big_endian_unittest.cc

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/big_endian.h"

#include <stdint.h>

#include <limits>

#include "base/strings/string_piece.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {

TEST(ReadBigEndianTest, ReadSignedPositive) {
  uint8_t data[] = {0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x1A, 0x2A};
  int8_t s8 = 0;
  int16_t s16 = 0;
  int32_t s32 = 0;
  int64_t s64 = 0;
  ReadBigEndian(data, &s8);
  ReadBigEndian(data, &s16);
  ReadBigEndian(data, &s32);
  ReadBigEndian(data, &s64);
  EXPECT_EQ(0x0A, s8);
  EXPECT_EQ(0x0A0B, s16);
  EXPECT_EQ(int32_t{0x0A0B0C0D}, s32);
  EXPECT_EQ(int64_t{0x0A0B0C0D0E0F1A2All}, s64);
}

TEST(ReadBigEndianTest, ReadSignedNegative) {
  uint8_t data[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
  int8_t s8 = 0;
  int16_t s16 = 0;
  int32_t s32 = 0;
  int64_t s64 = 0;
  ReadBigEndian(data, &s8);
  ReadBigEndian(data, &s16);
  ReadBigEndian(data, &s32);
  ReadBigEndian(data, &s64);
  EXPECT_EQ(-1, s8);
  EXPECT_EQ(-1, s16);
  EXPECT_EQ(-1, s32);
  EXPECT_EQ(-1, s64);
}

TEST(ReadBigEndianTest, ReadUnsignedSigned) {
  uint8_t data[] = {0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0, 0xA1, 0xA2};
  uint8_t u8 = 0;
  uint16_t u16 = 0;
  uint32_t u32 = 0;
  uint64_t u64 = 0;
  ReadBigEndian(data, &u8);
  ReadBigEndian(data, &u16);
  ReadBigEndian(data, &u32);
  ReadBigEndian(data, &u64);
  EXPECT_EQ(0xA0, u8);
  EXPECT_EQ(0xA0B0, u16);
  EXPECT_EQ(0xA0B0C0D0, u32);
  EXPECT_EQ(0xA0B0C0D0E0F0A1A2ull, u64);
}

TEST(ReadBigEndianTest, TryAll16BitValues) {
  using signed_type = int16_t;
  uint8_t data[sizeof(signed_type)];
  for (int i = std::numeric_limits<signed_type>::min();
       i <= std::numeric_limits<signed_type>::max(); i++) {
    signed_type expected = i;
    signed_type actual = 0;
    WriteBigEndian(reinterpret_cast<char*>(data), expected);
    ReadBigEndian(data, &actual);
    EXPECT_EQ(expected, actual);
  }
}

TEST(BigEndianReaderTest, ReadsValues) {
  uint8_t data[] = {0,   1,   2,   3,   4,   5,    6,    7,    8,    9,   0xA,
                    0xB, 0xC, 0xD, 0xE, 0xF, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E};
  char buf[2];
  uint8_t u8;
  uint16_t u16;
  uint32_t u32;
  uint64_t u64;
  base::StringPiece piece;
  BigEndianReader reader(data, sizeof(data));

  EXPECT_TRUE(reader.Skip(2));
  EXPECT_EQ(data + 2, reader.ptr());
  EXPECT_EQ(reader.remaining(), sizeof(data) - 2);
  EXPECT_TRUE(reader.ReadBytes(buf, sizeof(buf)));
  EXPECT_EQ(0x2, buf[0]);
  EXPECT_EQ(0x3, buf[1]);
  EXPECT_TRUE(reader.ReadU8(&u8));
  EXPECT_EQ(0x4, u8);
  EXPECT_TRUE(reader.ReadU16(&u16));
  EXPECT_EQ(0x0506, u16);
  EXPECT_TRUE(reader.ReadU32(&u32));
  EXPECT_EQ(0x0708090Au, u32);
  EXPECT_TRUE(reader.ReadU64(&u64));
  EXPECT_EQ(0x0B0C0D0E0F1A2B3Cllu, u64);
  base::StringPiece expected(reinterpret_cast<const char*>(reader.ptr()), 2);
  EXPECT_TRUE(reader.ReadPiece(&piece, 2));
  EXPECT_EQ(2u, piece.size());
  EXPECT_EQ(expected.data(), piece.data());
}

TEST(BigEndianReaderTest, ReadsLengthPrefixedValues) {
  {
    uint8_t u8_prefixed_data[] = {8,   8,   9,    0xA,  0xB,  0xC,  0xD,
                                  0xE, 0xF, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E};
    BigEndianReader reader(u8_prefixed_data, sizeof(u8_prefixed_data));

    base::StringPiece piece;
    ASSERT_TRUE(reader.ReadU8LengthPrefixed(&piece));
    // |reader| should skip both a u8 and the length-8 length-prefixed field.
    EXPECT_EQ(reader.ptr(), u8_prefixed_data + 9);
    EXPECT_EQ(piece.size(), 8u);
    EXPECT_EQ(reinterpret_cast<const uint8_t*>(piece.data()),
              u8_prefixed_data + 1);
  }

  {
    uint8_t u16_prefixed_data[] = {0,    8,    0xD,  0xE,  0xF,
                                   0x1A, 0x2B, 0x3C, 0x4D, 0x5E};
    BigEndianReader reader(u16_prefixed_data, sizeof(u16_prefixed_data));
    base::StringPiece piece;
    ASSERT_TRUE(reader.ReadU16LengthPrefixed(&piece));
    // |reader| should skip both a u16 and the length-8 length-prefixed field.
    EXPECT_EQ(reader.ptr(), u16_prefixed_data + 10);
    EXPECT_EQ(piece.size(), 8u);
    EXPECT_EQ(reinterpret_cast<const uint8_t*>(piece.data()),
              u16_prefixed_data + 2);

    // With no data left, we shouldn't be able to
    // read another u8 length prefix (or a u16 length prefix,
    // for that matter).
    EXPECT_FALSE(reader.ReadU8LengthPrefixed(&piece));
    EXPECT_FALSE(reader.ReadU16LengthPrefixed(&piece));
  }

  {
    // Make sure there's no issue reading a zero-value length prefix.
    uint8_t u16_prefixed_data[3] = {};
    BigEndianReader reader(u16_prefixed_data, sizeof(u16_prefixed_data));
    base::StringPiece piece;
    ASSERT_TRUE(reader.ReadU16LengthPrefixed(&piece));
    EXPECT_EQ(reader.ptr(), u16_prefixed_data + 2);
    EXPECT_EQ(reinterpret_cast<const uint8_t*>(piece.data()),
              u16_prefixed_data + 2);
    EXPECT_EQ(piece.size(), 0u);
  }
}

TEST(BigEndianReaderTest, LengthPrefixedReadsFailGracefully) {
  // We can't read 0xF (or, for that matter, 0xF8) bytes after the length
  // prefix: there isn't enough data.
  uint8_t data[] = {0xF, 8,   9,    0xA,  0xB,  0xC,  0xD,
                    0xE, 0xF, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E};
  BigEndianReader reader(data, sizeof(data));
  base::StringPiece piece;
  EXPECT_FALSE(reader.ReadU8LengthPrefixed(&piece));
  EXPECT_EQ(data, reader.ptr());

  EXPECT_FALSE(reader.ReadU16LengthPrefixed(&piece));
  EXPECT_EQ(data, reader.ptr());
}

TEST(BigEndianReaderTest, RespectsLength) {
  uint8_t data[8];
  char buf[2];
  uint8_t u8;
  uint16_t u16;
  uint32_t u32;
  uint64_t u64;
  base::StringPiece piece;
  BigEndianReader reader(data, sizeof(data));
  // 8 left
  EXPECT_FALSE(reader.Skip(9));
  EXPECT_TRUE(reader.Skip(1));
  // 7 left
  EXPECT_FALSE(reader.ReadU64(&u64));
  EXPECT_TRUE(reader.Skip(4));
  // 3 left
  EXPECT_FALSE(reader.ReadU32(&u32));
  EXPECT_FALSE(reader.ReadPiece(&piece, 4));
  EXPECT_TRUE(reader.Skip(2));
  // 1 left
  EXPECT_FALSE(reader.ReadU16(&u16));
  EXPECT_FALSE(reader.ReadBytes(buf, 2));
  EXPECT_TRUE(reader.Skip(1));
  // 0 left
  EXPECT_FALSE(reader.ReadU8(&u8));
  EXPECT_EQ(0u, reader.remaining());
}

TEST(BigEndianReaderTest, SafePointerMath) {
  uint8_t data[] = "foo";
  BigEndianReader reader(data, sizeof(data));
  // The test should fail without ever dereferencing the |dummy_buf| pointer.
  char* dummy_buf = reinterpret_cast<char*>(0xdeadbeef);
  // Craft an extreme length value that would cause |reader.data() + len| to
  // overflow.
  size_t extreme_length = std::numeric_limits<size_t>::max() - 1;
  base::StringPiece piece;
  EXPECT_FALSE(reader.Skip(extreme_length));
  EXPECT_FALSE(reader.ReadBytes(dummy_buf, extreme_length));
  EXPECT_FALSE(reader.ReadPiece(&piece, extreme_length));
}

TEST(BigEndianWriterTest, WritesValues) {
  char expected[] = { 0, 0, 2, 3, 4, 5, 6, 7, 8, 9, 0xA, 0xB, 0xC, 0xD, 0xE,
                      0xF, 0x1A, 0x2B, 0x3C };
  char data[sizeof(expected)];
  char buf[] = { 0x2, 0x3 };
  memset(data, 0, sizeof(data));
  BigEndianWriter writer(data, sizeof(data));

  EXPECT_TRUE(writer.Skip(2));
  EXPECT_TRUE(writer.WriteBytes(buf, sizeof(buf)));
  EXPECT_TRUE(writer.WriteU8(0x4));
  EXPECT_TRUE(writer.WriteU16(0x0506));
  EXPECT_TRUE(writer.WriteU32(0x0708090A));
  EXPECT_TRUE(writer.WriteU64(0x0B0C0D0E0F1A2B3Cllu));
  EXPECT_EQ(0, memcmp(expected, data, sizeof(expected)));
}

TEST(BigEndianWriterTest, RespectsLength) {
  char data[8];
  char buf[2];
  uint8_t u8 = 0;
  uint16_t u16 = 0;
  uint32_t u32 = 0;
  uint64_t u64 = 0;
  BigEndianWriter writer(data, sizeof(data));
  // 8 left
  EXPECT_FALSE(writer.Skip(9));
  EXPECT_TRUE(writer.Skip(1));
  // 7 left
  EXPECT_FALSE(writer.WriteU64(u64));
  EXPECT_TRUE(writer.Skip(4));
  // 3 left
  EXPECT_FALSE(writer.WriteU32(u32));
  EXPECT_TRUE(writer.Skip(2));
  // 1 left
  EXPECT_FALSE(writer.WriteU16(u16));
  EXPECT_FALSE(writer.WriteBytes(buf, 2));
  EXPECT_TRUE(writer.Skip(1));
  // 0 left
  EXPECT_FALSE(writer.WriteU8(u8));
  EXPECT_EQ(0u, writer.remaining());
}

TEST(BigEndianWriterTest, SafePointerMath) {
  char data[3];
  BigEndianWriter writer(data, sizeof(data));
  // The test should fail without ever dereferencing the |dummy_buf| pointer.
  const char* dummy_buf = reinterpret_cast<const char*>(0xdeadbeef);
  // Craft an extreme length value that would cause |reader.data() + len| to
  // overflow.
  size_t extreme_length = std::numeric_limits<size_t>::max() - 1;
  EXPECT_FALSE(writer.Skip(extreme_length));
  EXPECT_FALSE(writer.WriteBytes(dummy_buf, extreme_length));
}

}  // namespace base