flatcar-scripts/chroot_version_hooks.d/47_path_overrides
David James 76764885b9 Convert make_chroot.sh and enter_chroot.sh to run as root.
sudo takes 150ms per invocation on Goobuntu, and with 10 invocations in
enter_chroot.sh, this means that we're wasting a lot of time, every time
cros_sdk is invoked. Cutting these unnecessary invocations reduces the time
required to run enter_chroot.sh from 2.3s to 0.8s.

CL:36618 is the companion change that updates cros_sdk to invoke
sudo unshare -m prior to calling enter_chroot.sh.

Summary of changes:

1. Remove all calls to sudo and just run the commands directly.
  - Remove the mount queue and any sudo_multi optimizations.
  - Rename sudo_chroot -> bare_chroot because we don't run sudo anymore there.
  - Remove code for validating sudo timestamp.
2. Allow the scripts to work as root:
  - Ensure that files created by cros_sdk that previously were owned by the
    user still are owned by the user (either using chown or cp -p).
  - Use $SUDO_USER to find the user's account.
  - Use $SUDO_HOME instead of $HOME to find the user's home dir.
  - Remove outdated code for disabling automount on Lucid, which doesn't work
    when run as root.
  - Update code for calculating the user's git username to use sudo to switch
    to the user. Also move it to make_chroot.sh so that this change doesn't
    impact performance.
3. Cleanup
  - Remove environment syncer process in favor of just syncing once when chroot
    is entered.
  - Remove teardown and instead rely on unshare to unmount the mounts. To make
    sure that outside processes never notice the mounts, we use mount -n. This
    also ensures that /etc/mtab never contains stale mounts.
  - Remove path-overrides, since it is no longer needed.

BUG=chromium-os:35714, chromium-os:35679
TEST=Trybot runs.
CQ-DEPEND=CL:36618

Change-Id: I919a8aadb08fafde97348e8511573c28fdd47186
Reviewed-on: https://gerrit.chromium.org/gerrit/36619
Tested-by: David James <davidjames@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: David James <davidjames@chromium.org>
2012-10-30 14:49:48 -07:00

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# 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.
# Path overrides are no longer in use, so this script is just a placeholder.