60 lines
2.1 KiB
C++
60 lines
2.1 KiB
C++
// Copyright 2024 The Abseil Authors
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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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// https://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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#ifndef ABSL_BASE_INTERNAL_POISON_H_
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#define ABSL_BASE_INTERNAL_POISON_H_
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#include <cstdint>
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#include "absl/base/config.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace base_internal {
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inline void* GetBadPointerInternal() {
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// A likely bad pointer. Pointers are required to have high bits that are all
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// zero or all one for certain 64-bit CPUs. This pointer value will hopefully
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// cause a crash on dereference and also be clearly recognizable as invalid.
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constexpr uint64_t kBadPtr = 0xBAD0BAD0BAD0BAD0;
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auto ret = reinterpret_cast<void*>(static_cast<uintptr_t>(kBadPtr));
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#ifndef _MSC_VER // MSVC doesn't support inline asm with `volatile`.
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// Try to prevent the compiler from optimizing out the undefined behavior.
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asm volatile("" : : "r"(ret) :); // NOLINT
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#endif
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return ret;
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}
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void* InitializePoisonedPointerInternal();
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inline void* get_poisoned_pointer() {
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#if defined(NDEBUG) && !defined(ABSL_HAVE_ADDRESS_SANITIZER) && \
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!defined(ABSL_HAVE_MEMORY_SANITIZER)
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// In optimized non-sanitized builds, avoid the function-local static because
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// of the codegen and runtime cost.
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return GetBadPointerInternal();
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#else
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// Non-optimized builds may use more robust implementation. Note that we can't
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// use a static global because Chromium doesn't allow non-constinit globals.
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static void* ptr = InitializePoisonedPointerInternal();
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return ptr;
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#endif
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}
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} // namespace base_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_BASE_INTERNAL_POISON_H_
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