Allow RO rootfs and writeable stateful.

Allow RO rootfs and writeable stateful.

BUG=9423
TEST=mount an image --safe, rootfs OK

Change-Id: I4bc48e742e2438a1d2cae17c752743e02bd124fd

[Nick Sanders, 2010-11-16 22:27:56]

This allows editing of the stateful partition without corrupting the rootfs.

[sosa, 2010-11-16 23:04:24]

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh
File mount_gpt_image.sh (right):

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh#newcode141
mount_gpt_image.sh:141: if [ ${FLAGS_read_only} -eq ${FLAGS_FALSE} -a \
Should be -o FLAGS_safe = true ... if the stateful partition is mounted rw ever
this should be run.

[Nick Sanders, 2010-11-17 00:15:33]

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh
File mount_gpt_image.sh (right):

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh#newcode141
mount_gpt_image.sh:141: if [ ${FLAGS_read_only} -eq ${FLAGS_FALSE} -a \
What does this do exactly, why do we want to write onto the stateful partition?

On 2010/11/16 23:04:24, sosa wrote:
> Should be -o FLAGS_safe = true ... if the stateful partition is mounted rw
ever
> this should be run.

[sosa, 2010-11-17 00:32:38]

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh
File mount_gpt_image.sh (right):

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh#newcode141
mount_gpt_image.sh:141: if [ ${FLAGS_read_only} -eq ${FLAGS_FALSE} -a \
In a nutshell, there are symlinks in /usr/local (i.e.
/mnt/stateful_partition/dev_image) that allow someone to emerge something with
--root=/usr/local.  It does things likes redirects /usr/local/usr/bin ->
/usr/local/bin, etc.  
These symlinks are setup on a finished image to run on the image (i.e. rooted
from /).  When we want to add packages on a build system onto an image ... we
have to replace / with the build root on the host.

Anyway, if someone wants to emerge something to /usr/local, they should be able
to do it using --safe and root=/tmp/s/usr/local (the equivlanent of what we do
in build_image).  Otherwise (if they try) they will emerge stuff into their own
/usr/local on their host system.

On 2010/11/17 00:15:33, Nick Sanders wrote:
> What does this do exactly, why do we want to write onto the stateful
partition?
> 
> On 2010/11/16 23:04:24, sosa wrote:
> > Should be -o FLAGS_safe = true ... if the stateful partition is mounted rw
> ever
> > this should be run.
>

[Nick Sanders, 2010-11-17 01:00:26]

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh
File mount_gpt_image.sh (right):

http://codereview.chromium.org/4974006/diff/4001/mount_gpt_image.sh#newcode141
mount_gpt_image.sh:141: if [ ${FLAGS_read_only} -eq ${FLAGS_FALSE} -a \
Ok, that makes sense, thanks!

[sosa, 2010-11-17 01:04:32]

LGTM