Add a stand-alone replayer

The replayer can be used to reproduce crashes for fuzz targets using the
FuzzedDataProvider only given the raw crashing input. This will help
maintainers of OSS-Fuzz projects to reproduce issues even though they
have no access to the Java reproducers, which ClusterFuzz does not
store.

Compared to the full Jazzer driver, it has the advantage that it is a
Java library (with a native library dependency) and can thus be
published to Maven.

Since we currently do not have multi-platform RBE or cross toolchains
set up on GitHub, the packages jars for the individual architectures are
merged in a GitHub Actions pipeline.

1 files changed, 76 insertions, 0 deletions

diff --git a/.github/workflows/build-replayer.yml b/.github/workflows/build-replayer.yml
new file mode 100644
index 00000000..aa617416
--- /dev/null
+++ b/.github/workflows/build-replayer.yml
@@ -0,0 +1,76 @@
+name: Release replayer
+
+on:
+  workflow_dispatch:
+
+jobs:
+
+  build_replayer:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-10.15]
+        include:
+          - os: ubuntu-latest
+            arch: "linux"
+            cache: "/home/runner/.cache/bazel-disk"
+          - os: macos-10.15
+            arch: "darwin"
+            cache: "/private/var/tmp/bazel-disk"
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up JDK
+        uses: actions/setup-java@v1
+        with:
+          java-version: 8
+
+      - name: Mount Bazel disk cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ matrix.cache }}
+          key: bazel-disk-cache-${{ matrix.arch }}-8
+
+      - name: Build
+        run: |
+          bazelisk build --config=ci --remote_header=x-buildbuddy-api-key=${{ secrets.BUILDBUDDY_API_KEY }} --disk_cache=${{ matrix.cache }} --java_runtime_version=localjdk_${{ matrix.jdk }} //agent/src/main/java/com/code_intelligence/jazzer/replay:Replayer_deploy.jar
+          cp -L bazel-bin/agent/src/main/java/com/code_intelligence/jazzer/replay/Replayer_deploy.jar replayer.jar
+
+      - name: Upload test logs
+        if: always()
+        uses: actions/upload-artifact@v2
+        with:
+          name: replayer_${{ matrix.arch }}.jar
+          path: replayer.jar
+
+  merge_jars:
+    runs-on: ubuntu-latest
+    needs: build_replayer
+
+    steps:
+      - name: Download macOS jar
+        uses: actions/download-artifact@v2
+        with:
+          name: replayer_darwin.jar
+          path: replayer_darwin
+
+      - name: Download Linux jar
+        uses: actions/download-artifact@v2
+        with:
+          name: replayer_linux.jar
+          path: replayer_linux
+
+      - name: Merge jars
+        run: |
+          mkdir merged
+          unzip -o replayer_darwin/replayer.jar -d merged
+          unzip -o replayer_linux/replayer.jar -d merged
+          jar cvmf merged/META-INF/MANIFEST.MF replayer.jar -C merged .
+
+      - name: Upload merged jar
+        uses: actions/upload-artifact@v2
+        with:
+          name: replayer.jar
+          path: replayer.jar
+