#!/bin/bash

if [ `whoami` != "root" ]; then
    echo "$0 must be run as root!"
    exit 1
fi

if [ $# -lt 3 ]; then
    echo "usage: $0 <major minor micro [revision], e.g. 2 6 21 r4>"
    exit 1
fi

MAJOR=$1
MINOR=$2
MICRO=$3
if [ $# -gt 3 ]; then
    REVISION=$4
fi
LOGFILE=/tmp/removeKernel-$$.log

# unmerge the kernel
cd /usr/src
KERNEL_DIR="linux-${MAJOR}.${MINOR}.${MICRO}-gentoo"
if [ "$REVISION" != "" ]; then
    KERNEL_DIR="${KERNEL_DIR}-${REVISION}"
fi
if [ -d $KERNEL_DIR ]; then
    KERNEL_NAME=gentoo-sources-${MAJOR}.${MINOR}.${MICRO}
    if [ "${REVISION}" != "" ]; then
        KERNEL_NAME="${KERNEL_NAME}-${REVISION}"
    fi

    echo "unmerge kernel $KERNEL_NAME" >> $LOGFILE 2>&1
    emerge --unmerge $KERNEL_NAME >> $LOGFILE 2>&1

    echo "remove $KERNEL_DIR" >> $LOGFILE 2>&1
    rm -r  $KERNEL_DIR >> $LOGFILE 2>&1
fi

# remove modules
cd /lib/modules
LIB_DIR=${MAJOR}.${MINOR}.${MICRO}-gentoo
if [ "$REVISION" != "" ]; then
    LIB_DIR="${LIB_DIR}-${REVISION}"
fi
if [ -d $LIB_DIR ]; then
    echo "remove modules from `pwd`/$LIB_DIR" >> $LOGFILE 2>&1
    rm -r $LIB_DIR >> $LOGFILE 2>&1
fi

# remove the kernel and stuff, check if /boot is mounted first
MOUNTED=`mount | grep /boot`
if [ "$MOUNTED" = "" ]; then
    echo "mount /boot" >> $LOGFILE 2>&1
    mount /boot >> $LOGFILE 2>&1
fi

cd /boot

ARCH=`uname -m`
if [ "$ARCH" = "i686" ]; then
    ARCH="x86"
fi

SUFFIX=genkernel-${ARCH}-${MAJOR}.${MINOR}.${MICRO}-gentoo
if [ "$REVISION" != "" ]; then
    SUFFIX="$SUFFIX-${REVISION}"
fi
rm System.map-${SUFFIX} >> $LOGFILE 2>&1
rm initramfs-${SUFFIX} >> $LOGFILE 2>&1

KERNEL="kernel-${SUFFIX}"
if [[ -f $KERNEL ]]; then
	rm $KERNEL >> $LOGFILE 2>&1
fi
KERNEL="vmlinuz-${MAJOR}.${MINOR}.${MICRO}-gentoo-${ARCH}"
if [[ -f $KERNEL ]]; then
	rm $KERNEL >> $LOGFILE 2>&1
fi

# if we got until here, just remove the logfile again
rm $LOGFILE