[OE-core] [PATCH V7 2/6] image.bbclass: add a hook funtion to support readonly 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.

[YOCTO #3406]

Signed-off-by: Chen Qi <Qi.Chen at windriver.com>
---
 meta/classes/image.bbclass |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index e494689..834497a 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -185,7 +185,6 @@ do_build[nostamp] = "1"
 # task, so that we have a single fakeroot context for the whole process.
 do_rootfs[umask] = "022"
 
-
 run_intercept_scriptlets () {
 	if [ -d ${WORKDIR}/intercept_scripts ]; then
 		cd ${WORKDIR}/intercept_scripts
@@ -396,6 +395,21 @@ 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 -i '/rootfs/ s/defaults/ro/' ${IMAGE_ROOTFS}/etc/fstab
+	# 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
+}
+
 # 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