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

[Saul Wold <sgw@linux.intel.com>]

On 12/26/2012 06:57 PM, 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.
>
> [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
For the above 2 sed/mv, can't you use sed -i instead, cuts down on the 
exec overhead.

Sau!

> +	# 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
>