Add script which can instrument a test system for dbusspy at boot time

BUG=chromium-os:23229
TEST=ran this against a ToT alex img, image_to_usb, boots, installs, works

Change-Id: Ia1e589a8b920332c1a247986e6bbc3cad17ed751
Reviewed-on: https://gerrit.chromium.org/gerrit/14650
Commit-Ready: Jim Hebert <jimhebert@chromium.org>
Tested-by: Jim Hebert <jimhebert@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>

mod_for_dbusspy/dbus.conf

@@ -0,0 +1,12 @@
+# Copyright (c) 2012 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.
+
+# Drop this in as dbus.conf after renaming the normal dbus.conf to
+# "realdbus.conf". That will ensure this attaches to dbus first.
+
+start on started realdbus
+
+respawn
+
+exec dbus-spy -w /var/log/dbusspy.log

mod_test_image_for_dbusspy.sh

@@ -0,0 +1,70 @@
+#!/bin/bash
+
+# Copyright (c) 2012 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 modify a keyfob-based chromeos test image to log all dbus
+# activity from boot-time forward in a machine-readable replay format.
+# This is not part of the main "mod-for-test" for several reasons:
+# * it is overly invasive to the boot sequence,
+# * it has major run-time performance downsides,
+# * it consumes potentially huge amounts of disk space over time.
+# Any one of these are too-great of a depature from "normal" Chrome OS
+# to be appropriate for a "faithful" test-system. Note that dbus-monitor(1)
+# is available for casual/interactive use in normal mod-for-test systems.
+# Dbusspy-instrumented systems are only intended for narrow use cases, like
+# corpus collection for fuzzing, where the above trade-offs are acceptable.
+
+. "/usr/lib/crosutils/common.sh" || { echo "Unable to load common.sh"; exit 1; }
+
+assert_inside_chroot
+
+DEFINE_string image "$FLAGS_image" "Location of the test image file" i
+
+# Parse command line
+FLAGS "$@" || exit 1
+eval set -- "$FLAGS_ARGV"
+
+FLAGS_image=$(eval readlink -f "${FLAGS_image}")
+
+IMAGE_DIR=$(dirname "${FLAGS_image}")
+IMAGE_NAME=$(basename "${FLAGS_image}")
+ROOT_FS_DIR="${IMAGE_DIR}/rootfs"
+DBUS_CONF="$(dirname "$0")/mod_for_dbusspy/dbus.conf"
+DEVKEYS_DIR="/usr/share/vboot/devkeys"
+VBOOT_DIR="${CHROOT_TRUNK_DIR}/src/platform/vboot_reference/scripts/"\
+"image_signing"
+
+cleanup() {
+  "${SCRIPTS_DIR}/mount_gpt_image.sh" -u -r "$ROOT_FS_DIR"
+}
+
+if [ ! -d "$VBOOT_DIR" ]; then
+  die "The required path: $VBOOT_DIR does not exist.  This directory needs"\
+      "to be sync'd into your chroot.\n $ cros_workon start vboot_reference"
+fi
+
+trap cleanup EXIT
+
+# Mounts gpt image and sets up var, /usr/local and symlinks.
+"$SCRIPTS_DIR/mount_gpt_image.sh" --image="$IMAGE_NAME" --from="$IMAGE_DIR" \
+  --rootfs_mountpt="$ROOT_FS_DIR"
+
+# A bunch of existing stuff is set to start up as soon as dbus is considered
+# to have started. Instead of modifying all of those things to instead
+# wait for dbus-spy to be started, drop dbus-spy in as "dbus" which,
+# in turn, waits on "realdbus." This way we don't race other services
+# and are guaranteed to capture all dbus events from boot onward.
+sudo cp -a "${ROOT_FS_DIR}/etc/init/dbus.conf" \
+  "${ROOT_FS_DIR}/etc/init/realdbus.conf"
+sudo cp "${DBUS_CONF}" "${ROOT_FS_DIR}/etc/init/dbus.conf"
+
+# Unmount and re-sign. See crosbug.com/18709 for why this isn't using
+# cros_make_image_bootable.
+cleanup
+TMP_BIN_PATH="${FLAGS_image}.new"
+"${VBOOT_DIR}/sign_official_build.sh" usb "${FLAGS_image}" \
+                                     "${DEVKEYS_DIR}" \
+                                     "${TMP_BIN_PATH}"
+mv "${TMP_BIN_PATH}" "${FLAGS_image}"