Wrong implemented stream reader
-------------------------------
Key: PDFBOX-1098
URL: https://issues.apache.org/jira/browse/PDFBOX-1098
Project: PDFBox
Issue Type: Bug
Components: Parsing
Reporter: Thomas Chojecki
Priority: Critical
The BaseParser#readUntilEndStream(OutputStream) method is parsing streams the
wrong way. [1]
This method will start reading a stream till the keyword "endstream" is reached
and don't care about the length value inside the dictionary. This
implementation brokes nearly every pdf document with a pdf embedded inside a
stream [2].
Encoder that is used for compressing streams can be block-based (like
FlateDecode which is mostly used). If a block of data that should be compressed
don't spare space after compressing, the encode do not compress this block and
mark it as uncompressed. So a stream can containing compressed and uncompressed
parts. So if someone try to embed pdf documents with streams inside a stream,
the encoder will left most parts of the document uncompressed. Such parts can
contain plan text like "endstream" or other critical keywords that can cause
the parser to stop.
So we need to read the whole stream length that was wrote inside the dictionary
and don't look at "endstream" keywords until the end is reached.
The current stream parser cause a ZIPException with the Message "Unexpected end
of ZLIB input stream".
A sample pdf and a patch is coming soon.
[1] PDF 32000-1:2008 -> 7.3.8.2 Stream Extent
[2] PDF 32000-1:2008 -> 7.11.4 Embedded File Streams
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