Add rust-example CI job

Builds libroqr-ffi and roqr-relayd, builds examples/rust with warnings as
errors, and runs the example against a relay in echo mode as an end-to-end
smoke test (asserts all frames are echoed back). Relies on the Rust toolchain
preinstalled on ubuntu-latest. Documented in the guide's CI table.

Author: mondain

.github/workflows/ci.yml

@@ -84,3 +84,45 @@ jobs:
         env:
           TSAN_OPTIONS: "halt_on_error=0 history_size=7 second_deadlock_stack=1 suppressions=${{ github.workspace }}/cmake/tsan.supp"
         run: ctest --test-dir build --output-on-failure --timeout 300
+
+  rust-example:
+    name: rust ffi example
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: sudo apt-get update && sudo apt-get install -y
+             cmake g++ ninja-build libssl-dev openssl
+      - name: Build picoquic deps
+        run: eval "$(scripts/setup_picoquic_deps.sh)"
+      # Build only what the example needs: the FFI shared library and the relay.
+      - name: Build libroqr-ffi and roqr-relayd
+        run: |
+          eval "$(scripts/setup_picoquic_deps.sh)"
+          cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug \
+            -DROQR_BUILD_QUIC=ON -DROQR_BUILD_RTMP=ON -DROQR_BUILD_TOOLS=ON \
+            -DROQR_BUILD_FFI=ON -DROQR_BUILD_EXAMPLES=OFF \
+            -DROQR_BUILD_TESTS=OFF -DROQR_BUILD_JNI=OFF
+          cmake --build build --target roqr-ffi roqr-relayd --parallel
+      # ubuntu-latest ships a stable Rust toolchain; no install step needed.
+      - name: Build the Rust example
+        env:
+          ROQR_FFI_LIB_DIR: ${{ github.workspace }}/build/ffi
+          RUSTFLAGS: "-D warnings"
+        run: cargo build --manifest-path examples/rust/Cargo.toml
+      # End-to-end: the example connects to a relay in echo mode and must get
+      # every frame back. build.rs baked an rpath to ROQR_FFI_LIB_DIR, so the
+      # binary finds libroqr-ffi.so without LD_LIBRARY_PATH.
+      - name: Echo round-trip smoke test
+        run: |
+          openssl req -x509 -newkey ec -pkeyopt ec_paramgen_curve:prime256v1 \
+            -keyout key.pem -out cert.pem -days 365 -nodes -subj "/CN=localhost"
+          ./build/bin/roqr-relayd --cert cert.pem --key key.pem --port 4443 --mode echo &
+          relay_pid=$!
+          trap 'kill "$relay_pid" 2>/dev/null || true' EXIT
+          sleep 2
+          set +e
+          examples/rust/target/debug/roqr-rust-client 127.0.0.1 4443
+          rc=$?
+          set -e
+          exit $rc

docs/guide.md

@@ -131,6 +131,7 @@ network-thread callbacks — suppressing it could hide a real callback race.
 | `core-only (no picoquic)` | Builds and tests just the sans-I/O core (`ROQR_BUILD_QUIC=OFF`). |
 | `full (gcc)` / `full (clang)` | Full build with QUIC, tools, examples; runs the whole suite including the ffmpeg e2e tests. |
 | `thread-sanitizer (clang)` | Full build with `ROQR_SANITIZE=thread`; runs the suite under TSAN with the suppressions file. A race in ROQR code fails the job. |
+| `rust ffi example` | Builds `libroqr-ffi` and `roqr-relayd`, builds `examples/rust` (warnings-as-errors), and runs the example against a relay in echo mode as an end-to-end smoke test. |
 
 ### Project layout