export autoresize autoresize_unit

define autoresize :=
#!/bin/sh

rootfs="$$(mount |grep -w / |cut -d' ' -f1)"

case $$rootfs in
  /dev/mmcblk?p2) rootdev="$${rootfs%p2}";;
  /dev/[sh]d?2) rootdev="$${rootfs%2}";;
  *) exit 0;;
esac

before="$$(sfdisk --dump "$$rootdev")"

sfdisk --dump "$$rootdev" |sed '$$s;, size=.*,;,;;' \
| sfdisk --force "$$rootdev"

after="$$(sfdisk --dump "$$rootdev")"

if [ "$$before" = "$$after" ]; then
  # second stage
  resize2fs "$$rootfs"
  systemctl disable autoresize
else
  # finish first stage
  shutdown -r now
fi

endef

define autoresize_unit :=
[Unit]
Description=Resize root filesystem at boot

[Service]
ExecStart=/opt/autoresize.sh

[Install]
WantedBy=multi-user.target
endef

.PHONY: _autoresize
_config: _autoresize

_autoresize: ${CFGROOT}
	mkdir -p "$${CFGROOT}/etc/systemd/system/"
	printf '%s\n' "$$autoresize" >"$${CFGROOT}/opt/autoresize.sh"
	chmod 755 "$${CFGROOT}/opt/autoresize.sh"
	printf '%s\n' "$$autoresize_unit" >"$${CFGROOT}/etc/systemd/system/autoresize.service"
	chroot "$${CFGROOT}" systemctl enable autoresize