CI: build and run our fuzz targets

This builds them in one job, and then spawns N parallel jobs to run each built
fuzz target for five minutes.

.github/workflows/rust.yml

@@ -41,6 +41,50 @@ jobs:
             $(find ./target/debug -type f -perm -100 | grep gimli | head -n 1) \
             > /dev/null
 
+  build_fuzz_targets:
+    name: Build fuzz targets
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install rustup
+        run: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal
+      - name: Install nightly rust
+        run: |
+          rustup install nightly
+          rustup default nightly
+      - name: Install `cargo fuzz`
+        run: cargo install cargo-fuzz --vers "^0.7.4"
+      - run: cargo fuzz build -Oa
+      - uses: actions/upload-artifact@v1
+        with:
+          name: fuzz-targets
+          path: fuzz/target/x86_64-unknown-linux-gnu/release/debug_*
+      - uses: actions/upload-artifact@v1
+        with:
+          name: fuzz-targets
+          path: fuzz/target/x86_64-unknown-linux-gnu/release/eh_*
+
+  run_fuzz_targets:
+    strategy:
+      matrix:
+        fuzz_target: ["debug_abbrev", "debug_aranges", "debug_info", "debug_line", "eh_frame", "eh_frame_hdr"]
+    name: "Run `${{matrix.fuzz_target}}` fuzz target"
+    needs: build_fuzz_targets
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone the fuzz corpora
+        uses: actions/checkout@v2
+        with:
+          repository: gimli-rs/gimli-libfuzzer-corpora
+          path: corpora
+      - name: Download fuzz targets
+        uses: actions/download-artifact@v1
+        with:
+          name: fuzz-targets
+      - name: "Run `${{matrix.fuzz_target}}` fuzz target"
+        # Note: 300 seconds = 5 minutes.
+        run: ./${{matrix.fuzz_target}} ./corpora/${{matrix.fuzz_target}} -max_total_time=300
+
   features:
     runs-on: ubuntu-latest
     steps: