common.sh: switch out echo -ne for printf and fix incorrect offset

common.sh

 # 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.
 
 # Common constants for build scripts
 # This must evaluate properly for both /bin/bash and /bin/sh
 
 # All scripts should die on error unless commands are specifically excepted
 # by prefixing with '!' or surrounded by 'set +e' / 'set -e'.
 # TODO: Re-enable this once shflags is less prone to dying.
@@ skipping 457 matching lines @@
 # [1] 32-bit flag we are modifying:
 #  http://git.chromium.org/cgi-bin/gitweb.cgi?p=kernel.git;a=blob;f=include/linux/ext2_fs.h#l417
 # [2] Mount behavior is enforced here:
 #  http://git.chromium.org/cgi-bin/gitweb.cgi?p=kernel.git;a=blob;f=fs/ext2/super.c#l857
 #
 # N.B., if the high order feature bits are used in the future, we will need to
 #       revisit this technique.
 disable_rw_mount() {
   local rootfs="$1"
   local offset="${2-0}"  # in bytes
-  local ro_compat_offset=$((0x467 + 3))  # Set 'highest' byte
-  echo -ne '\xff' |
+  local ro_compat_offset=$((0x464 + 3))  # Set 'highest' byte
+  printf '\377' |
     sudo dd of="$rootfs" seek=$((offset + ro_compat_offset)) \
             conv=notrunc count=1 bs=1
 }
 
 enable_rw_mount() {
   local rootfs="$1"
   local offset="${2-0}"
-  local ro_compat_offset=$((0x467 + 3))  # Set 'highest' byte
-  echo -ne '\x00' |
+  local ro_compat_offset=$((0x464 + 3))  # Set 'highest' byte
+  printf '\000' |
     sudo dd of="$rootfs" seek=$((offset + ro_compat_offset)) \
             conv=notrunc count=1 bs=1
 }
 
 # Get current timestamp. Assumes common.sh runs at startup.
 start_time=$(date +%s)
 
 # Print time elsapsed since start_time.
 print_time_elapsed() {
   end_time=$(date +%s)
@@ skipping 15 matching lines @@
 chroot_hacks_from_outside() {
   # Give args better names.
   local chroot_dir="${1}"
 
   # Add root as a sudoer if not already done.
   if ! sudo grep -q '^root ALL=(ALL) ALL$' "${chroot_dir}/etc/sudoers" ; then
     info "Upgrading old chroot (pre 2010-10-19) - adding root to sudoers"
     sudo bash -c "echo root ALL=\(ALL\) ALL >> \"${chroot_dir}/etc/sudoers\""
   fi
 }