[High] audit_export streaming swallows serde_json::to_writer errors → malformed JSON possible

Severity: High · Domain: Error handling · Source: audit-04-error-handling.md

Location

crates/librefang-api/src/routes/audit.rs:380-388

Problem

The shape is:

let mut buf = Vec::new();
buf.push(b',');                                  // separator first
let _ = serde_json::to_writer(&mut buf, &value); // ignored

If to_writer fails, the chunk contains only , — producing output like [ , {...}, , {...} ], which is invalid JSON. Even if to_writer into a Vec<u8> is practically infallible (no I/O), the let _ = masks the invariant; any future refactor that swaps the writer for a real tokio::io::AsyncWrite instantly silently corrupts exports.

Fix

Either:

serde_json::to_writer(&mut buf, &value)
    .expect("serializing serde_json::Value into Vec<u8> is infallible");

or build via to_vec and concatenate:

let payload = serde_json::to_vec(&value).expect("infallible");
if !first { buf.push(b','); }
buf.extend_from_slice(&payload);

Tests

• Property test: round-trip arbitrary audit rows through export → serde_json::from_slice::<Vec<Value>> succeeds for every output.