.github: ci for ts_ffi

Currently, this just builds the examples. The examples are updated to
not be in subdirs per-executable, so that on non-Windows the executables
can be named just the plain example name.

Signed-off-by: Nathan Perry <nathan@tailscale.com>
Change-Id: I46e2c71ec600adbf13a442247c1e5dcc6a6a6964

Author: npry

.github/workflows/c.yml

@@ -0,0 +1,68 @@
+name: c
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - v*
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+env:
+  # cache-busting key -- change it if the build changes in a way that invalidates old
+  # cached state
+  cache_key: init
+
+jobs:
+  build_test:
+    name: build (rust ${{ matrix.rust_toolchain.label }}, ${{ matrix.target.runner }})
+    runs-on: ${{ matrix.target.runner }}
+
+    strategy:
+      matrix:
+        rust_toolchain:
+          - version: 1.94.0
+            label: latest
+
+        target:
+          - triple: x86_64-unknown-linux-gnu
+            runner: linux-x86_64-16cpu
+          - triple: aarch64-unknown-linux-gnu
+            runner: linux-arm64-16cpu
+          # macos uses clang, not working yet
+          # - triple: aarch64-apple-darwin
+          #        runner: macos-26
+
+    defaults:
+      run:
+        working-directory: ts_ffi
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Cache Rust
+        id: cache-rust-c
+        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            ~/.rustup/toolchains
+            target/
+          key: ${{ matrix.target.triple }}-rs-c-${{ env.cache_key }}-${{ matrix.rust_toolchain.version }}-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Install Rust toolchain
+        id: install-toolchain
+        if: steps.cache-rust-c.outputs.cache-hit != 'true'
+        uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # master 4/22/2026
+        with:
+          toolchain: ${{ matrix.rust_toolchain.version }}
+
+      - name: Build examples
+        run: make -C examples

ts_ffi/examples/Makefile

@@ -44,8 +44,8 @@ all: $(TARGETS)
 clean:
 	rm -f $(TARGETS)
 
-$(TARGETS): %$(TARGET_SUFFIX): libtailscalers $(wildcard %/*.c)
-	$(CC) -o $@ $(wildcard $*/*.c) $(CFLAGS)
+$(TARGETS): %$(TARGET_SUFFIX): %.c libtailscalers
+	$(CC) -o $@ $< $(CFLAGS)
 
 libtailscalers:
 	cargo build -p ts_ffi --profile $(RUST_PROFILE) $(RUST_TARGET_FLAG)