Rust and C examples are not equivalent

The Rust server example handles the writable streams but the C example does not handle that. I wasted some time figuring out how to handle partially processed streams as I was only looking at the C example. It would be nice (and expected) if the C examples are equivalent to Rust examples.

Compare the Rust server example with the corresponding C example, focusing first on how each handles writable streams and partially processed streams. Done means the C example handles writable streams equivalently to the Rust example; the issue names no specific files or tests, so locate the examples in the repository before running or updating relevant checks.

Written by the indexing model from the issue text.