4c513f2c7e
Newer versions of libc++ check that an allocator can be rebound to the
same element type. We need to add a rebind member to ZeroingAllocator
to fix this compiler error:
prebuilts/clang/host/linux-x86/clang-r498229/include/c++/v1/vector:376:19: error: static assertion failed due to requirement 'is_same<android::vold::ZeroingAllocator, std::allocator<char>>::value': [allocator.requirements] states that rebinding an allocator to the same type should result in the original allocator
static_assert(is_same<allocator_type, __rebind_alloc<__alloc_traits, value_type> >::value,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It likely doesn't matter in practice because this allocator is only
used with std::vector, which probably doesn't use allocator rebinding,
because it won't allocate an internal node type (e.g. unlike std::map,
std::list, etc).
Alternatively, ZeroingAllocator could be changed to a
ZeroingAllocator<T> that can zero arbitrary types, but it doesn't seem
necessary currently, and types other than char wouldn't be used.
Bug: b/175635923
Test: treehugger
Change-Id: I42e9d8f02a18637fc67e94cc1358d2ed733a7268
53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_VOLD_KEYBUFFER_H
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#define ANDROID_VOLD_KEYBUFFER_H
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#include <string.h>
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#include <memory>
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#include <type_traits>
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#include <vector>
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namespace android {
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namespace vold {
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// Allocator that delegates useful work to standard one but zeroes data before deallocating.
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class ZeroingAllocator : public std::allocator<char> {
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public:
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void deallocate(pointer p, size_type n) {
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memset_explicit(p, 0, n);
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std::allocator<char>::deallocate(p, n);
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}
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template <class Other>
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struct rebind {
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static_assert(std::is_same_v<char, Other>, "ZeroingAllocator is only defined for char");
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using other = ZeroingAllocator;
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};
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};
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// Char vector that zeroes memory when deallocating.
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using KeyBuffer = std::vector<char, ZeroingAllocator>;
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// Convenience methods to concatenate key buffers.
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KeyBuffer operator+(KeyBuffer&& lhs, const KeyBuffer& rhs);
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KeyBuffer operator+(KeyBuffer&& lhs, const char* rhs);
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} // namespace vold
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} // namespace android
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#endif
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