Re: [PATCH 2/4] image.bbclass: add two hook funtions to support read-only rootfs

[ChenQi <Qi.Chen@windriver.com>]

On 12/27/2012 04:42 PM, Martin Jansa wrote:
> On Thu, Dec 27, 2012 at 10:57:39AM +0800, Qi.Chen@windriver.com wrote:
>> From: Chen Qi <Qi.Chen@windriver.com>
>>
>> read_only_rootfs_hook: this funtion is invoked only if 'read-only-rootfs'
>> is in IMAGE_FEATURES. It tweaks some basic files and makes populate-
>> volatile.sh script run at rootfs time.
>>
>> choose_volatile_conf_file: this function properly chooses the right
>> conf file for volatile storage handling according to the IMAGE_FEATURES.
> choose_volatile_conf_file is always called from core-image with or
> without read-only-rootfs in IMAGE_FEATURES.
>
> So it will use /etc/default/volatiles_stage/volatiles-readonly-minimal
> without read-only-rootfs.
>
> Cheers,
Yes. And I did this on purpose.

I want to ship the conf file no matter we're building a 
'read-only-rootfs' image or not.
In this way, changing 'ROOTFS_READ_ONLY' to 'yes' on a currently running 
system and rebooting will give the user a working system with read-only 
rootfs.

If the rootfs is not read-only, this conf file will not be applied, both 
at rootfs construction time and at system startup time.

Best Regards,
Chen Qi

>> [YOCTO #3406]
>>
>> Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
>> ---
>>   meta/classes/image.bbclass |   29 +++++++++++++++++++++++++++++
>>   1 file changed, 29 insertions(+)
>>
>> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
>> index 8bf718a..15d42d0 100644
>> --- a/meta/classes/image.bbclass
>> +++ b/meta/classes/image.bbclass
>> @@ -394,6 +394,35 @@ zap_root_password () {
>>   	mv ${IMAGE_ROOTFS}/etc/passwd.new ${IMAGE_ROOTFS}/etc/passwd
>>   }
>>   
>> +# A hook function to support read-only-rootfs IMAGE_FEATURES
>> +read_only_rootfs_hook () {
>> +	# Tweak the mount option in fstab
>> +	sed '/rootfs/ s/defaults/ro/' < ${IMAGE_ROOTFS}/etc/fstab > ${IMAGE_ROOTFS}/etc/fstab.new
>> +	mv ${IMAGE_ROOTFS}/etc/fstab.new ${IMAGE_ROOTFS}/etc/fstab
>> +	# Change the value of ROOTFS_READ_ONLY in /etc/default/rcS to yes
>> +	sed 's/ROOTFS_READ_ONLY=no/ROOTFS_READ_ONLY=yes/' < ${IMAGE_ROOTFS}/etc/default/rcS > ${IMAGE_ROOTFS}/etc/default/rcS.new
>> +	mv ${IMAGE_ROOTFS}/etc/default/rcS.new ${IMAGE_ROOTFS}/etc/default/rcS
>> +	# Run populate-volatile.sh at rootfs time to set up basic files
>> +	# and directories to support read-only rootfs.
>> +	if [ ! -e ${IMAGE_ROOTFS}/etc/init.d/populate-volatile.sh ]; then
>> +		echo "${IMAGE_ROOTFS}/etc/init.d/populate-volatile.sh doesn't exist."
>> +		exit 1
>> +	else
>> +		${IMAGE_ROOTFS}/etc/init.d/populate-volatile.sh
>> +	fi
>> +}
>> +
>> +# Choose the correct config file for volatile storage handling according to the image type
>> +choose_volatile_conf_file () {
>> +	if ${@base_contains("IMAGE_FEATURES", "x11-sato", "true", "false" ,d)}; then
>> +		cp ${IMAGE_ROOTFS}/etc/default/volatiles_stage/volatiles-readonly-sato \
>> +			${IMAGE_ROOTFS}/etc/default/volatiles/00_core_readonly
>> +	else
>> +		cp ${IMAGE_ROOTFS}/etc/default/volatiles_stage/volatiles-readonly-minimal \
>> +			${IMAGE_ROOTFS}/etc/default/volatiles/00_core_readonly
>> +	fi
>> +}
>> +
>>   # allow openssh accept login with empty password string
>>   openssh_allow_empty_password () {
>>   	if [ -e ${IMAGE_ROOTFS}${sysconfdir}/ssh/sshd_config ]; then
>> -- 
>> 1.7.9.5
>>
>>
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