#!/bin/bash

################################################################################
#    Copyright 2007 by Tobias Schlitt <toby@php.net>                           #
################################################################################
#                                                                              #
#    This program is free software; you can redistribute it and/or modify      #
#    it under the terms of the GNU General Public License as published by      #
#    the Free Software Foundation; either version 3 of the License, or         #
#    (at your option) any later version.                                       #
#                                                                              #
#    This program is distributed in the hope that it will be useful,           #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of            #
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             #
#    GNU General Public License for more details.                              #
#                                                                              #
#    You should have received a copy of the GNU General Public License         #
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.     #
#                                                                              #
################################################################################

# Run this program as root with the name of your new kernel as the parameter.
# E.g.
#    $ sudo makekernel.sh linux-2.6.22-gentoo-r8
# to build the kernel stored in /usr/src/linux-2.6.22-gentoo-r8 as the new kernel

#
# Configuration
#

# Edit the following values to suite your needs

# Base dir where the kernel config is stored
KERNEL_SOURCE="/usr/src"
# Mount point for the boot partition
BOOT_DIR="/boot"

# The grub configuration file
GRUB_CONF="$BOOT_DIR/grub/grub.conf"
# The file where makekernel.sh will create the new grub.conf
GRUB_CONF_NEW="$BOOT_DIR/grub/.grub.conf.new"
# The file where the old grub.conf will be backed up
GRUB_CONF_BACKUP="$BOOT_DIR/grub/grub.conf.bak"

# Title line in grub.conf. %s will be replaced by the kernel version
GRUB_TITLE_LINE="Gentoo-%s"
# The part after 'root ' in grub.conf
GRUB_ROOT_OPTION="(hd0,0)"
# Options to pass to the new kernel
GRUB_KERNEL_OPTIONS="root=/dev/sda3"

# Parameters to the "module-rebuild" tool (will only affect you if this is installed)
MODULE_REBUILD_OPTIONS="-X"

#
# Starting up, do NOT change anything below this line unless you know what you are doing!
#

if [[ `whoami` == "root" ]]
then
	echo "Good to see you are root! ;)"
else
	echo "You need to be root to use this script!"
	exit -1
fi

if [ $# -lt 1 ]
then
	echo "Please specify new kernel name"
	exit 1;
fi

#
# Auto detection of config values
#

# Strip trailing slash if there
KERNEL_NAME=`echo "$1" | sed 's/\/$//g'`;
KERNEL_DIR="$KERNEL_SOURCE/$KERNEL_NAME"
KERNEL_VERSION=`echo "$KERNEL_NAME" | sed 's/linux-//g'`

LINUX_DIR="$KERNEL_SOURCE/linux"
LINUX_OLD_DIR="$KERNEL_SOURCE/linux.old"

OLD_DIR=`pwd`

#
# Move around linux links
#

if [[ -h "$LINUX_OLD_DIR" ]]
then
	rm "$LINUX_OLD_DIR" || ( echo "--- Could not delete $LINUX_OLD_DIR ---" && exit 1 )
fi

if [[ -h "$LINUX_DIR" ]]
then
    mv "$LINUX_DIR" "$LINUX_OLD_DIR"
fi

ln -s "$KERNEL_DIR" "$LINUX_DIR" || ( echo "--- Could not create link from $KERNEL_DIR to $LINUX_DIR ---" && exit 1 )

#
# Copy old config
#

if [[ ! -e "$LINUX_DIR/.config" ]]
then
	cp "$LINUX_OLD_DIR/.config" "$LINUX_DIR/.config" || ( echo "--- Could not copy .config ---" && exit 1 )
fi

#
# Change into kernel dir
#

cd "$LINUX_DIR" || ( echo "--- Could not change to $LINUX_DIR ---" && exit 1 )

#
# Perform make operations

echo "Performing make oldconfig, this may produce a lot of output..."
make oldconfig || ( echo "--- make oldconfig failed ---" && exit 1 )

echo ""
echo ""
echo "---------------------------------------------------------------------"
echo "------------------- makekernel.sh back in action! -------------------"
echo "---------------------------------------------------------------------"
echo ""
echo ""

echo "Now doing make clean..."
make clean &>"$LINUX_DIR/makekernel.clean.log" || ( echo "--- make clean failed, see $LINUX_DIR/makekernel.clean.log for more infos ---" && exit 1 )
rm "$LINUX_DIR/makekernel.clean.log"

echo "Now performing make, this can take a while."
echo "You can watch progress with 'tail -f $LINUX_DIR/makekernel.make.log' on another shell."
echo "Hang on..."
make &>"$LINUX_DIR/makekernel.make.log" || ( echo "--- make failed, see $LINUX_DIR/makekernel.make.log for more infos ---" && exit 1 )
rm "$LINUX_DIR/makekernel.make.log"

echo "Now performing make, this can take a while."
echo "You can watch progress with 'tail -f $LINUX_DIF/makekernel.modules.log' on another shell."
echo "Hang on..."
make modules_install &>"$LINUX_DIF/makekernel.modules.log" || ( echo "--- make modules_install failed, see $LINUX_DIR/makekernel.make.log for more infos ---" && exit 1 )
rm "$LINUX_DIF/makekernel.modules.log"

#
# Mount /boot
#

if mount | grep -q "$BOOT_DIR"
then
 	echo "$BOOT_DIR allready mounted, will not be unmounted later."
	BOOT_DIR_MOUNTED=true
else
	echo "Mounting $BOOT_DIR..."
	mount $BOOT_DIR || ( echo "--- Could not mount $BOOT_DIR, not in /etc/fstab? ---" && exit 1 )
fi

#
# Copying boot files
#

echo "Copying kernel files..."
cp "arch/i386/boot/bzImage" "$BOOT_DIR/kernel-$KERNEL_VERSION" || ( echo "--- Could not copy bzImage ---" && exit 1 )
cp ".config" "$BOOT_DIR/.config-$KERNEL_VERSION" || echo "--- Could not copy .config ---"
cp "System.map" "$BOOT_DIR/System.map-$KERNEL_VERSION" || echo "--- Could not copy System.map ---"

#
# Alter grub.conf
#

if grep -q "$KERNEL_VERSION" "$GRUB_CONF"
then
	echo "Kernel version $KERNEL_VERSION already in $GRUB_CONF."
else
	echo "Creating new $GRUB_CONF including kernel version $KERNEL_VERSION in $GRUB_CONF_NEW..."

	# Determine first kernel entry
	HEAD_LINE_COUNT=`grep -n 'title' "$GRUB_CONF" | sed 's/^\([0-9]*\):.*/\1/g' | head -n 1`
	# Go 2 line backwards
	let "HEAD_LINE_COUNT -= 1"

	head -n"$HEAD_LINE_COUNT" "$GRUB_CONF" > "$GRUB_CONF_NEW"
	echo "# Generated by makekernel.sh on" `date` >> "$GRUB_CONF_NEW"
	echo "title $GRUB_TITLE_LINE" | sed "s/%s/$KERNEL_VERSION/" >> "$GRUB_CONF_NEW"
	echo "root $GRUB_ROOT_OPTION" >> "$GRUB_CONF_NEW"
	echo "kernel /boot/kernel-$KERNEL_VERSION $GRUB_KERNEL_OPTIONS" >> "$GRUB_CONF_NEW"
	echo "" >> "$GRUB_CONF_NEW"
	
	let "TAIL_LINE_COUNT = `cat $GRUB_CONF | wc -l` - $HEAD_LINE_COUNT"
	
	tail -n "$TAIL_LINE_COUNT" "$GRUB_CONF" >> "$GRUB_CONF_NEW"

	echo "Successfully wrote new $GRUB_CONF in $GRUB_CONF_NEW."
	echo "Backing up old $GRUB_CONF to $GRUB_CONF_BACKUP."

	mv "$GRUB_CONF" "$GRUB_CONF_BACKUP" || ( echo "--- Could not move $GRUB_CONF to $GRUB_CONF_BACKUP ---" && exit 1 )

	echo "Overwriting $GRUB_CONF with newly created $GRUB_CONF_NEW."

	mv "$GRUB_CONF_NEW" "$GRUB_CONF" || ( echo "--- Could not move $GRUB_CONF_NEW to $GRUB_CONF ---" && exit 1 )
fi

# Unmounit /boot

if [ $BOOT_DIR_MOUNTED ]
then
	echo "$BOOT_DIR dir was already mounted, do not unmount"
else
	echo "Unmounting $BOOT_DIR"
	umount "$BOOT_DIR" || echo "--- Could not unmount $BOOT_DIR, do this manually! ---"
fi

if [[ -e /usr/sbin/module-rebuild ]]
then
	echo "Rebuilding external modules..."
	( /usr/sbin/module-rebuild "$MODULE_REBUILD_OPTIONS" rebuild 2>&1 > "$LINUX_DIR/makekernel.rebuild.log" && rm "$LINUX_DIR/makekernel.rebuild.log" ) || echo "--- Rebuilding modules failed! Try module-rebuild manually or manually rebuild your external modules. See $LINUX_DIR/makekernel.rebuild.log for details. ---"
	echo "External modules rebuilt successfully"
fi

echo "Going back to where you came from..."

cd "$OLD_DIR"

echo "Kernel install complete. Your new kernel will be active on next reboot."
echo ""
echo "Thanks for using this script."