rem: bytes_split (size_t nchars, char *buf, size_t bufsize)
add: bytes_split (uintmax_t n_bytes, char *buf, size_t bufsize)
context: bytes_split (size_t nchars, char *buf, size_t bufsize){  size_t n_read;  int new_file_flag = 1;  size_t to_read;  size_t to_write = nchars;  char *bp_out;  do    {      n_read = full_read (input_desc, buf, bufsize);      if (n_read == SAFE_READ_ERROR)        error (EXIT_FAILURE, errno, "%s", infile);      bp_out = buf;      to_read = n_read;      for (;;)	{	  if (to_read < to_write)	    {	      if (to_read)	/* do not write 0 bytes! */		{		  cwrite (new_file_flag, bp_out, to_read);		  to_write -= to_read;		  new_file_flag = 0;		}	      break;	    }	  cwrite (new_file_flag, bp_out, to_write);	  bp_out += to_write;	  to_read -= to_write;	  new_file_flag = 1;	  to_write = nchars;	}    }  while (n_read == bufsize);}