Function read_http_request_line 

pub fn read_http_request_line(
    stream: &mut TcpStream,
    deadline: Instant,
    max_line_bytes: usize,
) -> Result<Vec<u8>>

Read only a bounded CRLF request line, without waiting for headers or a body.

Leaves later bytes in the original socket, so a fixture can classify a concurrent request before deciding whether to complete it. Uses blocking reads and the caller’s absolute deadline; no buffering consumes later bytes. Callers retain stream provenance, application classification and response policy.

Errors

Rejects invalid bounds, truncated/oversized/non-UTF-8 lines and deadline/I/O failures.