// Copyright (c) 2021-2024, 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