forked from OSchip/llvm-project
94 lines
2.4 KiB
C++
94 lines
2.4 KiB
C++
//===-- scudo_utils.h -------------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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///
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/// Header for scudo_utils.cpp.
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///
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//===----------------------------------------------------------------------===//
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#ifndef SCUDO_UTILS_H_
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#define SCUDO_UTILS_H_
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#include <string.h>
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#include "sanitizer_common/sanitizer_common.h"
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namespace __scudo {
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template <class Dest, class Source>
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inline Dest bit_cast(const Source& source) {
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static_assert(sizeof(Dest) == sizeof(Source), "Sizes are not equal!");
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Dest dest;
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memcpy(&dest, &source, sizeof(dest));
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return dest;
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}
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void NORETURN dieWithMessage(const char *Format, ...);
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enum CPUFeature {
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CRC32CPUFeature = 0,
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MaxCPUFeature,
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};
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bool testCPUFeature(CPUFeature feature);
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INLINE u64 rotl(const u64 X, int K) {
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return (X << K) | (X >> (64 - K));
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}
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// XoRoShiRo128+ PRNG (http://xoroshiro.di.unimi.it/).
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struct XoRoShiRo128Plus {
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public:
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void init() {
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if (UNLIKELY(!GetRandom(reinterpret_cast<void *>(State), sizeof(State)))) {
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// Early processes (eg: init) do not have /dev/urandom yet, but we still
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// have to provide them with some degree of entropy. Not having a secure
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// seed is not as problematic for them, as they are less likely to be
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// the target of heap based vulnerabilities exploitation attempts.
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State[0] = NanoTime();
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State[1] = 0;
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}
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fillCache();
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}
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u8 getU8() {
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if (UNLIKELY(isCacheEmpty()))
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fillCache();
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const u8 Result = static_cast<u8>(CachedBytes & 0xff);
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CachedBytes >>= 8;
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CachedBytesAvailable--;
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return Result;
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}
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u64 getU64() { return next(); }
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private:
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u8 CachedBytesAvailable;
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u64 CachedBytes;
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u64 State[2];
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u64 next() {
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const u64 S0 = State[0];
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u64 S1 = State[1];
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const u64 Result = S0 + S1;
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S1 ^= S0;
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State[0] = rotl(S0, 55) ^ S1 ^ (S1 << 14);
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State[1] = rotl(S1, 36);
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return Result;
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}
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bool isCacheEmpty() {
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return CachedBytesAvailable == 0;
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}
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void fillCache() {
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CachedBytes = next();
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CachedBytesAvailable = sizeof(CachedBytes);
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}
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};
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typedef XoRoShiRo128Plus ScudoPrng;
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} // namespace __scudo
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#endif // SCUDO_UTILS_H_
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