Add defaults for cros_make_image_bootable.

bin/cros_make_image_bootable

Index: bin/cros_make_image_bootable
diff --git a/bin/cros_make_image_bootable b/bin/cros_make_image_bootable
index 20c21911d66bc4330e17083e44ebc4fda562dc6d..3ea148145fd8d8e73c9e7633e9ce4de094aa540a 100755
--- a/bin/cros_make_image_bootable
+++ b/bin/cros_make_image_bootable
@@ -28,8 +28,9 @@ if [ $# -lt 2 ]; then
   exit 1
 fi
 
-BOOT_DESC_FILE="${1}/boot.desc"
-IMAGE="${1}/${2}"
+IMAGE_DIR="$(readlink -f "${1}")"
+BOOT_DESC_FILE="${IMAGE_DIR}/boot.desc"
+IMAGE="${IMAGE_DIR}/${2}"
 shift
 shift
 FLAG_OVERRIDES="${@}"
@@ -233,6 +234,16 @@ make_image_bootable() {
     -s "${FLAGS_statefulfs_mountpoint}"
 }
 
+# Use default of current image location if the output dir doesn't exist.
+if [ ! -d ${FLAGS_output_dir} ]; then
+  warn "Output dir not found, using ${IMAGE_DIR}."
+  FLAGS_output_dir="${IMAGE_DIR}"
+  FLAGS_rootfs_hash="${IMAGE_DIR}/rootfs.hash"
+  FLAGS_rootfs_mountpoint="${IMAGE_DIR}/rootfs_dir"
+  FLAGS_statefulfs_mountpoint="${IMAGE_DIR}/stateful_dir"
+  FLAGS_espfs_mountpoint="${IMAGE_DIR}/esp"
+fi
+
 # Create the directories if they don't exist.
 mkdir -p ${FLAGS_rootfs_mountpoint}
 mkdir -p ${FLAGS_statefulfs_mountpoint}