1 //===-- compression.cpp -----------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "gwp_asan/stack_trace_compressor.h"
10 #include "gwp_asan/tests/harness.h"
11
12 namespace gwp_asan {
13 namespace compression {
14
TEST(GwpAsanCompressionTest,SingleByteVarInt)15 TEST(GwpAsanCompressionTest, SingleByteVarInt) {
16 uint8_t Compressed[1];
17
18 uintptr_t Uncompressed = 0x00;
19 EXPECT_EQ(1u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
20 EXPECT_EQ(Compressed[0], 0x00);
21
22 Uncompressed = 0x01;
23 EXPECT_EQ(1u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
24 EXPECT_EQ(Compressed[0], 0x02); // +1 => 2 in zigzag.
25
26 Uncompressed = 0x3f;
27 EXPECT_EQ(1u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
28 EXPECT_EQ(Compressed[0], 0x7e); // +63 => 127 in zigzag.
29 }
30
TEST(GwpAsanCompressionTest,MultiByteVarInt)31 TEST(GwpAsanCompressionTest, MultiByteVarInt) {
32 uint8_t Compressed[sizeof(uintptr_t) + 1];
33
34 uintptr_t Uncompressed = 0x40;
35 EXPECT_EQ(2u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
36 EXPECT_EQ(Compressed[0], 0x80); // +64 => 128 in zigzag.
37 EXPECT_EQ(Compressed[1], 0x01);
38
39 Uncompressed = 0x41;
40 EXPECT_EQ(2u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
41 EXPECT_EQ(Compressed[0], 0x82); // +65 => 130 in zigzag
42 EXPECT_EQ(Compressed[1], 0x01);
43
44 Uncompressed = 0x1fff;
45 EXPECT_EQ(2u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
46 EXPECT_EQ(Compressed[0], 0xfe); // +8191 => 16382 in zigzag
47 EXPECT_EQ(Compressed[1], 0x7f);
48
49 Uncompressed = 0x2000;
50 EXPECT_EQ(3u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
51 EXPECT_EQ(Compressed[0], 0x80); // +8192 => 16384 in zigzag
52 EXPECT_EQ(Compressed[1], 0x80);
53 EXPECT_EQ(Compressed[2], 0x01);
54
55 Uncompressed = 0x7f010ff0;
56 EXPECT_EQ(5u, pack(&Uncompressed, 1u, Compressed, sizeof(Compressed)));
57 EXPECT_EQ(Compressed[0], 0xe0); // +0x7f010ff0 => 0xFE021FE0 in zigzag
58 EXPECT_EQ(Compressed[1], 0xbf);
59 EXPECT_EQ(Compressed[2], 0x88);
60 EXPECT_EQ(Compressed[3], 0xf0);
61 EXPECT_EQ(Compressed[4], 0x0f);
62 }
63
TEST(GwpAsanCompressionTest,CorrectDifference)64 TEST(GwpAsanCompressionTest, CorrectDifference) {
65 uint8_t Compressed[10];
66 uintptr_t Uncompressed[2] = {0x00, 0x00};
67
68 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
69 Compressed, sizeof(Compressed)));
70 EXPECT_EQ(Compressed[1], 0x00); // +0 difference => 0 in zigzag.
71
72 Uncompressed[1] = 0x01;
73 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
74 Compressed, sizeof(Compressed)));
75 EXPECT_EQ(Compressed[1], 0x02); // +1 difference => 2 in zigzag.
76
77 Uncompressed[1] = 0x02;
78 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
79 Compressed, sizeof(Compressed)));
80 EXPECT_EQ(Compressed[1], 0x04); // +2 difference => 4 in zigzag.
81
82 Uncompressed[1] = 0x80;
83 EXPECT_EQ(3u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
84 Compressed, sizeof(Compressed)));
85 EXPECT_EQ(Compressed[1], 0x80); // +128 difference => +256 in zigzag (note the
86 EXPECT_EQ(Compressed[2], 0x02); // varint encoding here).
87
88 Uncompressed[0] = 0x01;
89 Uncompressed[1] = 0x00;
90 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
91 Compressed, sizeof(Compressed)));
92 EXPECT_EQ(Compressed[1], 0x01); // -1 difference => +1 in zigzag.
93
94 Uncompressed[0] = 0x02;
95 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
96 Compressed, sizeof(Compressed)));
97 EXPECT_EQ(Compressed[1], 0x03); // -2 difference => +3 in zigzag.
98
99 Uncompressed[0] = 0x80;
100 EXPECT_EQ(4u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
101 Compressed, sizeof(Compressed)));
102 EXPECT_EQ(Compressed[2], 0xff); // -128 difference => +255 in zigzag (note the
103 EXPECT_EQ(Compressed[3], 0x01); // varint encoding here).
104 }
105
106 // Space needed to encode the biggest uintptr_t as a varint is ceil((8 / 7) *
107 // sizeof(uintptr_t)), as each 7 bits requires 8 bits of space.
108 constexpr size_t kBytesForLargestVarInt = (sizeof(uintptr_t) * 8) / 7 + 1;
109
110 // Ensures that when the closest diff between two pointers is via. underflow,
111 // we take the underflow option.
TEST(GwpAsanCompressionTest,ClosestDiffIsUnderflow)112 TEST(GwpAsanCompressionTest, ClosestDiffIsUnderflow) {
113 uint8_t Compressed[2];
114 uintptr_t Uncompressed[2] = {0x00, UINTPTR_MAX};
115
116 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
117 Compressed, sizeof(Compressed)));
118 // -1 difference => +1 in zigzag.
119 EXPECT_EQ(Compressed[1], 0x01);
120 }
121
122 // Ensures that when the closest diff between two pointers is via. overflow,
123 // that we take this option.
TEST(GwpAsanCompressionTest,ClosestDiffIsOverflow)124 TEST(GwpAsanCompressionTest, ClosestDiffIsOverflow) {
125 uint8_t Compressed[2];
126 uintptr_t Uncompressed[2] = {UINTPTR_MAX, 0x00};
127
128 // Note here that the first element is encoded as the difference from zero.
129 EXPECT_EQ(2u, pack(Uncompressed, sizeof(Uncompressed) / sizeof(uintptr_t),
130 Compressed, sizeof(Compressed)));
131 // -1 difference => +1 in zigzag (the first pointer is encoded as -1).
132 EXPECT_EQ(Compressed[0], 0x01);
133 // +1 difference => +2 in zigzag.
134 EXPECT_EQ(Compressed[1], 0x02);
135 }
136
runPackUnpack(uintptr_t * Test,size_t NumEntries)137 void runPackUnpack(uintptr_t *Test, size_t NumEntries) {
138 // Setup the input/output buffers based on the maximum possible size.
139 uintptr_t *Uncompressed =
140 static_cast<uintptr_t *>(alloca(NumEntries * sizeof(uintptr_t)));
141 size_t CompressedBufferSize = NumEntries * kBytesForLargestVarInt;
142 uint8_t *Compressed = static_cast<uint8_t *>(alloca(CompressedBufferSize));
143
144 // Pack the provided testcase, recoding the number of bytes it took for
145 // storage.
146 size_t BytesUsedForPacking =
147 pack(Test, NumEntries, Compressed, CompressedBufferSize);
148 EXPECT_NE(BytesUsedForPacking, 0u);
149
150 // Unpack the testcase and ensure that the correct number of entries was
151 // unpacked.
152 EXPECT_EQ(NumEntries,
153 unpack(Compressed, BytesUsedForPacking, Uncompressed, NumEntries));
154
155 // Ensure that the unpacked trace is the same as the original testcase.
156 for (size_t i = 0; i < NumEntries; ++i) {
157 EXPECT_EQ(Uncompressed[i], Test[i]);
158 }
159 }
160
TEST(GwpAsanCompressionTest,UncompressVarInt)161 TEST(GwpAsanCompressionTest, UncompressVarInt) {
162 uint8_t Compressed[] = {0x00, 0xaa, 0xaf, 0xd0, 0xda, 0x04};
163 uintptr_t Uncompressed[2];
164
165 EXPECT_EQ(2u, unpack(Compressed, sizeof(Compressed), Uncompressed, 2u));
166 EXPECT_EQ(Uncompressed[0], 0x00u);
167 EXPECT_EQ(Uncompressed[1], 0x25aa0bd5u);
168 }
169
TEST(GwpAsanCompressionTest,UncompressVarIntUnderflow)170 TEST(GwpAsanCompressionTest, UncompressVarIntUnderflow) {
171 uint8_t Compressed[] = {0x00, 0xab, 0xaf, 0xd0, 0xda, 0x04};
172 uintptr_t Uncompressed[2];
173
174 EXPECT_EQ(2u, unpack(Compressed, sizeof(Compressed), Uncompressed, 2u));
175 EXPECT_EQ(Uncompressed[0], 0x00u);
176 EXPECT_EQ(Uncompressed[1], UINTPTR_MAX - 0x25aa0bd5u);
177 }
178
TEST(GwpAsanCompressionTest,CompressUncompressAscending)179 TEST(GwpAsanCompressionTest, CompressUncompressAscending) {
180 uintptr_t Test[] = {1, 2, 3};
181 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
182 }
183
TEST(GwpAsanCompressionTest,CompressUncompressDescending)184 TEST(GwpAsanCompressionTest, CompressUncompressDescending) {
185 uintptr_t Test[] = {3, 2, 1};
186 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
187 }
188
TEST(GwpAsanCompressionTest,CompressUncompressRepeated)189 TEST(GwpAsanCompressionTest, CompressUncompressRepeated) {
190 uintptr_t Test[] = {3, 3, 3};
191 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
192 }
193
TEST(GwpAsanCompressionTest,CompressUncompressZigZag)194 TEST(GwpAsanCompressionTest, CompressUncompressZigZag) {
195 uintptr_t Test[] = {1, 3, 2, 4, 1, 2};
196 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
197 }
198
TEST(GwpAsanCompressionTest,CompressUncompressVarInt)199 TEST(GwpAsanCompressionTest, CompressUncompressVarInt) {
200 uintptr_t Test[] = {0x1981561, 0x18560, 0x25ab9135, 0x1232562};
201 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
202 }
203
TEST(GwpAsanCompressionTest,CompressUncompressLargestDifference)204 TEST(GwpAsanCompressionTest, CompressUncompressLargestDifference) {
205 uintptr_t Test[] = {0x00, INTPTR_MAX, UINTPTR_MAX, INTPTR_MAX, 0x00};
206 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
207 }
208
TEST(GwpAsanCompressionTest,CompressUncompressBigPointers)209 TEST(GwpAsanCompressionTest, CompressUncompressBigPointers) {
210 uintptr_t Test[] = {UINTPTR_MAX, UINTPTR_MAX - 10};
211 runPackUnpack(Test, sizeof(Test) / sizeof(uintptr_t));
212
213 uintptr_t Test2[] = {UINTPTR_MAX - 10, UINTPTR_MAX};
214 runPackUnpack(Test2, sizeof(Test2) / sizeof(uintptr_t));
215 }
216
TEST(GwpAsanCompressionTest,UncompressFailsWithOutOfBoundsVarInt)217 TEST(GwpAsanCompressionTest, UncompressFailsWithOutOfBoundsVarInt) {
218 uint8_t Compressed[kBytesForLargestVarInt + 1];
219 for (size_t i = 0; i < kBytesForLargestVarInt; ++i) {
220 Compressed[i] = 0x80;
221 }
222 Compressed[kBytesForLargestVarInt] = 0x00;
223
224 uintptr_t Uncompressed;
225 EXPECT_EQ(unpack(Compressed, kBytesForLargestVarInt + 1, &Uncompressed, 1),
226 0u);
227 }
228
TEST(GwpAsanCompressionTest,UncompressFailsWithTooSmallBuffer)229 TEST(GwpAsanCompressionTest, UncompressFailsWithTooSmallBuffer) {
230 uint8_t Compressed[] = {0x80, 0x00};
231
232 uintptr_t Uncompressed;
233 EXPECT_EQ(unpack(Compressed, 1u, &Uncompressed, 1), 0u);
234 }
235
TEST(GwpAsanCompressionTest,CompressPartiallySucceedsWithTooSmallBuffer)236 TEST(GwpAsanCompressionTest, CompressPartiallySucceedsWithTooSmallBuffer) {
237 uintptr_t Uncompressed[] = {
238 0x80, // Requires 2 bytes for varint.
239 0x100, // Requires two bytes for varint difference of 0x80.
240 0xff, // Requires single byte for varint difference of -0x01
241 };
242 uint8_t Compressed[3 * kBytesForLargestVarInt];
243
244 // Zero and one byte buffers shouldn't encode anything (see above for size
245 // requirements).
246 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 0u), 0u);
247 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 1u), 0u);
248
249 // Two byte buffer should hold a single varint-encoded value.
250 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 2u), 2u);
251
252 // Three bytes isn't enough to cover the first two pointers, as both take two
253 // bytes each to store. Expect a single value to be compressed.
254 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 3u), 2u);
255
256 // Four bytes is enough for the first two pointers to be stored.
257 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 4u), 4u);
258
259 // And five is enough for all three pointers to be stored.
260 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 5u), 5u);
261 // And a buffer that's bigger than five bytes should still only write five
262 // bytes.
263 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 6u), 5u);
264 EXPECT_EQ(pack(Uncompressed, 3u, Compressed, 3 * kBytesForLargestVarInt), 5u);
265 }
266 } // namespace compression
267 } // namespace gwp_asan
268