0                  Indicates success.
    -1                 Indicates an error; errno is set to one of the
                       following values:

                       o  EIO - An I/O error occurred while reading
                          from or writing to the file system.

                       o  ENOMEM - The range specified by
                          [addr, addr + len] is invalid for a
                          process's address space, or the range
                          specifies one or more unmapped pages.

                       o  EINVAL - The addr argument is not a
                          multiple of the page size as returned by
                          sysconf(_SC_PAGE_SIZE).

                       o  EFAULT - The range [addr, addr + len]
                          includes an invalid address.