Add fuzzer test for preg_parser

components/policy/core/common/preg_parser_fuzzer.cc

Index: components/policy/core/common/preg_parser_fuzzer.cc
diff --git a/components/policy/core/common/preg_parser_fuzzer.cc b/components/policy/core/common/preg_parser_fuzzer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c81b0c54ed725360fe38bfbfd2f2758c920c1420
--- /dev/null
+++ b/components/policy/core/common/preg_parser_fuzzer.cc
@@ -0,0 +1,41 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <base/strings/utf_string_conversions.h>
+#include "base/strings/string16.h"
+
+#include "components/policy/core/common/policy_load_status.h"
+#include "components/policy/core/common/preg_parser.h"
+#include "components/policy/core/common/registry_dict.h"
+
+namespace {
+
+const char kRegistryChromePolicyKey[] = "SOFTWARE\\Policies\\Chromium";
+
+}  // namespace
+
+namespace policy {
+namespace preg_parser {
+
+// Disable logging.
+struct Environment {
+  Environment() { logging::SetMinLogLevel(logging::LOG_FATAL); }
+};
+
+Environment* env = new Environment();
+
+// Entry point for LibFuzzer.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  RegistryDict dict;
+  PolicyLoadStatus status;
+  const base::string16 root = base::ASCIIToUTF16(kRegistryChromePolicyKey);

[Oliver Chang, 2017/04/13 00:25:23]

nit: it might be a little more efficient if base::ASCIIToUTF16() is only done
once rather than every time LLVMFuzzerTestOneInput is called.

[ljusten (tachyonic), 2017/04/13 11:17:15]

I put it in env, but it's going to leak. Do you generally not care in fuzzers?

[Oliver Chang, 2017/04/13 19:58:24]

That's fine! It's only allocated once during fuzzing and we only consider
something to be a real leak if we lose the reference to it after we exit.

+  ReadDataInternal(data, size, root, &dict, &status, "data");
+  return 0;
+}
+
+}  //  namespace preg_parser
+}  //  namespace policy