monero/tests/unit_tests/varint.cpp

// Copyright (c) 2014-2024, The Monero Project
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// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers

#include <cstring>
#include <cstdint>
#include <cstdio>
#include <iostream>
#include <vector>
#include <boost/foreach.hpp>
#include "cryptonote_basic/cryptonote_basic.h"
#include "cryptonote_basic/cryptonote_basic_impl.h"
#include "serialization/binary_archive.h"
#include "serialization/json_archive.h"
#include "serialization/debug_archive.h"
#include "serialization/variant.h"
#include "serialization/containers.h"
#include "serialization/binary_utils.h"
#include "gtest/gtest.h"
using namespace std;

TEST(varint, equal)
{
  for (uint64_t idx = 0; idx < 65537; ++idx)
  {
    char buf[12];
    char *bufptr = buf;
    tools::write_varint(bufptr, idx);
    uint64_t bytes = bufptr - buf;
    ASSERT_TRUE (bytes > 0 && bytes <= sizeof(buf));

    uint64_t idx2;
    std::string s(buf, bytes);
    int read = tools::read_varint(s.begin(), s.end(), idx2);
    ASSERT_EQ (read, bytes);
    ASSERT_TRUE(idx2 == idx);
  }
}

TEST(varint, max_uint64_t_bytes)
{
  unsigned char bytes[100]{};
  unsigned char *p = bytes;
  tools::write_varint(p, std::numeric_limits<std::uint64_t>::max());
  std::size_t i = 0;
  while (bytes[i]) ++i;
  ASSERT_EQ(10, i);        // tests size of max 64-bit uint
  ASSERT_EQ(bytes + i, p); // tests iterator is modified in-place
}

template <typename T>
static void subtest_varint_byte_size_for_single_value(const std::size_t expected_bytes, const T val)
{
  static_assert(std::is_integral_v<T> && std::is_unsigned_v<T>);
  static constexpr int DIGITS = std::numeric_limits<T>::digits;
  static_assert(DIGITS == CHAR_BIT * sizeof(T));
  static_assert(sizeof(T));
  static_assert(sizeof(T) <= 8); // 64-bit or less

  unsigned char bytes[100]{};
  unsigned char *p = bytes;
  tools::write_varint(p, val);
  ASSERT_EQ(expected_bytes, p - bytes);
  ASSERT_EQ(expected_bytes, tools::get_varint_byte_size(val));
}

template <typename T>
static void subtest_varint_byte_size_for_type()
{
  static_assert(std::is_integral_v<T> && std::is_unsigned_v<T>);
  static constexpr int DIGITS = std::numeric_limits<T>::digits;
  static_assert(DIGITS == CHAR_BIT * sizeof(T));
  static_assert(sizeof(T));

  for (T n = 0; n < 128; ++n)
  {
    subtest_varint_byte_size_for_single_value(1, n);
  }

  for (T n = 128; n < 255; ++n)
  {
    subtest_varint_byte_size_for_single_value(2, n);
  }

  subtest_varint_byte_size_for_single_value(2, T{255});

  if constexpr (DIGITS > 8)
  {
    static_assert(DIGITS >= 16);
    for (T n = 256; n < 16384; ++n)
    {
      subtest_varint_byte_size_for_single_value(2, n);
    }

    for (T n = 16384; n < 65535; ++n)
    {
      subtest_varint_byte_size_for_single_value(3, n);
    }

    subtest_varint_byte_size_for_single_value(3, T{65535});

    if constexpr (DIGITS > 16)
    {
      static_assert(DIGITS >= 32);
      subtest_varint_byte_size_for_single_value(3, T{2097151});
      subtest_varint_byte_size_for_single_value(4, T{2097152});
      subtest_varint_byte_size_for_single_value(4, T{268435455});
      subtest_varint_byte_size_for_single_value(5, T{268435456});
      subtest_varint_byte_size_for_single_value(5, T{4294967295});

      if constexpr (DIGITS > 32)
      {
        static_assert(DIGITS >= 64);
        subtest_varint_byte_size_for_single_value(5, T{34359738367});
        subtest_varint_byte_size_for_single_value(6, T{34359738368});
        subtest_varint_byte_size_for_single_value(6, T{4398046511103});
        subtest_varint_byte_size_for_single_value(7, T{4398046511104});
        subtest_varint_byte_size_for_single_value(7, T{562949953421311});
        subtest_varint_byte_size_for_single_value(8, T{562949953421312});
        subtest_varint_byte_size_for_single_value(8, T{72057594037927935});
        subtest_varint_byte_size_for_single_value(9, T{72057594037927936});
        subtest_varint_byte_size_for_single_value(9, T{9223372036854775807});
        subtest_varint_byte_size_for_single_value(10, T{9223372036854775808ull});
        subtest_varint_byte_size_for_single_value(10, T{18446744073709551615ull});
      }
    }
  }
};

TEST(varint, get_varint_byte_size)
{
  subtest_varint_byte_size_for_type<std::uint8_t>();
  subtest_varint_byte_size_for_type<std::uint16_t>();
  subtest_varint_byte_size_for_type<std::uint32_t>();
  subtest_varint_byte_size_for_type<std::uint64_t>();
}