Function mmap

cpp/src/arrow/io/mman.h:74–126

}

static inline void* mmap(void* addr, size_t len, int prot, int flags, int fildes,
                         off_t off) {
  HANDLE fm, h;

  void* map = MAP_FAILED;
  const uint64_t off64 = static_cast<uint64_t>(off);
  const uint64_t maxSize = off64 + len;

  const DWORD dwFileOffsetLow = static_cast<DWORD>(off64 & 0xFFFFFFFFUL);
  const DWORD dwFileOffsetHigh = static_cast<DWORD>((off64 >> 32) & 0xFFFFFFFFUL);
  const DWORD dwMaxSizeLow = static_cast<DWORD>(maxSize & 0xFFFFFFFFUL);
  const DWORD dwMaxSizeHigh = static_cast<DWORD>((maxSize >> 32) & 0xFFFFFFFFUL);

  const DWORD protect = __map_mmap_prot_page(prot);
  const DWORD desiredAccess = __map_mmap_prot_file(prot);

  errno = 0;

  if (len == 0
      /* Unsupported flag combinations */
      || (flags & MAP_FIXED) != 0
      /* Unsupported protection combinations */
      || prot == PROT_EXEC) {
    errno = EINVAL;
    return MAP_FAILED;
  }

  h = ((flags & MAP_ANONYMOUS) == 0) ? (HANDLE)_get_osfhandle(fildes)
                                     : INVALID_HANDLE_VALUE;

  if ((flags & MAP_ANONYMOUS) == 0 && h == INVALID_HANDLE_VALUE) {
    errno = EBADF;
    return MAP_FAILED;
  }

  fm = CreateFileMapping(h, NULL, protect, dwMaxSizeHigh, dwMaxSizeLow, NULL);

  if (fm == NULL) {
    errno = __map_mman_error(GetLastError(), EPERM);
    return MAP_FAILED;
  }

  map = MapViewOfFile(fm, desiredAccess, dwFileOffsetHigh, dwFileOffsetLow, len);

  CloseHandle(fm);

  if (map == NULL) {
    errno = __map_mman_error(GetLastError(), EPERM);
    return MAP_FAILED;
  }

  return map;
}

static inline int munmap(void* addr, size_t len) {
  if (UnmapViewOfFile(addr)) return 0;