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https://github.com/qpdf/qpdf.git
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Refactor: separate code that determines whether to filter a stream
This commit is contained in:
Jay Berkenbilt
parent
4cbe2abcc0
commit
09027344b9
@ -529,6 +529,9 @@ class QPDFWriter
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void writeTrailer(trailer_e which, int size,
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bool xref_stream, qpdf_offset_t prev,
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int linearization_pass);
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bool willFilterStream(QPDFObjectHandle stream,
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bool& compress_stream, bool& is_metadata,
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PointerHolder<Buffer>* stream_data);
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void unparseObject(QPDFObjectHandle object, int level, int flags,
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// for stream dictionaries
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size_t stream_length = 0, bool compress = false);
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@ -1463,6 +1463,96 @@ QPDFWriter::writeTrailer(trailer_e which, int size, bool xref_stream,
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writeString(">>");
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}
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bool
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QPDFWriter::willFilterStream(QPDFObjectHandle stream,
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bool& compress_stream, bool& is_metadata,
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PointerHolder<Buffer>* stream_data)
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{
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compress_stream = false;
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is_metadata = false;
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QPDFObjGen old_og = stream.getObjGen();
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QPDFObjectHandle stream_dict = stream.getDict();
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if (stream_dict.getKey("/Type").isName() &&
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(stream_dict.getKey("/Type").getName() == "/Metadata"))
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{
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is_metadata = true;
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}
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bool filter = (stream.isDataModified() ||
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this->m->compress_streams ||
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this->m->stream_decode_level);
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if (this->m->compress_streams)
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{
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// Don't filter if the stream is already compressed with
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// FlateDecode. This way we don't make it worse if the
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// original file used a better Flate algorithm, and we
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// don't spend time and CPU cycles uncompressing and
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// recompressing stuff. This can be overridden with
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// setRecompressFlate(true).
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QPDFObjectHandle filter_obj = stream_dict.getKey("/Filter");
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if ((! this->m->recompress_flate) &&
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(! stream.isDataModified()) &&
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filter_obj.isName() &&
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((filter_obj.getName() == "/FlateDecode") ||
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(filter_obj.getName() == "/Fl")))
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{
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QTC::TC("qpdf", "QPDFWriter not recompressing /FlateDecode");
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filter = false;
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}
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}
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bool normalize = false;
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bool uncompress = false;
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if (is_metadata &&
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((! this->m->encrypted) || (this->m->encrypt_metadata == false)))
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{
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QTC::TC("qpdf", "QPDFWriter not compressing metadata");
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filter = true;
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compress_stream = false;
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uncompress = true;
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}
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else if (this->m->normalize_content &&
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this->m->normalized_streams.count(old_og))
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{
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normalize = true;
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filter = true;
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}
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else if (filter && this->m->compress_streams)
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{
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compress_stream = true;
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QTC::TC("qpdf", "QPDFWriter compressing uncompressed stream");
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}
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bool filtered = false;
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for (int attempt = 1; attempt <= 2; ++attempt)
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{
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pushPipeline(new Pl_Buffer("stream data"));
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PipelinePopper pp_stream_data(this, stream_data);
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activatePipelineStack(pp_stream_data);
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filtered =
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stream.pipeStreamData(
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this->m->pipeline,
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(((filter && normalize) ? qpdf_ef_normalize : 0) |
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((filter && compress_stream) ? qpdf_ef_compress : 0)),
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(filter
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? (uncompress ? qpdf_dl_all : this->m->stream_decode_level)
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: qpdf_dl_none), false, (attempt == 1));
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if (filter && (! filtered))
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{
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// Try again
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filter = false;
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}
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else
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{
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break;
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}
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}
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if (! filtered)
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{
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compress_stream = false;
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}
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return filtered;
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}
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void
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QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
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int flags, size_t stream_length,
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@ -1502,13 +1592,12 @@ QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
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else if (object.isDictionary())
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{
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// Make a shallow copy of this object so we can modify it
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// safely without affecting the original. This code makes
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// assumptions about things that are made true in
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// prepareFileForWrite, such as that certain things are direct
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// objects so that replacing them doesn't leave unreferenced
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// objects in the output. We can use unsafeShallowCopy here
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// because we are all we are doing is removing or replacing
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// top-level keys.
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// safely without affecting the original. This code has logic
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// to skip certain keys in agreement with prepareFileForWrite
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// and with skip_stream_parameters so that replacing them
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// doesn't leave unreferenced objects in the output. We can
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// use unsafeShallowCopy here because we are all we are doing
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// is removing or replacing top-level keys.
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object = object.unsafeShallowCopy();
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// Handle special cases for specific dictionaries.
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@ -1760,94 +1849,17 @@ QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
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{
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this->m->cur_stream_length_id = new_id + 1;
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}
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QPDFObjectHandle stream_dict = object.getDict();
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bool is_metadata = false;
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if (stream_dict.getKey("/Type").isName() &&
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(stream_dict.getKey("/Type").getName() == "/Metadata"))
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{
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is_metadata = true;
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}
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bool filter = (object.isDataModified() ||
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this->m->compress_streams ||
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this->m->stream_decode_level);
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if (this->m->compress_streams)
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{
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// Don't filter if the stream is already compressed with
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// FlateDecode. This way we don't make it worse if the
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// original file used a better Flate algorithm, and we
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// don't spend time and CPU cycles uncompressing and
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// recompressing stuff. This can be overridden with
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// setRecompressFlate(true).
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QPDFObjectHandle filter_obj = stream_dict.getKey("/Filter");
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if ((! this->m->recompress_flate) &&
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(! object.isDataModified()) &&
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filter_obj.isName() &&
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((filter_obj.getName() == "/FlateDecode") ||
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(filter_obj.getName() == "/Fl")))
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{
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QTC::TC("qpdf", "QPDFWriter not recompressing /FlateDecode");
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filter = false;
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}
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}
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bool normalize = false;
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bool compress_stream = false;
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bool uncompress = false;
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if (is_metadata &&
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((! this->m->encrypted) || (this->m->encrypt_metadata == false)))
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{
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QTC::TC("qpdf", "QPDFWriter not compressing metadata");
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filter = true;
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compress_stream = false;
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uncompress = true;
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}
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else if (this->m->normalize_content &&
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this->m->normalized_streams.count(old_og))
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{
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normalize = true;
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filter = true;
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}
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else if (filter && this->m->compress_streams)
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{
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compress_stream = true;
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QTC::TC("qpdf", "QPDFWriter compressing uncompressed stream");
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}
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flags |= f_stream;
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bool compress_stream = false;
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bool is_metadata = false;
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PointerHolder<Buffer> stream_data;
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bool filtered = false;
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for (int attempt = 1; attempt <= 2; ++attempt)
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{
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pushPipeline(new Pl_Buffer("stream data"));
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PipelinePopper pp_stream_data(this, &stream_data);
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activatePipelineStack(pp_stream_data);
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filtered =
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object.pipeStreamData(
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this->m->pipeline,
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(((filter && normalize) ? qpdf_ef_normalize : 0) |
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((filter && compress_stream) ? qpdf_ef_compress : 0)),
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(filter
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? (uncompress ? qpdf_dl_all : this->m->stream_decode_level)
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: qpdf_dl_none), false, (attempt == 1));
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if (filter && (! filtered))
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{
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// Try again
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filter = false;
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}
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else
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{
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break;
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}
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}
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if (filtered)
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if (willFilterStream(object, compress_stream,
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is_metadata, &stream_data))
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{
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flags |= f_filtered;
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}
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else
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{
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compress_stream = false;
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}
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QPDFObjectHandle stream_dict = object.getDict();
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this->m->cur_stream_length = stream_data->getSize();
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if (is_metadata && this->m->encrypted && (! this->m->encrypt_metadata))
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