Switch to GPT-format disk images.

src/platform/memento_softwareupdate/memento_updater.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.
 
 # This is the autoupdater for Memento. When called it consults Omaha to see
 # if there's an update available. If so, it downloads it to the other
 # partition on the Memento USB stick, then alters the MBR and partitions
 # as needed so the next reboot will boot into the newly installed partition.
@@ skipping 87 matching lines @@
 if [[ -z "$IMG_URL" || -z "$CHECKSUM" ]]
 then
   log no update
   exit 0
 fi
 # TODO(adlr): make sure we have enough space for the download. we are
 # already correct if we don't have space, but it would be nice to fail
 # fast.
 log Update Found: $IMG_URL checksum: $CHECKSUM
 
-# figure out which device i'm on, and which to download to.
-ROOT_ARG=$(cat /proc/cmdline | tr ' ' '\n' | grep ^root= | cut -d = -f 2-)
-LOCAL_DEV="$ROOT_ARG"
-# do some device sanity checks
-if expr match "$ROOT_ARG" '^UUID=' > /dev/null
-then
-  LOCAL_DEV=$(readlink -f /dev/disk/by-uuid/${ROOT_ARG#UUID=})
-elif expr match "$ROOT_ARG" '^LABEL=' > /dev/null
-then
-  LOCAL_DEV=$(readlink -f /dev/disk/by-label/${ROOT_ARG#LABEL=})
-fi
+# Figure out which partition I'm on, and which to download to.
+LOCAL_DEV=$(rootdev)
 
-# we install onto the other dev. so if we end in 1, other ends in 2, and
+# We install onto the other partition so if we end in 3, other ends in 5, and
 # vice versa
-INSTALL_DEV=$(echo $LOCAL_DEV | tr '1234' '2143')
+INSTALL_DEV=$(echo $LOCAL_DEV | tr '35' '53')
+NEW_PART_NUM=${INSTALL_DEV##*/*[a-z]}
+# The kernel needs to be installed to its own partition. We'll handle that in
+# the postinst script (from the new rootfs). partitions 2&3 are image A,
+# partitions 4&5 are image B.
+KINSTALL_DEV=$(echo $INSTALL_DEV | tr '35' '24')
 
-ROOT_DEV=$(echo $LOCAL_DEV | tr -d '1234')  # strip trailing number
+# Find whole disk device.
+ROOT_DEV=${LOCAL_DEV%%[0-9]*}
 
-# do some device sanity checks
-if ! expr match "$LOCAL_DEV" '^/dev/[a-z][a-z]*[1234]$' > /dev/null
+# Do some device sanity checks.
+if ! expr match "$LOCAL_DEV" '^/dev/[a-z][a-z]*[12345]$' > /dev/null
 then
   log "didnt find good local device. local: $LOCAL_DEV install: $INSTALL_DEV"
   exit 1
 fi
-if ! expr match "$INSTALL_DEV" '^/dev/[a-z][a-z]*[1234]$' > /dev/null
+if ! expr match "$INSTALL_DEV" '^/dev/[a-z][a-z]*[12345]$' > /dev/null
 then
   log "didnt find good install device. local: $LOCAL_DEV install: $INSTALL_DEV"
   exit 1
 fi
 if [ "$LOCAL_DEV" == "$INSTALL_DEV" ]
 then
   log local and installation device are the same: "$LOCAL_DEV"
   exit 1
 fi
 
 log Booted from "$LOCAL_DEV" and installing onto "$INSTALL_DEV"
 
-# make sure installation device is unmounted
+# Make sure installation device is unmounted.
 if [ "$INSTALL_DEV" == ""$(grep "^$INSTALL_DEV " /proc/mounts | \
                            cut -d ' ' -f 1 | uniq) ]
 then
-  # drive is mounted. must unmount
+  # Drive is mounted, must unmount.
   log unmounting "$INSTALL_DEV"
   umount "$INSTALL_DEV"
-  # check if it's still mounted for some strange reason
+  # Check if it's still mounted for some strange reason.
   if [ "$INSTALL_DEV" == ""$(grep "^$INSTALL_DEV " /proc/mounts | \
                              cut -d ' ' -f 1 | uniq) ]
   then
     log unable to unmount "$INSTALL_DEV", which is where i need to write to
     exit 1
   fi
 fi
 
-# download file to the device
+# Download file to the device.
 log downloading image. this may take a while
 
 # wget - fetch file, send to stdout
 # tee - save a copy off to device, also send to stdout
 # openssl - calculate the sha1 hash of stdin, send checksum to stdout
 # tr - convert trailing newline to a space
 # pipestatus - append return codes for all prior commands. should all be 0
 
 CHECKSUM_FILE="/tmp/memento_autoupdate_checksum"
 RETURNED_CODES=$(wget -O - --load-cookies <(echo "$COOKIES") \
@@ skipping 57 matching lines @@
   if [ "$ForceUpdate" != "yes" ] &&
     version_number_greater_than "$APP_VERSION" "$NEW_VERSION"
   then
     log "Can't upgrade to older version: " "$NEW_VERSION"
     umount "$MOUNTPOINT"
     rmdir "$MOUNTPOINT"
     exit 1
   fi
 fi
 
-"$MOUNTPOINT"/postinst "$INSTALL_DEV" 2>&1 | cat >> "$MEMENTO_AU_LOG"; \
-  [ "${PIPESTATUS[*]}" = "0 0" ]
+"$MOUNTPOINT"/postinst "$INSTALL_DEV" "$KINSTALL_DEV" 2>&1 | \
+  cat >> "$MEMENTO_AU_LOG"
+[ "${PIPESTATUS[*]}" = "0 0" ]
 POSTINST_RETURN_CODE=$?
 umount "$MOUNTPOINT"
 rmdir "$MOUNTPOINT"
 
 # $1 is return code, $2 is command
 function abort_update_if_cmd_failed_long {
   if [ "$1" -ne "0" ]
   then
     log "$2 failed with error code  $1 . aborting update"
     exit 1
   fi
 }
 
 function abort_update_if_cmd_failed {
   abort_update_if_cmd_failed_long "$?" "!!"
 }
 
-# if it failed, don't update MBR but just to be safe, zero out a page of
-# install device
+# If it failed, don't update MBR but just to be safe, zero out a page of
+# install device.
 abort_update_if_cmd_failed_long "$POSTINST_RETURN_CODE" "$MOUNTPOINT"/postinst
 
 # postinstall on new partition succeeded.
 # fix up MBR and make our own partition not something casper will find
 
 # update MBR to make the other partition bootable
 # the slash-magic converts '/' -> '\/' so it's valid in a regex
 log updating MBR of usb device
 
 # flush linux caches; seems to be necessary
 sync
 echo 3 > /proc/sys/vm/drop_caches
-
-LAYOUT_FILE=/tmp/new_partition_layout
-sfdisk -d $ROOT_DEV | sed -e "s/${INSTALL_DEV//\//\\/} .*[^e]$/&, bootable/" \
-                          -e "s/\(${LOCAL_DEV//\//\\/} .*\), bootable/\1/" \
-  > "$LAYOUT_FILE"
-sfdisk --force $ROOT_DEV < "$LAYOUT_FILE" 2>&1 | cat >> "$MEMENTO_AU_LOG"
+# Configure the PMBR to boot the new image.
+# TODO: ChromeOS EFI BIOS will need a different command to set the GPT
+# partition attributes bits to mark the new image as bootable.
+# NOTE: This won't work for ARM, because we'll need to regenerate the U-Boot
+# script when the kernel size and location are changed. Luckily it won't
+# matter because we'll ship with the GPT-based selection process. The U-Boot
+# script is just a temporary hack for bringup.
+# FIX: The current gpt tool requires a -b arg to specify the PMBR bootcode. We
+# don't want to change the code, so we have to extract it, then put it back.
+# We'll fix this RSN.
+dd if=${ROOT_DEV} bs=512 count=1 of=/tmp/oldpmbr.bin
+gpt -S boot -i $NEW_PART_NUM -b /tmp/oldpmbr.bin ${ROOT_DEV} 2>&1 | \
+  cat >> "$MEMENTO_AU_LOG"
 abort_update_if_cmd_failed
 
 # mark update as complete so we don't try to update again
 touch "$UPDATED_COMPLETED_FILE"
 
 # tell user to reboot
 log Autoupdate applied. You should now reboot
 echo UPDATED