "$full_image" /tmp/nbd*.mount 2> /dev/null &&
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error "$image already mounted"
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grep -q -F -x "$full_mdir" /tmp/nbd*.mount 2> /dev/null &&
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error "$mdir already in use"
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# find free nbd device
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nbd_size=1
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for nbd in /sys/class/block/nbd*; do
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[ -n "${nbd##*/nbd[0-9]}" ] && \
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[ -n "${nbd##*/nbd[0-9][0-9]}" ] && \
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continue
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nbd_size=$(cat "${nbd}/size")
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[ "$nbd_size" -gt 0 ] || break
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done
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[ "$nbd_size" -gt 0 ] && error "no free nbd devices"
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nbd=$(basename "$nbd")
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# reserve nbd device
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printf "%s\n%s\n" "$full_image" "$full_mdir" > "/tmp/${nbd}.mount" || exit $?
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# qemu-nbd
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$SUDO qemu-nbd -c "/dev/$nbd" -f "$img_fmt" "$full_image"
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ret=$?
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if [ $ret -ne 0 ]; then
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rm -f "/tmp/${nbd}.mount"
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exit $ret
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fi
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# mount
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nbd_dev=/dev/$nbd
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[ "$partition" -gt 0 ] && nbd_dev="${nbd_dev}p${partition}"
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options=$mnt_options
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[ -n "$read_only" ] && options="$options,ro"
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[ -n "$set_uid" ] && options="$options,uid=$(id -u),gid=$(id -g)"
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options=${options#,}
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$SUDO mount ${fstype:+-t "$fstype"} ${options:+-o "$options"} \
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"$nbd_dev" "$full_mdir"
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ret=$?
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if [ $ret -eq 0 ]; then
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echo "$prog completed, using device $nbd_dev"
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else
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sync
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$SUDO qemu-nbd -d "/dev/$nbd" > /dev/null 2>&1
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rm -f "/tmp/${nbd}.mount"
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fi
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exit $ret
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) 9>> /var/lock/qemu-mount.lock
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