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.

3 files changed, 60 insertions, 0 deletions

diff --git a/examples/BUILD.bazel b/examples/BUILD.bazel
index ca17ba3f..d721b81d 100644
--- a/examples/BUILD.bazel
+++ b/examples/BUILD.bazel
@@ -150,6 +150,36 @@ java_fuzz_target_test(
     ],
 )
 
+java_binary(
+    name = "JsonSanitizerDenylistCrash",
+    args = [
+        "com.example.JsonSanitizerDenylistFuzzer",
+        "$(location :json_sanitizer_denylist_crash)",
+    ],
+    data = [
+        ":json_sanitizer_denylist_crash",
+    ],
+    main_class = "com.code_intelligence.jazzer.replay.Replayer",
+    runtime_deps = [
+        ":JsonSanitizerDenylistFuzzer_target_deploy.jar",
+        "//agent/src/main/java/com/code_intelligence/jazzer/replay:Replayer_deploy.jar",
+    ],
+)
+
+sh_test(
+    name = "JsonSanitizerDenylistCrashTest",
+    srcs = ["check_for_finding.sh"],
+    args = [
+        "$(location :JsonSanitizerDenylistCrash)",
+        "com.example.JsonSanitizerDenylistFuzzer",
+        "$(location :json_sanitizer_denylist_crash)",
+    ],
+    data = [
+        ":JsonSanitizerDenylistCrash",
+        ":json_sanitizer_denylist_crash",
+    ],
+)
+
 java_fuzz_target_test(
     name = "JsonSanitizerIdempotenceFuzzer",
     srcs = [
diff --git a/examples/check_for_finding.sh b/examples/check_for_finding.sh
new file mode 100755
index 00000000..f60c011c
--- /dev/null
+++ b/examples/check_for_finding.sh
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Copyright 2021 Code Intelligence GmbH
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+eval "$@"
+# Assert that we either found a crash in java (exit code 77) or an ASan crash
+# (exit code 76).
+declare -i exit_code=$?
+if [ $exit_code -eq 77 ] || [ $exit_code -eq 76 ]
+then
+  if [ "$(ls "$DEFAULT_CRASH_PREFIX/")" ]; then
+    exit 0
+  else
+    exit 1
+  fi
+else
+  echo "Unexpected exit code: $exit_code"
+  exit 1
+fi
diff --git a/examples/json_sanitizer_denylist_crash b/examples/json_sanitizer_denylist_crash
new file mode 100644
index 00000000..7324203a
--- /dev/null
+++ b/examples/json_sanitizer_denylist_crash