[OE-core] [PATCH 02/12] image.bbclass: add a hook funtion to support readonly rootfs

[Mark Hatle]

On 1/24/13 2:16 AM, Qi.Chen at windriver.com wrote:
> From: Chen Qi <Qi.Chen at 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.
>
> For now, it has real effect only if the init system is sysvinit.
>
> [YOCTO #3406]
>
> Signed-off-by: Chen Qi <Qi.Chen at windriver.com>
> ---
>   meta/classes/image.bbclass |   18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
> index 0293d2e..91045fc 100644
> --- a/meta/classes/image.bbclass
> +++ b/meta/classes/image.bbclass
> @@ -201,6 +201,24 @@ run_intercept_scriptlets () {
>   	fi
>   }
>
> +# A hook function to support read-only-rootfs IMAGE_FEATURES
> +# Currently, it only supports sysvinit system.
> +read_only_rootfs_hook () {
> +	if ${@base_contains("DISTRO_FEATURES", "sysvinit", "true", "false", d)}; then
> +	        # Tweak the mount option in fstab
> +		sed -i '/rootfs/ s/defaults/ro/' ${IMAGE_ROOTFS}/etc/fstab

There is a slight bug in the above.  Not all configurations will contain an 
/etc/fstab!  So you need to check for the existence of the file before you try 
to sed it.

(Initramfs is where I hit a problem trying to test this.)

--Mark

> +	        # Change the value of ROOTFS_READ_ONLY in /etc/default/rcS to yes
> +		if [ -e ${IMAGE_ROOTFS}/etc/default/rcS ]; then
> +			sed -i 's/ROOTFS_READ_ONLY=no/ROOTFS_READ_ONLY=yes/' ${IMAGE_ROOTFS}/etc/default/rcS
> +		fi
> +	        # 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
> +			${IMAGE_ROOTFS}/etc/init.d/populate-volatile.sh
> +		fi
> +	fi
> +}
> +
>   fakeroot do_rootfs () {
>   	#set -x
>   	# When use the rpm incremental image generation, don't remove the rootfs
>