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de5a5fa1 MP |
1 | //===-- ubsan_type_hash.h ---------------------------------------*- C++ -*-===// |
2 | // | |
b667dd70 ML |
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 | |
de5a5fa1 MP |
6 | // |
7 | //===----------------------------------------------------------------------===// | |
8 | // | |
9 | // Hashing of types for Clang's undefined behavior checker. | |
10 | // | |
11 | //===----------------------------------------------------------------------===// | |
12 | #ifndef UBSAN_TYPE_HASH_H | |
13 | #define UBSAN_TYPE_HASH_H | |
14 | ||
15 | #include "sanitizer_common/sanitizer_common.h" | |
16 | ||
17 | namespace __ubsan { | |
18 | ||
19 | typedef uptr HashValue; | |
20 | ||
21 | /// \brief Information about the dynamic type of an object (extracted from its | |
22 | /// vptr). | |
23 | class DynamicTypeInfo { | |
24 | const char *MostDerivedTypeName; | |
25 | sptr Offset; | |
26 | const char *SubobjectTypeName; | |
27 | ||
28 | public: | |
29 | DynamicTypeInfo(const char *MDTN, sptr Offset, const char *STN) | |
30 | : MostDerivedTypeName(MDTN), Offset(Offset), SubobjectTypeName(STN) {} | |
31 | ||
32 | /// Determine whether the object had a valid dynamic type. | |
33 | bool isValid() const { return MostDerivedTypeName; } | |
34 | /// Get the name of the most-derived type of the object. | |
35 | const char *getMostDerivedTypeName() const { return MostDerivedTypeName; } | |
36 | /// Get the offset from the most-derived type to this base class. | |
37 | sptr getOffset() const { return Offset; } | |
38 | /// Get the name of the most-derived type at the specified offset. | |
39 | const char *getSubobjectTypeName() const { return SubobjectTypeName; } | |
40 | }; | |
41 | ||
42 | /// \brief Get information about the dynamic type of an object. | |
696d846a MO |
43 | DynamicTypeInfo getDynamicTypeInfoFromObject(void *Object); |
44 | ||
45 | /// \brief Get information about the dynamic type of an object from its vtable. | |
46 | DynamicTypeInfo getDynamicTypeInfoFromVtable(void *Vtable); | |
de5a5fa1 MP |
47 | |
48 | /// \brief Check whether the dynamic type of \p Object has a \p Type subobject | |
49 | /// at offset 0. | |
50 | /// \return \c true if the type matches, \c false if not. | |
51 | bool checkDynamicType(void *Object, void *Type, HashValue Hash); | |
52 | ||
53 | const unsigned VptrTypeCacheSize = 128; | |
54 | ||
10189819 MO |
55 | /// A sanity check for Vtable. Offsets to top must be reasonably small |
56 | /// numbers (by absolute value). It's a weak check for Vtable corruption. | |
57 | const int VptrMaxOffsetToTop = 1<<20; | |
58 | ||
de5a5fa1 MP |
59 | /// \brief A cache of the results of checkDynamicType. \c checkDynamicType would |
60 | /// return \c true (modulo hash collisions) if | |
61 | /// \code | |
62 | /// __ubsan_vptr_type_cache[Hash % VptrTypeCacheSize] == Hash | |
63 | /// \endcode | |
64 | extern "C" SANITIZER_INTERFACE_ATTRIBUTE | |
65 | HashValue __ubsan_vptr_type_cache[VptrTypeCacheSize]; | |
66 | ||
b667dd70 ML |
67 | /// \brief Do whatever is required by the ABI to check for std::type_info |
68 | /// equivalence beyond simple pointer comparison. | |
69 | bool checkTypeInfoEquality(const void *TypeInfo1, const void *TypeInfo2); | |
70 | ||
de5a5fa1 MP |
71 | } // namespace __ubsan |
72 | ||
73 | #endif // UBSAN_TYPE_HASH_H |