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ac3c81a8ed
qpdf/libqpdf/QPDF_Stream.cc
Jay Berkenbilt ac9c1f0d56 Security: replace operator[] with at 
For std::string and std::vector, replace operator[] with at.  This was
done using an automated process.  See README.hardening for details.
2013-10-18 10:45:14 -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_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_Count.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");
}
}
QPDF_Stream::~QPDF_Stream()
{
}
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";
}
QPDFObject::object_type_e
QPDF_Stream::getTypeCode() const
{
return QPDFObject::ot_stream;
}
char const*
QPDF_Stream::getTypeName() const
{
return "stream";
}
QPDFObjectHandle
QPDF_Stream::getDict() const
{
return this->stream_dict;
}
PointerHolder<Buffer>
QPDF_Stream::getStreamData()
{
Pl_Buffer buf("stream data buffer");
if (! pipeStreamData(&buf, true, false, false))
{
throw std::logic_error("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, false, 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, 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") && (key == "/Predictor"))
{
QPDFObjectHandle predictor_obj = decode_obj.getKey(key);
if (predictor_obj.isInteger())
{
predictor = predictor_obj.getIntValue();
if (! ((predictor == 1) || (predictor == 12)))
{
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")
{
QPDFObjectHandle columns_obj = decode_obj.getKey(key);
if (columns_obj.isInteger())
{
columns = columns_obj.getIntValue();
}
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,
int& predictor, int& columns,
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");
throw QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
"", this->offset,
"stream filter type is not name or array");
}
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 == "/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;
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())
{
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()))
{
// We should just issue a warning and treat this as not
// filterable.
throw QPDFExc(qpdf_e_damaged_pdf, qpdf->getFilename(),
"", this->offset,
"stream /DecodeParms length is"
" inconsistent with filters");
}
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, 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, bool filter,
bool normalize, bool compress)
{
std::vector<std::string> filters;
int predictor = 1;
int columns = 0;
bool early_code_change = true;
if (filter)
{
filter = filterable(filters, predictor, columns, early_code_change);
}
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;
if (filter)
{
if (compress)
{
pipeline = new Pl_Flate("compress object stream", pipeline,
Pl_Flate::a_deflate);
to_delete.push_back(pipeline);
}
if (normalize)
{
pipeline = new Pl_QPDFTokenizer("normalizer", 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 == "/Crypt")
{
// Ignore -- handled by pipeStreamData
}
else if (filter == "/FlateDecode")
{
if (predictor == 12)
{
QTC::TC("qpdf", "QPDF_Stream PNG filter");
pipeline = new Pl_PNGFilter(
"png decode", pipeline, Pl_PNGFilter::a_decode,
columns, 0 /* not used */);
to_delete.push_back(pipeline);
}
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
{
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");
throw std::logic_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");
QPDF::Pipe::pipeStreamData(this->qpdf, this->objid, this->generation,
this->offset, this->length,
this->stream_dict, pipeline);
}
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::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;
QPDFObjectHandle length_obj = new_dict.getKey("/Length");
if (length_obj.isInteger())
{
this->length = length_obj.getIntValue();
}
else
{
this->length = 0;
}
}
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