add the ability to umount automounted devices from within the chroot

src/scripts/image_to_usb.sh

 #!/bin/bash
 
 # Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script to convert the output of build_image.sh to a usb image.
 
 # Load common constants.  This should be the first executable line.
 # The path to common.sh should be relative to your script's location.
@@ skipping 214 matching lines @@
     if [ "${SURE}" != "y" ]
     then
       echo "Ok, better safe than sorry."
       exit 1
     fi
   fi
 
   echo "Attempting to unmount any mounts on the USB device..."
   for i in $(mount | grep ^"${FLAGS_to}" | awk '{print $1}')
   do
-    sudo umount "$i"
+    if sudo umount "$i" 2>&1 >/dev/null | grep "not found"; then
+      echo
+      echo "The device you have specified is already mounted at some point "
+      echo "that is not visible from inside the chroot.  Please unmount the "
+      echo "device manually from outside the chroot and try again."
+      echo
+      exit 1
+    fi
   done
   sleep 3
 
   echo "Copying ${SRC_IMAGE} to ${FLAGS_to}..."
   sudo dd if="${SRC_IMAGE}" of="${FLAGS_to}" bs=4M
 
   echo "Done."
 else
   # Output to a file, so just make a copy.
   echo "Copying ${SRC_IMAGE} to ${FLAGS_to}..."
   cp -f "${SRC_IMAGE}" "${FLAGS_to}"
 
   echo "Done.  To copy to a USB drive, outside the chroot, do something like:"
   echo "   sudo dd if=${FLAGS_to} of=/dev/sdX bs=4M"
   echo "where /dev/sdX is the entire drive."
   if [ ${INSIDE_CHROOT} -eq 1 ]
   then
     example=$(basename "${FLAGS_to}")
     echo "NOTE: Since you are currently inside the chroot, and you'll need to"
     echo "run dd outside the chroot, the path to the USB image will be"
     echo "different (ex: ~/chromeos/trunk/src/build/images/SOME_DIR/$example)."
   fi
 fi