1// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
2// See https://llvm.org/LICENSE.txt for license information.
3// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
4
5// Make sure the fuzzer eventually finds all possible values of a variable
6// within a range.
7#include <cassert>
8#include <cstdint>
9#include <cstdio>
10#include <cstdlib>
11#include <cstring>
12#include <set>
13
14const size_t N = 1 << 12;
15
16// Define an array of counters that will be understood by libFuzzer
17// as extra coverage signal. The array must be:
18// * uint8_t
19// * in the section named __libfuzzer_extra_counters.
20// The target code may declare more than one such array.
21//
22// Use either `Counters[Idx] = 1` or `Counters[Idx]++;`
23// depending on whether multiple occurrences of the event 'Idx'
24// is important to distinguish from one occurrence.
25#ifdef __linux__
26__attribute__((section("__libfuzzer_extra_counters")))
27#endif
28static uint8_t Counters[N];
29
30extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
31 static std::set<uint16_t> SeenIdx;
32 if (Size != 4) return 0;
33 uint32_t Idx;
34 memcpy(&Idx, Data, 4);
35 Idx %= N;
36 assert(Counters[Idx] == 0); // libFuzzer should reset these between the runs.
37 // Or Counters[Idx]=1 if we don't care how many times this happened.
38 Counters[Idx]++;
39 SeenIdx.insert(Idx);
40 if (SeenIdx.size() == N) {
41 fprintf(stderr, "BINGO: found all values\n");
42 abort();
43 }
44 return 0;
45}
46