[fuzzer] Add support for token-based fuzzing (e.g. for C++). Allow string flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233745 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Fuzzer/test/CMakeLists.txt

@@ -6,6 +6,7 @@ set(CMAKE_CXX_FLAGS_RELEASE "${LIBFUZZER_FLAGS_BASE} -O0 -fsanitize-coverage=4")
 
 set(Tests
   CounterTest
+  CxxTokensTest
   FourIndependentBranchesTest
   FullCoverageSetTest
   InfiniteTest

lib/Fuzzer/test/CxxTokensTest.cpp

@@ -0,0 +1,24 @@
+// Simple test for a fuzzer. The fuzzer must find a sequence of C++ tokens.
+#include <cstdint>
+#include <cstdlib>
+#include <cstddef>
+#include <cstring>
+#include <iostream>
+
+static void Found() {
+  std::cout << "Found the target, exiting\n";
+  exit(1);
+}
+
+extern "C" void TestOneInput(const uint8_t *Data, size_t Size) {
+  // looking for "thread_local unsigned A;"
+  if (Size < 24) return;
+  if (0 == memcmp(&Data[0], "thread_local", 12))
+    if (Data[12] == ' ')
+      if (0 == memcmp(&Data[13], "unsigned", 8))
+        if (Data[21] == ' ')
+          if (Data[22] == 'A')
+            if (Data[23] == ';')
+              Found();
+}
+

lib/Fuzzer/test/fuzzer.test

@@ -23,3 +23,6 @@ CounterTest: BINGO
 
 RUN: not ./LLVMFuzzer-DFSanSimpleCmpTest -seed=1 -timeout=15 2>&1 | FileCheck %s --check-prefix=DFSanSimpleCmpTest
 DFSanSimpleCmpTest: Found the target:
+
+RUN: not ./LLVMFuzzer-CxxTokensTest -seed=1 -timeout=15 -tokens=%S/../cxx_fuzzer_tokens.txt 2>&1 | FileCheck %s --check-prefix=CxxTokensTest
+CxxTokensTest: Found the target, exiting