[libFuzzer] make trace-based fuzzing not crash in presence of threads

llvm-svn: 256876

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/Fuzzer/test/ThreadedTest.cpp b/llvm/lib/Fuzzer/test/ThreadedTest.cpp
new file mode 100644
index 0000000..7aa114a
--- /dev/null
+++ b/llvm/lib/Fuzzer/test/ThreadedTest.cpp
@@ -0,0 +1,23 @@
+// Threaded test for a fuzzer. The fuzzer should not crash.
+#include <assert.h>
+#include <cstdint>
+#include <cstddef>
+#include <cstring>
+#include <thread>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  if (Size < 8) return 0;
+  assert(Data);
+  auto C = [&] {
+    size_t Res = 0;
+    for (size_t i = 0; i < Size / 2; i++)
+      Res += memcmp(Data, Data + Size / 2, 4);
+    return Res;
+  };
+  std::thread T[] = {std::thread(C), std::thread(C), std::thread(C),
+                     std::thread(C), std::thread(C), std::thread(C)};
+  for (auto &X : T)
+    X.join();
+  return 0;
+}
+