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Diffstat (limited to 'security/sandbox/chromium/base/containers/hash_tables.h')
| -rw-r--r-- | security/sandbox/chromium/base/containers/hash_tables.h | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/containers/hash_tables.h b/security/sandbox/chromium/base/containers/hash_tables.h new file mode 100644 index 000000000..c421dddf3 --- /dev/null +++ b/security/sandbox/chromium/base/containers/hash_tables.h @@ -0,0 +1,281 @@ +// Copyright (c) 2011 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. +// + +// +// Deal with the differences between Microsoft and GNU implemenations +// of hash_map. Allows all platforms to use |base::hash_map| and +// |base::hash_set|. +// eg: +// base::hash_map<int> my_map; +// base::hash_set<int> my_set; +// +// NOTE: It is an explicit non-goal of this class to provide a generic hash +// function for pointers. If you want to hash a pointers to a particular class, +// please define the template specialization elsewhere (for example, in its +// header file) and keep it specific to just pointers to that class. This is +// because identity hashes are not desirable for all types that might show up +// in containers as pointers. + +#ifndef BASE_CONTAINERS_HASH_TABLES_H_ +#define BASE_CONTAINERS_HASH_TABLES_H_ + +#include <stddef.h> +#include <stdint.h> + +#include <utility> + +#include "base/strings/string16.h" +#include "build/build_config.h" + +#if defined(COMPILER_MSVC) +#include <unordered_map> +#include <unordered_set> + +#define BASE_HASH_NAMESPACE std + +#elif defined(COMPILER_GCC) + +#define BASE_HASH_NAMESPACE base_hash + +// This is a hack to disable the gcc 4.4 warning about hash_map and hash_set +// being deprecated. We can get rid of this when we upgrade to VS2008 and we +// can use <tr1/unordered_map> and <tr1/unordered_set>. +#ifdef __DEPRECATED +#define CHROME_OLD__DEPRECATED __DEPRECATED +#undef __DEPRECATED +#endif + +#include <ext/hash_map> +#include <ext/hash_set> +#define BASE_HASH_IMPL_NAMESPACE __gnu_cxx + +#include <string> + +#ifdef CHROME_OLD__DEPRECATED +#define __DEPRECATED CHROME_OLD__DEPRECATED +#undef CHROME_OLD__DEPRECATED +#endif + +namespace BASE_HASH_NAMESPACE { + +// The pre-standard hash behaves like C++11's std::hash, except around pointers. +// const char* is specialized to hash the C string and hash functions for +// general T* are missing. Define a BASE_HASH_NAMESPACE::hash which aligns with +// the C++11 behavior. + +template<typename T> +struct hash { + std::size_t operator()(const T& value) const { + return BASE_HASH_IMPL_NAMESPACE::hash<T>()(value); + } +}; + +template<typename T> +struct hash<T*> { + std::size_t operator()(T* value) const { + return BASE_HASH_IMPL_NAMESPACE::hash<uintptr_t>()( + reinterpret_cast<uintptr_t>(value)); + } +}; + +// The GNU C++ library provides identity hash functions for many integral types, +// but not for |long long|. This hash function will truncate if |size_t| is +// narrower than |long long|. This is probably good enough for what we will +// use it for. + +#define DEFINE_TRIVIAL_HASH(integral_type) \ + template<> \ + struct hash<integral_type> { \ + std::size_t operator()(integral_type value) const { \ + return static_cast<std::size_t>(value); \ + } \ + } + +DEFINE_TRIVIAL_HASH(long long); +DEFINE_TRIVIAL_HASH(unsigned long long); + +#undef DEFINE_TRIVIAL_HASH + +// Implement string hash functions so that strings of various flavors can +// be used as keys in STL maps and sets. The hash algorithm comes from the +// GNU C++ library, in <tr1/functional>. It is duplicated here because GCC +// versions prior to 4.3.2 are unable to compile <tr1/functional> when RTTI +// is disabled, as it is in our build. + +#define DEFINE_STRING_HASH(string_type) \ + template<> \ + struct hash<string_type> { \ + std::size_t operator()(const string_type& s) const { \ + std::size_t result = 0; \ + for (string_type::const_iterator i = s.begin(); i != s.end(); ++i) \ + result = (result * 131) + *i; \ + return result; \ + } \ + } + +DEFINE_STRING_HASH(std::string); +DEFINE_STRING_HASH(base::string16); + +#undef DEFINE_STRING_HASH + +} // namespace BASE_HASH_NAMESPACE + +#else // COMPILER +#error define BASE_HASH_NAMESPACE for your compiler +#endif // COMPILER + +namespace base { + +// On MSVC, use the C++11 containers. +#if defined(COMPILER_MSVC) + +template<class Key, class T, + class Hash = std::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<std::pair<const Key, T>>> +using hash_map = std::unordered_map<Key, T, Hash, Pred, Alloc>; + +template<class Key, class T, + class Hash = std::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<std::pair<const Key, T>>> +using hash_multimap = std::unordered_multimap<Key, T, Hash, Pred, Alloc>; + +template<class Key, + class Hash = std::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<Key>> +using hash_multiset = std::unordered_multiset<Key, Hash, Pred, Alloc>; + +template<class Key, + class Hash = std::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<Key>> +using hash_set = std::unordered_set<Key, Hash, Pred, Alloc>; + +#else // !COMPILER_MSVC + +// Otherwise, use the pre-standard ones, but override the default hash to match +// C++11. +template<class Key, class T, + class Hash = BASE_HASH_NAMESPACE::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<std::pair<const Key, T>>> +using hash_map = BASE_HASH_IMPL_NAMESPACE::hash_map<Key, T, Hash, Pred, Alloc>; + +template<class Key, class T, + class Hash = BASE_HASH_NAMESPACE::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<std::pair<const Key, T>>> +using hash_multimap = + BASE_HASH_IMPL_NAMESPACE::hash_multimap<Key, T, Hash, Pred, Alloc>; + +template<class Key, + class Hash = BASE_HASH_NAMESPACE::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<Key>> +using hash_multiset = + BASE_HASH_IMPL_NAMESPACE::hash_multiset<Key, Hash, Pred, Alloc>; + +template<class Key, + class Hash = BASE_HASH_NAMESPACE::hash<Key>, + class Pred = std::equal_to<Key>, + class Alloc = std::allocator<Key>> +using hash_set = BASE_HASH_IMPL_NAMESPACE::hash_set<Key, Hash, Pred, Alloc>; + +#undef BASE_HASH_IMPL_NAMESPACE + +#endif // COMPILER_MSVC + +// Implement hashing for pairs of at-most 32 bit integer values. +// When size_t is 32 bits, we turn the 64-bit hash code into 32 bits by using +// multiply-add hashing. This algorithm, as described in +// Theorem 4.3.3 of the thesis "Über die Komplexität der Multiplikation in +// eingeschränkten Branchingprogrammmodellen" by Woelfel, is: +// +// h32(x32, y32) = (h64(x32, y32) * rand_odd64 + rand16 * 2^16) % 2^64 / 2^32 +// +// Contact danakj@chromium.org for any questions. +inline std::size_t HashInts32(uint32_t value1, uint32_t value2) { + uint64_t value1_64 = value1; + uint64_t hash64 = (value1_64 << 32) | value2; + + if (sizeof(std::size_t) >= sizeof(uint64_t)) + return static_cast<std::size_t>(hash64); + + uint64_t odd_random = 481046412LL << 32 | 1025306955LL; + uint32_t shift_random = 10121U << 16; + + hash64 = hash64 * odd_random + shift_random; + std::size_t high_bits = static_cast<std::size_t>( + hash64 >> (8 * (sizeof(uint64_t) - sizeof(std::size_t)))); + return high_bits; +} + +// Implement hashing for pairs of up-to 64-bit integer values. +// We use the compound integer hash method to produce a 64-bit hash code, by +// breaking the two 64-bit inputs into 4 32-bit values: +// http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000 +// Then we reduce our result to 32 bits if required, similar to above. +inline std::size_t HashInts64(uint64_t value1, uint64_t value2) { + uint32_t short_random1 = 842304669U; + uint32_t short_random2 = 619063811U; + uint32_t short_random3 = 937041849U; + uint32_t short_random4 = 3309708029U; + + uint32_t value1a = static_cast<uint32_t>(value1 & 0xffffffff); + uint32_t value1b = static_cast<uint32_t>((value1 >> 32) & 0xffffffff); + uint32_t value2a = static_cast<uint32_t>(value2 & 0xffffffff); + uint32_t value2b = static_cast<uint32_t>((value2 >> 32) & 0xffffffff); + + uint64_t product1 = static_cast<uint64_t>(value1a) * short_random1; + uint64_t product2 = static_cast<uint64_t>(value1b) * short_random2; + uint64_t product3 = static_cast<uint64_t>(value2a) * short_random3; + uint64_t product4 = static_cast<uint64_t>(value2b) * short_random4; + + uint64_t hash64 = product1 + product2 + product3 + product4; + + if (sizeof(std::size_t) >= sizeof(uint64_t)) + return static_cast<std::size_t>(hash64); + + uint64_t odd_random = 1578233944LL << 32 | 194370989LL; + uint32_t shift_random = 20591U << 16; + + hash64 = hash64 * odd_random + shift_random; + std::size_t high_bits = static_cast<std::size_t>( + hash64 >> (8 * (sizeof(uint64_t) - sizeof(std::size_t)))); + return high_bits; +} + +template<typename T1, typename T2> +inline std::size_t HashPair(T1 value1, T2 value2) { + // This condition is expected to be compile-time evaluated and optimised away + // in release builds. + if (sizeof(T1) > sizeof(uint32_t) || (sizeof(T2) > sizeof(uint32_t))) + return HashInts64(value1, value2); + + return HashInts32(value1, value2); +} + +} // namespace base + +namespace BASE_HASH_NAMESPACE { + +// Implement methods for hashing a pair of integers, so they can be used as +// keys in STL containers. + +template<typename Type1, typename Type2> +struct hash<std::pair<Type1, Type2> > { + std::size_t operator()(std::pair<Type1, Type2> value) const { + return base::HashPair(value.first, value.second); + } +}; + +} // namespace BASE_HASH_NAMESPACE + +#undef DEFINE_PAIR_HASH_FUNCTION_START +#undef DEFINE_PAIR_HASH_FUNCTION_END + +#endif // BASE_CONTAINERS_HASH_TABLES_H_ |