initscripts: add read-only-rootfs-hook.sh script

Add read-only-rootfs-hook.sh script to support a read-only rootfs.
This script makes a union mount of /var/lib and /var/volatile/lib,
making /var/lib directory writable.

[YOCTO #3406]

(From OE-Core rev: a9591158962eee1f8ae04168d6256032ecd7bc6b)

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>

2 files changed, 22 insertions, 0 deletions

diff --git a/meta/recipes-core/initscripts/initscripts-1.0/read-only-rootfs-hook.sh b/meta/recipes-core/initscripts/initscripts-1.0/read-only-rootfs-hook.sh
new file mode 100644
index 0000000000..3a295eea0b
--- /dev/null
+++ b/meta/recipes-core/initscripts/initscripts-1.0/read-only-rootfs-hook.sh
@@ -0,0 +1,19 @@
+#!/bin/sh
+
+. /etc/default/rcS
+
+[ "$ROOTFS_READ_ONLY" = "no" ] && exit 0
+
+# Make sure unionfs is in /proc/filesystems
+if ! grep -q unionfs /proc/filesystems; then
+    echo "ERROR: unionfs not supported by kernel!"
+    exit 1
+fi
+
+mkdir -p /var/volatile/lib
+mount -t unionfs -o dirs=/var/volatile/lib:/var/lib=ro none /var/lib
+
+if [ $? != 0 ]; then
+    echo "ERROR: Union mount failed!"
+    exit 1
+fi
diff --git a/meta/recipes-core/initscripts/initscripts_1.0.bb b/meta/recipes-core/initscripts/initscripts_1.0.bb
index 69b9bfbe32..68f80346ef 100644
--- a/meta/recipes-core/initscripts/initscripts_1.0.bb
+++ b/meta/recipes-core/initscripts/initscripts_1.0.bb
@@ -28,6 +28,7 @@ SRC_URI = "file://functions \
            file://sysfs.sh \
            file://device_table.txt \
            file://populate-volatile.sh \
+           file://read-only-rootfs-hook.sh \
            file://volatiles \
            file://save-rtc.sh \
            file://GPLv2.patch"
@@ -85,6 +86,7 @@ do_install () {
         install -m 0755    ${WORKDIR}/devpts            ${D}${sysconfdir}/default
         install -m 0755    ${WORKDIR}/sysfs.sh          ${D}${sysconfdir}/init.d
         install -m 0755    ${WORKDIR}/populate-volatile.sh ${D}${sysconfdir}/init.d
+        install -m 0755    ${WORKDIR}/read-only-rootfs-hook.sh ${D}${sysconfdir}/init.d
         install -m 0755    ${WORKDIR}/save-rtc.sh       ${D}${sysconfdir}/init.d
         install -m 0644    ${WORKDIR}/volatiles         ${D}${sysconfdir}/default/volatiles/00_core
 
@@ -116,6 +118,7 @@ do_install () {
         update-rc.d -r ${D} bootmisc.sh start 55 S .
         update-rc.d -r ${D} sysfs.sh start 02 S .
         update-rc.d -r ${D} populate-volatile.sh start 37 S .
+        update-rc.d -r ${D} read-only-rootfs-hook.sh start 41 S .
         update-rc.d -r ${D} devpts.sh start 38 S .
         if [ "${TARGET_ARCH}" = "arm" ]; then
                 update-rc.d -r ${D} alignment.sh start 06 S .