qpdf/libqpdf/QPDF_Stream.cc

#include <qpdf/QPDF_Stream.hh>

#include <qpdf/QUtil.hh>
#include <qpdf/Pipeline.hh>
#include <qpdf/Pl_Flate.hh>
#include <qpdf/Pl_Buffer.hh>
#include <qpdf/Pl_Count.hh>
#include <qpdf/ContentNormalizer.hh>
#include <qpdf/QTC.hh>
#include <qpdf/QPDF.hh>
#include <qpdf/QPDFExc.hh>
#include <qpdf/Pl_QPDFTokenizer.hh>
#include <qpdf/QIntC.hh>
#include <qpdf/SF_FlateLzwDecode.hh>
#include <qpdf/SF_DCTDecode.hh>
#include <qpdf/SF_RunLengthDecode.hh>
#include <qpdf/SF_ASCII85Decode.hh>
#include <qpdf/SF_ASCIIHexDecode.hh>

#include <stdexcept>

class SF_Crypt: public QPDFStreamFilter
{
  public:
    SF_Crypt() = default;
    virtual ~SF_Crypt() = default;

    virtual bool setDecodeParms(QPDFObjectHandle decode_parms)
    {
        if (decode_parms.isNull())
        {
            return true;
        }
        bool filterable = true;
        for (auto const& key: decode_parms.getKeys())
        {
            if (((key == "/Type") || (key == "/Name")) &&
                (decode_parms.getKey("/Type").isNull() ||
                 (decode_parms.getKey("/Type").isName() &&
                  (decode_parms.getKey("/Type").getName() ==
                   "/CryptFilterDecodeParms"))))
            {
                // we handle this in decryptStream
            }
            else
            {
                filterable = false;
            }
        }
        return filterable;
    }

    virtual Pipeline* getDecodePipeline(Pipeline*)
    {
        // Not used -- handled by pipeStreamData
        return nullptr;
    }
};

std::map<std::string, std::string> QPDF_Stream::filter_abbreviations = {
    // The PDF specification provides these filter abbreviations for
    // use in inline images, but according to table H.1 in the pre-ISO
    // versions of the PDF specification, Adobe Reader also accepts
    // them for stream filters.
    {"/AHx", "/ASCIIHexDecode"},
    {"/A85", "/ASCII85Decode"},
    {"/LZW", "/LZWDecode"},
    {"/Fl", "/FlateDecode"},
    {"/RL", "/RunLengthDecode"},
    {"/CCF", "/CCITTFaxDecode"},
    {"/DCT", "/DCTDecode"},
};

std::map<
    std::string,
    std::function<std::shared_ptr<QPDFStreamFilter>()>>
QPDF_Stream::filter_factories = {
    {"/Crypt", []() { return std::make_shared<SF_Crypt>(); }},
    {"/FlateDecode", SF_FlateLzwDecode::flate_factory},
    {"/LZWDecode", SF_FlateLzwDecode::lzw_factory},
    {"/RunLengthDecode", SF_RunLengthDecode::factory},
    {"/DCTDecode", SF_DCTDecode::factory},
    {"/ASCII85Decode", SF_ASCII85Decode::factory},
    {"/ASCIIHexDecode", SF_ASCIIHexDecode::factory},
};

QPDF_Stream::QPDF_Stream(QPDF* qpdf, int objid, int generation,
			 QPDFObjectHandle stream_dict,
			 qpdf_offset_t offset, size_t length) :
    qpdf(qpdf),
    objid(objid),
    generation(generation),
    filter_on_write(true),
    stream_dict(stream_dict),
    offset(offset),
    length(length)
{
    if (! stream_dict.isDictionary())
    {
	throw std::logic_error(
	    "stream object instantiated with non-dictionary "
	    "object for dictionary");
    }
    setStreamDescription();
}

QPDF_Stream::~QPDF_Stream()
{
}

void
QPDF_Stream::registerStreamFilter(
    std::string const& filter_name,
    std::function<std::shared_ptr<QPDFStreamFilter>()> factory)
{
    filter_factories[filter_name] = factory;
}

void
QPDF_Stream::setFilterOnWrite(bool val)
{
    this->filter_on_write = val;
}

bool
QPDF_Stream::getFilterOnWrite() const
{
    return this->filter_on_write;
}

void
QPDF_Stream::releaseResolved()
{
    this->stream_provider = 0;
    QPDFObjectHandle::ReleaseResolver::releaseResolved(this->stream_dict);
}

void
QPDF_Stream::setObjGen(int objid, int generation)
{
    if (! ((this->objid == 0) && (this->generation == 0)))
    {
	throw std::logic_error(
	    "attempt to set object ID and generation of a stream"
	    " that already has them");
    }
    this->objid = objid;
    this->generation = generation;
}

std::string
QPDF_Stream::unparse()
{
    // Unparse stream objects as indirect references
    return QUtil::int_to_string(this->objid) + " " +
	QUtil::int_to_string(this->generation) + " R";
}

JSON
QPDF_Stream::getJSON()
{
    return this->stream_dict.getJSON();
}

QPDFObject::object_type_e
QPDF_Stream::getTypeCode() const
{
    return QPDFObject::ot_stream;
}

char const*
QPDF_Stream::getTypeName() const
{
    return "stream";
}

void
QPDF_Stream::setDescription(QPDF* qpdf, std::string const& description)
{
    this->QPDFObject::setDescription(qpdf, description);
    setDictDescription();
}

void
QPDF_Stream::setStreamDescription()
{
    setDescription(
        this->qpdf,
        this->qpdf->getFilename() +
        ", stream object " + QUtil::int_to_string(this->objid) + " " +
        QUtil::int_to_string(this->generation));
}

void
QPDF_Stream::setDictDescription()
{
    QPDF* qpdf = 0;
    std::string description;
    if ((! this->stream_dict.hasObjectDescription()) &&
        getDescription(qpdf, description))
    {
        this->stream_dict.setObjectDescription(
            qpdf, description + " -> stream dictionary");
    }
}

QPDFObjectHandle
QPDF_Stream::getDict() const
{
    return this->stream_dict;
}

bool
QPDF_Stream::isDataModified() const
{
    return (! this->token_filters.empty());
}

qpdf_offset_t
QPDF_Stream::getOffset() const
{
    return this->offset;
}

size_t
QPDF_Stream::getLength() const
{
    return this->length;
}

PointerHolder<Buffer>
QPDF_Stream::getStreamDataBuffer() const
{
    return this->stream_data;
}

PointerHolder<QPDFObjectHandle::StreamDataProvider>
QPDF_Stream::getStreamDataProvider() const
{
    return this->stream_provider;
}

PointerHolder<Buffer>
QPDF_Stream::getStreamData(qpdf_stream_decode_level_e decode_level)
{
    Pl_Buffer buf("stream data buffer");
    bool filtered;
    pipeStreamData(&buf, &filtered, 0, decode_level, false, false);
    if (! filtered)
    {
	throw QPDFExc(qpdf_e_unsupported, qpdf->getFilename(),
                      "", this->offset,
                      "getStreamData called on unfilterable stream");
    }
    QTC::TC("qpdf", "QPDF_Stream getStreamData");
    return buf.getBuffer();
}

PointerHolder<Buffer>
QPDF_Stream::getRawStreamData()
{
    Pl_Buffer buf("stream data buffer");
    if (! pipeStreamData(&buf, nullptr, 0, qpdf_dl_none, false, false))
    {
	throw QPDFExc(qpdf_e_unsupported, qpdf->getFilename(),
                      "", this->offset,
                      "error getting raw stream data");
    }
    QTC::TC("qpdf", "QPDF_Stream getRawStreamData");
    return buf.getBuffer();
}

bool
QPDF_Stream::filterable(
    std::vector<std::shared_ptr<QPDFStreamFilter>>& filters,
    bool& specialized_compression,
    bool& lossy_compression)
{
    // Check filters

    QPDFObjectHandle filter_obj = this->stream_dict.getKey("/Filter");
    bool filters_okay = true;

    std::vector<std::string> filter_names;

    if (filter_obj.isNull())
    {
	// No filters
    }
    else if (filter_obj.isName())
    {
	// One filter
	filter_names.push_back(filter_obj.getName());
    }
    else if (filter_obj.isArray())
    {
	// Potentially multiple filters
	int n = filter_obj.getArrayNItems();
	for (int i = 0; i < n; ++i)
	{
	    QPDFObjectHandle item = filter_obj.getArrayItem(i);
	    if (item.isName())
	    {
		filter_names.push_back(item.getName());
	    }
	    else
	    {
		filters_okay = false;
	    }
	}
    }
    else
    {
	filters_okay = false;
    }

    if (! filters_okay)
    {
	QTC::TC("qpdf", "QPDF_Stream invalid filter");
	warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
                     "", this->offset,
                     "stream filter type is not name or array"));
        return false;
    }

    bool filterable = true;

    for (auto& filter_name: filter_names)
    {
	if (filter_abbreviations.count(filter_name))
	{
	    QTC::TC("qpdf", "QPDF_Stream expand filter abbreviation");
	    filter_name = filter_abbreviations[filter_name];
	}

        auto ff = filter_factories.find(filter_name);
        if (ff == filter_factories.end())
        {
            filterable = false;
        }
        else
        {
            filters.push_back((ff->second)());
        }
    }

    if (! filterable)
    {
        return false;
    }

    // filters now contains a list of filters to be applied in order.
    // See which ones we can support.

    // See if we can support any decode parameters that are specified.

    QPDFObjectHandle decode_obj = this->stream_dict.getKey("/DecodeParms");
    std::vector<QPDFObjectHandle> decode_parms;
    if (decode_obj.isArray() && (decode_obj.getArrayNItems() == 0))
    {
        decode_obj = QPDFObjectHandle::newNull();
    }
    if (decode_obj.isArray())
    {
        for (int i = 0; i < decode_obj.getArrayNItems(); ++i)
        {
            decode_parms.push_back(decode_obj.getArrayItem(i));
        }
    }
    else
    {
        for (unsigned int i = 0; i < filter_names.size(); ++i)
        {
            decode_parms.push_back(decode_obj);
        }
    }

    // Ignore /DecodeParms entirely if /Filters is empty.  At least
    // one case of a file whose /DecodeParms was [ << >> ] when
    // /Filters was empty has been seen in the wild.
    if ((filters.size() != 0) && (decode_parms.size() != filters.size()))
    {
        warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
                     "", this->offset,
                     "stream /DecodeParms length is"
                     " inconsistent with filters"));
        filterable = false;
    }

    if (! filterable)
    {
        return false;
    }

    for (size_t i = 0; i < filters.size(); ++i)
    {
        auto filter = filters.at(i);
        auto decode_item = decode_parms.at(i);

        if (filter->setDecodeParms(decode_item))
        {
            if (filter->isSpecializedCompression())
            {
                specialized_compression = true;
            }
            if (filter->isLossyCompression())
            {
                specialized_compression = true;
                lossy_compression = true;
            }
        }
        else
        {
            filterable = false;
        }
    }

    return filterable;
}

bool
QPDF_Stream::pipeStreamData(Pipeline* pipeline, bool* filterp,
                            int encode_flags,
                            qpdf_stream_decode_level_e decode_level,
                            bool suppress_warnings, bool will_retry)
{
    std::vector<std::shared_ptr<QPDFStreamFilter>> filters;
    bool specialized_compression = false;
    bool lossy_compression = false;
    bool ignored;
    if (filterp == nullptr)
    {
        filterp = &ignored;
    }
    bool& filter = *filterp;
    filter = (! ((encode_flags == 0) && (decode_level == qpdf_dl_none)));
    bool success = true;
    if (filter)
    {
	filter = filterable(
            filters, specialized_compression, lossy_compression);
        if ((decode_level < qpdf_dl_all) && lossy_compression)
        {
            filter = false;
        }
        if ((decode_level < qpdf_dl_specialized) && specialized_compression)
        {
            filter = false;
        }
        QTC::TC("qpdf", "QPDF_Stream special filters",
                (! filter) ? 0 :
                lossy_compression ? 1 :
                specialized_compression ? 2 :
                3);
    }

    if (pipeline == 0)
    {
	QTC::TC("qpdf", "QPDF_Stream pipeStreamData with null pipeline");
        // Return value is whether we can filter in this case.
	return filter;
    }

    // Construct the pipeline in reverse order. Force pipelines we
    // create to be deleted when this function finishes. Pipelines
    // created by QPDFStreamFilter objects will be deleted by those
    // objects.
    std::vector<PointerHolder<Pipeline>> to_delete;

    PointerHolder<ContentNormalizer> normalizer;
    if (filter)
    {
	if (encode_flags & qpdf_ef_compress)
	{
	    pipeline = new Pl_Flate("compress stream", pipeline,
				    Pl_Flate::a_deflate);
	    to_delete.push_back(pipeline);
	}

	if (encode_flags & qpdf_ef_normalize)
	{
            normalizer = new ContentNormalizer();
	    pipeline = new Pl_QPDFTokenizer(
                "normalizer", normalizer.getPointer(), pipeline);
	    to_delete.push_back(pipeline);
	}

        for (std::vector<PointerHolder<
                 QPDFObjectHandle::TokenFilter> >::reverse_iterator iter =
                 this->token_filters.rbegin();
             iter != this->token_filters.rend(); ++iter)
        {
            pipeline = new Pl_QPDFTokenizer(
                "token filter", (*iter).getPointer(), pipeline);
            to_delete.push_back(pipeline);
        }

	for (auto f_iter = filters.rbegin();
             f_iter != filters.rend(); ++f_iter)
	{
            auto decode_pipeline = (*f_iter)->getDecodePipeline(pipeline);
            if (decode_pipeline)
            {
                pipeline = decode_pipeline;
            }
            Pl_Flate* flate = dynamic_cast<Pl_Flate*>(pipeline);
            if (flate != nullptr)
            {
                flate->setWarnCallback([this](char const* msg, int code) {
                    warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
                                 "", this->offset, msg));
                });
            }
	}
    }

    if (this->stream_data.getPointer())
    {
	QTC::TC("qpdf", "QPDF_Stream pipe replaced stream data");
	pipeline->write(this->stream_data->getBuffer(),
			this->stream_data->getSize());
	pipeline->finish();
    }
    else if (this->stream_provider.getPointer())
    {
	Pl_Count count("stream provider count", pipeline);
        if (this->stream_provider->supportsRetry())
        {
            if (! this->stream_provider->provideStreamData(
                    this->objid, this->generation, &count,
                    suppress_warnings, will_retry))
            {
                filter = false;
                success = false;
            }
        }
        else
        {
            this->stream_provider->provideStreamData(
                this->objid, this->generation, &count);
        }
	qpdf_offset_t actual_length = count.getCount();
	qpdf_offset_t desired_length = 0;
        if (success && this->stream_dict.hasKey("/Length"))
        {
	    desired_length = this->stream_dict.getKey("/Length").getIntValue();
            if (actual_length == desired_length)
            {
                QTC::TC("qpdf", "QPDF_Stream pipe use stream provider");
            }
            else
            {
                QTC::TC("qpdf", "QPDF_Stream provider length mismatch");
                // This would be caused by programmer error on the
                // part of a library user, not by invalid input data.
                throw std::runtime_error(
                    "stream data provider for " +
                    QUtil::int_to_string(this->objid) + " " +
                    QUtil::int_to_string(this->generation) +
                    " provided " +
                    QUtil::int_to_string(actual_length) +
                    " bytes instead of expected " +
                    QUtil::int_to_string(desired_length) + " bytes");
            }
        }
        else if (success)
        {
            QTC::TC("qpdf", "QPDF_Stream provider length not provided");
            this->stream_dict.replaceKey(
                "/Length", QPDFObjectHandle::newInteger(actual_length));
        }
    }
    else if (this->offset == 0)
    {
	QTC::TC("qpdf", "QPDF_Stream pipe no stream data");
	throw std::logic_error(
	    "pipeStreamData called for stream with no data");
    }
    else
    {
	QTC::TC("qpdf", "QPDF_Stream pipe original stream data");
	if (! QPDF::Pipe::pipeStreamData(this->qpdf, this->objid, this->generation,
                                         this->offset, this->length,
                                         this->stream_dict, pipeline,
                                         suppress_warnings,
                                         will_retry))
        {
            filter = false;
            success = false;
        }
    }

    if (filter &&
        (! suppress_warnings) &&
        normalizer.getPointer() &&
        normalizer->anyBadTokens())
    {
        warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
                     "", this->offset,
                     "content normalization encountered bad tokens"));
        if (normalizer->lastTokenWasBad())
        {
            QTC::TC("qpdf", "QPDF_Stream bad token at end during normalize");
            warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
                         "", this->offset,
                         "normalized content ended with a bad token;"
                         " you may be able to resolve this by"
                         " coalescing content streams in combination"
                         " with normalizing content. From the command"
                         " line, specify --coalesce-contents"));
        }
        warn(QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
                     "", this->offset,
                     "Resulting stream data may be corrupted but is"
                     " may still useful for manual inspection."
                     " For more information on this warning, search"
                     " for content normalization in the manual."));
    }

    return success;
}

void
QPDF_Stream::replaceStreamData(PointerHolder<Buffer> data,
			       QPDFObjectHandle const& filter,
			       QPDFObjectHandle const& decode_parms)
{
    this->stream_data = data;
    this->stream_provider = 0;
    replaceFilterData(filter, decode_parms, data->getSize());
}

void
QPDF_Stream::replaceStreamData(
    PointerHolder<QPDFObjectHandle::StreamDataProvider> provider,
    QPDFObjectHandle const& filter,
    QPDFObjectHandle const& decode_parms)
{
    this->stream_provider = provider;
    this->stream_data = 0;
    replaceFilterData(filter, decode_parms, 0);
}

void
QPDF_Stream::addTokenFilter(
    PointerHolder<QPDFObjectHandle::TokenFilter> token_filter)
{
    this->token_filters.push_back(token_filter);
}

void
QPDF_Stream::replaceFilterData(QPDFObjectHandle const& filter,
			       QPDFObjectHandle const& decode_parms,
			       size_t length)
{
    this->stream_dict.replaceOrRemoveKey("/Filter", filter);
    this->stream_dict.replaceOrRemoveKey("/DecodeParms", decode_parms);
    if (length == 0)
    {
        QTC::TC("qpdf", "QPDF_Stream unknown stream length");
        this->stream_dict.removeKey("/Length");
    }
    else
    {
        this->stream_dict.replaceKey(
            "/Length", QPDFObjectHandle::newInteger(
                QIntC::to_longlong(length)));
    }
}

void
QPDF_Stream::replaceDict(QPDFObjectHandle new_dict)
{
    this->stream_dict = new_dict;
    setDictDescription();
    QPDFObjectHandle length_obj = new_dict.getKey("/Length");
    if (length_obj.isInteger())
    {
        this->length = QIntC::to_size(length_obj.getUIntValue());
    }
    else
    {
        this->length = 0;
    }
}

void
QPDF_Stream::warn(QPDFExc const& e)
{
    this->qpdf->warn(e);
}