Re: [Qemu-devel] [PATCH 1/1] Make qemu_peek_buffer loop until it gets it's data

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> >> > +    while (index >= f->buf_size) {
> >> > +        int received = qemu_fill_buffer(f);
> >> > +
> >> > +        if (received <= 0) {
> >> 
> >> here, I don't know really what to do.  We just need one character, so
> >> the 1st call to qemu_fill_buffer() gives it to us, or we are already on
> >> problems.  i.e. no need of the while() loop.
> >
> > The problem is that peek_byte takes an offset, so while qemu_fill_buffer
> > will get us a byte, we actually need it to get us all the bytes upto the
> > offset, and that's not guaranteed from one call.
> 
> that is not a problem.
> 
> We never got a "hole" on the things that we ask for.  We ask for the
> "next byte", or the "next bytes", so in qemu_peek_byte() we are
> guaranteed (with current users) that we would only have to read a single
> byte.
> 
> I.e. qemu_peek_{buffer,byte}(....,offset, size) means that we have
> "already" peek until offset, and now we want size more bytes.

Hmm ok, that is convenient but is neither documented or enforced;
I'll rework my patch and at least document it, and possibly enforce it.

Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK