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// Copyright 2022 The Abseil Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/crc/crc32c.h"
#include <algorithm>
#include <cstdint>
#include <cstring>
#include <string>
#include "gtest/gtest.h"
#include "absl/crc/internal/crc32c.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
namespace {
TEST(CRC32C, RFC3720) {
// Test the results of the vectors from
// https://www.rfc-editor.org/rfc/rfc3720#appendix-B.4
char data[32];
// 32 bytes of ones.
memset(data, 0, sizeof(data));
EXPECT_EQ(absl::ComputeCrc32c(absl::string_view(data, sizeof(data))),
absl::crc32c_t{0x8a9136aa});
// 32 bytes of ones.
memset(data, 0xff, sizeof(data));
EXPECT_EQ(absl::ComputeCrc32c(absl::string_view(data, sizeof(data))),
absl::crc32c_t{0x62a8ab43});
// 32 incrementing bytes.
for (int i = 0; i < 32; ++i) data[i] = static_cast<char>(i);
EXPECT_EQ(absl::ComputeCrc32c(absl::string_view(data, sizeof(data))),
absl::crc32c_t{0x46dd794e});
// 32 decrementing bytes.
for (int i = 0; i < 32; ++i) data[i] = static_cast<char>(31 - i);
EXPECT_EQ(absl::ComputeCrc32c(absl::string_view(data, sizeof(data))),
absl::crc32c_t{0x113fdb5c});
// An iSCSI - SCSI Read (10) Command PDU.
constexpr uint8_t cmd[48] = {
0x01, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00,
0x00, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00, 0x18, 0x28, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};
EXPECT_EQ(absl::ComputeCrc32c(absl::string_view(
reinterpret_cast<const char*>(cmd), sizeof(cmd))),
absl::crc32c_t{0xd9963a56});
}
std::string TestString(size_t len) {
std::string result;
result.reserve(len);
for (size_t i = 0; i < len; ++i) {
result.push_back(static_cast<char>(i % 256));
}
return result;
}
TEST(CRC32C, Compute) {
EXPECT_EQ(absl::ComputeCrc32c(""), absl::crc32c_t{0});
EXPECT_EQ(absl::ComputeCrc32c("hello world"), absl::crc32c_t{0xc99465aa});
}
TEST(CRC32C, Extend) {
uint32_t base = 0xC99465AA; // CRC32C of "Hello World"
std::string extension = "Extension String";
EXPECT_EQ(
absl::ExtendCrc32c(absl::crc32c_t{base}, extension),
absl::crc32c_t{0xD2F65090}); // CRC32C of "Hello WorldExtension String"
}
TEST(CRC32C, ExtendByZeroes) {
std::string base = "hello world";
absl::crc32c_t base_crc = absl::crc32c_t{0xc99465aa};
for (const size_t extend_by : {100, 10000, 100000}) {
SCOPED_TRACE(extend_by);
absl::crc32c_t crc2 = absl::ExtendCrc32cByZeroes(base_crc, extend_by);
EXPECT_EQ(crc2, absl::ComputeCrc32c(base + std::string(extend_by, '\0')));
}
}
TEST(CRC32C, UnextendByZeroes) {
for (auto seed_crc : {absl::crc32c_t{0}, absl::crc32c_t{0xc99465aa}}) {
SCOPED_TRACE(seed_crc);
for (const size_t size_1 : {2, 200, 20000, 200000, 20000000}) {
for (const size_t size_2 : {0, 100, 10000, 100000, 10000000}) {
size_t extend_size = std::max(size_1, size_2);
size_t unextend_size = std::min(size_1, size_2);
SCOPED_TRACE(extend_size);
SCOPED_TRACE(unextend_size);
// Extending by A zeroes an unextending by B<A zeros should be identical
// to extending by A-B zeroes.
absl::crc32c_t crc1 = seed_crc;
crc1 = absl::ExtendCrc32cByZeroes(crc1, extend_size);
crc1 = absl::crc_internal::UnextendCrc32cByZeroes(crc1, unextend_size);
absl::crc32c_t crc2 = seed_crc;
crc2 = absl::ExtendCrc32cByZeroes(crc2, extend_size - unextend_size);
EXPECT_EQ(crc1, crc2);
}
}
}
for (const size_t size : {0, 1, 100, 10000}) {
SCOPED_TRACE(size);
std::string string_before = TestString(size);
std::string string_after = string_before + std::string(size, '\0');
absl::crc32c_t crc_before = absl::ComputeCrc32c(string_before);
absl::crc32c_t crc_after = absl::ComputeCrc32c(string_after);
EXPECT_EQ(crc_before,
absl::crc_internal::UnextendCrc32cByZeroes(crc_after, size));
}
}
TEST(CRC32C, Concat) {
std::string hello = "Hello, ";
std::string world = "world!";
std::string hello_world = absl::StrCat(hello, world);
absl::crc32c_t crc_a = absl::ComputeCrc32c(hello);
absl::crc32c_t crc_b = absl::ComputeCrc32c(world);
absl::crc32c_t crc_ab = absl::ComputeCrc32c(hello_world);
EXPECT_EQ(absl::ConcatCrc32c(crc_a, crc_b, world.size()), crc_ab);
}
TEST(CRC32C, Memcpy) {
for (size_t bytes : {0, 1, 20, 500, 100000}) {
SCOPED_TRACE(bytes);
std::string sample_string = TestString(bytes);
std::string target_buffer = std::string(bytes, '\0');
absl::crc32c_t memcpy_crc =
absl::MemcpyCrc32c(&(target_buffer[0]), sample_string.data(), bytes);
absl::crc32c_t compute_crc = absl::ComputeCrc32c(sample_string);
EXPECT_EQ(memcpy_crc, compute_crc);
EXPECT_EQ(sample_string, target_buffer);
}
}
TEST(CRC32C, RemovePrefix) {
std::string hello = "Hello, ";
std::string world = "world!";
std::string hello_world = absl::StrCat(hello, world);
absl::crc32c_t crc_a = absl::ComputeCrc32c(hello);
absl::crc32c_t crc_b = absl::ComputeCrc32c(world);
absl::crc32c_t crc_ab = absl::ComputeCrc32c(hello_world);
EXPECT_EQ(absl::RemoveCrc32cPrefix(crc_a, crc_ab, world.size()), crc_b);
}
TEST(CRC32C, RemoveSuffix) {
std::string hello = "Hello, ";
std::string world = "world!";
std::string hello_world = absl::StrCat(hello, world);
absl::crc32c_t crc_a = absl::ComputeCrc32c(hello);
absl::crc32c_t crc_b = absl::ComputeCrc32c(world);
absl::crc32c_t crc_ab = absl::ComputeCrc32c(hello_world);
EXPECT_EQ(absl::RemoveCrc32cSuffix(crc_ab, crc_b, world.size()), crc_a);
}
} // namespace
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