platform_specific/utilities_posix.cpp

//===-- utilities_posix.cpp -------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "gwp_asan/definitions.h"
#include "gwp_asan/utilities.h"

#include <assert.h>

#ifdef __BIONIC__
#include <stdlib.h>
extern "C" GWP_ASAN_WEAK void android_set_abort_message(const char *);
#else // __BIONIC__
#include <stdio.h>
#endif

namespace gwp_asan {

#ifdef __BIONIC__
void Check(bool Condition, const char *Message) {
  if (Condition)
    return;
  if (&android_set_abort_message != nullptr)
    android_set_abort_message(Message);
  abort();
}
#else  // __BIONIC__
void Check(bool Condition, const char *Message) {
  if (Condition)
    return;
  fprintf(stderr, "%s", Message);
  __builtin_trap();
}
#endif // __BIONIC__

// See `bionic/tests/malloc_test.cpp` in the Android source for documentation
// regarding their alignment guarantees. We always round up to the closest
// 8-byte window. As GWP-ASan's malloc(X) can always get exactly an X-sized
// allocation, an allocation that rounds up to 16-bytes will always be given a
// 16-byte aligned allocation.
static size_t alignBionic(size_t RealAllocationSize) {
  if (RealAllocationSize % 8 == 0)
    return RealAllocationSize;
  return RealAllocationSize + 8 - (RealAllocationSize % 8);
}

static size_t alignPowerOfTwo(size_t RealAllocationSize) {
  if (RealAllocationSize <= 2)
    return RealAllocationSize;
  if (RealAllocationSize <= 4)
    return 4;
  if (RealAllocationSize <= 8)
    return 8;
  if (RealAllocationSize % 16 == 0)
    return RealAllocationSize;
  return RealAllocationSize + 16 - (RealAllocationSize % 16);
}

#ifdef __BIONIC__
static constexpr AlignmentStrategy PlatformDefaultAlignment =
    AlignmentStrategy::BIONIC;
#else  // __BIONIC__
static constexpr AlignmentStrategy PlatformDefaultAlignment =
    AlignmentStrategy::POWER_OF_TWO;
#endif // __BIONIC__

size_t rightAlignedAllocationSize(size_t RealAllocationSize,
                                  AlignmentStrategy Align) {
  assert(RealAllocationSize > 0);
  if (Align == AlignmentStrategy::DEFAULT)
    Align = PlatformDefaultAlignment;

  switch (Align) {
  case AlignmentStrategy::BIONIC:
    return alignBionic(RealAllocationSize);
  case AlignmentStrategy::POWER_OF_TWO:
    return alignPowerOfTwo(RealAllocationSize);
  case AlignmentStrategy::PERFECT:
    return RealAllocationSize;
  case AlignmentStrategy::DEFAULT:
    __builtin_unreachable();
  }
}

} // namespace gwp_asan