Run LLVM Fuzzer Without Dependencies

replay.cc

#include <cassert>

#include <iostream>
#include <fstream>
#include <vector>

#define ATTR_WEAK __attribute__((weak))

extern "C" {
  int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
  ATTR_WEAK int LLVMFuzzerInitialize(int *argc, char ***argv);
  ATTR_WEAK int LLVMFuzzerDeinitialize();
}

// Fixup for standalone usage
#define MAP_SIZE_POW2       16
#define MAP_SIZE            (1 << MAP_SIZE_POW2)
extern "C" {
  ATTR_WEAK uint8_t  __afl_area_initial[MAP_SIZE];
  ATTR_WEAK uint8_t* __afl_area_ptr = __afl_area_initial;
  ATTR_WEAK __thread uint32_t __afl_prev_loc;
}

// Execute any files provided as parameters.
int ExecuteFilesOnyByOne(int argc, char **argv) {
  for (int i = 1; i < argc; i++) {
    std::ifstream in(argv[i]); in.seekg(0, in.end);
    size_t length = in.tellg(); in.seekg (0, in.beg);
    std::cout << "Reading " << length << " bytes from " << argv[i] << std::endl;
    // Allocate exactly length bytes so that we reliably catch buffer overflows.
    std::vector<char> bytes(length);
    in.read(bytes.data(), bytes.size());
    assert(in);
    LLVMFuzzerTestOneInput(reinterpret_cast<const uint8_t *>(bytes.data()),
                           bytes.size());
    std::cout << "Execution successfull" << std::endl;
  }
  return 0;
}

int main(int argc, char **argv) {
  fprintf(stderr,
          "======================= INFO =========================\n"
          "This binary is built to run LLVM fuzzing driver\n"
          "To run the target function on individual input(s) execute this:\n"
          "  %s INPUT_FILE1 [INPUT_FILE2 ... ]\n"
          "======================================================\n",
          argv[0]);

  if (LLVMFuzzerInitialize) LLVMFuzzerInitialize(&argc, &argv);
  ExecuteFilesOnyByOne(argc, argv);
  if (LLVMFuzzerDeinitialize) LLVMFuzzerDeinitialize();
  return 0;
}