| //===- FuzzerDataFlowTrace.cpp - DataFlowTrace ---*- 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // fuzzer::DataFlowTrace |
| //===----------------------------------------------------------------------===// |
| |
| #include "FuzzerDataFlowTrace.h" |
| #include "FuzzerIO.h" |
| #include "FuzzerRandom.h" |
| |
| #include <cstdlib> |
| #include <fstream> |
| #include <sstream> |
| #include <string> |
| #include <vector> |
| |
| namespace fuzzer { |
| static const char *kFunctionsTxt = "functions.txt"; |
| |
| bool BlockCoverage::AppendCoverage(const std::string &S) { |
| std::stringstream SS(S); |
| return AppendCoverage(SS); |
| } |
| |
| // Coverage lines have this form: |
| // CN X Y Z T |
| // where N is the number of the function, T is the total number of instrumented |
| // BBs, and X,Y,Z, if present, are the indecies of covered BB. |
| // BB #0, which is the entry block, is not explicitly listed. |
| bool BlockCoverage::AppendCoverage(std::istream &IN) { |
| std::string L; |
| while (std::getline(IN, L, '\n')) { |
| if (L.empty() || L[0] != 'C') |
| continue; // Ignore non-coverage lines. |
| std::stringstream SS(L.c_str() + 1); |
| size_t FunctionId = 0; |
| SS >> FunctionId; |
| Vector<uint32_t> CoveredBlocks; |
| while (true) { |
| uint32_t BB = 0; |
| SS >> BB; |
| if (!SS) break; |
| CoveredBlocks.push_back(BB); |
| } |
| if (CoveredBlocks.empty()) return false; |
| uint32_t NumBlocks = CoveredBlocks.back(); |
| CoveredBlocks.pop_back(); |
| for (auto BB : CoveredBlocks) |
| if (BB >= NumBlocks) return false; |
| auto It = Functions.find(FunctionId); |
| auto &Counters = |
| It == Functions.end() |
| ? Functions.insert({FunctionId, Vector<uint32_t>(NumBlocks)}) |
| .first->second |
| : It->second; |
| |
| if (Counters.size() != NumBlocks) return false; // wrong number of blocks. |
| |
| Counters[0]++; |
| for (auto BB : CoveredBlocks) |
| Counters[BB]++; |
| } |
| return true; |
| } |
| |
| // Assign weights to each function. |
| // General principles: |
| // * any uncovered function gets weight 0. |
| // * a function with lots of uncovered blocks gets bigger weight. |
| // * a function with a less frequently executed code gets bigger weight. |
| Vector<double> BlockCoverage::FunctionWeights(size_t NumFunctions) const { |
| Vector<double> Res(NumFunctions); |
| for (auto It : Functions) { |
| auto FunctionID = It.first; |
| auto Counters = It.second; |
| auto &Weight = Res[FunctionID]; |
| Weight = 1000.; // this function is covered. |
| Weight /= SmallestNonZeroCounter(Counters); |
| Weight *= NumberOfUncoveredBlocks(Counters) + 1; // make sure it's not 0. |
| } |
| return Res; |
| } |
| |
| void DataFlowTrace::ReadCoverage(const std::string &DirPath) { |
| Vector<SizedFile> Files; |
| GetSizedFilesFromDir(DirPath, &Files); |
| for (auto &SF : Files) { |
| auto Name = Basename(SF.File); |
| if (Name == kFunctionsTxt) continue; |
| std::ifstream IF(SF.File); |
| Coverage.AppendCoverage(IF); |
| } |
| } |
| |
| void DataFlowTrace::Init(const std::string &DirPath, |
| std::string *FocusFunction, |
| Random &Rand) { |
| if (DirPath.empty()) return; |
| Printf("INFO: DataFlowTrace: reading from '%s'\n", DirPath.c_str()); |
| Vector<SizedFile> Files; |
| GetSizedFilesFromDir(DirPath, &Files); |
| std::string L; |
| size_t FocusFuncIdx = SIZE_MAX; |
| Vector<std::string> FunctionNames; |
| |
| // Read functions.txt |
| std::ifstream IF(DirPlusFile(DirPath, kFunctionsTxt)); |
| size_t NumFunctions = 0; |
| while (std::getline(IF, L, '\n')) { |
| FunctionNames.push_back(L); |
| NumFunctions++; |
| if (*FocusFunction == L) |
| FocusFuncIdx = NumFunctions - 1; |
| } |
| |
| if (*FocusFunction == "auto") { |
| // AUTOFOCUS works like this: |
| // * reads the coverage data from the DFT files. |
| // * assigns weights to functions based on coverage. |
| // * chooses a random function according to the weights. |
| ReadCoverage(DirPath); |
| auto Weights = Coverage.FunctionWeights(NumFunctions); |
| Vector<double> Intervals(NumFunctions + 1); |
| std::iota(Intervals.begin(), Intervals.end(), 0); |
| auto Distribution = std::piecewise_constant_distribution<double>( |
| Intervals.begin(), Intervals.end(), Weights.begin()); |
| FocusFuncIdx = static_cast<size_t>(Distribution(Rand)); |
| *FocusFunction = FunctionNames[FocusFuncIdx]; |
| assert(FocusFuncIdx < NumFunctions); |
| Printf("INFO: AUTOFOCUS: %zd %s\n", FocusFuncIdx, |
| FunctionNames[FocusFuncIdx].c_str()); |
| for (size_t i = 0; i < NumFunctions; i++) { |
| if (!Weights[i]) continue; |
| Printf(" [%zd] W %g\tBB-tot %u\tBB-cov %u\tEntryFreq %u:\t%s\n", i, |
| Weights[i], Coverage.GetNumberOfBlocks(i), |
| Coverage.GetNumberOfCoveredBlocks(i), Coverage.GetCounter(i, 0), |
| FunctionNames[i].c_str()); |
| } |
| } |
| |
| if (!NumFunctions || FocusFuncIdx == SIZE_MAX || Files.size() <= 1) |
| return; |
| |
| // Read traces. |
| size_t NumTraceFiles = 0; |
| size_t NumTracesWithFocusFunction = 0; |
| for (auto &SF : Files) { |
| auto Name = Basename(SF.File); |
| if (Name == kFunctionsTxt) continue; |
| auto ParseError = [&](const char *Err) { |
| Printf("DataFlowTrace: parse error: %s\n File: %s\n Line: %s\n", Err, |
| Name.c_str(), L.c_str()); |
| }; |
| NumTraceFiles++; |
| // Printf("=== %s\n", Name.c_str()); |
| std::ifstream IF(SF.File); |
| while (std::getline(IF, L, '\n')) { |
| if (!L.empty() && L[0] == 'C') |
| continue; // Ignore coverage. |
| size_t SpacePos = L.find(' '); |
| if (SpacePos == std::string::npos) |
| return ParseError("no space in the trace line"); |
| if (L.empty() || L[0] != 'F') |
| return ParseError("the trace line doesn't start with 'F'"); |
| size_t N = std::atol(L.c_str() + 1); |
| if (N >= NumFunctions) |
| return ParseError("N is greater than the number of functions"); |
| if (N == FocusFuncIdx) { |
| NumTracesWithFocusFunction++; |
| const char *Beg = L.c_str() + SpacePos + 1; |
| const char *End = L.c_str() + L.size(); |
| assert(Beg < End); |
| size_t Len = End - Beg; |
| Vector<uint8_t> V(Len); |
| for (size_t I = 0; I < Len; I++) { |
| if (Beg[I] != '0' && Beg[I] != '1') |
| ParseError("the trace should contain only 0 or 1"); |
| V[I] = Beg[I] == '1'; |
| } |
| Traces[Name] = V; |
| // Print just a few small traces. |
| if (NumTracesWithFocusFunction <= 3 && Len <= 16) |
| Printf("%s => |%s|\n", Name.c_str(), L.c_str() + SpacePos + 1); |
| break; // No need to parse the following lines. |
| } |
| } |
| } |
| assert(NumTraceFiles == Files.size() - 1); |
| Printf("INFO: DataFlowTrace: %zd trace files, %zd functions, " |
| "%zd traces with focus function\n", |
| NumTraceFiles, NumFunctions, NumTracesWithFocusFunction); |
| } |
| |
| } // namespace fuzzer |
| |