wrappers_c_checks.h

//===-- wrappers_c_checks.h -------------------------------------*- 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
//
//===----------------------------------------------------------------------===//

#ifndef SCUDO_CHECKS_H_
#define SCUDO_CHECKS_H_

#include "common.h"

#include <errno.h>

#ifndef __has_builtin
#define __has_builtin(X) 0
#endif

namespace scudo {

// A common errno setting logic shared by almost all Scudo C wrappers.
inline void *setErrnoOnNull(void *Ptr) {
  if (UNLIKELY(!Ptr))
    errno = ENOMEM;
  return Ptr;
}

// Checks return true on failure.

// Checks aligned_alloc() parameters, verifies that the alignment is a power of
// two and that the size is a multiple of alignment.
inline bool checkAlignedAllocAlignmentAndSize(uptr Alignment, uptr Size) {
  return !isPowerOfTwo(Alignment) || !isAligned(Size, Alignment);
}

// Checks posix_memalign() parameters, verifies that alignment is a power of two
// and a multiple of sizeof(void *).
inline bool checkPosixMemalignAlignment(uptr Alignment) {
  return !isPowerOfTwo(Alignment) || !isAligned(Alignment, sizeof(void *));
}

// Returns true if calloc(Size, N) overflows on Size*N calculation. Use a
// builtin supported by recent clang & GCC if it exists, otherwise fallback to a
// costly division.
inline bool checkForCallocOverflow(uptr Size, uptr N, uptr *Product) {
#if __has_builtin(__builtin_umull_overflow) && (SCUDO_WORDSIZE == 64U)
  return __builtin_umull_overflow(Size, N,
                                  reinterpret_cast<unsigned long *>(Product));
#elif __has_builtin(__builtin_umul_overflow) && (SCUDO_WORDSIZE == 32U)
  // On, e.g. armv7, uptr/uintptr_t may be defined as unsigned long
  return __builtin_umul_overflow(Size, N,
                                 reinterpret_cast<unsigned int *>(Product));
#else
  *Product = Size * N;
  if (!Size)
    return false;
  return (*Product / Size) != N;
#endif
}

// Returns true if the size passed to pvalloc overflows when rounded to the next
// multiple of PageSize.
inline bool checkForPvallocOverflow(uptr Size, uptr PageSize) {
  return roundUp(Size, PageSize) < Size;
}

} // namespace scudo

#endif // SCUDO_CHECKS_H_