#include <qpdf/Buffer.hh>

#include <qpdf/BufferInputSource.hh>

#include <qpdf/Pl_DCT.hh>

#include <qpdf/Pl_Discard.hh>

#include <qpdf/Pl_Flate.hh>

#include <qpdf/Pl_PNGFilter.hh>

#include <qpdf/Pl_RunLength.hh>

#include <qpdf/Pl_TIFFPredictor.hh>

#include <qpdf/QPDF.hh>

#include <qpdf/QPDFPageObjectHelper.hh>

#include <qpdf/QPDFWriter.hh>

#include <qpdf/QUtil.hh>

#include <cstdlib>

class DiscardContents: public QPDFObjectHandle::ParserCallbacks

{

  public:

    ~DiscardContents() override = default;

    void

    handleObject(QPDFObjectHandle) override

    {

    }

    void

    handleEOF() override

    {

    }

};

class FuzzHelper

{

  public:

    FuzzHelper(unsigned char const* data, size_t size);

    void run();

  private:

    std::shared_ptr<QPDF> getQpdf();

    std::shared_ptr<QPDFWriter> getWriter(std::shared_ptr<QPDF>);

    void doWrite(std::shared_ptr<QPDFWriter> w);

    void testWrite();

    void doChecks();

    Buffer input_buffer;

    Pl_Discard discard;

};

FuzzHelper::FuzzHelper(unsigned char const* data, size_t size) :

    // We do not modify data, so it is safe to remove the const for Buffer

    input_buffer(const_cast<unsigned char*>(data), size)

{

}

std::shared_ptr<QPDF>

FuzzHelper::getQpdf()

{

    auto is =

        std::shared_ptr<InputSource>(new BufferInputSource("fuzz input", &this->input_buffer));

    auto qpdf = QPDF::create();

    qpdf->setMaxWarnings(200);

    qpdf->processInputSource(is);

    return qpdf;

}

std::shared_ptr<QPDFWriter>

FuzzHelper::getWriter(std::shared_ptr<QPDF> qpdf)

{

    auto w = std::make_shared<QPDFWriter>(*qpdf);

    w->setOutputPipeline(&this->discard);

    w->setDecodeLevel(qpdf_dl_all);

    return w;

}

void

FuzzHelper::doWrite(std::shared_ptr<QPDFWriter> w)

{

    try {

        w->write();

    } catch (QPDFExc const& e) {

        std::cerr << e.what() << '\n';

    } catch (std::runtime_error const& e) {

        std::cerr << e.what() << '\n';

    }

}

void

FuzzHelper::testWrite()

{

    // Write in various ways to exercise QPDFWriter

    std::shared_ptr<QPDF> q;

    std::shared_ptr<QPDFWriter> w;

    q = getQpdf();

    w = getWriter(q);

    w->setDeterministicID(true);

    w->setObjectStreamMode(qpdf_o_generate);

    w->setLinearization(true);

    doWrite(w);

}

void

FuzzHelper::doChecks()

{

    // Limit the memory used to decompress JPEG files during fuzzing. Excessive memory use during

    // fuzzing is due to corrupt JPEG data which sometimes cannot be detected before

    // jpeg_start_decompress is called. During normal use of qpdf very large JPEGs can occasionally

    // occur legitimately and therefore must be allowed during normal operations.

    Pl_DCT::setMemoryLimit(100'000'000);

    Pl_DCT::setScanLimit(50);

    Pl_PNGFilter::setMemoryLimit(1'000'000);

    Pl_RunLength::setMemoryLimit(1'000'000);

    Pl_TIFFPredictor::setMemoryLimit(1'000'000);

    Pl_Flate::memory_limit(200'000);

    // Do not decompress corrupt data. This may cause extended runtime within jpeglib without

    // exercising additional code paths in qpdf, and potentially causing counterproductive timeouts.

    Pl_DCT::setThrowOnCorruptData(true);

    // Get as much coverage as possible in parts of the library that

    // might benefit from fuzzing.

    std::cerr << "\ninfo: starting testWrite\n";

    testWrite();

}

void

FuzzHelper::run()

{

    // The goal here is that you should be able to throw anything at

    // libqpdf and it will respond without any memory errors and never

    // do anything worse than throwing a QPDFExc or

    // std::runtime_error. Throwing any other kind of exception,

    // segfaulting, or having a memory error (when built with

    // appropriate sanitizers) will all cause abnormal exit.

    try {

        doChecks();

    } catch (QPDFExc const& e) {

        std::cerr << "QPDFExc: " << e.what() << '\n';

    } catch (std::runtime_error const& e) {

        std::cerr << "runtime_error: " << e.what() << '\n';

    }

}

extern "C" int

LLVMFuzzerTestOneInput(unsigned char const* data, size_t size)

{

#ifndef _WIN32

    // Used by jpeg library to work around false positives in memory

    // sanitizer.

    setenv("JSIMD_FORCENONE", "1", 1);

#endif

    FuzzHelper f(data, size);

    f.run();

    return 0;

}