Force our umount w/in the chroot.

Do this via ensuring that any common.sh invoker
of raw umount (say a root script) sees our umount
path.

Additionally, inject into default profiles our override,
and via an upgrade scriptlet.

This is round two; originally appeared as CL:32088, was
reverted due to:
https://uberchromegw.corp.google.com/i/chromiumos/builders/chromiumos%20sdk/builds/2314/steps/BuildBoard/logs/stdio

The fix however is just adding a single sudo mkdir. :/

BUG=chromium-os:23443
TEST=cros_sdk --replace --bootstrap
TEST=cros_sdk --replace

Change-Id: I0dc7522a9c623f40081d4f138cea0c2c45171fea
Reviewed-on: https://gerrit.chromium.org/gerrit/32365
Commit-Ready: Brian Harring <ferringb@chromium.org>
Tested-by: Brian Harring <ferringb@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>

chroot_version_hooks.d/47_path_overrides

@@ -0,0 +1,13 @@
+# 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.
+
+# Ensure that crosutils path overrides are in use; note that chroot
+# creation also invokes this, thus why we check for CROS_CHROOT; for
+# the normal upgrade pathway, it's non existant.  For chroot creation,
+# It points to the chroot base.
+sudo mkdir -p "${CROS_CHROOT}/etc/profile.d/"
+echo 'export PATH="/usr/local/path-overrides${PATH:+:${PATH}}"' | \
+  sudo tee "${CROS_CHROOT}"/etc/profile.d/crosutils-path-overrides.sh \
+    > /dev/null
+sudo chmod 644 "${CROS_CHROOT}"/etc/profile.d/crosutils-path-overrides.sh

common.sh

@@ -466,12 +466,12 @@ assert_not_root_user() {
 # Usage: check_flags_only_and_allow_null_arg "$@" && set --
 check_flags_only_and_allow_null_arg() {
   do_shift=1
-  if [[ $# == 1 && -z "$@" ]]; then
+  if [ $# = 1 -a -z "$1" ]; then
     echo "$0: warning: ignoring null argument" >&2
     shift
     do_shift=0
   fi
-  if [[ $# -gt 0 ]]; then
+  if [ $# -gt 0 ]; then
     echo "error: invalid arguments: \"$@\"" >&2
     flags_help
     exit 1
@@ -1071,3 +1071,22 @@ switch_to_strict_mode() {
 
 # TODO: Re-enable this once shflags is set -e safe.
 #switch_to_strict_mode
+
+# The following code is used to ensure our umount wrapper is in use.
+# Shouldn't be invoked by anything other than common.sh
+_enable_path_overrides(){
+  # Ensure that our PATH overrides are in use.
+  local override_dir=$(readlink -f "${SCRIPT_ROOT}/path-overrides")
+  local IFS=:
+  local x
+  for x in ${PATH}; do
+    x=$(readlink -f "${x}")
+    if [ "${x}" = "${override_dir}" ]; then
+      # Already is in path; nothing more to do.
+      return
+    fi
+  done
+  export PATH="${override_dir}${PATH:+:${PATH}}"
+}
+
+_enable_path_overrides

sdk_lib/enter_chroot.sh

@@ -274,8 +274,12 @@ setup_env() {
         queue_mount /run/shm "--bind" /run/shm
       fi
     fi
-    queue_mount "${FLAGS_trunk}" "--bind" "${CHROOT_TRUNK_DIR}"
+    # Get path overrides for the chroot in place now- it's possible
+    # that they may be needed for early teardown.
+    queue_mount "${FLAGS_trunk}/src/scripts/path-overrides" "--bind" \
+      "/usr/local/path-overrides"
 
+    queue_mount "${FLAGS_trunk}" "--bind" "${CHROOT_TRUNK_DIR}"
 
     debug "Setting up referenced repositories if required."
     REFERENCE_DIR=$(git config --file  \

sdk_lib/make_chroot.sh

@@ -177,6 +177,11 @@ init_setup () {
    sudo bash -e "${SCRIPT_ROOT}/chroot_version_hooks.d/45_rewrite_sudoers.d" \
      "${FLAGS_chroot}" "${USER}" "${ENVIRONMENT_WHITELIST[@]}"
 
+   # Turn on the path overrides; subshelled to protect our env from whatever
+   # vars the scriptlet may bleed.
+   ( CROS_CHROOT="${FLAGS_chroot}"
+     . "${SCRIPT_ROOT}/chroot_version_hooks.d/47_path_overrides" )
+
    sudo find "${FLAGS_chroot}/etc/"sudoers* -type f -exec chmod 0440 {} +
    # Fix bad group for some.
    sudo chown -R root:root "${FLAGS_chroot}/etc/"sudoers*