# fn2vma path function => vma_in_hex
fn2vma() {
    nm -CD "$1" | grep " $2\$" | grep -o "^[^ ]*" | sed -e 's/^0*/0x0/'
}

# vma2offset path vma => file_offset_in_dec
vma2offset() {
    local query="$2"
    objdump -h "$1" | grep -Po "( +[0-9a-f]+){4}" | sed -Ee 's/ +0+/ 0x0/g' |
        while read line; do
            read size vma lma offset <<< "$line"
            local vma_end=$(("$vma" + "$size"))
            if [[ "$query" -ge "$vma" ]] && [[ "$query" -le "$vma_end" ]]; then
                echo $(("$query" - "$vma" + "$offset"))
                return
            fi
        done
}

# patch_bytes path offset bytes_in_hex
patch_binary() {
    local patch_path=$(mktemp)
    echo -ne "$3" > "$patch_path"
    local patch_length=$(stat --printf="%s" "$patch_path")

    local backup_path=$(mktemp)
    cp "$1" "$backup_path" -f

    local part2_begin="$2"
    local part3_begin=$(("$part2_begin" + "$patch_length" + 1))
    head "$backup_path" -c "$part2_begin" > "$1"
    cat "$patch_path" >> "$1"
    tail "$backup_path" -c "+$part3_begin" >> "$1"

    rm "$patch_path" "$backup_path"
}

patch() {
    local binary="$1"
    local symbol="$2"
    local content="$3"

    local vma=$(fn2vma "$binary" "$symbol")
    [[ -z "$vma" ]] && echo "Symbol not found" && exit 1
    echo "VMA of $symbol = $vma"

    local offset=$(vma2offset "$binary" "$vma")
    [[ -z "$vma" ]] && echo "Offset not found" && exit 2
    echo "File offset = $offset"

    patch_binary "$binary" "$offset" "$content"
    echo "Patch completed"
}

patch_understand() {
  patch "$1" \
        "HeliosLicenseManager::testGuiLicense(int&, HeliosLicenseManager::LoginStatus&, bool)" \
        "\xb8\x01\x00\x00\x00\xc3"

  patch "$1" \
        "STI::MaintainApp::TestHeliosHeartbeat()" \
        "\xc3"
}