Add second batch of fuzzers for libutils

This adds fuzzers for:
- CallStack
- Looper
- LruCache
- Printer
- ProcessCallStack
- PropertyMap
- RWLock
- RefBase
- StopWatch.
Test: Ran each fuzzer for 10 minutes. Rough coverage est. (likely far below actual value): 10.97%

Signed-off-by: Dylan Katz <dylan.katz@leviathansecurity.com>
Change-Id: I2f9f35c18b13338c282fb7f9c3ea4099ecb2c56f
diff --git a/libutils/ProcessCallStack_fuzz.cpp b/libutils/ProcessCallStack_fuzz.cpp
new file mode 100644
index 0000000..30136cd
--- /dev/null
+++ b/libutils/ProcessCallStack_fuzz.cpp
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <atomic>
+#include <thread>
+
+#include "fuzzer/FuzzedDataProvider.h"
+#include "utils/ProcessCallStack.h"
+using android::ProcessCallStack;
+
+static constexpr int MAX_NAME_SIZE = 1000;
+static constexpr int MAX_LOG_META_SIZE = 1000;
+static constexpr uint8_t MAX_THREADS = 10;
+
+std::atomic_bool ranCallStackUpdate(false);
+void loop() {
+    while (!ranCallStackUpdate.load()) {
+        std::this_thread::sleep_for(std::chrono::milliseconds(50));
+    }
+}
+
+void spawnThreads(FuzzedDataProvider* dataProvider) {
+    std::vector<std::thread> threads = std::vector<std::thread>();
+
+    // Get the number of threads to generate
+    uint8_t count = dataProvider->ConsumeIntegralInRange<uint8_t>(1, MAX_THREADS);
+
+    // Generate threads
+    for (uint8_t i = 0; i < count; i++) {
+        std::string threadName =
+                dataProvider->ConsumeRandomLengthString(MAX_NAME_SIZE).append(std::to_string(i));
+        std::thread th = std::thread(loop);
+        pthread_setname_np(th.native_handle(), threadName.c_str());
+        threads.push_back(move(th));
+    }
+
+    // Collect thread information
+    ProcessCallStack callStack = ProcessCallStack();
+    callStack.update();
+
+    // Tell our patiently waiting threads they can be done now.
+    ranCallStackUpdate.store(true);
+
+    std::string logTag = dataProvider->ConsumeRandomLengthString(MAX_LOG_META_SIZE);
+    std::string prefix = dataProvider->ConsumeRandomLengthString(MAX_LOG_META_SIZE);
+    // Both of these, along with dump, all call print() under the hood,
+    // Which is covered by the Printer fuzzer.
+    callStack.log(logTag.c_str());
+    callStack.toString(prefix.c_str());
+
+    // Check size
+    callStack.size();
+
+    // wait for any remaining threads
+    for (auto& thread : threads) {
+        thread.join();
+    }
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    FuzzedDataProvider dataProvider(data, size);
+    spawnThreads(&dataProvider);
+    return 0;
+}