Image export fails when ${WORK_DIR} contains relative paths

[tblaha]

Hey all!

I'm building my image with pi-gen as a submodule and so I configured WORK_DIR=${BASE_DIR}/../../build/pi-ing/work, and I've noticed that this breaks the command that should find the loopback device, because the mount table is of course absolute:

pi-gen/export-image/05-finalise/01-run.sh

Lines 86 to 96 in 01d24ef

	if [ "${USE_QCOW2}" = "0" ] && [ "${NO_PRERUN_QCOW2}" = "0" ]; then
	ROOT_DEV="$(mount | grep "${ROOTFS_DIR} " | cut -f1 -d' ')"
	unmount "${ROOTFS_DIR}"
	zerofree "${ROOT_DEV}"
	unmount_image "${IMG_FILE}"
	else
	unload_qimage
	make_bootable_image "${STAGE_WORK_DIR}/${IMG_FILENAME}${IMG_SUFFIX}.qcow2" "$IMG_FILE"
	fi

I would propose to add $(realpath ${POTENTIALLY_RELATIVE_PATH}) where ever necessary (eg my problem was fixed when applying this to the ROOTFS_DIR definition in build.sh).

Regards,
Till

[XECDesign]

I wouldn't be opposed to merging a PR with the fix. Thanks!