RFA/RFC: vCont for the remote protocol [client]

[Andrew Cagney]

> Is GDB trying to move away from alloca?  The internals manual says:
> 
>    GDB can use the non-portable function `alloca' for the allocation of
>    small temporary values (such as strings).

> So I use it to avoid cleanups.  OTOH, it occurs to me that
> rs->remote_packet_size is a bit large; OTOOH, remote.c uses this idiom
> all over the place already.
> 
> I've used xmalloc instead, since the buf is used for getpkt and thus
> must be remote_packet_size large.
> 
> Here's what I am about to check in.

There are two probems:

- the buffer can get very very large and that can blow the stack
- it isn't possible to audit this code (with out a deep understanding of 
that value) and hence demonstrate that the sprintf won't smash the 
stack/heap

You'll need to also change the sprintf to snprintf (parameterized with 
remote_packet_size.

Andrew