upstream_version = $$(printf '%s\n' '$(OPK_SOURCE_VERSION_UPSTREAM)' | \
	sed 's/~/-/')
upstream_archive = linux-libre-$(upstream_version).tar.bz2
upstream_releases = http://linux-libre.fsfla.org/pub/linux-libre/releases
upstream_url = $(upstream_releases)/$(upstream_version)/$(upstream_archive)
source_archive = ../linux-libre-$(OPK_SOURCE_VERSION_UPSTREAM).orig.tar.bz2
keys = 7E7D47A7

$(source_archive):
	wget "$(upstream_url)"
	set -e; if gpg --version >/dev/null 2>&1; then \
		wget "$(upstream_url).sign"; \
		[ -e ../keyring.gpg ] || \
			gpg --keyring ../keyring.gpg --no-default-keyring \
				--recv-keys $(keys) || true; \
		gpg --verify --keyring ../keyring.gpg \
			"$(upstream_archive).sign"; \
	fi
	mv "$(upstream_archive)" "$(source_archive)"

source: $(source_archive)