image_to_live.sh: fix ip address detection

image_to_live.sh

 #!/bin/bash
 
 # Copyright (c) 2009-2010 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.
 
 # Script to update an image onto a live running ChromiumOS instance.
 
 # --- BEGIN COMMON.SH BOILERPLATE ---
 # Load common CrOS utilities.  Inside the chroot this file is installed in
@@ skipping 83 matching lines @@
   remote_sh "$@"
 }
 
 # Returns the hostname of this machine.
 # It tries to find the ipaddress using ifconfig, however, it will
 # default to $HOSTNAME on failure.  We try to use the ip address first as
 # some targets may have dns resolution issues trying to contact back
 # to us.
 function get_hostname {
   local hostname
-  # Try to parse ifconfig for ip address
-  hostname=$(ifconfig eth0 \
-      | grep 'inet addr' \
-      | sed 's/.\+inet addr:\(\S\+\).\+/\1/') || hostname=${HOSTNAME}
+  # Try to parse ifconfig for ip address. Use sudo, because not all distros
+  # allow a common user to call ifconfig.
+  # TODO(zbehan): What if target is not connected via eth0? Update over wifi?
+  # Dedicated usb NIC? Perhaps this detection should be done in the target,
+  # which will get the return address in one way or another. Or maybe we should
+  # just open a ssh tunnel and use localhost.
+  hostname=$(sudo ifconfig eth0 |
+      grep 'inet addr' |
+      cut -f2 -d':' |
+      cut -f1 -d' ')
+
+  # Fallback to $HOSTNAME if that failed
+  [ -z "${hostname}" ] && hostname=${HOSTNAME}
+
   echo ${hostname}
 }
 
 # Reinterprets path from outside the chroot for use inside.
 # Returns "" if "" given.
 # $1 - The path to reinterpret.
 function reinterpret_path_for_chroot() {
   if [ -z "${1}" ]; then
     echo ""
   else
@@ skipping 310 matching lines @@
     local release_description=$(echo ${REMOTE_OUT} | cut -d '=' -f 2)
     info "Update was successful and rebooted to $release_description"
   fi
 
   print_time_elapsed
 
   exit 0
 }
 
 main $@