1 files changed, 54 insertions, 0 deletions
diff --git a/agent/src/jmh/java/com/code_intelligence/jazzer/instrumentor/UnsafeSimpleIncrementCoverageMap.java b/agent/src/jmh/java/com/code_intelligence/jazzer/instrumentor/UnsafeSimpleIncrementCoverageMap.java
new file mode 100644
index 00000000..60fb8c8d
--- /dev/null
+++ b/agent/src/jmh/java/com/code_intelligence/jazzer/instrumentor/UnsafeSimpleIncrementCoverageMap.java
@@ -0,0 +1,54 @@
+// Copyright 2022 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.
+
+package com.code_intelligence.jazzer.instrumentor;
+
+import java.lang.reflect.Field;
+import sun.misc.Unsafe;
+
+public final class UnsafeSimpleIncrementCoverageMap {
+  private static final Unsafe UNSAFE;
+
+  static {
+    Unsafe unsafe;
+    try {
+      Field f = Unsafe.class.getDeclaredField("theUnsafe");
+      f.setAccessible(true);
+      unsafe = (Unsafe) f.get(null);
+    } catch (IllegalAccessException | NoSuchFieldException e) {
+      e.printStackTrace();
+      System.exit(1);
+      // Not reached.
+      unsafe = null;
+    }
+    UNSAFE = unsafe;
+  }
+
+  // The current target, JsonSanitizer, uses less than 2048 coverage counters.
+  private static final long NUM_COUNTERS = 4096;
+  private static final long countersAddress = UNSAFE.allocateMemory(NUM_COUNTERS);
+
+  static {
+    UNSAFE.setMemory(countersAddress, NUM_COUNTERS, (byte) 0);
+  }
+
+  public static void enlargeIfNeeded(int nextId) {
+    // Statically sized counters buffer.
+  }
+
+  public static void recordCoverage(final int id) {
+    final long address = countersAddress + id;
+    UNSAFE.putByte(address, (byte) (UNSAFE.getByte(address) + 1));
+  }
+}