Add regex fuzzer

A fuzzer that mutates a WGSL code by finding two regions enclosed by
semicolons and swapping them randomly.

Change-Id: I5b14eb21fd2924227d05ac516f806c6e2efa6198
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/58395
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Alastair Donaldson <afdx@google.com>
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Alastair Donaldson <afdx@google.com>

fuzzers/tint_regex_fuzzer/fuzzer.cc

@@ -0,0 +1,85 @@
+// Copyright 2021 The Tint Authors.
+//
+// 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 <cstddef>
+#include <cstdint>
+
+#include "fuzzers/tint_common_fuzzer.h"
+#include "fuzzers/tint_regex_fuzzer/cli.h"
+
+#include "fuzzers/tint_regex_fuzzer/wgsl_mutator.h"
+
+#include "src/reader/wgsl/parser.h"
+#include "src/writer/wgsl/generator.h"
+
+namespace tint {
+namespace fuzzers {
+namespace regex_fuzzer {
+namespace {
+
+CliParams cli_params{};
+
+extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv) {
+  // Parse CLI parameters. `ParseCliParams` will call `exit` if some parameter
+  // is invalid.
+  cli_params = ParseCliParams(argc, *argv);
+  return 0;
+}
+
+extern "C" size_t LLVMFuzzerCustomMutator(uint8_t* data,
+                                          size_t size,
+                                          size_t max_size,
+                                          unsigned seed) {
+  const std::vector<std::string> delimiters{";"};
+  std::mt19937 generator(seed);
+  std::uniform_int_distribution<size_t> distribution(0, delimiters.size() - 1);
+  size_t ind = distribution(generator);
+
+  return FuzzEnclosedRegions(size, max_size, delimiters[ind], data, &generator);
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size == 0) {
+    return 0;
+  }
+
+  struct Target {
+    FuzzingTarget fuzzing_target;
+    OutputFormat output_format;
+    const char* name;
+  };
+
+  Target targets[] = {{FuzzingTarget::kWgsl, OutputFormat::kWGSL, "WGSL"},
+                      {FuzzingTarget::kHlsl, OutputFormat::kHLSL, "HLSL"},
+                      {FuzzingTarget::kMsl, OutputFormat::kMSL, "MSL"},
+                      {FuzzingTarget::kSpv, OutputFormat::kSpv, "SPV"}};
+
+  for (auto target : targets) {
+    if ((target.fuzzing_target & cli_params.fuzzing_target) !=
+        target.fuzzing_target) {
+      continue;
+    }
+
+    CommonFuzzer fuzzer(InputFormat::kWGSL, target.output_format);
+    fuzzer.EnableInspector();
+    fuzzer.Run(data, size);
+  }
+
+  return 0;
+}
+
+}  // namespace
+}  // namespace regex_fuzzer
+}  // namespace fuzzers
+}  // namespace tint