Hmmm.
Looking at the LZSS decompresser in the scumm he engine, that works by just allocating big enough chunks of memory to decompress the entire stream. This is all fine and good. But *my* variant of LZSS doesn’t tell me how big the decompressed data is, only the compressed data. This, it turns out, is a bit of an arse.
At the moment I’m planning just to say “it’s never gonna be bigger than this” as a nasty hack, just to get something working. In the future, when I’m feeling a bit more confident, I’ll write an LZSS-compressed stream class (unless someone beats me to it :-).