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snappy/snappy_unittest.cc

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// Copyright 2005 and onwards Google Inc.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <random>
#include <string>
#include <utility>
#include <vector>
#include "snappy-test.h"
#include "gtest/gtest.h"
#include "snappy-internal.h"
#include "snappy-sinksource.h"
#include "snappy.h"
#include "snappy_test_data.h"
DEFINE_bool(snappy_dump_decompression_table, false,
"If true, we print the decompression table during tests.");
namespace snappy {
namespace {
#if defined(HAVE_FUNC_MMAP) && defined(HAVE_FUNC_SYSCONF)
// To test against code that reads beyond its input, this class copies a
// string to a newly allocated group of pages, the last of which
// is made unreadable via mprotect. Note that we need to allocate the
// memory with mmap(), as POSIX allows mprotect() only on memory allocated
// with mmap(), and some malloc/posix_memalign implementations expect to
// be able to read previously allocated memory while doing heap allocations.
class DataEndingAtUnreadablePage {
public:
explicit DataEndingAtUnreadablePage(const std::string& s) {
const size_t page_size = sysconf(_SC_PAGESIZE);
const size_t size = s.size();
// Round up space for string to a multiple of page_size.
size_t space_for_string = (size + page_size - 1) & ~(page_size - 1);
alloc_size_ = space_for_string + page_size;
mem_ = mmap(NULL, alloc_size_,
PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
CHECK_NE(MAP_FAILED, mem_);
protected_page_ = reinterpret_cast<char*>(mem_) + space_for_string;
char* dst = protected_page_ - size;
std::memcpy(dst, s.data(), size);
data_ = dst;
size_ = size;
// Make guard page unreadable.
CHECK_EQ(0, mprotect(protected_page_, page_size, PROT_NONE));
}
~DataEndingAtUnreadablePage() {
const size_t page_size = sysconf(_SC_PAGESIZE);
// Undo the mprotect.
CHECK_EQ(0, mprotect(protected_page_, page_size, PROT_READ|PROT_WRITE));
CHECK_EQ(0, munmap(mem_, alloc_size_));
}
const char* data() const { return data_; }
size_t size() const { return size_; }
private:
size_t alloc_size_;
void* mem_;
char* protected_page_;
const char* data_;
size_t size_;
};
#else // defined(HAVE_FUNC_MMAP) && defined(HAVE_FUNC_SYSCONF)
// Fallback for systems without mmap.
using DataEndingAtUnreadablePage = std::string;
#endif
int VerifyString(const std::string& input) {
std::string compressed;
DataEndingAtUnreadablePage i(input);
const size_t written = snappy::Compress(i.data(), i.size(), &compressed);
CHECK_EQ(written, compressed.size());
CHECK_LE(compressed.size(),
snappy::MaxCompressedLength(input.size()));
CHECK(snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
std::string uncompressed;
DataEndingAtUnreadablePage c(compressed);
CHECK(snappy::Uncompress(c.data(), c.size(), &uncompressed));
CHECK_EQ(uncompressed, input);
return uncompressed.size();
}
void VerifyStringSink(const std::string& input) {
std::string compressed;
DataEndingAtUnreadablePage i(input);
const size_t written = snappy::Compress(i.data(), i.size(), &compressed);
CHECK_EQ(written, compressed.size());
CHECK_LE(compressed.size(),
snappy::MaxCompressedLength(input.size()));
CHECK(snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
std::string uncompressed;
uncompressed.resize(input.size());
snappy::UncheckedByteArraySink sink(string_as_array(&uncompressed));
DataEndingAtUnreadablePage c(compressed);
snappy::ByteArraySource source(c.data(), c.size());
CHECK(snappy::Uncompress(&source, &sink));
CHECK_EQ(uncompressed, input);
}
void VerifyIOVec(const std::string& input) {
std::string compressed;
DataEndingAtUnreadablePage i(input);
const size_t written = snappy::Compress(i.data(), i.size(), &compressed);
CHECK_EQ(written, compressed.size());
CHECK_LE(compressed.size(),
snappy::MaxCompressedLength(input.size()));
CHECK(snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
// Try uncompressing into an iovec containing a random number of entries
// ranging from 1 to 10.
char* buf = new char[input.size()];
std::minstd_rand0 rng(input.size());
std::uniform_int_distribution<size_t> uniform_1_to_10(1, 10);
size_t num = uniform_1_to_10(rng);
if (input.size() < num) {
num = input.size();
}
struct iovec* iov = new iovec[num];
size_t used_so_far = 0;
std::bernoulli_distribution one_in_five(1.0 / 5);
for (size_t i = 0; i < num; ++i) {
assert(used_so_far < input.size());
iov[i].iov_base = buf + used_so_far;
if (i == num - 1) {
iov[i].iov_len = input.size() - used_so_far;
} else {
// Randomly choose to insert a 0 byte entry.
if (one_in_five(rng)) {
iov[i].iov_len = 0;
} else {
std::uniform_int_distribution<size_t> uniform_not_used_so_far(
0, input.size() - used_so_far - 1);
iov[i].iov_len = uniform_not_used_so_far(rng);
}
}
used_so_far += iov[i].iov_len;
}
CHECK(snappy::RawUncompressToIOVec(
compressed.data(), compressed.size(), iov, num));
CHECK(!memcmp(buf, input.data(), input.size()));
delete[] iov;
delete[] buf;
}
// Test that data compressed by a compressor that does not
// obey block sizes is uncompressed properly.
void VerifyNonBlockedCompression(const std::string& input) {
if (input.length() > snappy::kBlockSize) {
// We cannot test larger blocks than the maximum block size, obviously.
return;
}
std::string prefix;
Varint::Append32(&prefix, input.size());
// Setup compression table
snappy::internal::WorkingMemory wmem(input.size());
int table_size;
uint16_t* table = wmem.GetHashTable(input.size(), &table_size);
// Compress entire input in one shot
std::string compressed;
compressed += prefix;
compressed.resize(prefix.size()+snappy::MaxCompressedLength(input.size()));
char* dest = string_as_array(&compressed) + prefix.size();
char* end = snappy::internal::CompressFragment(input.data(), input.size(),
dest, table, table_size);
compressed.resize(end - compressed.data());
// Uncompress into std::string
std::string uncomp_str;
CHECK(snappy::Uncompress(compressed.data(), compressed.size(), &uncomp_str));
CHECK_EQ(uncomp_str, input);
// Uncompress using source/sink
std::string uncomp_str2;
uncomp_str2.resize(input.size());
snappy::UncheckedByteArraySink sink(string_as_array(&uncomp_str2));
snappy::ByteArraySource source(compressed.data(), compressed.size());
CHECK(snappy::Uncompress(&source, &sink));
CHECK_EQ(uncomp_str2, input);
// Uncompress into iovec
{
static const int kNumBlocks = 10;
struct iovec vec[kNumBlocks];
const int block_size = 1 + input.size() / kNumBlocks;
std::string iovec_data(block_size * kNumBlocks, 'x');
for (int i = 0; i < kNumBlocks; ++i) {
vec[i].iov_base = string_as_array(&iovec_data) + i * block_size;
vec[i].iov_len = block_size;
}
CHECK(snappy::RawUncompressToIOVec(compressed.data(), compressed.size(),
vec, kNumBlocks));
CHECK_EQ(std::string(iovec_data.data(), input.size()), input);
}
}
// Expand the input so that it is at least K times as big as block size
std::string Expand(const std::string& input) {
static const int K = 3;
std::string data = input;
while (data.size() < K * snappy::kBlockSize) {
data += input;
}
return data;
}
int Verify(const std::string& input) {
VLOG(1) << "Verifying input of size " << input.size();
// Compress using string based routines
const int result = VerifyString(input);
// Verify using sink based routines
VerifyStringSink(input);
VerifyNonBlockedCompression(input);
VerifyIOVec(input);
if (!input.empty()) {
const std::string expanded = Expand(input);
VerifyNonBlockedCompression(expanded);
VerifyIOVec(input);
}
return result;
}
bool IsValidCompressedBuffer(const std::string& c) {
return snappy::IsValidCompressedBuffer(c.data(), c.size());
}
bool Uncompress(const std::string& c, std::string* u) {
return snappy::Uncompress(c.data(), c.size(), u);
}
// This test checks to ensure that snappy doesn't coredump if it gets
// corrupted data.
TEST(CorruptedTest, VerifyCorrupted) {
std::string source = "making sure we don't crash with corrupted input";
VLOG(1) << source;
std::string dest;
std::string uncmp;
snappy::Compress(source.data(), source.size(), &dest);
// Mess around with the data. It's hard to simulate all possible
// corruptions; this is just one example ...
CHECK_GT(dest.size(), 3);
dest[1]--;
dest[3]++;
// this really ought to fail.
CHECK(!IsValidCompressedBuffer(dest));
CHECK(!Uncompress(dest, &uncmp));
// This is testing for a security bug - a buffer that decompresses to 100k
// but we lie in the snappy header and only reserve 0 bytes of memory :)
source.resize(100000);
for (char& source_char : source) {
source_char = 'A';
}
snappy::Compress(source.data(), source.size(), &dest);
dest[0] = dest[1] = dest[2] = dest[3] = 0;
CHECK(!IsValidCompressedBuffer(dest));
CHECK(!Uncompress(dest, &uncmp));
if (sizeof(void *) == 4) {
// Another security check; check a crazy big length can't DoS us with an
// over-allocation.
// Currently this is done only for 32-bit builds. On 64-bit builds,
// where 3 GB might be an acceptable allocation size, Uncompress()
// attempts to decompress, and sometimes causes the test to run out of
// memory.
dest[0] = dest[1] = dest[2] = dest[3] = '\xff';
// This decodes to a really large size, i.e., about 3 GB.
dest[4] = 'k';
CHECK(!IsValidCompressedBuffer(dest));
CHECK(!Uncompress(dest, &uncmp));
} else {
LOG(WARNING) << "Crazy decompression lengths not checked on 64-bit build";
}
// This decodes to about 2 MB; much smaller, but should still fail.
dest[0] = dest[1] = dest[2] = '\xff';
dest[3] = 0x00;
CHECK(!IsValidCompressedBuffer(dest));
CHECK(!Uncompress(dest, &uncmp));
// try reading stuff in from a bad file.
for (int i = 1; i <= 3; ++i) {
std::string data =
ReadTestDataFile(StrFormat("baddata%d.snappy", i).c_str(), 0);
std::string uncmp;
// check that we don't return a crazy length
size_t ulen;
CHECK(!snappy::GetUncompressedLength(data.data(), data.size(), &ulen)
|| (ulen < (1<<20)));
uint32_t ulen2;
snappy::ByteArraySource source(data.data(), data.size());
CHECK(!snappy::GetUncompressedLength(&source, &ulen2) ||
(ulen2 < (1<<20)));
CHECK(!IsValidCompressedBuffer(data));
CHECK(!Uncompress(data, &uncmp));
}
}
// Helper routines to construct arbitrary compressed strings.
// These mirror the compression code in snappy.cc, but are copied
// here so that we can bypass some limitations in the how snappy.cc
// invokes these routines.
void AppendLiteral(std::string* dst, const std::string& literal) {
if (literal.empty()) return;
int n = literal.size() - 1;
if (n < 60) {
// Fit length in tag byte
dst->push_back(0 | (n << 2));
} else {
// Encode in upcoming bytes
char number[4];
int count = 0;
while (n > 0) {
number[count++] = n & 0xff;
n >>= 8;
}
dst->push_back(0 | ((59+count) << 2));
*dst += std::string(number, count);
}
*dst += literal;
}
void AppendCopy(std::string* dst, int offset, int length) {
while (length > 0) {
// Figure out how much to copy in one shot
int to_copy;
if (length >= 68) {
to_copy = 64;
} else if (length > 64) {
to_copy = 60;
} else {
to_copy = length;
}
length -= to_copy;
if ((to_copy >= 4) && (to_copy < 12) && (offset < 2048)) {
assert(to_copy-4 < 8); // Must fit in 3 bits
dst->push_back(1 | ((to_copy-4) << 2) | ((offset >> 8) << 5));
dst->push_back(offset & 0xff);
} else if (offset < 65536) {
dst->push_back(2 | ((to_copy-1) << 2));
dst->push_back(offset & 0xff);
dst->push_back(offset >> 8);
} else {
dst->push_back(3 | ((to_copy-1) << 2));
dst->push_back(offset & 0xff);
dst->push_back((offset >> 8) & 0xff);
dst->push_back((offset >> 16) & 0xff);
dst->push_back((offset >> 24) & 0xff);
}
}
}
TEST(Snappy, SimpleTests) {
Verify("");
Verify("a");
Verify("ab");
Verify("abc");
Verify("aaaaaaa" + std::string(16, 'b') + std::string("aaaaa") + "abc");
Verify("aaaaaaa" + std::string(256, 'b') + std::string("aaaaa") + "abc");
Verify("aaaaaaa" + std::string(2047, 'b') + std::string("aaaaa") + "abc");
Verify("aaaaaaa" + std::string(65536, 'b') + std::string("aaaaa") + "abc");
Verify("abcaaaaaaa" + std::string(65536, 'b') + std::string("aaaaa") + "abc");
}
// Regression test for cr/345340892.
TEST(Snappy, AppendSelfPatternExtensionEdgeCases) {
Verify("abcabcabcabcabcabcab");
Verify("abcabcabcabcabcabcab0123456789ABCDEF");
Verify("abcabcabcabcabcabcabcabcabcabcabcabc");
Verify("abcabcabcabcabcabcabcabcabcabcabcabc0123456789ABCDEF");
}
// Regression test for cr/345340892.
TEST(Snappy, AppendSelfPatternExtensionEdgeCasesExhaustive) {
std::mt19937 rng;
std::uniform_int_distribution<int> uniform_byte(0, 255);
for (int pattern_size = 1; pattern_size <= 18; ++pattern_size) {
for (int length = 1; length <= 64; ++length) {
for (int extra_bytes_after_pattern : {0, 1, 15, 16, 128}) {
const int size = pattern_size + length + extra_bytes_after_pattern;
std::string input;
input.resize(size);
for (int i = 0; i < pattern_size; ++i) {
input[i] = 'a' + i;
}
for (int i = 0; i < length; ++i) {
input[pattern_size + i] = input[i];
}
for (int i = 0; i < extra_bytes_after_pattern; ++i) {
input[pattern_size + length + i] =
static_cast<char>(uniform_byte(rng));
}
Verify(input);
}
}
}
}
// Verify max blowup (lots of four-byte copies)
TEST(Snappy, MaxBlowup) {
std::mt19937 rng;
std::uniform_int_distribution<int> uniform_byte(0, 255);
std::string input;
for (int i = 0; i < 80000; ++i)
input.push_back(static_cast<char>(uniform_byte(rng)));
for (int i = 0; i < 80000; i += 4) {
std::string four_bytes(input.end() - i - 4, input.end() - i);
input.append(four_bytes);
}
Verify(input);
}
TEST(Snappy, RandomData) {
std::minstd_rand0 rng(absl::GetFlag(FLAGS_test_random_seed));
std::uniform_int_distribution<int> uniform_0_to_3(0, 3);
std::uniform_int_distribution<int> uniform_0_to_8(0, 8);
std::uniform_int_distribution<int> uniform_byte(0, 255);
std::uniform_int_distribution<size_t> uniform_4k(0, 4095);
std::uniform_int_distribution<size_t> uniform_64k(0, 65535);
std::bernoulli_distribution one_in_ten(1.0 / 10);
constexpr int num_ops = 20000;
for (int i = 0; i < num_ops; ++i) {
if ((i % 1000) == 0) {
VLOG(0) << "Random op " << i << " of " << num_ops;
}
std::string x;
size_t len = uniform_4k(rng);
if (i < 100) {
len = 65536 + uniform_64k(rng);
}
while (x.size() < len) {
int run_len = 1;
if (one_in_ten(rng)) {
int skewed_bits = uniform_0_to_8(rng);
// int is guaranteed to hold at least 16 bits, this uses at most 8 bits.
std::uniform_int_distribution<int> skewed_low(0,
(1 << skewed_bits) - 1);
run_len = skewed_low(rng);
}
char c = static_cast<char>(uniform_byte(rng));
if (i >= 100) {
int skewed_bits = uniform_0_to_3(rng);
// int is guaranteed to hold at least 16 bits, this uses at most 3 bits.
std::uniform_int_distribution<int> skewed_low(0,
(1 << skewed_bits) - 1);
c = static_cast<char>(skewed_low(rng));
}
while (run_len-- > 0 && x.size() < len) {
x.push_back(c);
}
}
Verify(x);
}
}
TEST(Snappy, FourByteOffset) {
// The new compressor cannot generate four-byte offsets since
// it chops up the input into 32KB pieces. So we hand-emit the
// copy manually.
// The two fragments that make up the input string.
std::string fragment1 = "012345689abcdefghijklmnopqrstuvwxyz";
std::string fragment2 = "some other string";
// How many times each fragment is emitted.
const int n1 = 2;
const int n2 = 100000 / fragment2.size();
const size_t length = n1 * fragment1.size() + n2 * fragment2.size();
std::string compressed;
Varint::Append32(&compressed, length);
AppendLiteral(&compressed, fragment1);
std::string src = fragment1;
for (int i = 0; i < n2; ++i) {
AppendLiteral(&compressed, fragment2);
src += fragment2;
}
AppendCopy(&compressed, src.size(), fragment1.size());
src += fragment1;
CHECK_EQ(length, src.size());
std::string uncompressed;
CHECK(snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
CHECK(snappy::Uncompress(compressed.data(), compressed.size(),
&uncompressed));
CHECK_EQ(uncompressed, src);
}
TEST(Snappy, IOVecEdgeCases) {
// Test some tricky edge cases in the iovec output that are not necessarily
// exercised by random tests.
// Our output blocks look like this initially (the last iovec is bigger
// than depicted):
// [ ] [ ] [ ] [ ] [ ]
static const int kLengths[] = { 2, 1, 4, 8, 128 };
struct iovec iov[ARRAYSIZE(kLengths)];
for (int i = 0; i < ARRAYSIZE(kLengths); ++i) {
iov[i].iov_base = new char[kLengths[i]];
iov[i].iov_len = kLengths[i];
}
std::string compressed;
Varint::Append32(&compressed, 22);
// A literal whose output crosses three blocks.
// [ab] [c] [123 ] [ ] [ ]
AppendLiteral(&compressed, "abc123");
// A copy whose output crosses two blocks (source and destination
// segments marked).
// [ab] [c] [1231] [23 ] [ ]
// ^--^ --
AppendCopy(&compressed, 3, 3);
// A copy where the input is, at first, in the block before the output:
//
// [ab] [c] [1231] [231231 ] [ ]
// ^--- ^---
// Then during the copy, the pointers move such that the input and
// output pointers are in the same block:
//
// [ab] [c] [1231] [23123123] [ ]
// ^- ^-
// And then they move again, so that the output pointer is no longer
// in the same block as the input pointer:
// [ab] [c] [1231] [23123123] [123 ]
// ^-- ^--
AppendCopy(&compressed, 6, 9);
// Finally, a copy where the input is from several blocks back,
// and it also crosses three blocks:
//
// [ab] [c] [1231] [23123123] [123b ]
// ^ ^
// [ab] [c] [1231] [23123123] [123bc ]
// ^ ^
// [ab] [c] [1231] [23123123] [123bc12 ]
// ^- ^-
AppendCopy(&compressed, 17, 4);
CHECK(snappy::RawUncompressToIOVec(
compressed.data(), compressed.size(), iov, ARRAYSIZE(iov)));
CHECK_EQ(0, memcmp(iov[0].iov_base, "ab", 2));
CHECK_EQ(0, memcmp(iov[1].iov_base, "c", 1));
CHECK_EQ(0, memcmp(iov[2].iov_base, "1231", 4));
CHECK_EQ(0, memcmp(iov[3].iov_base, "23123123", 8));
CHECK_EQ(0, memcmp(iov[4].iov_base, "123bc12", 7));
for (int i = 0; i < ARRAYSIZE(kLengths); ++i) {
delete[] reinterpret_cast<char *>(iov[i].iov_base);
}
}
TEST(Snappy, IOVecLiteralOverflow) {
static const int kLengths[] = { 3, 4 };
struct iovec iov[ARRAYSIZE(kLengths)];
for (int i = 0; i < ARRAYSIZE(kLengths); ++i) {
iov[i].iov_base = new char[kLengths[i]];
iov[i].iov_len = kLengths[i];
}
std::string compressed;
Varint::Append32(&compressed, 8);
AppendLiteral(&compressed, "12345678");
CHECK(!snappy::RawUncompressToIOVec(
compressed.data(), compressed.size(), iov, ARRAYSIZE(iov)));
for (int i = 0; i < ARRAYSIZE(kLengths); ++i) {
delete[] reinterpret_cast<char *>(iov[i].iov_base);
}
}
TEST(Snappy, IOVecCopyOverflow) {
static const int kLengths[] = { 3, 4 };
struct iovec iov[ARRAYSIZE(kLengths)];
for (int i = 0; i < ARRAYSIZE(kLengths); ++i) {
iov[i].iov_base = new char[kLengths[i]];
iov[i].iov_len = kLengths[i];
}
std::string compressed;
Varint::Append32(&compressed, 8);
AppendLiteral(&compressed, "123");
AppendCopy(&compressed, 3, 5);
CHECK(!snappy::RawUncompressToIOVec(
compressed.data(), compressed.size(), iov, ARRAYSIZE(iov)));
for (int i = 0; i < ARRAYSIZE(kLengths); ++i) {
delete[] reinterpret_cast<char *>(iov[i].iov_base);
}
}
bool CheckUncompressedLength(const std::string& compressed, size_t* ulength) {
const bool result1 = snappy::GetUncompressedLength(compressed.data(),
compressed.size(),
ulength);
snappy::ByteArraySource source(compressed.data(), compressed.size());
uint32_t length;
const bool result2 = snappy::GetUncompressedLength(&source, &length);
CHECK_EQ(result1, result2);
return result1;
}
TEST(SnappyCorruption, TruncatedVarint) {
std::string compressed, uncompressed;
size_t ulength;
compressed.push_back('\xf0');
CHECK(!CheckUncompressedLength(compressed, &ulength));
CHECK(!snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
CHECK(!snappy::Uncompress(compressed.data(), compressed.size(),
&uncompressed));
}
TEST(SnappyCorruption, UnterminatedVarint) {
std::string compressed, uncompressed;
size_t ulength;
compressed.push_back('\x80');
compressed.push_back('\x80');
compressed.push_back('\x80');
compressed.push_back('\x80');
compressed.push_back('\x80');
compressed.push_back(10);
CHECK(!CheckUncompressedLength(compressed, &ulength));
CHECK(!snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
CHECK(!snappy::Uncompress(compressed.data(), compressed.size(),
&uncompressed));
}
TEST(SnappyCorruption, OverflowingVarint) {
std::string compressed, uncompressed;
size_t ulength;
compressed.push_back('\xfb');
compressed.push_back('\xff');
compressed.push_back('\xff');
compressed.push_back('\xff');
compressed.push_back('\x7f');
CHECK(!CheckUncompressedLength(compressed, &ulength));
CHECK(!snappy::IsValidCompressedBuffer(compressed.data(), compressed.size()));
CHECK(!snappy::Uncompress(compressed.data(), compressed.size(),
&uncompressed));
}
TEST(Snappy, ReadPastEndOfBuffer) {
// Check that we do not read past end of input
// Make a compressed string that ends with a single-byte literal
std::string compressed;
Varint::Append32(&compressed, 1);
AppendLiteral(&compressed, "x");
std::string uncompressed;
DataEndingAtUnreadablePage c(compressed);
CHECK(snappy::Uncompress(c.data(), c.size(), &uncompressed));
CHECK_EQ(uncompressed, std::string("x"));
}
// Check for an infinite loop caused by a copy with offset==0
TEST(Snappy, ZeroOffsetCopy) {
const char* compressed = "\x40\x12\x00\x00";
// \x40 Length (must be > kMaxIncrementCopyOverflow)
// \x12\x00\x00 Copy with offset==0, length==5
char uncompressed[100];
EXPECT_FALSE(snappy::RawUncompress(compressed, 4, uncompressed));
}
TEST(Snappy, ZeroOffsetCopyValidation) {
const char* compressed = "\x05\x12\x00\x00";
// \x05 Length
// \x12\x00\x00 Copy with offset==0, length==5
EXPECT_FALSE(snappy::IsValidCompressedBuffer(compressed, 4));
}
int TestFindMatchLength(const char* s1, const char *s2, unsigned length) {
uint64_t data;
std::pair<size_t, bool> p =
snappy::internal::FindMatchLength(s1, s2, s2 + length, &data);
CHECK_EQ(p.first < 8, p.second);
return p.first;
}
TEST(Snappy, FindMatchLength) {
// Exercise all different code paths through the function.
// 64-bit version:
// Hit s1_limit in 64-bit loop, hit s1_limit in single-character loop.
EXPECT_EQ(6, TestFindMatchLength("012345", "012345", 6));
EXPECT_EQ(11, TestFindMatchLength("01234567abc", "01234567abc", 11));
// Hit s1_limit in 64-bit loop, find a non-match in single-character loop.
EXPECT_EQ(9, TestFindMatchLength("01234567abc", "01234567axc", 9));
// Same, but edge cases.
EXPECT_EQ(11, TestFindMatchLength("01234567abc!", "01234567abc!", 11));
EXPECT_EQ(11, TestFindMatchLength("01234567abc!", "01234567abc?", 11));
// Find non-match at once in first loop.
EXPECT_EQ(0, TestFindMatchLength("01234567xxxxxxxx", "?1234567xxxxxxxx", 16));
EXPECT_EQ(1, TestFindMatchLength("01234567xxxxxxxx", "0?234567xxxxxxxx", 16));
EXPECT_EQ(4, TestFindMatchLength("01234567xxxxxxxx", "01237654xxxxxxxx", 16));
EXPECT_EQ(7, TestFindMatchLength("01234567xxxxxxxx", "0123456?xxxxxxxx", 16));
// Find non-match in first loop after one block.
EXPECT_EQ(8, TestFindMatchLength("abcdefgh01234567xxxxxxxx",
"abcdefgh?1234567xxxxxxxx", 24));
EXPECT_EQ(9, TestFindMatchLength("abcdefgh01234567xxxxxxxx",
"abcdefgh0?234567xxxxxxxx", 24));
EXPECT_EQ(12, TestFindMatchLength("abcdefgh01234567xxxxxxxx",
"abcdefgh01237654xxxxxxxx", 24));
EXPECT_EQ(15, TestFindMatchLength("abcdefgh01234567xxxxxxxx",
"abcdefgh0123456?xxxxxxxx", 24));
// 32-bit version:
// Short matches.
EXPECT_EQ(0, TestFindMatchLength("01234567", "?1234567", 8));
EXPECT_EQ(1, TestFindMatchLength("01234567", "0?234567", 8));
EXPECT_EQ(2, TestFindMatchLength("01234567", "01?34567", 8));
EXPECT_EQ(3, TestFindMatchLength("01234567", "012?4567", 8));
EXPECT_EQ(4, TestFindMatchLength("01234567", "0123?567", 8));
EXPECT_EQ(5, TestFindMatchLength("01234567", "01234?67", 8));
EXPECT_EQ(6, TestFindMatchLength("01234567", "012345?7", 8));
EXPECT_EQ(7, TestFindMatchLength("01234567", "0123456?", 8));
EXPECT_EQ(7, TestFindMatchLength("01234567", "0123456?", 7));
EXPECT_EQ(7, TestFindMatchLength("01234567!", "0123456??", 7));
// Hit s1_limit in 32-bit loop, hit s1_limit in single-character loop.
EXPECT_EQ(10, TestFindMatchLength("xxxxxxabcd", "xxxxxxabcd", 10));
EXPECT_EQ(10, TestFindMatchLength("xxxxxxabcd?", "xxxxxxabcd?", 10));
EXPECT_EQ(13, TestFindMatchLength("xxxxxxabcdef", "xxxxxxabcdef", 13));
// Same, but edge cases.
EXPECT_EQ(12, TestFindMatchLength("xxxxxx0123abc!", "xxxxxx0123abc!", 12));
EXPECT_EQ(12, TestFindMatchLength("xxxxxx0123abc!", "xxxxxx0123abc?", 12));
// Hit s1_limit in 32-bit loop, find a non-match in single-character loop.
EXPECT_EQ(11, TestFindMatchLength("xxxxxx0123abc", "xxxxxx0123axc", 13));
// Find non-match at once in first loop.
EXPECT_EQ(6, TestFindMatchLength("xxxxxx0123xxxxxxxx",
"xxxxxx?123xxxxxxxx", 18));
EXPECT_EQ(7, TestFindMatchLength("xxxxxx0123xxxxxxxx",
"xxxxxx0?23xxxxxxxx", 18));
EXPECT_EQ(8, TestFindMatchLength("xxxxxx0123xxxxxxxx",
"xxxxxx0132xxxxxxxx", 18));
EXPECT_EQ(9, TestFindMatchLength("xxxxxx0123xxxxxxxx",
"xxxxxx012?xxxxxxxx", 18));
// Same, but edge cases.
EXPECT_EQ(6, TestFindMatchLength("xxxxxx0123", "xxxxxx?123", 10));
EXPECT_EQ(7, TestFindMatchLength("xxxxxx0123", "xxxxxx0?23", 10));
EXPECT_EQ(8, TestFindMatchLength("xxxxxx0123", "xxxxxx0132", 10));
EXPECT_EQ(9, TestFindMatchLength("xxxxxx0123", "xxxxxx012?", 10));
// Find non-match in first loop after one block.
EXPECT_EQ(10, TestFindMatchLength("xxxxxxabcd0123xx",
"xxxxxxabcd?123xx", 16));
EXPECT_EQ(11, TestFindMatchLength("xxxxxxabcd0123xx",
"xxxxxxabcd0?23xx", 16));
EXPECT_EQ(12, TestFindMatchLength("xxxxxxabcd0123xx",
"xxxxxxabcd0132xx", 16));
EXPECT_EQ(13, TestFindMatchLength("xxxxxxabcd0123xx",
"xxxxxxabcd012?xx", 16));
// Same, but edge cases.
EXPECT_EQ(10, TestFindMatchLength("xxxxxxabcd0123", "xxxxxxabcd?123", 14));
EXPECT_EQ(11, TestFindMatchLength("xxxxxxabcd0123", "xxxxxxabcd0?23", 14));
EXPECT_EQ(12, TestFindMatchLength("xxxxxxabcd0123", "xxxxxxabcd0132", 14));
EXPECT_EQ(13, TestFindMatchLength("xxxxxxabcd0123", "xxxxxxabcd012?", 14));
}
TEST(Snappy, FindMatchLengthRandom) {
constexpr int kNumTrials = 10000;
constexpr int kTypicalLength = 10;
std::minstd_rand0 rng(absl::GetFlag(FLAGS_test_random_seed));
std::uniform_int_distribution<int> uniform_byte(0, 255);
std::bernoulli_distribution one_in_two(1.0 / 2);
std::bernoulli_distribution one_in_typical_length(1.0 / kTypicalLength);
for (int i = 0; i < kNumTrials; ++i) {
std::string s, t;
char a = static_cast<char>(uniform_byte(rng));
char b = static_cast<char>(uniform_byte(rng));
while (!one_in_typical_length(rng)) {
s.push_back(one_in_two(rng) ? a : b);
t.push_back(one_in_two(rng) ? a : b);
}
DataEndingAtUnreadablePage u(s);
DataEndingAtUnreadablePage v(t);
size_t matched = TestFindMatchLength(u.data(), v.data(), t.size());
if (matched == t.size()) {
EXPECT_EQ(s, t);
} else {
EXPECT_NE(s[matched], t[matched]);
for (size_t j = 0; j < matched; ++j) {
EXPECT_EQ(s[j], t[j]);
}
}
}
}
uint16_t MakeEntry(unsigned int extra, unsigned int len,
unsigned int copy_offset) {
// Check that all of the fields fit within the allocated space
assert(extra == (extra & 0x7)); // At most 3 bits
assert(copy_offset == (copy_offset & 0x7)); // At most 3 bits
assert(len == (len & 0x7f)); // At most 7 bits
return len | (copy_offset << 8) | (extra << 11);
}
// Check that the decompression table is correct, and optionally print out
// the computed one.
TEST(Snappy, VerifyCharTable) {
using snappy::internal::LITERAL;
using snappy::internal::COPY_1_BYTE_OFFSET;
using snappy::internal::COPY_2_BYTE_OFFSET;
using snappy::internal::COPY_4_BYTE_OFFSET;
using snappy::internal::char_table;
uint16_t dst[256];
// Place invalid entries in all places to detect missing initialization
int assigned = 0;
for (int i = 0; i < 256; ++i) {
dst[i] = 0xffff;
}
// Small LITERAL entries. We store (len-1) in the top 6 bits.
for (uint8_t len = 1; len <= 60; ++len) {
dst[LITERAL | ((len - 1) << 2)] = MakeEntry(0, len, 0);
assigned++;
}
// Large LITERAL entries. We use 60..63 in the high 6 bits to
// encode the number of bytes of length info that follow the opcode.
for (uint8_t extra_bytes = 1; extra_bytes <= 4; ++extra_bytes) {
// We set the length field in the lookup table to 1 because extra
// bytes encode len-1.
dst[LITERAL | ((extra_bytes + 59) << 2)] = MakeEntry(extra_bytes, 1, 0);
assigned++;
}
// COPY_1_BYTE_OFFSET.
//
// The tag byte in the compressed data stores len-4 in 3 bits, and
// offset/256 in 5 bits. offset%256 is stored in the next byte.
//
// This format is used for length in range [4..11] and offset in
// range [0..2047]
for (uint8_t len = 4; len < 12; ++len) {
for (uint16_t offset = 0; offset < 2048; offset += 256) {
uint8_t offset_high = static_cast<uint8_t>(offset >> 8);
dst[COPY_1_BYTE_OFFSET | ((len - 4) << 2) | (offset_high << 5)] =
MakeEntry(1, len, offset_high);
assigned++;
}
}
// COPY_2_BYTE_OFFSET.
// Tag contains len-1 in top 6 bits, and offset in next two bytes.
for (uint8_t len = 1; len <= 64; ++len) {
dst[COPY_2_BYTE_OFFSET | ((len - 1) << 2)] = MakeEntry(2, len, 0);
assigned++;
}
// COPY_4_BYTE_OFFSET.
// Tag contents len-1 in top 6 bits, and offset in next four bytes.
for (uint8_t len = 1; len <= 64; ++len) {
dst[COPY_4_BYTE_OFFSET | ((len - 1) << 2)] = MakeEntry(4, len, 0);
assigned++;
}
// Check that each entry was initialized exactly once.
EXPECT_EQ(256, assigned) << "Assigned only " << assigned << " of 256";
for (int i = 0; i < 256; ++i) {
EXPECT_NE(0xffff, dst[i]) << "Did not assign byte " << i;
}
if (absl::GetFlag(FLAGS_snappy_dump_decompression_table)) {
std::printf("static const uint16_t char_table[256] = {\n ");
for (int i = 0; i < 256; ++i) {
std::printf("0x%04x%s",
dst[i],
((i == 255) ? "\n" : (((i % 8) == 7) ? ",\n " : ", ")));
}
std::printf("};\n");
}
// Check that computed table matched recorded table.
for (int i = 0; i < 256; ++i) {
EXPECT_EQ(dst[i], char_table[i]) << "Mismatch in byte " << i;
}
}
TEST(Snappy, TestBenchmarkFiles) {
for (int i = 0; i < ARRAYSIZE(kTestDataFiles); ++i) {
Verify(ReadTestDataFile(kTestDataFiles[i].filename,
kTestDataFiles[i].size_limit));
}
}
} // namespace
} // namespace snappy
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