cros_make_image_bootable, mount_gpt_image, common.sh: root filesystem changes: ext2, ro by default

mount_gpt_image.sh

 #!/bin/bash
 
 # Copyright (c) 2010 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.
 
 # Helper script that mounts chromium os image from a device or directory
 # and creates mount points for /var and /usr/local (if in dev_mode).
 
 . "$(dirname "$0")/common.sh"
@@ skipping 61 matching lines @@
     sudo mount ${ro_flag} "${FLAGS_from}12" "${FLAGS_esp_mountpt}"
   fi
 }
 
 function get_gpt_partitions() {
   local filename="${FLAGS_image}"
 
   # Mount the rootfs partition using a loopback device.
   local offset=$(partoffset "${FLAGS_from}/${filename}" 3)
   local ro_flag=""
-  [ ${FLAGS_read_only} -eq ${FLAGS_TRUE} ] && ro_flag="-o ro"
+  if [ ${FLAGS_read_only} -eq ${FLAGS_TRUE} ]; then
+    ro_flag="-o ro"
+  else
+    # Make sure any callers can actually mount and modify the fs
+    # if desired.
+    # cros_make_image_bootable should restore the bit if needed.
+    enable_rw_mount "${FLAGS_from}/${filename}" "$(( offset * 512 ))"
+  fi
 
   sudo mount ${ro_flag} -o loop,offset=$(( offset * 512 )) \
     "${FLAGS_from}/${filename}" "${FLAGS_rootfs_mountpt}"
 
   # Mount the stateful partition using a loopback device.
   offset=$(partoffset "${FLAGS_from}/${filename}" 1)
   sudo mount ${ro_flag} -o loop,offset=$(( offset * 512 )) \
     "${FLAGS_from}/${filename}" "${FLAGS_stateful_mountpt}"
 
   # Mount the stateful partition using a loopback device.
@@ skipping 42 matching lines @@
 
 # Turn path into an absolute path.
 FLAGS_from=`eval readlink -f ${FLAGS_from}`
 
 # Perform desired operation.
 if [ ${FLAGS_unmount} -eq ${FLAGS_TRUE} ] ; then
   unmount_image
 else
   mount_image
 fi