#!/usr/bin/false
# This script is for SOURCING ONLY

# Error codes
export RELIANT_OK=0
export RELIANT_FAIL=1
export RELIANT_SECURITY_FAIL=2
export RELIANT_BUG=3

# Boolean values
export RELIANT_TRUE=1
export RELIANT_FALSE=0


# Prints $1 to stderr
reliant_warn() {
    echo "[WARN]: $*" 1>&2
}
reliant_error() {
    echo "[ERROR]: $*" 1>&2
}

# Converts the error code in $1 to a string
reliant_err2str() {
    case "$1" in
	0) echo "OK" ;;
	1) echo "FAIL" ;;
	2) echo "SECURITY FAIL" ;;
	3) echo "BUG" ;;
	*) echo "UNKNOWN" ;;
    esac
}

# Performs the emergency shutdown operation
reliant_emergency_shutdown() {
    echo 3 > /proc/sys/vm/drop_caches 2>/dev/null || true
    dmesg -C                                      || true
    systemctl poweroff                            || true
    sudo poweroff                                 || true
    poweroff
}

# Fails with a message from $1 and prints the help string if available
reliant_fail() {
    reliant_error "$*"
  
    # Check if help information has been defined by the main script
    if [ "$(type reliant_print_help | head -1)" = "reliant_print_help is a function" ]; then
	echo
	reliant_print_help
    else
	echo
	echo "Help is not available."
    fi
    
    exit 1
}

# Reads the configuration file from the path supplied in $1
reliant_read_config() {
    # Get the filename
    if [ "$#" -ne 1 ]; then
	reliant_error "reliant_read_config: invalid number of arguments, expected 1, got $#"
	return 1
    fi
    
    # Ensure it exists
    if [ -z "$1" ] || [ ! -f "$1" ]; then
	reliant_error "reliant_read_config: configuration file $1 does not exist"
	return 1
    fi

    # Default values
    RELIANT_SKIP_CHECKSUM=""
    RELIANT_SPARSE_SAMPLES=512
    RELIANT_RW_DOMAINS="sys-net sys-whonix"
    RELIANT_PARANOID_="false"

    # Attempt to read it
    RELIANT_CONFIG_FILE="$1"
    while IFS="=" read -r key value; do
	case "$key" in
	    "RELIANT_SECURE_DEVICE")  RELIANT_SECURE_DEVICE="$value"  ;;
	    "RELIANT_SKIP_CHECKSUM")  RELIANT_SKIP_CHECKSUM="$value"  ;;
	    "RELIANT_SPARSE_SAMPLES") RELIANT_SPARSE_SAMPLES="$value" ;;
	    "RELIANT_RW_DOMAINS")     RELIANT_RW_DOMAINS="$value"     ;;
	    "RELIANT_PARANOID")       RELIANT_PARANOID_="$value"      ;;
	    *) reliant_error "reliant_read_config: invalid key in config: $key"; return 1 ;;
        esac
    done < "$RELIANT_CONFIG_FILE"

    # Ensure the required values have been assigned
    if [ -z "$RELIANT_SECURE_DEVICE" ]; then
	reliant_error "reliant_read_config: RELIANT_SECURE_DEVICE not present in config"
	return 1
    fi

    # Perform some validation
    if [ ! -b "$RELIANT_SECURE_DEVICE" ]; then
	reliant_error "reliant_read_config: $RELIANT_SECURE_DEVICE does not exist or is not a block device"
	return 1
    fi

    IFS=' '
    for device in $RELIANT_SKIP_CHECKSUM; do
	if [ ! -b "$device" ]; then
	    reliant_error "reliant_read_config: $device does not exist or is not a block device"
	    return 1
	fi
    done

    # RELIANT_PARANOID must be a boolean type
    case "$RELIANT_PARANOID_" in
	"true")  RELIANT_PARANOID=$RELIANT_TRUE ;;
	"false") RELIANT_PARANOID=$RELIANT_FALSE ;;
	*) reliant_error "reliant_read_config: invalid value for RELIANT_PARANOID: $RELIANT_PARANOID, expected true or false"; return 1 ;;
    esac

    # RELIANT_SPARSE_SAMPLES must be an integer
    if ! [ "$RELIANT_SPARSE_SAMPLES" -eq "$RELIANT_SPARSE_SAMPLES" ] 2>/dev/null; then
	reliant_error "reliant_read_config: invalid value for RELIANT_SPARSE_SAMPLES: $RELIANT_SPARSE_SAMPLES, expected an integer"
	return 1
    fi

    # Export the configuration
    export RELIANT_SPARSE_SAMPLES="$RELIANT_SPARSE_SAMPLES"
    export RELIANT_SECURE_DEVICE="$RELIANT_SECURE_DEVICE"
    export RELIANT_SKIP_CHECKSUM="$RELIANT_SKIP_CHECKSUM"
    export RELIANT_RW_DOMAINS="$RELIANT_RW_DOMAINS"
    export RELIANT_PARANOID="$RELIANT_PARANOID"

    # Done
    return 0
}

# We assume that when sourcing this file, the origin script is likely
# going to need the global configuration, so import it immediately
reliant_read_config /etc/reliant.conf