upstream_archive = $(OPK_SOURCE)-$(OPK_SOURCE_VERSION_UPSTREAM).tar.xz
upstream_url = http://ftp.gnu.org/pub/gnu/$(OPK_SOURCE)/$(upstream_archive)
source_archive = ../libunistring-$(OPK_SOURCE_VERSION_UPSTREAM).orig.tar.xz

gpg = GNUPGHOME=gnupghome/ gpg --no-default-keyring --keyring ../keyring.gpg
keys = \
	'4622 25C3 B46F 3487 9FC8  496C D605 848E D7E6 9871'

$(source_archive):
	wget -c '$(upstream_url)' '$(upstream_url).sig'
	install -m 0700 -d gnupghome/
	[ -e ../keyring.gpg ] || \
		$(gpg) --keyserver hkp://pool.sks-keyservers.net \
			--recv-keys $(keys); \
	rm -f ../keyring.gpg~; \
	if ! $(gpg) --verify '$(upstream_archive).sig'; then \
		rm -Rf gnupghome/; \
		exit 1; \
	fi
	rm -Rf gnupghome/
	mv '$(upstream_archive)' '$@'

source: $(source_archive)