f->_flags |= _IO_ERR_SEEN; break;
_IO_file_write (f, data, n)     _IO_FILE *f;     const void *data;     _IO_ssize_t n;{  _IO_ssize_t to_do = n;  while (to_do > 0)    {      _IO_ssize_t count = _IO_write (f->_fileno, data, to_do);      if (count == EOF)	{#if 0 && defined EINTR	  /* We must not do this optimization since POSIX.1 explicitly	     requests that the stream operations must return with the	     error EINTR if this happens.  There must be the	     possibility that stream operations time out.  --drepper  */	  if (errno == EINTR)	    continue;	  else#endif	    {	      f->_flags |= _IO_ERR_SEEN;	      break;            }        }      to_do -= count;      data = (void *) ((char *) data + count);    }  n -= to_do;  if (f->_offset >= 0)    f->_offset += n;  return n;}