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qpdf/libqpdf/QPDF_Stream.cc
Jay Berkenbilt cb769c62e5 WHITESPACE ONLY -- expand tabs in source code
This comment expands all tabs using an 8-character tab-width. You
should ignore this commit when using git blame or use git blame -w.

In the early days, I used to use tabs where possible for indentation,
since emacs did this automatically. In recent years, I have switched
to only using spaces, which means qpdf source code has been a mixture
of spaces and tabs. I have avoided cleaning this up because of not
wanting gratuitous whitespaces change to cloud the output of git
blame, but I changed my mind after discussing with users who view qpdf
source code in editors/IDEs that have other tab widths by default and
in light of the fact that I am planning to start applying automatic
code formatting soon.
2022-02-08 11:51:15 -05:00

692 lines
19 KiB
C++

#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.hasKey("/Type")) ||
decode_parms.isDictionaryOfType("/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.getBufferSharedPointer();
}
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.getBufferSharedPointer();
}
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<std::shared_ptr<Pipeline>> to_delete;
PointerHolder<ContentNormalizer> normalizer;
std::shared_ptr<Pipeline> new_pipeline;
if (filter)
{
if (encode_flags & qpdf_ef_compress)
{
new_pipeline = std::make_shared<Pl_Flate>(
"compress stream", pipeline, Pl_Flate::a_deflate);
to_delete.push_back(new_pipeline);
pipeline = new_pipeline.get();
}
if (encode_flags & qpdf_ef_normalize)
{
normalizer = make_pointer_holder<ContentNormalizer>();
new_pipeline = std::make_shared<Pl_QPDFTokenizer>(
"normalizer", normalizer.get(), pipeline);
to_delete.push_back(new_pipeline);
pipeline = new_pipeline.get();
}
for (auto iter = this->token_filters.rbegin();
iter != this->token_filters.rend(); ++iter)
{
new_pipeline = std::make_shared<Pl_QPDFTokenizer>(
"token filter", (*iter).get(), pipeline);
to_delete.push_back(new_pipeline);
pipeline = new_pipeline.get();
}
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.get())
{
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.get())
{
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.get() &&
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);
}