Run dbus-uuidgen on system startup (again).

Run dbus-uuidgen on system startup (again).

A few weeks ago, dbus-uuidgen command was removed from the platform/init/dbus.conf script, but after the "upgrade-everything-to-Karmic" change, I think generating the uuid has become mandatorty again.
Without the uuid file (/var/lib/dbus/machine-id), ibus-daemon which uses D-Bus as its IPC channel does not work at all. I'm not sure but possibly the same is true for dbus-daemon?

chronos@localhost:/home/chronos$ ibus-daemon
process 2254: D-Bus library appears to be incorrectly set up; failed to read machine uuid: Failed to open "/var/lib/dbus/machine-id": No such file or directory
See the manual page for dbus-uuidgen to correct this issue.

BUG=1127
TEST=On xterm, run /usr/bin/ibus-setup and verify the command does not show an error like "ibus-daemon is not working."

[Yusuke Sato, 2009-12-22 06:45:52]

Ted, (cc: Dave)

This is 3-lines patch for startup scripts. Can you please review this?

[Yusuke Sato, 2010-01-04 12:54:26]

ping?

[tedbo, 2010-01-04 21:24:23]

I'd like to avoid adding new bind mounts when possible. In this case, I would do
this one of two ways:

1. In customize_rootfs.sh, run:

dbus-uuidgen --ensure="$ROOT_FS_DIR"/var/lib/dbus/machine-id"

This would mean that every image would have a unique machine-id but all devices
would have the same one. In practice this probably works fine since I suspect
that machine-id only needs to be unique if we start using dbus to talk between
devices. I don't think that we'll do that but still this is a bit sketchy.

2. In customize_rootfs, create a symlink "/var/lib/dbus/machine-id ->
/var/cache/machine-id". Then modify the dbus upstart script as I suggested in my
comment inline. You might even wrap it in:

if [ ! -f "/var/cache/machine-id" ]; then
  dbus-uuidgen --ensure=/var/cache/machine-id
fi

The dbus-uuidgen won't generate a new uuid if it exists, but test should be
built-in so it saves loading a binary during boot in the common case.

---

I'm not sure which I prefer. The second option seems more "correct" in
conforming to what dbus wants, but the first means we have to run one less
program on startup and have one less unique machine identifier which can be good
for other reasons.

http://codereview.chromium.org/508018/diff/1/2
File src/platform/init/dbus.conf (right):

http://codereview.chromium.org/508018/diff/1/2#newcode18
src/platform/init/dbus.conf:18: /bin/dbus-uuidgen --ensure
I'll explain further in the comments, but I would recommend:

/bin/dbus-uuidgen --ensure=/var/cache/machine-id

That way we can leave /var/lib/dbus as read-only and not special case it.

[Yusuke Sato, 2010-01-05 06:26:27]

Thanks for the suggestion. I've updated my change following your suggestion #2.
Please take another look.

Though #1 looks simpler, I think it makes the bus name of IBus a bit more
predictable (please note that IBus uses the machine-id as a part of its session
bus name). Since IBus handles sensitive data like user key input, I guess that
would be not good for security.

--Yusuke

http://codereview.chromium.org/508018/diff/1/2
File src/platform/init/dbus.conf (right):

http://codereview.chromium.org/508018/diff/1/2#newcode18
src/platform/init/dbus.conf:18: /bin/dbus-uuidgen --ensure
On 2010/01/04 21:24:23, tedbo wrote:
> I'll explain further in the comments, but I would recommend:
> 
> /bin/dbus-uuidgen --ensure=/var/cache/machine-id
> 
> That way we can leave /var/lib/dbus as read-only and not special case it.

Done.

http://codereview.chromium.org/508018/diff/5002/3003
File src/scripts/customize_rootfs.sh (right):

http://codereview.chromium.org/508018/diff/5002/3003#newcode243
src/scripts/customize_rootfs.sh:243: sudo ln -s /var/cache
"${ROOT_FS_DIR}/var/lib/dbus"
I also tried 'ln -s /var/cache/machine-id
"${ROOT_FS_DIR}/var/lib/dbus/machine-id"' but it didn't work.

build_image.sh seems to remove dead symlinks.

[tedbo, 2010-01-06 06:28:31]

LGTM

Thanks.

[tedbo, 2010-01-06 07:10:16]

LGTM

I forgot to reply to your comment. I do prefer the file-only symlink if it can
be made to work.

http://codereview.chromium.org/508018/diff/5002/3003
File src/scripts/customize_rootfs.sh (right):

http://codereview.chromium.org/508018/diff/5002/3003#newcode243
src/scripts/customize_rootfs.sh:243: sudo ln -s /var/cache
"${ROOT_FS_DIR}/var/lib/dbus"
On 2010/01/05 06:26:28, Yusuke Sato wrote:
> I also tried 'ln -s /var/cache/machine-id
> "${ROOT_FS_DIR}/var/lib/dbus/machine-id"' but it didn't work.
> 
> build_image.sh seems to remove dead symlinks.
> 
No, that should have worked. The build_image script doesn't do anything with
dead symlinks. If you can get that working it is preferred. Maybe you forgot the
"sudo"? If you do try it again, don't forget to remove the "rm -rf ..." above.

[Yusuke Sato, 2010-01-07 03:57:04]

http://codereview.chromium.org/508018/diff/5002/3003
File src/scripts/customize_rootfs.sh (right):

http://codereview.chromium.org/508018/diff/5002/3003#newcode243
src/scripts/customize_rootfs.sh:243: sudo ln -s /var/cache
"${ROOT_FS_DIR}/var/lib/dbus"
I tried file link again and it worked fine this time. Hmm.. probably I was
missing something. Anyway, fixed. Thanks.

[tedbo, 2010-01-07 05:47:30]

LGTM

Thanks!