Corinna Vinschen <vinschen@redhat.com> writes:

> Given all chars are sizeof(wchar_t), how's the buffer ever going to
> become unaligned?

It places the wchar_t at the end of _ubuf, which is 3 bytes long, making
it unaligned:

  fp->_p = &fp->_ubuf[sizeof (fp->_ubuf) - sizeof (wchar_t)];

-- 
-keith