dracut modules: implement squashfs-img script

dracut-modules/90void-usb/squashfs-img.sh

@@ -1 +1,27 @@
 #!/bin/bash
+
+type getarg > /dev/null 2>&1 || source /lib/dracut-lib.sh
+
+[ ! -d /sysroot/container ] && mkdir -p /sysroot/container
+
+CONTAINER="$(getarg void-usb-container)"
+case "$CONTAINER" in
+  LABEL=* | UUID=* | PARTUUID=* | PARTLABEL=*)
+    CONTAINER="$(label_uuid_to_dev "$CONTAINER")"
+    ;;
+  /dev/*)
+    true
+    ;;
+  *)
+    echo -e "Invalid value for 'void-usb-container' kernel command line parameter!\nDropping into emergency shell."
+    emergency_shell
+esac
+
+mount -t f2fs -o nodev,nosuid "$CONTAINER" /sysroot/container
+
+if [ -f /sysroot/container/squashfs.img ]; then
+  losetup -r -f /sysroot/container/squashfs.img
+else
+  echo "Failed to find squashfs image. Dropping into an emergency shell. Good luck!"
+  emergency_shell
+fi