//===-- compression.cpp -----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "gwp_asan/stack_trace_compressor.h"
#include "gwp_asan/tests/harness.h"
namespace gwp_asan {
namespace compression {
TEST(GwpAsanCompressionTest, SingleByteVarInt) {
uint8_t Compressed[1];
uintptr_t Uncompressed = 0x00;
EXPECT_EQ(1u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0x00);
Uncompressed = 0x01;
EXPECT_EQ(1u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0x02); // +1 => 2 in zigzag.
Uncompressed = 0x3f;
EXPECT_EQ(1u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0x7e); // +63 => 127 in zigzag.
}
TEST(GwpAsanCompressionTest, MultiByteVarInt) {
uint8_t Compressed[sizeof(uintptr_t) + 1];
uintptr_t Uncompressed = 0x40;
EXPECT_EQ(2u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0x80); // +64 => 128 in zigzag.
EXPECT_EQ(Compressed[1], 0x01);
Uncompressed = 0x41;
EXPECT_EQ(2u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0x82); // +65 => 130 in zigzag
EXPECT_EQ(Compressed[1], 0x01);
Uncompressed = 0x1fff;
EXPECT_EQ(2u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0xfe); // +8191 => 16382 in zigzag
EXPECT_EQ(Compressed[1], 0x7f);
Uncompressed = 0x2000;
EXPECT_EQ(3u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0x80); // +8192 => 16384 in zigzag
EXPECT_EQ(Compressed[1], 0x80);
EXPECT_EQ(Compressed[2], 0x01);
Uncompressed = 0x7f010ff0;
EXPECT_EQ(5u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[0], 0xe0); // +0x7f010ff0 => 0xFE021FE0 in zigzag
EXPECT_EQ(Compressed[1], 0xbf);
EXPECT_EQ(Compressed[2], 0x88);
EXPECT_EQ(Compressed[3], 0xf0);
EXPECT_EQ(Compressed[4], 0x0f);
}
TEST(GwpAsanCompressionTest, CorrectDifference) {
uint8_t Compressed[10];
uintptr_t Uncompressed[2] = {0x00, 0x00};
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[1], 0x00); // +0 difference => 0 in zigzag.
Uncompressed[1] = 0x01;
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[1], 0x02); // +1 difference => 2 in zigzag.
Uncompressed[1] = 0x02;
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[1], 0x04); // +2 difference => 4 in zigzag.
Uncompressed[1] = 0x80;
EXPECT_EQ(3u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[1], 0x80); // +128 difference => +256 in zigzag (note the
EXPECT_EQ(Compressed[2], 0x02); // varint encoding here).
Uncompressed[0] = 0x01;
Uncompressed[1] = 0x00;
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[1], 0x01); // -1 difference => +1 in zigzag.
Uncompressed[0] = 0x02;
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[1], 0x03); // -2 difference => +3 in zigzag.
Uncompressed[0] = 0x80;
EXPECT_EQ(4u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
EXPECT_EQ(Compressed[2], 0xff); // -128 difference => +255 in zigzag (note the
EXPECT_EQ(Compressed[3], 0x01); // varint encoding here).
}
// Space needed to encode the biggest uintptr_t as a varint is ceil((8 / 7) *
// sizeof(uintptr_t)), as each 7 bits requires 8 bits of space.
constexpr size_t kBytesForLargestVarInt = (sizeof(uintptr_t) * 8) / 7 + 1;
// Ensures that when the closest diff between two pointers is via. underflow,
// we take the underflow option.
TEST(GwpAsanCompressionTest, ClosestDiffIsUnderflow) {
uint8_t Compressed[2];
uintptr_t Uncompressed[2] = {0x00, UINTPTR_MAX};
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
// -1 difference => +1 in zigzag.
EXPECT_EQ(Compressed[1], 0x01);
}
// Ensures that when the closest diff between two pointers is via. overflow,
// that we take this option.
TEST(GwpAsanCompressionTest, ClosestDiffIsOverflow) {
uint8_t Compressed[2];
uintptr_t Uncompressed[2] = {UINTPTR_MAX, 0x00};
// Note here that the first element is encoded as the difference from zero.
EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
Compressed, sizeof(Compressed)));
// -1 difference => +1 in zigzag (the first pointer is encoded as -1).
EXPECT_EQ(Compressed[0], 0x01);
// +1 difference => +2 in zigzag.
EXPECT_EQ(Compressed[1], 0x02);
}
void runPackUnpack(uintptr_t *Test, size_t NumEntries) {
// Setup the input/output buffers based on the maximum possible size.
uintptr_t *Uncompressed =
static_cast<uintptr_t *>(alloca(NumEntries * sizeof(uintptr_t)));
size_t CompressedBufferSize = NumEntries * kBytesForLargestVarInt;
uint8_t *Compressed = static_cast<uint8_t *>(alloca(CompressedBufferSize));
// Pack the provided testcase, recoding the number of bytes it took for
// storage.
size_t BytesUsedForPacking =
pack(Test, NumEntries, Compressed, CompressedBufferSize);
EXPECT_NE(BytesUsedForPacking, 0u);
// Unpack the testcase and ensure that the correct number of entries was
// unpacked.
EXPECT_EQ(NumEntries,
unpack(Compressed, BytesUsedForPacking, Uncompressed, NumEntries));
// Ensure that the unpacked trace is the same as the original testcase.
for (size_t i = 0; i < NumEntries; ++i) {
EXPECT_EQ(Uncompressed[i], Test[i]);
}
}
TEST(GwpAsanCompressionTest, UncompressVarInt) {
uint8_t Compressed[] = {0x00, 0xaa, 0xaf, 0xd0, 0xda, 0x04};
uintptr_t Uncompressed[2];
EXPECT_EQ(2u, unpack(Compressed, sizeof(Compressed), Uncompressed, 2u));
EXPECT_EQ(Uncompressed[0], 0x00u);
EXPECT_EQ(Uncompressed[1], 0x25aa0bd5u);
}
TEST(GwpAsanCompressionTest, UncompressVarIntUnderflow) {
uint8_t Compressed[] = {0x00, 0xab, 0xaf, 0xd0, 0xda, 0x04};
uintptr_t Uncompressed[2];
EXPECT_EQ(2u, unpack(Compressed, sizeof(Compressed), Uncompressed, 2u));
EXPECT_EQ(Uncompressed[0], 0x00u);
EXPECT_EQ(Uncompressed[1], UINTPTR_MAX - 0x25aa0bd5u);
}
TEST(GwpAsanCompressionTest, CompressUncompressAscending) {
uintptr_t Test[] = {1, 2, 3};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, CompressUncompressDescending) {
uintptr_t Test[] = {3, 2, 1};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, CompressUncompressRepeated) {
uintptr_t Test[] = {3, 3, 3};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, CompressUncompressZigZag) {
uintptr_t Test[] = {1, 3, 2, 4, 1, 2};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, CompressUncompressVarInt) {
uintptr_t Test[] = {0x1981561, 0x18560, 0x25ab9135, 0x1232562};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, CompressUncompressLargestDifference) {
uintptr_t Test[] = {0x00, INTPTR_MAX, UINTPTR_MAX, INTPTR_MAX, 0x00};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, CompressUncompressBigPointers) {
uintptr_t Test[] = {UINTPTR_MAX, UINTPTR_MAX - 10};
runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
uintptr_t Test2[] = {UINTPTR_MAX - 10, UINTPTR_MAX};
runPackUnpack(Test2, sizeof(Test2) / sizeof(uintptr_t));
}
TEST(GwpAsanCompressionTest, UncompressFailsWithOutOfBoundsVarInt) {
uint8_t Compressed[kBytesForLargestVarInt + 1];
for (size_t i = 0; i < kBytesForLargestVarInt; ++i) {
Compressed[i] = 0x80;
}
Compressed[kBytesForLargestVarInt] = 0x00;
uintptr_t Uncompressed;
EXPECT_EQ(unpack(Compressed, kBytesForLargestVarInt + 1, &Uncompressed, 1),
0u);
}
TEST(GwpAsanCompressionTest, UncompressFailsWithTooSmallBuffer) {
uint8_t Compressed[] = {0x80, 0x00};
uintptr_t Uncompressed;
EXPECT_EQ(unpack(Compressed, 1u, &Uncompressed, 1), 0u);
}
TEST(GwpAsanCompressionTest, CompressPartiallySucceedsWithTooSmallBuffer) {
uintptr_t Uncompressed[] = {
0x80, // Requires 2 bytes for varint.
0x100, // Requires two bytes for varint difference of 0x80.
0xff, // Requires single byte for varint difference of -0x01
};
uint8_t Compressed[3 * kBytesForLargestVarInt];
// Zero and one byte buffers shouldn't encode anything (see above for size
// requirements).
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 0u), 0u);
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 1u), 0u);
// Two byte buffer should hold a single varint-encoded value.
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 2u), 2u);
// Three bytes isn't enough to cover the first two pointers, as both take two
// bytes each to store. Expect a single value to be compressed.
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 3u), 2u);
// Four bytes is enough for the first two pointers to be stored.
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 4u), 4u);
// And five is enough for all three pointers to be stored.
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 5u), 5u);
// And a buffer that's bigger than five bytes should still only write five
// bytes.
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 6u), 5u);
EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 3 * kBytesForLargestVarInt), 5u);
}
} // namespace compression
} // namespace gwp_asan
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