testing/fuzzers/pdf_codec_fax_fuzzer.cc

// Copyright 2016 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <cstdint>
#include <memory>

#include "core/fxcodec/fax/faxmodule.h"
#include "core/fxcodec/scanlinedecoder.h"
#include "core/fxcrt/compiler_specific.h"
#include "core/fxcrt/span.h"
#include "testing/fuzzers/pdfium_fuzzer_util.h"

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  static constexpr size_t kParameterSize = 21;
  if (size < kParameterSize) {
    return 0;
  }

  // Limit data size to prevent fuzzer timeout.
  static constexpr size_t kMaxDataSize = 256 * 1024;
  if (size > kParameterSize + kMaxDataSize) {
    return 0;
  }

  // SAFETY: trusted arguments from fuzzer.
  auto span = UNSAFE_BUFFERS(pdfium::span(data, size));

  int width = GetInteger(data);
  int height = GetInteger(UNSAFE_TODO(data + 4));
  int K = GetInteger(UNSAFE_TODO(data + 8));
  int Columns = GetInteger(UNSAFE_TODO(data + 12));
  int Rows = GetInteger(UNSAFE_TODO(data + 16));
  bool EndOfLine = !(UNSAFE_TODO(data[20]) & 0x01);
  bool ByteAlign = !(UNSAFE_TODO(data[20]) & 0x02);
  // This controls if fxcodec::FaxDecoder::InvertBuffer() gets called.
  // The method is not interesting, and calling it doubles the runtime.
  const bool kBlackIs1 = false;

  std::unique_ptr<ScanlineDecoder> decoder =
      FaxModule::CreateDecoder(span.subspan(kParameterSize), width, height, K,
                               EndOfLine, ByteAlign, kBlackIs1, Columns, Rows);

  if (decoder) {
    int line = 0;
    while (!decoder->GetScanline(line).empty()) {
      line++;
    }
  }

  return 0;
}