1 /* Copyright (c) 2017, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #include <limits.h> 16 #include <stdint.h> 17 18 #include <type_traits> 19 20 #include <gtest/gtest.h> 21 22 #include "test/test_util.h" 23 24 25 template <typename T> 26 static void CheckRepresentation(T value) { 27 SCOPED_TRACE(value); 28 29 // Convert to the corresponding two's-complement unsigned value. We use an 30 // unsigned value so the right-shift below has defined value. Right-shifts of 31 // negative numbers in C are implementation defined. 32 // 33 // If |T| is already unsigned, this is a no-op, as desired. 34 // 35 // If |T| is signed, conversion to unsigned is defined to repeatedly add or 36 // subtract (numerically, not within |T|) one more than the unsigned type's 37 // maximum value until it fits (this must be a power of two). This is the 38 // conversion we want. 39 using UnsignedT = typename std::make_unsigned<T>::type; 40 UnsignedT value_u = static_cast<UnsignedT>(value); 41 EXPECT_EQ(sizeof(UnsignedT), sizeof(T)); 42 43 // Integers must be little-endian. 44 uint8_t expected[sizeof(UnsignedT)]; 45 for (size_t i = 0; i < sizeof(UnsignedT); i++) { 46 expected[i] = static_cast<uint8_t>(value_u); 47 // Divide instead of right-shift to appease compilers that warn if |T| is a 48 // char. The explicit cast is also needed to appease MSVC if integer 49 // promotion happened. 50 value_u = static_cast<UnsignedT>(value_u / 256); 51 } 52 EXPECT_EQ(0u, value_u); 53 54 // Check that |value| has the expected representation. 55 EXPECT_EQ(Bytes(expected), 56 Bytes(reinterpret_cast<const uint8_t *>(&value), sizeof(value))); 57 } 58 59 TEST(CompilerTest, IntegerRepresentation) { 60 EXPECT_EQ(8, CHAR_BIT); 61 EXPECT_EQ(0xff, static_cast<int>(UCHAR_MAX)); 62 63 // uint8_t is assumed to be unsigned char. I.e., casting to uint8_t should be 64 // as good as unsigned char for strict aliasing purposes. 65 uint8_t u8 = 0; 66 unsigned char *ptr = &u8; 67 (void)ptr; 68 69 // Sized integers have the expected size. 70 EXPECT_EQ(1u, sizeof(uint8_t)); 71 EXPECT_EQ(2u, sizeof(uint16_t)); 72 EXPECT_EQ(4u, sizeof(uint32_t)); 73 EXPECT_EQ(8u, sizeof(uint64_t)); 74 75 // size_t does not exceed uint64_t. 76 EXPECT_LE(sizeof(size_t), 8u); 77 78 // int must be 32-bit or larger. 79 EXPECT_LE(0x7fffffff, INT_MAX); 80 EXPECT_LE(0xffffffffu, UINT_MAX); 81 82 CheckRepresentation(static_cast<signed char>(127)); 83 CheckRepresentation(static_cast<signed char>(1)); 84 CheckRepresentation(static_cast<signed char>(0)); 85 CheckRepresentation(static_cast<signed char>(-1)); 86 CheckRepresentation(static_cast<signed char>(-42)); 87 CheckRepresentation(static_cast<signed char>(-128)); 88 89 CheckRepresentation(static_cast<int>(INT_MAX)); 90 CheckRepresentation(static_cast<int>(0x12345678)); 91 CheckRepresentation(static_cast<int>(1)); 92 CheckRepresentation(static_cast<int>(0)); 93 CheckRepresentation(static_cast<int>(-1)); 94 CheckRepresentation(static_cast<int>(-0x12345678)); 95 CheckRepresentation(static_cast<int>(INT_MIN)); 96 97 CheckRepresentation(static_cast<unsigned>(UINT_MAX)); 98 CheckRepresentation(static_cast<unsigned>(0x12345678)); 99 CheckRepresentation(static_cast<unsigned>(1)); 100 CheckRepresentation(static_cast<unsigned>(0)); 101 102 CheckRepresentation(static_cast<long>(LONG_MAX)); 103 CheckRepresentation(static_cast<long>(0x12345678)); 104 CheckRepresentation(static_cast<long>(1)); 105 CheckRepresentation(static_cast<long>(0)); 106 CheckRepresentation(static_cast<long>(-1)); 107 CheckRepresentation(static_cast<long>(-0x12345678)); 108 CheckRepresentation(static_cast<long>(LONG_MIN)); 109 110 CheckRepresentation(static_cast<unsigned long>(ULONG_MAX)); 111 CheckRepresentation(static_cast<unsigned long>(0x12345678)); 112 CheckRepresentation(static_cast<unsigned long>(1)); 113 CheckRepresentation(static_cast<unsigned long>(0)); 114 115 CheckRepresentation(static_cast<int16_t>(0x7fff)); 116 CheckRepresentation(static_cast<int16_t>(0x1234)); 117 CheckRepresentation(static_cast<int16_t>(1)); 118 CheckRepresentation(static_cast<int16_t>(0)); 119 CheckRepresentation(static_cast<int16_t>(-1)); 120 CheckRepresentation(static_cast<int16_t>(-0x7fff - 1)); 121 122 CheckRepresentation(static_cast<uint16_t>(0xffff)); 123 CheckRepresentation(static_cast<uint16_t>(0x1234)); 124 CheckRepresentation(static_cast<uint16_t>(1)); 125 CheckRepresentation(static_cast<uint16_t>(0)); 126 127 CheckRepresentation(static_cast<int32_t>(0x7fffffff)); 128 CheckRepresentation(static_cast<int32_t>(0x12345678)); 129 CheckRepresentation(static_cast<int32_t>(1)); 130 CheckRepresentation(static_cast<int32_t>(0)); 131 CheckRepresentation(static_cast<int32_t>(-1)); 132 CheckRepresentation(static_cast<int32_t>(-0x7fffffff - 1)); 133 134 CheckRepresentation(static_cast<uint32_t>(0xffffffff)); 135 CheckRepresentation(static_cast<uint32_t>(0x12345678)); 136 CheckRepresentation(static_cast<uint32_t>(1)); 137 CheckRepresentation(static_cast<uint32_t>(0)); 138 139 CheckRepresentation(static_cast<int64_t>(0x7fffffffffffffff)); 140 CheckRepresentation(static_cast<int64_t>(0x123456789abcdef0)); 141 CheckRepresentation(static_cast<int64_t>(1)); 142 CheckRepresentation(static_cast<int64_t>(0)); 143 CheckRepresentation(static_cast<int64_t>(-1)); 144 CheckRepresentation(static_cast<int64_t>(-0x7fffffffffffffff - 1)); 145 146 CheckRepresentation(static_cast<uint64_t>(0xffffffffffffffff)); 147 CheckRepresentation(static_cast<uint64_t>(0x12345678abcdef0)); 148 CheckRepresentation(static_cast<uint64_t>(1)); 149 CheckRepresentation(static_cast<uint64_t>(0)); 150 } 151 152 TEST(CompilerTest, PointerRepresentation) { 153 // Converting pointers to integers and doing arithmetic on those values are 154 // both defined. Converting those values back into pointers is undefined, 155 // but, for aliasing checks, we require that the implementation-defined 156 // result of that computation commutes with pointer arithmetic. 157 char chars[256]; 158 for (size_t i = 0; i < sizeof(chars); i++) { 159 EXPECT_EQ(reinterpret_cast<uintptr_t>(chars) + i, 160 reinterpret_cast<uintptr_t>(chars + i)); 161 } 162 163 int ints[256]; 164 for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(ints); i++) { 165 EXPECT_EQ(reinterpret_cast<uintptr_t>(ints) + i * sizeof(int), 166 reinterpret_cast<uintptr_t>(ints + i)); 167 } 168 169 // nullptr must be represented by all zeros in memory. This is necessary so 170 // structs may be initialized by memset(0). 171 int *null = nullptr; 172 uint8_t bytes[sizeof(null)] = {0}; 173 EXPECT_EQ(Bytes(bytes), 174 Bytes(reinterpret_cast<uint8_t *>(&null), sizeof(null))); 175 } 176
