[compiler-rt] FuzzedDataProvider: Add PickValueInArray for std::array

[MarcoFalke]

Summary

This makes PickValueInArray work for std::array<T, s> (C++11). I've also tested the C++17 std::array (with compiler-deduced template parameters)

Author:
MarcoFalke <[e-mail]>

[MarcoFalke]

Made unit test pass 😅

[Dor1s]

Thanks for the patch. LGTM

Do you need help committing this?

[MarcoFalke]

Yes, please. I don't have commit right.

Edit: For author and email you can use:

Author: MarcoFalke <[e-mail]>

[Dor1s]

@morehouse @metzman Matt and Jonathan, could any of you please commit this? I don't have a checkout handy plus haven't figured out my current CLA situation.

[metzman]

In D93412#2461136, @Dor1s wrote:

@morehouse @metzman Matt and Jonathan, could any of you please commit this? I don't have a checkout handy plus haven't figured out my current CLA situation.

I can merge but I think @kcc likes it if someone from dynamic tools approves before I merge changes.

[Dor1s]

rebase

[Dor1s]

lint

compiler-rt/include/fuzzer/FuzzedDataProvider.h

 //===- FuzzedDataProvider.h - Utility header for fuzz targets ---*- C++ -* ===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 // A single header library providing an utility class to break up an array of
 // bytes. Whenever run on the same input, provides the same output, as long as
 // its methods are called in the same order, with the same arguments.
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_
 #define LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_
 
 #include <algorithm>
+#include <array>
 #include <climits>
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <initializer_list>
 #include <string>
 #include <type_traits>
 #include <utility>
public:
 
   bool ConsumeBool();
 
   // Returns a value chosen from the given enum.
   template <typename T> T ConsumeEnum();
 
   // Returns a value from the given array.
   template <typename T, size_t size> T PickValueInArray(const T (&array)[size]);
+  template <typename T, size_t size>
+  T PickValueInArray(const std::array<T, size> &array);
   template <typename T> T PickValueInArray(std::initializer_list<const T> list);
 
   // Writes data to the given destination and returns number of bytes written.
   size_t ConsumeData(void *destination, size_t num_bytes);
 
   // Reports the remaining bytes available for fuzzed input.
   size_t remaining_bytes() { return remaining_bytes_; }
 

 
 // Returns a copy of the value selected from the given fixed-size |array|.
 template <typename T, size_t size>
 T FuzzedDataProvider::PickValueInArray(const T (&array)[size]) {
   static_assert(size > 0, "The array must be non empty.");
   return array[ConsumeIntegralInRange<size_t>(0, size - 1)];
 }
 
+template <typename T, size_t size>
+T FuzzedDataProvider::PickValueInArray(const std::array<T, size> &array) {
+  static_assert(size > 0, "The array must be non empty.");
+  return array[ConsumeIntegralInRange<size_t>(0, size - 1)];
+}
+
 template <typename T>
 T FuzzedDataProvider::PickValueInArray(std::initializer_list<const T> list) {
   // TODO(Dor1s): switch to static_assert once C++14 is allowed.
   if (!list.size())
     abort();
 
   return *(list.begin() + ConsumeIntegralInRange<size_t>(0, list.size() - 1));
 }

compiler-rt/lib/fuzzer/tests/FuzzedDataProviderUnittest.cpp

 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include "gtest/gtest.h"
 #include <cstdint>
 #include <cstdlib>
 
 #include <fuzzer/FuzzedDataProvider.h>
 
 // The test is intentionally extensive, as behavior of |FuzzedDataProvider| must
 // not be broken, given than many fuzz targets depend on it. Changing the
 // behavior might invalidate existing corpora and make the fuzz targets using
TEST(FuzzedDataProvider, ConsumeBool) {
   EXPECT_EQ(false, DataProv.ConsumeBool());
 
   // Exhaust the buffer.
   auto String = DataProv.ConsumeBytesAsString(31337);
   EXPECT_EQ(size_t(1014), String.length());
   EXPECT_EQ(false, DataProv.ConsumeBool());
 }
 
+TEST(FuzzedDataProvider, PickValueInStdArray) {
+  FuzzedDataProvider DataProv(Data, sizeof(Data));
+  const std::array<int, 5> Array = {1, 2, 3, 4, 5};
+  EXPECT_EQ(5, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(2, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(2, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(3, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(3, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(3, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(1, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(3, DataProv.PickValueInArray(Array));
+  EXPECT_EQ(2, DataProv.PickValueInArray(Array));
+}
+
 TEST(FuzzedDataProvider, PickValueInArray) {
   FuzzedDataProvider DataProv(Data, sizeof(Data));
   const int Array[] = {1, 2, 3, 4, 5};
   EXPECT_EQ(5, DataProv.PickValueInArray(Array));
   EXPECT_EQ(2, DataProv.PickValueInArray(Array));
   EXPECT_EQ(2, DataProv.PickValueInArray(Array));
   EXPECT_EQ(3, DataProv.PickValueInArray(Array));
   EXPECT_EQ(3, DataProv.PickValueInArray(Array));