#!/bin/bash
#
# cpictl - Configure the Control-Program-Information (CPI) settings
#
# This is an internal helper script that is used by the "cpi.service"
# systemd unit and the "90-cpi.rules" udev rule.
#
# The bash shell is really needed. Other shells have different ideas of how
# bitwise operators work.
#
# Copyright 2017 IBM Corp.
#
# s390-tools is free software; you can redistribute it and/or modify
# it under the terms of the MIT license. See LICENSE for details.
#

readonly CPI_LOCK="/var/lock/cpictl.lock"

readonly PRG="${0##*/}"

readonly SYSTEM_LEVEL_PATH="/sys/firmware/cpi/system_level"
readonly SYSTEM_TYPE_PATH="/sys/firmware/cpi/system_type"
readonly SYSTEM_NAME_PATH="/sys/firmware/cpi/system_name"
readonly SYSPLEX_NAME_PATH="/sys/firmware/cpi/sysplex_name"
readonly CPI_SET="/sys/firmware/cpi/set"

declare LEVEL
declare TYPE
declare NAME
declare SYSPLEX

declare -i DRYRUN=0

# Exit codes
readonly EXIT_SUCCESS=0
readonly EXIT_FAILURE=1
readonly EXIT_ARG_TOO_LONG=3
readonly EXIT_INVALID_CHARS=4

print_help_and_exit()
{
	cat <<EndHelp
Usage: $PRG [OPTIONS]

Configure the Control-Program-Information (CPI) settings.

  -b, --set-bit BIT      Set and commit the bit BIT in the flags
  -e, --environment      Set and commit the system type, level, name and
                         sysplex name with values taken from environment
                         variables
  -h, --help             Print this help, then exit
  -L, --level LEVEL      Set and commit OS level to LEVEL (format xx.yy.zzABCD)
  -N, --name SYSTEM      Set and commit the system name to SYSTEM
  -S, --sysplex SYSPLEX  Set and commit the sysplex name to SYSPLEX
  -T, --type TYPE        Set and commit OS type to TYPE
  -v, --version          Print version information, then exit
  --commit               Ignore all other options and commit any uncommitted
                         values
  --dry-run              Do not actually set or commit anything, but show what
                         would be done
  --show                 Ignore all other options and show current (possibly
                         uncommitted) values

Environment variables used for the --defaults option:
  CPI_SYSTEM_TYPE, CPI_SYSTEM_LEVEL, CPI_SYSTEM_NAME, CPI_SYSPLEX_NAME

Available bits for the --set-bit option:
  kvm: Indicate that system is a KVM host

The maximum length for system type, system name, and sysplex name is 8
characters. The allowed characters are: [A-Z0-9 @#$]

This tool should be called as root.
EndHelp
	exit $EXIT_SUCCESS
}

print_version_and_exit()
{
	cat <<EndVersion
$PRG: Configure the CPI settings version %S390_TOOLS_VERSION%
Copyright IBM Corp. 2017
EndVersion
	exit $EXIT_SUCCESS
}

cpi_show()
{
	cat <<-EndShow
	System type:  $(cat "$SYSTEM_TYPE_PATH")
	System level: $(cat "$SYSTEM_LEVEL_PATH")
	System name:  $(cat "$SYSTEM_NAME_PATH")
	Sysplex name: $(cat "$SYSPLEX_NAME_PATH")
	EndShow
}

print_parse_error_and_exit()
{
	echo "Try '$PRG --help' for more information." >&2
	exit $EXIT_FAILURE
}

fail_with()
{
	echo "$1" >&2
	echo "Try '$PRG --help' for more information." >&2
	exit ${2:-$EXIT_FAILURE}
}

cpi_commit()
{
	echo 1 > "$CPI_SET"
}

do_length_check()
{
	[ ${#1} -gt 8 ] &&
		fail_with "$PRG: Specified $2 too long. The maximum length is 8 characters." $EXIT_ARG_TOO_LONG
}

do_character_check()
{
	echo "$1" | grep -q -E '^[a-zA-Z0-9@#$ ]*$' ||
		fail_with "$PRG: Invalid characters in $2. Valid characters are: A-Z0-9 @#$" $EXIT_INVALID_CHARS
}

cpi_set_bit()
{
	LEVEL=$(printf '0x%x' $((LEVEL | (1 << (63 - $1)) )) )
}

cpi_set_oslevel()
{
	local kver=$(echo "${1:-$(uname -r)}" | grep -E -o '^[0-9]+[.][0-9]+[.][0-9]+')
	local maj=$((${kver%%.*} % 256))
	local min=${kver#*.}
	min=$((${min%.*} % 256))
	local rev=$((${kver##*.} % 256))
	local hexlevel=$(printf '0x%02x%02x%02x' $maj $min $rev)
	LEVEL=$(printf '0x%016x' $(((LEVEL & 0xFFFFFFFFFF000000) | hexlevel)))
}

cpi_set_type()
{
	TYPE="$1"
	do_length_check "$TYPE" "system type"
	do_character_check "$TYPE" "system type"
}

cpi_set_sysplex()
{
	SYSPLEX="$1"
	do_length_check "$SYSPLEX" "sysplex name"
	do_character_check "$SYSPLEX" "sysplex name"
}

cpi_set_name()
{
	NAME="$1"
	do_length_check "$NAME" "system name"
	do_character_check "$NAME" "system name"
}

# cpictl starts here

if [ $# -le 0 ]; then
	echo "$PRG: No parameters specified"
	print_parse_error_and_exit
fi

opts=$(getopt -o b:ehL:N:S:T:v -l set-bit:,environment,help,level:,name:,sysplex:,type:,commit,dry-run,show,version -n $PRG -- "$@")
if [ $? -ne 0 ]; then
	print_parse_error_and_exit
fi

# This guarantees that only one instance will be running, and will serialize
# the execution of multiple instances
[ -e "$CPI_LOCK" -a ! -w "$CPI_LOCK" ] &&
	fail_with "$PRG: Cannot access lock file: $CPI_LOCK"
[ ! -w "${CPI_LOCK%/*}" ] &&
	fail_with "$PRG: Cannot access lock file: $CPI_LOCK"

exec 9<> "$CPI_LOCK"
flock -x 9

# Get current values from sys/firmware
read LEVEL < "$SYSTEM_LEVEL_PATH"
read TYPE < "$SYSTEM_TYPE_PATH"
read NAME < "$SYSTEM_NAME_PATH"
read SYSPLEX < "$SYSPLEX_NAME_PATH"

# Parse command line options: Use eval to remove getopt quotes
eval set -- $opts
while [ -n $1 ]; do
	case "$1" in
	--help|-h)
		print_help_and_exit
		;;
	--version|-v)
		print_version_and_exit
		;;
	-b|--set-bit)
		case "$2" in
		kvm)
			cpi_set_bit 0
			;;
		*)
			fail_with "$PRG: Unknown bit \"$2\" for the $1 option"
			;;
		esac
		shift 2
		;;
	-L|--level)
		cpi_set_oslevel "$2"
		shift 2
		;;
	-e|--environment)
		cpi_set_type "$CPI_SYSTEM_TYPE"
		cpi_set_name "$CPI_SYSTEM_NAME"
		cpi_set_oslevel "$CPI_SYSTEM_LEVEL"
		cpi_set_sysplex "$CPI_SYSPLEX_NAME"
		shift
		;;
	-T|--type)
		cpi_set_type "$2"
		shift 2
		;;
	-S|--sysplex)
		cpi_set_sysplex "$2"
		shift 2
		;;
	-N|--name)
		cpi_set_name "$2"
		shift 2
		;;
	--show)
		cpi_show
		exit $EXIT_SUCCESS
		;;
	--commit)
		cpi_commit
		exit $EXIT_SUCCESS
		;;
	--dry-run)
		DRYRUN=1
		shift
		;;
	--)
		shift
		break
		;;
	*)
		break;
		;;
	esac
done

# Print settings for --dry-run or commit them to sysfs otherwise

if [ $DRYRUN -eq 1 ]; then
	cat <<-EndDryrun
	System type:  $TYPE
	System level: $LEVEL
	System name:  $NAME
	Sysplex name: $SYSPLEX
	EndDryrun
else
	echo "$LEVEL" > "$SYSTEM_LEVEL_PATH"
	echo "$TYPE" > "$SYSTEM_TYPE_PATH"
	echo "$NAME" > "$SYSTEM_NAME_PATH"
	echo "$SYSPLEX" > "$SYSPLEX_NAME_PATH"
	cpi_commit
fi

exit $EXIT_SUCCESS