build_image: fix hash perms & arm image path

This should fix the bad parsing and the failed archiving.
EMphasis on should. I'll keep monitoring.

TEST=in progress
BUG=none

Review URL: http://codereview.chromium.org/2812044

build_image

@@ -327,7 +327,8 @@ make_image_bootable() {
 $(cat ${OUTPUT_DIR}/boot.config | tr -s '\n' ' ')"
     kernel_part="${kernel_part} ${FLAGS_arm_extra_bootargs}'"
     local kpart_offset="--kernel_partition_offset=${koffset}"
-    local kpart_size="--kernel_partition_sectors=$(partsize ${image_name} 2)"
+    local kpart_size="\
+      --kernel_partition_sectors=$(partsize ${OUTPUT_DIR}/${image_name} 2)"
     kernel_part="${kernel_part} ${kpart_size} ${kpart_offset}"
     bootloader_to="${OUTPUT_DIR}/arm.mbr"
   fi

build_kernel_image.sh

@@ -78,6 +78,9 @@ if [[ -n "${FLAGS_rootfs_image}" && -n "${FLAGS_rootfs_hash}" ]]; then
                         ${FLAGS_rootfs_image} \
                         ${root_fs_blocks} \
                         ${FLAGS_rootfs_hash})
+  if [[ -f "${FLAGS_rootfs_hash}" ]]; then
+    sudo chmod a+r "${FLAGS_rootfs_hash}"
+  fi
   # Don't claim the root device unless the root= flag is pointed to
   # the verified boot device.  Doing so will claim /dev/sdDP out from
   # under the system.