Hopefully someone can provide an answer to my question.

I wanted to know about SHA-1 hash values on the gnutella network, specifically with regard to partial file downloads. As I currently understand, if I have a partial download of a full file (let's call it file x), I can share that partial piece of file x on the network to other peers.

If file x has a unique SHA-1 hash value, and I have a portion of file x, (which itself would have a different SHA-1 hash value?), how does my computer broadcast to other peers that I have the SHA-1 value of file x, and not the SHA-1 value of the portion of file x? Is this even possible or am I just misinformed about how things work on the gnutella network?

Thanks