tdf#140606 make PDF parsing more lenient and prevent a crash
If the external document can't be opened, it tried to continue
with the export anyway, which eventually lead to a crash. This
is fixed by handling this situation and prevent a crash, however
the part of the document in this case isn't exported.
The document couldn't be opened because of a parsing error - there
was a unexpected null character instead of a whitespace, which
made the parser panic. Fix this by making the parser more lenient
in such a situation when there is an unexpected null and try to
continue parsing.
Bug document seems to be created with a buggy PDF writer, but other
PDF readers don't complain when parsing the document so it looks to
be a valid. qpdf --check doesn't complain either.
Added a test that checks a document with a null parses.
Change-Id: I61eb281e821ccd195ef006d778556e25d1c7f5e3
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111820
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
diff --git a/vcl/inc/pdf/ExternalPDFStreams.hxx b/vcl/inc/pdf/ExternalPDFStreams.hxx
index dc484e1..7840217 100644
--- a/vcl/inc/pdf/ExternalPDFStreams.hxx
+++ b/vcl/inc/pdf/ExternalPDFStreams.hxx
@@ -34,21 +34,25 @@
std::map<sal_Int32, sal_Int32>& getCopiedResources() { return maCopiedResources; }
filter::PDFDocument& getPDFDocument()
std::shared_ptr<filter::PDFDocument>& getPDFDocument()
{
if (!mpPDFDocument)
{
SvMemoryStream aPDFStream;
aPDFStream.WriteBytes(maDataContainer.getData(), maDataContainer.getSize());
aPDFStream.Seek(0);
mpPDFDocument = std::make_shared<filter::PDFDocument>();
if (!mpPDFDocument->Read(aPDFStream))
auto pPDFDocument = std::make_shared<filter::PDFDocument>();
if (!pPDFDocument->Read(aPDFStream))
{
SAL_WARN("vcl.pdfwriter",
"PDFWriterImpl::writeReferenceXObject: reading the PDF document failed");
}
else
{
mpPDFDocument = pPDFDocument;
}
}
return *mpPDFDocument;
return mpPDFDocument;
}
};
diff --git a/vcl/qa/cppunit/PDFDocumentTest.cxx b/vcl/qa/cppunit/PDFDocumentTest.cxx
index 2246f8e..35af8e6 100644
--- a/vcl/qa/cppunit/PDFDocumentTest.cxx
+++ b/vcl/qa/cppunit/PDFDocumentTest.cxx
@@ -156,6 +156,18 @@
}
}
CPPUNIT_TEST_FIXTURE(PDFDocumentTest, testParseDocumentWithNullAsWhitespace)
{
// tdf#140606
// Bug document contained a null, which cause the parser to panic,
// but other PDF readers can handle the file well.
OUString aURL = m_directories.getURLFromSrc(DATA_DIRECTORY) + "DocumentWithNull.pdf";
vcl::filter::PDFDocument aDocument;
SvFileStream aStream(aURL, StreamMode::READ);
CPPUNIT_ASSERT(aDocument.Read(aStream));
}
namespace
{
vcl::filter::PDFObjectElement*
diff --git a/vcl/qa/cppunit/data/DocumentWithNull.pdf b/vcl/qa/cppunit/data/DocumentWithNull.pdf
new file mode 100644
index 0000000..f6d9269
--- /dev/null
+++ b/vcl/qa/cppunit/data/DocumentWithNull.pdf
Binary files differ
diff --git a/vcl/source/filter/ipdf/pdfdocument.cxx b/vcl/source/filter/ipdf/pdfdocument.cxx
index acf5849..5ebe05e 100644
--- a/vcl/source/filter/ipdf/pdfdocument.cxx
+++ b/vcl/source/filter/ipdf/pdfdocument.cxx
@@ -1324,12 +1324,18 @@
}
else
{
if (!rtl::isAsciiWhiteSpace(static_cast<unsigned char>(ch)))
auto uChar = static_cast<unsigned char>(ch);
// Be more lenient and allow unexpected null char
if (!rtl::isAsciiWhiteSpace(uChar) && uChar != 0)
{
SAL_WARN("vcl.filter", "PDFDocument::Tokenize: unexpected character: "
<< ch << " at byte position " << rStream.Tell());
SAL_WARN("vcl.filter",
"PDFDocument::Tokenize: unexpected character with code "
<< sal_Int32(ch) << " at byte position " << rStream.Tell());
return false;
}
SAL_WARN_IF(uChar == 0, "vcl.filter",
"PDFDocument::Tokenize: unexpected null character at "
<< rStream.Tell() << " - ignoring");
}
break;
}
diff --git a/vcl/source/gdi/pdfwriter_impl.cxx b/vcl/source/gdi/pdfwriter_impl.cxx
index 967dcf6..f7c6f82 100644
--- a/vcl/source/gdi/pdfwriter_impl.cxx
+++ b/vcl/source/gdi/pdfwriter_impl.cxx
@@ -8458,10 +8458,16 @@
// object.
if (rEmit.m_nExternalPDFDataIndex < 0)
return;
auto & rExternalPDFStream = m_aExternalPDFStreams.get(rEmit.m_nExternalPDFDataIndex);
auto & rPDFDocument = rExternalPDFStream.getPDFDocument();
auto& rExternalPDFStream = m_aExternalPDFStreams.get(rEmit.m_nExternalPDFDataIndex);
auto& pPDFDocument = rExternalPDFStream.getPDFDocument();
if (!pPDFDocument)
{
// Couldn't parse the document and can't continue
SAL_WARN("vcl.pdfwriter", "PDFWriterImpl::writeReferenceXObject: failed to parse the document");
return;
}
std::vector<filter::PDFObjectElement*> aPages = rPDFDocument.GetPages();
std::vector<filter::PDFObjectElement*> aPages = pPDFDocument->GetPages();
if (aPages.empty())
{
SAL_WARN("vcl.pdfwriter", "PDFWriterImpl::writeReferenceXObject: no pages");
