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qpdf/libqpdf/QPDF_Stream.cc
Jay Berkenbilt 31bde2f9d7 Handle empty DecodeParams array for (fixes #331) 
On read, ignore /DecodeParms when empty list; on write, delete it.
Some files have been found that include an empty list for
/DecodeParms, but this is not technically compliant with the spec, and
the only sensible interpretation is to treat it as if there are no
decode parameters.
2019-06-09 17:19:49 -04:00

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#include <qpdf/QPDF_Stream.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/Pipeline.hh>
#include <qpdf/Pl_Flate.hh>
#include <qpdf/Pl_PNGFilter.hh>
#include <qpdf/Pl_TIFFPredictor.hh>
#include <qpdf/Pl_RC4.hh>
#include <qpdf/Pl_Buffer.hh>
#include <qpdf/Pl_ASCII85Decoder.hh>
#include <qpdf/Pl_ASCIIHexDecoder.hh>
#include <qpdf/Pl_LZWDecoder.hh>
#include <qpdf/Pl_RunLength.hh>
#include <qpdf/Pl_DCT.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 <stdexcept>
std::map<std::string, std::string> QPDF_Stream::filter_abbreviations;
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),
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::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,
"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");
if (! pipeStreamData(&buf, 0, decode_level, false, false))
{
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");
pipeStreamData(&buf, 0, qpdf_dl_none, false, false);
QTC::TC("qpdf", "QPDF_Stream getRawStreamData");
return buf.getBuffer();
}
bool
QPDF_Stream::understandDecodeParams(
std::string const& filter, QPDFObjectHandle decode_obj,
int& predictor, int& columns,
int& colors, int& bits_per_component,
bool& early_code_change)
{
bool filterable = true;
std::set<std::string> keys = decode_obj.getKeys();
for (std::set<std::string>::iterator iter = keys.begin();
iter != keys.end(); ++iter)
{
std::string const& key = *iter;
if (((filter == "/FlateDecode") || (filter == "/LZWDecode")) &&
(key == "/Predictor"))
{
QPDFObjectHandle predictor_obj = decode_obj.getKey(key);
if (predictor_obj.isInteger())
{
predictor = predictor_obj.getIntValue();
if (! ((predictor == 1) || (predictor == 2) ||
((predictor >= 10) && (predictor <= 15))))
{
filterable = false;
}
}
else
{
filterable = false;
}
}
else if ((filter == "/LZWDecode") && (key == "/EarlyChange"))
{
QPDFObjectHandle earlychange_obj = decode_obj.getKey(key);
if (earlychange_obj.isInteger())
{
int earlychange = earlychange_obj.getIntValue();
early_code_change = (earlychange == 1);
if (! ((earlychange == 0) || (earlychange == 1)))
{
filterable = false;
}
}
else
{
filterable = false;
}
}
else if ((key == "/Columns") ||
(key == "/Colors") ||
(key == "/BitsPerComponent"))
{
QPDFObjectHandle param_obj = decode_obj.getKey(key);
if (param_obj.isInteger())
{
int val = param_obj.getIntValue();
if (key == "/Columns")
{
columns = val;
}
else if (key == "/Colors")
{
colors = val;
}
else if (key == "/BitsPerComponent")
{
bits_per_component = val;
}
}
else
{
filterable = false;
}
}
else if ((filter == "/Crypt") &&
(((key == "/Type") || (key == "/Name")) &&
(decode_obj.getKey("/Type").isNull() ||
(decode_obj.getKey("/Type").isName() &&
(decode_obj.getKey("/Type").getName() ==
"/CryptFilterDecodeParms")))))
{
// we handle this in decryptStream
}
else
{
filterable = false;
}
}
return filterable;
}
bool
QPDF_Stream::filterable(std::vector<std::string>& filters,
bool& specialized_compression,
bool& lossy_compression,
int& predictor, int& columns,
int& colors, int& bits_per_component,
bool& early_code_change)
{
if (filter_abbreviations.empty())
{
// 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.
filter_abbreviations["/AHx"] = "/ASCIIHexDecode";
filter_abbreviations["/A85"] = "/ASCII85Decode";
filter_abbreviations["/LZW"] = "/LZWDecode";
filter_abbreviations["/Fl"] = "/FlateDecode";
filter_abbreviations["/RL"] = "/RunLengthDecode";
filter_abbreviations["/CCF"] = "/CCITTFaxDecode";
filter_abbreviations["/DCT"] = "/DCTDecode";
}
// Check filters
QPDFObjectHandle filter_obj = this->stream_dict.getKey("/Filter");
bool filters_okay = true;
if (filter_obj.isNull())
{
// No filters
}
else if (filter_obj.isName())
{
// One filter
filters.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())
{
filters.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 (std::vector<std::string>::iterator iter = filters.begin();
iter != filters.end(); ++iter)
{
std::string& filter = *iter;
if (filter_abbreviations.count(filter))
{
QTC::TC("qpdf", "QPDF_Stream expand filter abbreviation");
filter = filter_abbreviations[filter];
}
if (filter == "/RunLengthDecode")
{
specialized_compression = true;
}
else if (filter == "/DCTDecode")
{
specialized_compression = true;
lossy_compression = true;
}
else if (! ((filter == "/Crypt") ||
(filter == "/FlateDecode") ||
(filter == "/LZWDecode") ||
(filter == "/ASCII85Decode") ||
(filter == "/ASCIIHexDecode")))
{
filterable = false;
}
}
if (! filterable)
{
return false;
}
// `filters' now contains a list of filters to be applied in
// order. See which ones we can support.
// Initialize values to their defaults as per the PDF spec
predictor = 1;
columns = 0;
colors = 1;
bits_per_component = 8;
early_code_change = true;
// 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 < filters.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 (unsigned int i = 0; i < filters.size(); ++i)
{
QPDFObjectHandle decode_item = decode_parms.at(i);
if (decode_item.isNull())
{
// okay
}
else if (decode_item.isDictionary())
{
if (! understandDecodeParams(
filters.at(i), decode_item,
predictor, columns, colors, bits_per_component,
early_code_change))
{
filterable = false;
}
}
else
{
filterable = false;
}
}
if ((predictor > 1) && (columns == 0))
{
// invalid
filterable = false;
}
if (! filterable)
{
return false;
}
return filterable;
}
bool
QPDF_Stream::pipeStreamData(Pipeline* pipeline,
unsigned long encode_flags,
qpdf_stream_decode_level_e decode_level,
bool suppress_warnings, bool will_retry)
{
std::vector<std::string> filters;
int predictor = 1;
int columns = 0;
int colors = 1;
int bits_per_component = 8;
bool early_code_change = true;
bool specialized_compression = false;
bool lossy_compression = false;
bool filter = (! ((encode_flags == 0) && (decode_level == qpdf_dl_none)));
if (filter)
{
filter = filterable(filters, specialized_compression, lossy_compression,
predictor, columns,
colors, bits_per_component,
early_code_change);
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 filter;
}
// Construct the pipeline in reverse order. Force pipelines we
// create to be deleted when this function finishes.
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 (std::vector<std::string>::reverse_iterator iter = filters.rbegin();
iter != filters.rend(); ++iter)
{
std::string const& filter = *iter;
if ((filter == "/FlateDecode") || (filter == "/LZWDecode"))
{
if ((predictor >= 10) && (predictor <= 15))
{
QTC::TC("qpdf", "QPDF_Stream PNG filter");
pipeline = new Pl_PNGFilter(
"png decode", pipeline, Pl_PNGFilter::a_decode,
columns, colors, bits_per_component);
to_delete.push_back(pipeline);
}
else if (predictor == 2)
{
QTC::TC("qpdf", "QPDF_Stream TIFF predictor");
pipeline = new Pl_TIFFPredictor(
"tiff decode", pipeline, Pl_TIFFPredictor::a_decode,
columns, colors, bits_per_component);
to_delete.push_back(pipeline);
}
}
if (filter == "/Crypt")
{
// Ignore -- handled by pipeStreamData
}
else if (filter == "/FlateDecode")
{
pipeline = new Pl_Flate("stream inflate",
pipeline, Pl_Flate::a_inflate);
to_delete.push_back(pipeline);
}
else if (filter == "/ASCII85Decode")
{
pipeline = new Pl_ASCII85Decoder("ascii85 decode", pipeline);
to_delete.push_back(pipeline);
}
else if (filter == "/ASCIIHexDecode")
{
pipeline = new Pl_ASCIIHexDecoder("asciiHex decode", pipeline);
to_delete.push_back(pipeline);
}
else if (filter == "/LZWDecode")
{
pipeline = new Pl_LZWDecoder("lzw decode", pipeline,
early_code_change);
to_delete.push_back(pipeline);
}
else if (filter == "/RunLengthDecode")
{
pipeline = new Pl_RunLength("runlength decode", pipeline,
Pl_RunLength::a_decode);
to_delete.push_back(pipeline);
}
else if (filter == "/DCTDecode")
{
pipeline = new Pl_DCT("DCT decode", pipeline);
to_delete.push_back(pipeline);
}
else
{
throw std::logic_error(
"INTERNAL ERROR: QPDFStream: unknown filter "
"encountered after check");
}
}
}
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);
this->stream_provider->provideStreamData(
this->objid, this->generation, &count);
qpdf_offset_t actual_length = count.getCount();
qpdf_offset_t desired_length = 0;
if (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
{
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;
}
}
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 filter;
}
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(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 = length_obj.getIntValue();
}
else
{
this->length = 0;
}
}
void
QPDF_Stream::warn(QPDFExc const& e)
{
QPDF::Warner::warn(this->qpdf, e);
}
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