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be7a6b5cb3
Summary: While hacking on some code, I ran into a situation where some zero-initialized stat structs weren't actually being zeroed. This was either a compiler bug or a situation where the build system was not correctly rebuilding everything after my changes, and I did not have enough disassembly available to investigate. Either way, since this code assumes zero bits in some nonobvious ways, explicitly assert they are. Reviewed By: xavierd Differential Revision: D23644819 fbshipit-source-id: eb6bff9ff997379113db1e1bf9d6a0a538f10f0b
43 lines
1011 B
C++
43 lines
1011 B
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#pragma once
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#include <folly/FBString.h>
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#include <string>
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namespace facebook::eden {
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/**
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* Asserts the specified memory consists entirely of zeroes, and aborts the
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* process if not.
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*/
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void assertZeroBits(const void* memory, size_t size);
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template <typename T>
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void assertZeroBits(const T& value) {
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assertZeroBits(&value, sizeof(T));
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}
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template <typename StringType>
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bool isStringStorageEmbedded(const StringType& t) {
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const void* tbegin = &t;
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const void* tend = &t + 1;
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return std::less_equal<const void*>{}(tbegin, t.data()) &&
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std::less<const void*>{}(t.data(), tend);
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}
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template <typename StringType>
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size_t estimateIndirectMemoryUsage(const StringType& s) {
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if (isStringStorageEmbedded(s)) {
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return 0;
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} else {
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return folly::goodMallocSize(s.capacity());
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}
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}
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} // namespace facebook::eden
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