image.bbclass: add a hook funtion to support readonly rootfs

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]

(From OE-Core rev: cae51a169e37b54becc08162aaa643acd53ffe2f)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 68bd342d61..2abda81507 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -224,6 +224,24 @@ 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 and fs_passno for rootfs in fstab
+                sed -i -e '/^[#[:space:]]*rootfs/{s/defaults/ro/;s/\([[:space:]]*[[:digit:]]\)\([[:space:]]*\)[[:digit:]]$/\1\20/}' ${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 [ -x ${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