From d74a8a677ede7a1b867ea97d0596e5f954d67e19 Mon Sep 17 00:00:00 2001
From: Ulrich Dangel <uli@spamt.net>
Date: Thu, 11 Mar 2010 20:57:43 +0100
Subject: [PATCH] Only set device to read-only if parent is also read-only

---
 scripts/forensic-mark-readonly | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/scripts/forensic-mark-readonly b/scripts/forensic-mark-readonly
index 299c661..909a512 100755
--- a/scripts/forensic-mark-readonly
+++ b/scripts/forensic-mark-readonly
@@ -6,12 +6,45 @@
 # License:       This file is licensed under the GPL v2 or any later version.
 ################################################################################
 
+function get_blockdev_dir() {
+    for dir in /sys/subsystem/block/ /sys/class/block/ /sys/block/ ; do
+        [ -d $dir ] && echo $dir && return
+    done
+}
+
+function base() {
+    echo ${1##*/}
+}
+function dir() {
+    echo ${1%/*}
+}
+
+function is_ro() {
+    [ "$(blockdev --getro $1)" = "1" ] && return 0 || return 1
+
+
+}
 # check for forensic/readonly bootoption
-if grep -qe forensic -qe readonly /proc/cmdline ; then
+if : ; then
  # we get $DEVNAME via udev's environment
  if [ -n "$DEVNAME" ] ; then
-   if [ "$(blockdev --getro $DEVNAME)" = "1" ] ; then
+    NAME=$(base $DEVNAME)
+    SYS_DIR=$(get_blockdev_dir)
+
+    if [ -n $SYS_DIR ] && [ -n $NAME ] ; then
+        DEVICE=$SYS_DIR/*/$NAME
+        if [ -d $DEVICE ] ; then
+            PARENT=$(dir $DEVICE)
+            PARENT=$(base $PARENT)
+            PARENT=/dev/$PARENT
+        fi
+    fi
+
+   if is_ro "$DEVNAME" ; then
      logger "forensic mode: device $DEVNAME already set to readonly mode, nothing to do"
+   elif [ -n "$PARENT" ] && ! is_ro "$PARENT" ; then
+     logger "forensic mode: parent device $PARENT is set readwrite, not modifying"
+     logger "forensic mode: use blockdev --setro $DEVNAME to set it manually"
    else
      logger "forensic mode: setting $DEVNAME [$ID_SERIAL] to readonly"
      if blockdev --setro "$DEVNAME" ; then
-- 
2.1.4