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// Copyright (c) 2021, The Monero Project
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#pragma once
#include <cstdint>
#include <type_traits>
#define WIRE_DECLARE_BLOB_NS(type) \
template<> \
struct is_blob<type> \
: std::true_type \
{}
#define WIRE_DECLARE_BLOB(type) \
namespace wire { WIRE_DECLARE_BLOB_NS(type); }
#define WIRE_DECLARE_OPTIONAL_ROOT(type) \
template<> \
struct is_optional_root<type> \
: std::true_type \
{}
namespace wire
{
template<typename T>
struct unwrap_reference
{
using type = std::remove_cv_t<std::remove_reference_t<T>>;
};
template<typename T>
struct unwrap_reference<std::reference_wrapper<T>>
: std::remove_cv<T>
{};
template<typename T>
using unwrap_reference_t = typename unwrap_reference<T>::type;
/*! Mark `T` as an array for writing, and reading when
`default_min_element_size<T::value_type>::value != 0`. See `array_` in
`wrapper/array.h`. */
template<typename T>
struct is_array : std::false_type
{};
/*! Mark `T` as fixed binary data for reading+writing. Concept requirements
for reading:
* `T` must be compatible with `epee::as_mut_byte_span` (`std::is_pod<T>`
and no padding).
Concept requirements for writing:
* `T` must be compatible with `epee::as_byte_span` (std::is_pod<T>` and
no padding). */
template<typename T>
struct is_blob : std::false_type
{};
/*! Forces field to be optional when empty. Concept requirements for `T` when
`is_optional_on_empty<T>::value == true`:
* must have an `empty()` method that toggles whether the associated
`wire::field_<...>` is omitted by the `wire::writer`.
* must have a `clear()` method where `empty() == true` upon completion,
used by the `wire::reader` when the `wire::field_<...>` is omitted. */
template<typename T>
struct is_optional_on_empty
: is_array<T> // all array types in old output engine were optional when empty
{};
//! When `T` is being read as root object, allow an empty read buffer.
template<typename T>
struct is_optional_root
: std::is_empty<T>
{};
//! A constraint for `wire_read::array` where a max of `N` elements can be read.
template<std::size_t N>
struct max_element_count
: std::integral_constant<std::size_t, N>
{
// The threshold is low - min_element_size is a better constraint metric
static constexpr std::size_t max_bytes() noexcept { return 512 * 1024; } // 512 KiB
//! \return True if `N` C++ objects of type `T` are below `max_bytes()` threshold.
template<typename T>
static constexpr bool check() noexcept
{
return N <= (max_bytes() / sizeof(T));
}
};
//! A constraint for `wire_read::array` where each element must use at least `N` bytes on the wire.
template<std::size_t N>
struct min_element_size
: std::integral_constant<std::size_t, N>
{
static constexpr std::size_t max_ratio() noexcept { return 4; }
//! \return True if C++ object of type `T` with minimum wire size `N` is below `max_ratio()`.
template<typename T>
static constexpr bool check() noexcept
{
return N != 0 ? ((sizeof(T) / N) <= max_ratio()) : false;
}
};
/*! Trait used in `wire/read.h` for default `min_element_size` behavior based
on an array of `T` objects and `R` reader type. This trait can be used
instead of the `wire::array(...)` (and associated macros) functionality, as
it sets a global value. The last argument is for `enable_if`. */
template<typename R, typename T, typename = void>
struct default_min_element_size
: std::integral_constant<std::size_t, 0>
{};
//! If `T` is a blob, a safe default for all formats is the size of the blob
template<typename R, typename T>
struct default_min_element_size<R, T, std::enable_if_t<is_blob<T>::value>>
: std::integral_constant<std::size_t, sizeof(T)>
{};
// example usage : `wire::sum(std::size_t(wire::available(fields))...)`
inline constexpr int sum() noexcept
{
return 0;
}
template<typename T, typename... U>
inline constexpr T sum(const T head, const U... tail) noexcept
{
return head + sum(tail...);
}
template<typename... T>
using min_element_sizeof = min_element_size<sum(sizeof(T)...)>;
//! If container has no `reserve(0)` function, this function is used
template<typename... T>
inline void reserve(const T&...) noexcept
{}
//! Container has `reserve(std::size_t)` function, use it
template<typename T>
inline auto reserve(T& container, const std::size_t count) -> decltype(container.reserve(count))
{ return container.reserve(count); }
//! If `T` has no `empty()` function, this function is used
template<typename... T>
inline constexpr bool empty(const T&...) noexcept
{
static_assert(sum(is_optional_on_empty<T>::value...) == 0, "type needs empty method");
return false;
}
//! `T` has `empty()` function, use it
template<typename T>
inline auto empty(const T& container) -> decltype(container.empty())
{ return container.empty(); }
//! If `T` has no `clear()` function, this function is used
template<typename... T>
inline void clear(const T&...) noexcept
{
static_assert(sum(is_optional_on_empty<T>::value...) == 0, "type needs clear method");
}
//! `T` has `clear()` function, use it
template<typename T>
inline auto clear(T& container) -> decltype(container.clear())
{ return container.clear(); }
} // wire
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