#!/bin/sh

#

# script to update /etc/sysconfig/kdump to use the latest 

# kernel package as the dump kernel

#

# optional argument --grub causes kdump kernel cmdline to

# be added to rt kernel grub entries

#

me=$(basename $0)

rpmcmd='rpm -q --last'

function fatal () {

    echo "$me: " $1

    exit -1

}

function usage () {

    echo "usage: $me [-g|--grub] [-r|--rhel] [-v|--verbose] [-h|--help]"

    echo "       --grub    - add crashkernel arg to rt grub entries"

    echo "       --rhel    - use the RHEL-7.1 kernel as the kdump kernel"

    echo "                   (the default is to use the RHEL-RT kernel)"

    echo "       --verbose - print out actions"

    echo "       --help    - print this message"

    exit -1

}

function report() {

    [ $verbose -eq 1 ] && echo $1

}

# return the latest package version of specified package name

function latest_package_ver() {

    local pkg=$1

    local ver=$($rpmcmd $pkg | head -1 | awk '{print $1}')

    if [ $? -ne 0 ]; then

	fatal "  error fetching version for $pkg"

    fi

    echo ${ver#$pkg-}

    return 0

}

# get the kernel version of hhe latest installed kernel

function vmlinux_ver() {

    local ver=$1

    local vmver=''

    for i in $(cd /boot; echo vmlinuz-*); do

	if [ "${i#vmlinuz-$ver}" != "$i" ]; then

	    vmver=${i#vmlinuz-}

	    echo $vmver

	    return 0

	fi

    done

    return 1

}

# find all the grub indexs for installed rhel-rt kernels

# returns a comma-separated list of indices for use

# by the grubby command

function find_rt_kernel_indexes_rhel_rt() {

    local awkscript='BEGIN{FS="="; ORS=","} $1 ~ /^index/{idx=$2;}

		$2 ~ /.rt.*.el7.x86_64/ &&

		$1 ~ /^kernel/ {print idx}'

    local rt_idx_list=$(/sbin/grubby --info=ALL | /usr/bin/awk "$awkscript")

    echo $rt_idx_list | sed -e 's/,$//'

    return 0

}

#############################################################################

# make sure we're root

if [ $UID -ne 0 ]; then

    echo "  must be root to run $me!"

    usage

fi

# process options

dogrub=0

userhel=0

verbose=0

TEMP=$(getopt --options "grvh" --longoptions="grub,rhel,verbose,help" -- "$@")

if [ $? -ne 0 ]; then

    usage

fi

eval set -- "$TEMP"

while true; do

    case "$1" in

	-g|--grub)

	    dogrub=1

	    shift

	    ;;

	-r|--rhel)

	    userhel=1

	    shift

	    ;;

	-v|--verbose)

	    verbose=1

	    shift

	    ;;

	-h|--help)

	    usage

	    ;;

	--) shift ; break ;;

	*)

	    echo "internal error!"

	    usage

	    ;;

    esac

done

# warn if /etc/sysconfig/kdump does not exist

if [ ! -f /etc/sysconfig/kdump ]; then

    echo "  File /etc/sysconfig/kdump not found."

    echo "  Please, check your kexec-tools installation."

    exit 1

fi

if [ $dogrub = 0 ]; then

    echo "Not performing changes to /etc/grub.conf"

    echo

    # check if there is memory reserved for the kexec kernel

    if ! cat /proc/cmdline | grep -e crashkernel > /dev/null; then

        echo "  Kernel DOES NOT have memory reserved for kdump kernel..."

        echo "  Use --grub option to enable crashkernel option on kernel command line"

	echo

    fi

fi

# select the right kdump kernel

if [ $userhel -eq 1 ]; then

	KDUMP_KERNEL="kernel"

else

	KDUMP_KERNEL="kernel-rt"

fi

# get the version of the latest installed kernel

kver=$(latest_package_ver $KDUMP_KERNEL)

if [ -z "$kver" ]; then

    fatal "  Can't find $KDUMP_KERNEL package information!"

fi

report "  making kernel-$kver the kdump kernel"

# find the vmlinux version info for the latest kernel package

vmlinux_version=$(vmlinux_ver $kver)

if [ -z "$vmlinux_version" ]; then

    fatal "  Can't get vmlinux version!"

fi

# now edit the /etc/sysconfig/kdump file

sed -e "s/^KDUMP_KERNELVER.*$/KDUMP_KERNELVER=\"$vmlinux_version\"/" \

    /etc/sysconfig/kdump >/tmp/kdump.$$

mv /etc/sysconfig/kdump /etc/sysconfig/kdump.save && \

    mv /tmp/kdump.$$ /etc/sysconfig/kdump

# if requested, update the grub entries for the rt kernels

if [ $dogrub = 1 ]; then

    rtver=$(latest_package_ver kernel-rt)

    if [ -z "$rtver" ]; then

	fatal "  Can't find kernel-rt package information!"

    fi

    # RHEL-RT kernel

    kernels=$(find_rt_kernel_indexes_rhel_rt)

    if [ ! -z $kernels ]; then

        report "  adding 'crashkernel=auto' arg to grub entries: $kernels"

        /sbin/grubby --update-kernel=$kernels --args="crashkernel=auto"

    fi

fi

exit $?