#!/bin/sh

TMPDIR=/tmp/unsupported-patch-for-87262.$$
mkdir $TMPDIR
cd $TMPDIR

OLD_VERSION=2.6.20-15-generic
NEW_VERSION=2.6.20-15-generic-with-unsupported-patch-for-87262

OLD_VMLINUZ=/boot/vmlinuz-$OLD_VERSION
NEW_VMLINUZ=/boot/vmlinuz-$NEW_VERSION

OLD_INITRD=/boot/initrd.img-$OLD_VERSION
NEW_INITRD=/boot/initrd.img-$NEW_VERSION

PREPATCH_MD5=`md5sum $OLD_VMLINUZ | colrm 33`
if [ x"$PREPATCH_MD5" != x"11e0cbf44b1dc1bacdcfaa6780161b54" ]; then
  echo "unexpected version of $OLD_VMLINUZ"
  exit 1
fi

echo working...
dd bs=7810 count=1 if=$OLD_VMLINUZ of=headers 2>/dev/null
dd bs=7810  skip=1 if=$OLD_VMLINUZ of=kernel.gz+extrabytes 2>/dev/null

echo working....
KERNEL_GZ_SIZE=`zcat kernel.gz+extrabytes 2>/dev/null | gzip -nc9 | wc -c`
dd skip=$KERNEL_GZ_SIZE bs=1 if=kernel.gz+extrabytes of=extrabytes 2>/dev/null
dd bs=$KERNEL_GZ_SIZE count=1 if=kernel.gz+extrabytes of=kernel.gz 2>/dev/null

echo working......
SIZE1=`stat -c%s kernel.gz+extrabytes`
SIZE2=$(echo `stat -c%s kernel.gz` + `stat -c%s extrabytes` | bc)
if [ ! $SIZE1 -eq $SIZE2 ]; then
	echo "error 1: sizes dont match"
	exit 1
fi

zcat kernel.gz > kernel.unpatched
zcat kernel.gz > kernel.patched
/bin/echo -ne '\0100\0100' \
  | dd conv=notrunc bs=1 seek=1499078 count=2 of=kernel.patched 2>/dev/null

echo working.........
od -Ax -tx1z kernel.unpatched > kernel.unpatched.hex 2>/dev/null
echo working............
od -Ax -tx1z kernel.patched > kernel.patched.hex 2>/dev/null
echo "diff of patch:"
diff kernel.unpatched.hex kernel.patched.hex

gzip -nc9 kernel.patched > kernel.patched.gz
# reset the patched kernel.gz timestamp to the original one
dd conv=notrunc bs=8 count=1 if=kernel.gz of=kernel.patched.gz 2>/dev/null

SIZE1=`stat -c%s kernel.gz`
SIZE2=`stat -c%s kernel.patched.gz`
if [ ! $SIZE1 -eq $SIZE2 ]; then
	echo "error 2: sizes dont match"
	exit 2
fi

mkdir -p boot
cat headers kernel.patched.gz extrabytes > .$NEW_VMLINUZ
SIZE1=`stat -c%s $OLD_VMLINUZ`
SIZE2=`stat -c%s .$NEW_VMLINUZ`
if [ ! $SIZE1 -eq $SIZE2 ]; then
	echo "error 3: sizes dont match"
	exit 3
fi

POSTPATCH_MD5=`md5sum .$NEW_VMLINUZ | colrm 33`
if [ x"$POSTPATCH_MD5" != x"d153dd91c1a1bff4d806df73b0ee5e7e" ]; then
  echo "patch failed. final md5sum didnt match expected value $POSTPATCH_MD5"
  exit 1
fi

echo  
echo "patch succeeded - found expected md5sum."
echo
echo "copying patched kernel into /boot. old kernel is untouched."
sudo mv .$NEW_VMLINUZ /boot
sudo cp -p $OLD_INITRD $NEW_INITRD
echo
echo "update-grub menu.lst?"
echo "hit ctrl-c if youve changed your mind or you want to do "
echo "it manually, otherwise hit enter to continue."
read line
sudo /usr/sbin/update-grub
echo
echo "unhiding grub menu, in case new kernel doesnt work."
sudo sed -i -e "s/^hiddenmenu/#hiddenmenu/" /boot/grub/menu.lst

echo
echo "creating uninstall script in /boot"
UNINSTALL=/boot/uninstall-unsupported-patch-for-87262.sh
echo "#!/bin/sh"                > $TMPDIR/$UNINSTALL
echo "sudo rm -f $NEW_VMLINUZ" >> $TMPDIR/$UNINSTALL
echo "sudo rm -f $NEW_INITRD"  >> $TMPDIR/$UNINSTALL
echo "sudo update-grub"        >> $TMPDIR/$UNINSTALL
echo "sudo rm -f $UNINSTALL"   >> $TMPDIR/$UNINSTALL
sudo mv $TMPDIR/$UNINSTALL $UNINSTALL
sudo chmod a+rx $UNINSTALL

echo
echo "all done.  you can reboot now."
echo "if you get a kernel panic, or it doesnt work for you, select "
echo "the previous, unpatched kernel, at startup time, and then run "
echo "$UNINSTALL"
echo "... to get rid of the patched kernel "
echo