| OLD | NEW |
| (Empty) |
| 1 // Copyright 2014 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 // Functions to help with verifying various |Mojo...Options| structs from the | |
| 6 // (public, C) API. These are "extensible" structs, which all have |struct_size| | |
| 7 // as their first member. All fields (other than |struct_size|) are optional, | |
| 8 // but any |flags| specified must be known to the system (otherwise, an error of | |
| 9 // |MOJO_RESULT_UNIMPLEMENTED| should be returned). | |
| 10 | |
| 11 #ifndef MOJO_EDK_SYSTEM_OPTIONS_VALIDATION_H_ | |
| 12 #define MOJO_EDK_SYSTEM_OPTIONS_VALIDATION_H_ | |
| 13 | |
| 14 #include <stddef.h> | |
| 15 #include <stdint.h> | |
| 16 | |
| 17 #include <algorithm> | |
| 18 | |
| 19 #include "base/logging.h" | |
| 20 #include "base/macros.h" | |
| 21 #include "mojo/edk/system/memory.h" | |
| 22 #include "mojo/edk/system/system_impl_export.h" | |
| 23 #include "mojo/public/c/system/types.h" | |
| 24 | |
| 25 namespace mojo { | |
| 26 namespace system { | |
| 27 | |
| 28 template <class Options> | |
| 29 class UserOptionsReader { | |
| 30 public: | |
| 31 // Constructor from a |UserPointer<const Options>| (which it checks -- this | |
| 32 // constructor has side effects!). | |
| 33 // Note: We initialize |options_reader_| without checking, since we do a check | |
| 34 // in |GetSizeForReader()|. | |
| 35 explicit UserOptionsReader(UserPointer<const Options> options) | |
| 36 : options_reader_(UserPointer<const char>::Reader::NoCheck(), | |
| 37 options.template ReinterpretCast<const char>(), | |
| 38 GetSizeForReader(options)) { | |
| 39 static_assert(offsetof(Options, struct_size) == 0, | |
| 40 "struct_size not first member of Options"); | |
| 41 // TODO(vtl): Enable when MSVC supports this (C++11 extended sizeof): | |
| 42 // static_assert(sizeof(Options::struct_size) == sizeof(uint32_t), | |
| 43 // "Options::struct_size not a uint32_t"); | |
| 44 // (Or maybe assert that its type is uint32_t?) | |
| 45 } | |
| 46 | |
| 47 bool is_valid() const { return !!options_reader_.GetPointer(); } | |
| 48 | |
| 49 const Options& options() const { | |
| 50 DCHECK(is_valid()); | |
| 51 return *reinterpret_cast<const Options*>(options_reader_.GetPointer()); | |
| 52 } | |
| 53 | |
| 54 // Checks that the given (variable-size) |options| passed to the constructor | |
| 55 // (plausibly) has a member at the given offset with the given size. You | |
| 56 // probably want to use |OPTIONS_STRUCT_HAS_MEMBER()| instead. | |
| 57 bool HasMember(size_t offset, size_t size) const { | |
| 58 DCHECK(is_valid()); | |
| 59 // We assume that |offset| and |size| are reasonable, since they should come | |
| 60 // from |offsetof(Options, some_member)| and |sizeof(Options::some_member)|, | |
| 61 // respectively. | |
| 62 return options().struct_size >= offset + size; | |
| 63 } | |
| 64 | |
| 65 private: | |
| 66 static inline size_t GetSizeForReader(UserPointer<const Options> options) { | |
| 67 uint32_t struct_size = | |
| 68 options.template ReinterpretCast<const uint32_t>().Get(); | |
| 69 if (struct_size < sizeof(uint32_t)) | |
| 70 return 0; | |
| 71 | |
| 72 // Check the full requested size. | |
| 73 // Note: Use |MOJO_ALIGNOF()| here to match the exact macro used in the | |
| 74 // declaration of Options structs. | |
| 75 internal::CheckUserPointerWithSize<MOJO_ALIGNOF(Options)>(options.pointer_, | |
| 76 struct_size); | |
| 77 options.template ReinterpretCast<const char>().CheckArray(struct_size); | |
| 78 // But we'll never look at more than |sizeof(Options)| bytes. | |
| 79 return std::min(static_cast<size_t>(struct_size), sizeof(Options)); | |
| 80 } | |
| 81 | |
| 82 UserPointer<const char>::Reader options_reader_; | |
| 83 | |
| 84 DISALLOW_COPY_AND_ASSIGN(UserOptionsReader); | |
| 85 }; | |
| 86 | |
| 87 // Macro to invoke |UserOptionsReader<Options>::HasMember()| parametrized by | |
| 88 // member name instead of offset and size. | |
| 89 // | |
| 90 // (We can't just give |HasMember()| a member pointer template argument instead, | |
| 91 // since there's no good/strictly-correct way to get an offset from that.) | |
| 92 // | |
| 93 // TODO(vtl): With C++11, use |sizeof(Options::member)| instead of (the | |
| 94 // contortion below). We might also be able to pull out the type |Options| from | |
| 95 // |reader| (using |decltype|) instead of requiring a parameter. | |
| 96 #define OPTIONS_STRUCT_HAS_MEMBER(Options, member, reader) \ | |
| 97 reader.HasMember(offsetof(Options, member), sizeof(reader.options().member)) | |
| 98 | |
| 99 } // namespace system | |
| 100 } // namespace mojo | |
| 101 | |
| 102 #endif // MOJO_EDK_SYSTEM_OPTIONS_VALIDATION_H_ | |
| OLD | NEW |