#!/bin/bash

# GRUB 2 template
G2TEMPL="20_memtest86+"

# GRUB 2 environment file
CONF_FILE="/etc/memtest86+.conf"

# GRUB2 configuration file
GRUB2CFG="/boot/grub2/grub.cfg"

# GRUB2 environment variable to control image type
CONF_VAR="INSTALL_ELF"

# whether to install ELF image
ELF=1

if [ "$1" = "--help" -o "$1" = "-h" ]; then
    cat <<:EOF
Usage:
  memtest-setup [-b|-e|-h]
  memtest-setup [--bin|--elf|--help]

The memtest-setup utility installs Memtest86+ into GRUB 2 boot loader menu.
It installs GRUB 2 template into /etc/grub.d directory.

GRUB 2 configuration file needs to be regenerated manually by running:

  grub2-mkconfig -o $GRUB2CFG

This is not done automatically because it could overwrite any custom changes
in GRUB 2 configuration file.

Options:
  -b, --bin     Install a binary Memtest86+ image.
  -e, --elf     Install an ELF Memtest86+ image (the default).
  -h, --help    Print a help message and exit.

:EOF
    exit 0
fi

[ "$1" = "-b" -o "$1" = "--bin" ] && ELF=0
[ "$1" = "-e" -o "$1" = "--elf" ] && ELF=1

if [ -d /sys/firmware/efi ]; then
    echo "ERROR: memtest86+ does not support EFI platforms."
    exit 254
fi

if [ ! -r "$GRUB2CFG" ]; then
   echo "ERROR: unable to read grub configuration file. Do you have enough permissions?"
   echo "Try to run as root."
   exit 249
fi

# install GRUB 2 template
if [ ! -d /etc/grub.d ]; then
    echo "ERROR: unable to find /etc/grub.d"
    exit 253
fi
if [ ! -r /usr/share/memtest86+/$G2TEMPL ]; then
    echo "ERROR: unable to find GRUB 2 template."
    exit 251
fi
if ! cp /usr/share/memtest86+/$G2TEMPL /etc/grub.d; then
    echo "ERROR: unable to copy GRUB 2 template, do you have write permission to"
    echo "/etc/grub.d?"
    # EX_IOERR
    exit 74
fi
if [ ! -w "$CONF_FILE" ]
then
    echo "ERROR: file '$CONF_FILE' is not writable."
    exit 250
fi
chmod a+x /etc/grub.d/$G2TEMPL
echo "GRUB 2 template installed."
echo "Do not forget to regenerate your grub.cfg by:"
echo "  # grub2-mkconfig -o $GRUB2CFG"

# update/add configuration variable to the configuration file
if grep -q "^\s*$CONF_VAR\s*=" "$CONF_FILE"
then
    sed -i "/^\s*$CONF_VAR\s*=/ s/\(\s*$CONF_VAR\s*=[\"']\?\)[^\"']*\([\"']\?\s*\)/\1${ELF}\2/g" "$CONF_FILE"
else
    echo "$CONF_VAR=\"$ELF\"" >> "$CONF_FILE"
fi

echo "Setup complete."