adding breakfs

shell/breakfs.sh

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+#
+# Script to corrupt a linux ext3/4 partition
+#
+# SPDX-License-Identifier: MIT
+
+# Check usage
+if [ "$#" != "1" ]
+then
+ echo "Usage: $0 /dev/sdb1"
+ exit 1
+fi
+
+# Check if the invoking user is root
+if [ "$EUID" != "0" ]
+then
+ echo 'Please run this script as a root privileged user'
+ exit 2
+fi
+
+# Find mount and check it's actually mounted
+MOUNT=$(mount | grep "$1" | awk '{print $3}')
+if [ -z "$MOUNT" ]
+then
+ echo "$1 is not mounted, please mount it first"
+ exit 3
+fi
+
+# Find journal inode and block size from device
+DUMP=$(dumpe2fs "$1" 2>&1 | grep -E -i "^Journal\ inode|^Block\ size")
+INODE=$(echo "$DUMP" | grep inode | awk '{print $3}')
+SIZE=$(echo "$DUMP" | grep size | awk '{print $3}')
+
+# If foo exists delete it, then create it
+if [ -e "$MOUNT/foo" ]
+then
+ rm -f "$MOUNT/foo"
+fi
+touch "$MOUNT/foo"
+sync
+
+# Find block location of the journal
+echo "stat <${INODE}>" > debugfs.cmd
+BLOCK=$(debugfs -f debugfs.cmd "$1" 2>&1 | sed -nr 's/\([0-9-]+\):\ ?([0-9]+)-[0-9].+/\1/p')
+rm -f debugfs.cmd
+
+# Overwrite the first block of the journal
+# shellcheck disable=SC2086
+dd if=/dev/urandom of="$1" bs=$SIZE count=1 skip=$BLOCK > /dev/null 2>&1
+sync
+
+# Attempt to write to foo, and then remove it, at least one should fail
+rm -f "$MOUNT/foo"
+echo foo > "$MOUNT/bar"
+
+# Exit
+exit 0