compiler-rt/test/fuzzer/CrossOverTest.cpp

   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 // Test for a fuzzer. The fuzzer must find the string
   6 // ABCDEFGHIJ
   7 // We use it as a test for each of CrossOver functionalities
   8 // by passing the following sets of two inputs to it:
   9 // {ABCDE00000, ZZZZZFGHIJ}
  10 // {ABCDEHIJ, ZFG} to specifically test InsertPartOf
  11 // {ABCDE00HIJ, ZFG} to specifically test CopyPartOf
  12 //
  13 #include <assert.h>
  14 #include <cstddef>
  15 #include <cstdint>
  16 #include <cstdlib>
  17 #include <iostream>
  18 #include <ostream>
  19
  20 static volatile int Sink;
  21 static volatile int *NullPtr;
  22
  23 // A modified jenkins_one_at_a_time_hash initialized by non-zero,
  24 // so that simple_hash(0) != 0. See also
  25 // https://en.wikipedia.org/wiki/Jenkins_hash_function
  26 static uint32_t simple_hash(const uint8_t *Data, size_t Size) {
  27   uint32_t Hash = 0x12039854;
  28   for (uint32_t i = 0; i < Size; i++) {
  29     Hash += Data[i];
  30     Hash += (Hash << 10);
  31     Hash ^= (Hash >> 6);
  32   }
  33   Hash += (Hash << 3);
  34   Hash ^= (Hash >> 11);
  35   Hash += (Hash << 15);
  36   return Hash;
  37 }
  38
  39 // Don't leave the string in the binary, so that fuzzer don't cheat;
  40 // const char *ABC = "ABCDEFGHIJ";
  41 // static uint32_t ExpectedHash = simple_hash((const uint8_t *)ABC, 10);
  42 static const uint32_t ExpectedHash = 0xe1677acb;
  43
  44 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
  45   // fprintf(stderr, "ExpectedHash: %x\n", ExpectedHash);
  46   if (Size == 10 && ExpectedHash == simple_hash(Data, Size))
  47     *NullPtr = 0;
  48   if (*Data == 'A')
  49     Sink++;
  50   if (*Data == 'Z')
  51     Sink--;
  52   return 0;
  53 }