upstream_archive = $(OPK_SOURCE)-$(OPK_SOURCE_VERSION_UPSTREAM).tar.gz
upstream_dir_url = ftp://sourceware.org/pub/$(OPK_SOURCE)
upstream_url = $(upstream_dir_url)/$(upstream_archive)
upstream_sum = $(upstream_dir_url)/md5.sum
source_archive = ../$(OPK_SOURCE)-$(OPK_SOURCE_VERSION_UPSTREAM).orig.tar.gz

$(source_archive):
	wget -c '$(upstream_url)'
	wget -O - '$(upstream_sum)' | grep -F '$(upstream_archive)' >MD5SUMS
	md5sum -c MD5SUMS
	rm -f MD5SUMS
	mv '$(upstream_archive)' '$(source_archive)'

source: $(source_archive)