Make the size of the helper VM image configurable

Add a new HELPER_SIZE variable for this purpose. Default size is
hardcoded to 400MB

snf-image-host/common.sh.in

@@ -372,6 +372,7 @@ fi
 : ${IMAGE_DEBUG:="no"}
 : ${VERSION_CHECK:="@VERSION_CHECK@"}
 : ${HELPER_DIR:="@HELPER_DIR@"}
+: ${HELPER_SIZE:="400"}
 : ${HELPER_SOFT_TIMEOUT:=20}
 : ${HELPER_HARD_TIMEOUT:=5}
 : ${HELPER_USER:="nobody"}

snf-image-host/defaults.in

@@ -20,6 +20,9 @@
 # HELPER_DIR: Directory hosting the helper files
 # HELPER_DIR="@localstatedir@/lib/snf-image/helper/"
 
+# HELPER_SIZE: Size of the helper VM image in MB
+# HELPER_SIZE="400"
+
 # HELPER_TIMOUT: Soft and hard timeout limits for helper instance. The helper
 # instance will be terminated after a given time if it hasn't exited by itself.
 # A TERM signal will be send if the instance is running after a

snf-image-host/snf-image-update-helper.in

@@ -114,7 +114,7 @@ rm -f "$HELPER_DIR/initrd" "$HELPER_DIR/kernel" "$HELPER_DIR/image"
 echo -n "Allocating space for helper disk image..."
 helper_img=$(mktemp "$HELPER_DIR/image.XXXXXX")
 add_cleanup rm -f "$helper_img"
-dd if=/dev/zero of="$helper_img" bs=1k count=400000 &> /dev/null
+dd if=/dev/zero of="$helper_img" bs=1M count="$HELPER_SIZE" &> /dev/null
 echo "done"
 
 echo "Creating partitions..."