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//===-- scudo_utils.h -------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// Header for scudo_utils.cpp.
///
//===----------------------------------------------------------------------===//
#ifndef SCUDO_UTILS_H_
#define SCUDO_UTILS_H_
#include "sanitizer_common/sanitizer_common.h"
#include <string.h>
namespace __scudo {
template <class Dest, class Source>
INLINE Dest bit_cast(const Source& source) {
static_assert(sizeof(Dest) == sizeof(Source), "Sizes are not equal!");
Dest dest;
memcpy(&dest, &source, sizeof(dest));
return dest;
}
void NORETURN dieWithMessage(const char *Format, ...);
bool hasHardwareCRC32();
INLINE u64 rotl(const u64 X, int K) {
return (X << K) | (X >> (64 - K));
}
// XoRoShiRo128+ PRNG (http://xoroshiro.di.unimi.it/).
struct XoRoShiRo128Plus {
public:
void init() {
if (UNLIKELY(!GetRandom(reinterpret_cast<void *>(State), sizeof(State),
/*blocking=*/false))) {
// On some platforms, early processes like `init` do not have an
// initialized random pool (getrandom blocks and /dev/urandom doesn't
// exist yet), but we still have to provide them with some degree of
// entropy. Not having a secure seed is not as problematic for them, as
// they are less likely to be the target of heap based vulnerabilities
// exploitation attempts.
State[0] = NanoTime();
State[1] = 0;
}
fillCache();
}
u8 getU8() {
if (UNLIKELY(isCacheEmpty()))
fillCache();
const u8 Result = static_cast<u8>(CachedBytes & 0xff);
CachedBytes >>= 8;
CachedBytesAvailable--;
return Result;
}
u64 getU64() { return next(); }
private:
u8 CachedBytesAvailable;
u64 CachedBytes;
u64 State[2];
u64 next() {
const u64 S0 = State[0];
u64 S1 = State[1];
const u64 Result = S0 + S1;
S1 ^= S0;
State[0] = rotl(S0, 55) ^ S1 ^ (S1 << 14);
State[1] = rotl(S1, 36);
return Result;
}
bool isCacheEmpty() {
return CachedBytesAvailable == 0;
}
void fillCache() {
CachedBytes = next();
CachedBytesAvailable = sizeof(CachedBytes);
}
};
typedef XoRoShiRo128Plus ScudoPrng;
} // namespace __scudo
#endif // SCUDO_UTILS_H_
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