cleanExtraSources(){
	mkdir -p config/archives/
	rm -f config/archives/extra-ppas.list.chroot \
	      config/archives/extra-ppas.pref.chroot \
	      config/archives/extra-ppas.key.chroot || true
}
addPPA(){
	gpg_tmpdir="$(mktemp -d)"
	run_gpg () {
		gpg --no-default-keyring --no-options --homedir "$gpg_tmpdir" \
			--secret-keyring "$gpg_tmpdir/secring.gpg" \
			--keyserver hkp://keyserver.ubuntu.com:80/ \
			"$@"
	}
	for extra_ppa in $@; do
		extra_ppa_pin=''
		extra_ppa_origin=''
		case $extra_ppa in
		    *:*)
			extra_ppa_pin=${extra_ppa#*:}
			extra_ppa=${extra_ppa%:*}
			;;
		esac
		extra_ppa_fingerprint="$(/usr/share/livecd-rootfs/get-ppa-fingerprint "$extra_ppa")"

		echo "deb http://ppa.launchpad.net/$extra_ppa/ubuntu @DISTRIBUTION@ main" >> config/archives/extra-ppas.list.chroot 
		echo "deb-src http://ppa.launchpad.net/$extra_ppa/ubuntu @DISTRIBUTION@ main" >> config/archives/extra-ppas.list.chroot 

		if [ -n "$extra_ppa_pin" ]; then
		    extra_ppa_origin="LP-PPA-$(echo $extra_ppa | sed -e 's,/ppa$,,' -e 's,/,-,')"
		    echo "Package: *" >> config/archives/extra-ppas.pref.chroot
		    echo "Pin: release o=$extra_ppa_origin" >> config/archives/extra-ppas.pref.chroot
		    echo "Pin-Priority: $extra_ppa_pin" >> config/archives/extra-ppas.pref.chroot
		    echo "" >> config/archives/extra-ppas.pref.chroot
		fi
		run_gpg --keyring "$gpg_tmpdir/pubring.gpg" \
			--recv "$extra_ppa_fingerprint"
		run_gpg --keyring "$gpg_tmpdir/pubring.gpg" \
			--output "$gpg_tmpdir/export.gpg" \
			--export "$extra_ppa_fingerprint"
		got_fingerprint="$(
			run_gpg --keyring "$gpg_tmpdir/export.gpg" \
				--fingerprint --batch --with-colons |
			grep '^fpr:' | cut -d: -f10)"
		if [ "$got_fingerprint" != "$extra_ppa_fingerprint" ]; then
			echo "Fingerprints do not match.  Got:" >&2
			echo "$got_fingerprint" | sed 's/^/  /' >&2
			echo "Expected:" >&2
			echo "  $extra_ppa_fingerprint" >&2
			exit 1
		fi
		cat "$gpg_tmpdir/export.gpg" >> config/archives/extra-ppas.key.chroot
		rm -f "$gpg_tmpdir/export.gpg"
	done
	rm -rf "$gpg_tmpdir"
	cp -a config/archives/extra-ppas.list.chroot \
	      config/archives/extra-ppas.list.binary
	cp -a config/archives/extra-ppas.key.chroot \
	      config/archives/extra-ppas.key.binary
	if [ -f config/archives/extra-ppas.pref.chroot ]; then
		cp -a config/archives/extra-ppas.pref.chroot \
		      config/archives/extra-ppas.pref.binary
	fi
}

addExtraMirror(){
	for extra_mirror in $@; do
		echo "deb $extra_mirror @DISTRIBUTION@ main restricted universe multiverse" >> config/archives/extra-ppas.list.chroot
	done
}

addExtraMirrorUntrusted(){
	for extra_mirror in $@; do
		echo "deb [trusted=yes] $extra_mirror @DISTRIBUTION@ main restricted universe multiverse" >> config/archives/extra-ppas.list.chroot
	done
}