1//===-- sanitizer_leb128.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#include "sanitizer_common/sanitizer_leb128.h"
9
10#include <type_traits>
11
12#include "gtest/gtest.h"
13#include "sanitizer_common/sanitizer_common.h"
14#include "sanitizer_internal_defs.h"
15
16namespace __sanitizer {
17
18template <typename T>
19class Leb128Test : public ::testing::Test {};
20
21using Leb128TestTypes = ::testing::Types<u8, u16, u32, u64>;
22TYPED_TEST_SUITE(Leb128Test, Leb128TestTypes, );
23
24static uptr BitsNeeded(u64 v) {
25  if (!v)
26    return 1;
27  uptr r = 0;
28  if (sizeof(uptr) != sizeof(u64)) {
29    uptr uptr_bits = 8 * sizeof(uptr);
30    while (v >> uptr_bits) {
31      r += uptr_bits;
32      v >>= uptr_bits;
33    }
34  }
35  return r + MostSignificantSetBitIndex(v) + 1;
36}
37
38TYPED_TEST(Leb128Test, SignedOverflow) {
39  using T = typename std::make_signed<TypeParam>::type;
40  u8 buffer[16] = {255};
41  T v = -128;
42  EXPECT_EQ(buffer + 1, EncodeSLEB128(v, buffer, buffer + 1));
43  EXPECT_EQ(buffer + 1, DecodeSLEB128(buffer, buffer + 1, &v));
44}
45
46TYPED_TEST(Leb128Test, Signed) {
47  using T = typename std::make_signed<TypeParam>::type;
48  T v = 0;
49  for (int i = 0; i < 100; ++i) {
50    u8 buffer[16] = {};
51    u8* p = EncodeSLEB128(v, std::begin(buffer), std::end(buffer));
52    EXPECT_EQ(int(BitsNeeded(v < 0 ? (-v - 1) : v) + 6 + 1) / 7, p - buffer)
53        << (int)v;
54    T v2;
55    u8* p2 = DecodeSLEB128(std::begin(buffer), std::end(buffer), &v2);
56    EXPECT_EQ(v, v2);
57    EXPECT_EQ(p, p2);
58    v = -TypeParam(v) * 3u + 1u;
59  }
60}
61
62TYPED_TEST(Leb128Test, UnsignedOverflow) {
63  using T = TypeParam;
64  u8 buffer[16] = {255};
65  T v = 255;
66  EXPECT_EQ(buffer + 1, EncodeULEB128(v, buffer, buffer + 1));
67  EXPECT_EQ(buffer + 1, DecodeULEB128(buffer, buffer + 1, &v));
68}
69
70TYPED_TEST(Leb128Test, Unsigned) {
71  using T = TypeParam;
72  T v = 0;
73  for (int i = 0; i < 100; ++i) {
74    u8 buffer[16] = {};
75    u8* p = EncodeULEB128(v, std::begin(buffer), std::end(buffer));
76    EXPECT_EQ(int(BitsNeeded(v) + 6) / 7, p - buffer);
77    T v2;
78    u8* p2 = DecodeULEB128(std::begin(buffer), std::end(buffer), &v2);
79    EXPECT_EQ(v, v2);
80    EXPECT_EQ(p, p2);
81    v = v * 3 + 1;
82  }
83}
84
85}  // namespace __sanitizer
86