//===- FuzzerMerge.h - merging corpa ----------------------------*- C++ -* ===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//

// Merging Corpora.

//

// The task:

//   Take the existing corpus (possibly empty) and merge new inputs into

//   it so that only inputs with new coverage ('features') are added.

//   The process should tolerate the crashes, OOMs, leaks, etc.

//

// Algorithm:

//   The outter process collects the set of files and writes their names

//   into a temporary "control" file, then repeatedly launches the inner

//   process until all inputs are processed.

//   The outer process does not actually execute the target code.

//

//   The inner process reads the control file and sees a) list of all the inputs

//   and b) the last processed input. Then it starts processing the inputs one

//   by one. Before processing every input it writes one line to control file:

//   STARTED INPUT_ID INPUT_SIZE

//   After processing an input it write another line:

//   DONE INPUT_ID Feature1 Feature2 Feature3 ...

//   If a crash happens while processing an input the last line in the control

//   file will be "STARTED INPUT_ID" and so the next process will know

//   where to resume.

//

//   Once all inputs are processed by the innner process(es) the outer process

//   reads the control files and does the merge based entirely on the contents

//   of control file.

//   It uses a single pass greedy algorithm choosing first the smallest inputs

//   within the same size the inputs that have more new features.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_FUZZER_MERGE_H

#define LLVM_FUZZER_MERGE_H

#include "FuzzerDefs.h"

#include <istream>

#include <ostream>

#include <set>

#include <vector>

namespace fuzzer {

struct MergeFileInfo {

  std::string Name;

  size_t Size = 0;

  Vector<uint32_t> Features;

};

struct Merger {

  Vector<MergeFileInfo> Files;

  size_t NumFilesInFirstCorpus = 0;

  size_t FirstNotProcessedFile = 0;

  std::string LastFailure;

  bool Parse(std::istream &IS, bool ParseCoverage);

  bool Parse(const std::string &Str, bool ParseCoverage);

  void ParseOrExit(std::istream &IS, bool ParseCoverage);

  void PrintSummary(std::ostream &OS);

  Set<uint32_t> ParseSummary(std::istream &IS);

  size_t Merge(const Set<uint32_t> &InitialFeatures,

               Vector<std::string> *NewFiles);

  size_t Merge(Vector<std::string> *NewFiles) {

    return Merge(Set<uint32_t>{}, NewFiles);

  }

  size_t ApproximateMemoryConsumption() const;

  Set<uint32_t> AllFeatures() const;

};

}  // namespace fuzzer

#endif  // LLVM_FUZZER_MERGE_H