upstream_archive = $(OPK_SOURCE)-$(OPK_SOURCE_VERSION_UPSTREAM).tar.gz
upstream_url = https://libav.org/releases/$(upstream_archive)
source_archive = ../$(OPK_SOURCE)-$(OPK_SOURCE_VERSION_UPSTREAM).orig.tar.gz
keys = 'B393 2517 957C 77DF 066E  ADC4 0D1B 6F07 658C B036'

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

source: $(source_archive)