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

[Qi.Chen at windriver.com]

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.

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 at 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