Lee Clagett
4 years ago
parent
8185054db7
commit
c26c93019a
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// Copyright (c) 2020, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#pragma once
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#include <cassert>
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#include <cstdint>
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#include <cstring>
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#include "byte_slice.h"
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#include "span.h"
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namespace epee
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{
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/*! \brief A partial drop-in replacement for `std::ostream`.
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Only a few base `std::ostream` functions are implemented - enough for
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rapidjson output currently.
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Advantages over `std::stringstream` or `rapidjson::StringBuffer`:
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- The internal buffer can be taken without a copy.
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- The internal buffer can be given to `byte_slice` with zero
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allocations for reference count.
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- The internal buffer can be given to `zmq_msg_data_init` without a
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copy or extra allocation.
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an additional advantage over `std::stringstream`:
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- Construction is significantly faster - the global `std::locale`
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does not have to be acquired (global thread synchronization), and
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an extra allocation for `std::stringbuf` is not needed (which is an
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addition to the buffer inside of that object). */
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class byte_stream
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{
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byte_buffer buffer_; //! Beginning of buffer
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std::uint8_t* next_write_; //! Current write position
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const std::uint8_t* end_; //! End of buffer
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std::size_t increase_size_; //! Minimum buffer size increase
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//! \post `requested <= available()`
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void overflow(const std::size_t requested);
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//! Ensures that at least `requested` bytes are available.
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void check(const std::size_t requested)
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{
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const std::size_t remaining = available();
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if (remaining < requested)
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overflow(requested);
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}
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public:
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using char_type = std::uint8_t;
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using Ch = char_type;
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//! \return Default minimum size increase on buffer overflow
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static constexpr std::size_t default_increase() noexcept { return 4096; }
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//! Increase internal buffer by at least `byte_stream_increase` bytes.
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byte_stream() noexcept
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: byte_stream(default_increase())
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{}
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//! Increase internal buffer by at least `increase` bytes.
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explicit byte_stream(const std::size_t increase) noexcept
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: buffer_(nullptr),
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next_write_(nullptr),
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end_(nullptr),
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increase_size_(increase)
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{}
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byte_stream(byte_stream&& rhs) noexcept;
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~byte_stream() noexcept = default;
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byte_stream& operator=(byte_stream&& rhs) noexcept;
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//! \return The minimum increase size on buffer overflow
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std::size_t increase_size() const noexcept { return increase_size_; }
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const std::uint8_t* data() const noexcept { return buffer_.get(); }
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std::uint8_t* tellp() const noexcept { return next_write_; }
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std::size_t available() const noexcept { return end_ - next_write_; }
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std::size_t size() const noexcept { return next_write_ - buffer_.get(); }
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std::size_t capacity() const noexcept { return end_ - buffer_.get(); }
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//! Compatibility with rapidjson.
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void Flush() const noexcept
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{}
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/*! Reserve at least `more` bytes.
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\post `size() + more <= available()`.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void reserve(const std::size_t more)
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{
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check(more);
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}
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/*! Copy `length` bytes starting at `ptr` to end of stream.
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\throw std::range_error If exceeding max size_t value.
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\throw std::bad_alloc If allocation fails. */
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void write(const std::uint8_t* ptr, const std::size_t length)
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{
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check(length);
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std::memcpy(tellp(), ptr, length);
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next_write_ += length;
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}
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/*! Copy `length` bytes starting at `ptr` to end of stream.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void write(const char* ptr, const std::size_t length)
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{
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write(reinterpret_cast<const std::uint8_t*>(ptr), length);
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}
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/*! Copy `source` to end of stream.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void write(const epee::span<const std::uint8_t> source)
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{
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write(source.data(), source.size());
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}
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/*! Copy `source` to end of stream.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void write(const epee::span<const char> source)
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{
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write(source.data(), source.size());
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}
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/*! Copy `ch` to end of stream.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void put(const std::uint8_t ch)
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{
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check(1);
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put_unsafe(ch);
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}
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/*! Copy `ch` to end of stream. Provides rapidjson compatability.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void Put(const std::uint8_t ch)
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{
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put(ch);
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}
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/*! Writes `ch` to end of stream without runtime capacity checks. Must use
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`reserve` before calling this function. Primarily for use with
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rapidjson, which writes characters at a time but reserves memory in
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blocks. Most applications want to use `put` or `write`. */
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void put_unsafe(const std::uint8_t ch) noexcept
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{
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assert(1 <= available());
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*(tellp()) = ch;
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++next_write_;
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}
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/*! Write `ch` to end of stream `count` times.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void put_n(const std::uint8_t ch, const std::size_t count)
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{
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check(count);
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std::memset(tellp(), count, ch);
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next_write_ += count;
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}
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/*! Copy `ch` to end of stream.
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\throw std::range_error if exceeding max `size_t` value.
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\throw std::bad_alloc if allocation fails. */
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void push_back(const std::uint8_t ch)
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{
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put(ch);
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}
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//! \return The internal buffer. \post `size() == capacity() == 0`.
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byte_buffer take_buffer() noexcept;
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};
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//! Compatability/optimization for rapidjson.
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inline void PutReserve(byte_stream& dest, const std::size_t length)
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{
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dest.reserve(length);
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}
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//! Compatability/optimization for rapidjson.
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inline void PutUnsafe(byte_stream& dest, const std::uint8_t ch)
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{
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dest.put_unsafe(ch);
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}
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//! Compability/optimization for rapidjson.
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inline void PutN(byte_stream& dest, const std::uint8_t ch, const std::size_t count)
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{
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dest.put_n(ch, count);
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}
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} // epee
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@ -0,0 +1,93 @@
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// Copyright (c) 2020, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "byte_stream.h"
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#include <algorithm>
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#include <limits>
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#include <utility>
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#include <iostream>
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namespace epee
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{
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void byte_stream::overflow(const std::size_t requested)
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{
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// Recalculating `need` bytes removes at least one instruction from every
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// inlined `put` call in header
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assert(available() < requested);
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const std::size_t need = requested - available();
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const std::size_t len = size();
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const std::size_t cap = capacity();
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const std::size_t increase = std::max(need, increase_size());
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next_write_ = nullptr;
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end_ = nullptr;
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buffer_ = byte_buffer_increase(std::move(buffer_), cap, increase);
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if (!buffer_)
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throw std::bad_alloc{};
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next_write_ = buffer_.get() + len;
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end_ = buffer_.get() + cap + increase;
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}
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byte_stream::byte_stream(byte_stream&& rhs) noexcept
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: buffer_(std::move(rhs.buffer_)),
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next_write_(rhs.next_write_),
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end_(rhs.end_),
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increase_size_(rhs.increase_size_)
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{
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rhs.next_write_ = nullptr;
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rhs.end_ = nullptr;
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}
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byte_stream& byte_stream::operator=(byte_stream&& rhs) noexcept
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{
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if (this != std::addressof(rhs))
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{
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buffer_ = std::move(rhs.buffer_);
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next_write_ = rhs.next_write_;
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end_ = rhs.end_;
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increase_size_ = rhs.increase_size_;
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rhs.next_write_ = nullptr;
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rhs.end_ = nullptr;
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}
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return *this;
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}
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byte_buffer byte_stream::take_buffer() noexcept
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{
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byte_buffer out{std::move(buffer_)};
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next_write_ = nullptr;
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end_ = nullptr;
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return out;
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}
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}
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