#!/bin/bash

function dev_from_partnum()
{
    local drive="$1"
    local partnum="$2"
    partition="$drive""$partnum"
    until [ -b "$drive"1 ] || [ -b "$drive"p1 ]; do
        sleep 1
    done
    if [ ! -b "$partition" ]; then
        partition="$drive"p"$partnum"
        if [ ! -b "$partition" ]; then
            echo "Can't find ${partnum}-th partition for \"$drive\""

            exit 1
        fi
    fi
}

function mount_efi()
{
    local drive="$1"

    dev_from_partnum "$drive" 1

    unset mnt
    mnt="$(mktemp -d)"
    if ! mount "$partition" "$mnt"; then
        mkfs.vfat "$partition"
        if ! mount "$partition" "$mnt"; then
            echo "Can't mount \"$partition\""
            cleanup_mnt
            exit 1
        fi
    fi 
}

function umount_efi()
{
    umount "$mnt"
    sync
    rmdir "$mnt"
}

function install_syslinux()
{
    local drive="$1"

    apt -yq install syslinux syslinux-common syslinux-efi

    dd bs=440 count=1 conv=notrunc \
        if=/usr/lib/syslinux/mbr/gptmbr.bin of="$drive"
    sync

    mount_efi "$drive"

    # legacy
    mkdir -p "$mnt"/syslinux
    cp /usr/lib/syslinux/modules/bios/*.c32 "$mnt"/syslinux/

    # UEFI
    mkdir -p "$mnt"/EFI/BOOT
    cp /usr/lib/SYSLINUX.EFI/efi64/syslinux.efi "$mnt"/EFI/BOOT/BOOTX64.EFI
    cp /usr/lib/syslinux/modules/efi64/ldlinux.e64 "$mnt"/EFI/BOOT/ldlinux.e64
    cp /usr/lib/syslinux/modules/efi64/*.c32 "$mnt"/EFI/BOOT/
    cp syslinux/{mainmenu,syslinux}.cfg "$mnt"/syslinux
    cp syslinux/syslx64.cfg "$mnt"/EFI/BOOT

    umount_efi

    dev_from_partnum "$drive" 1
    syslinux "$partition"
}

# vim: set ft=sh: