xmlsecurity OOXML export: register signature content types

Our own importer is happy about the export result already, but MSO is
more picky, and mandates the correct content types for both
_xmlsignatures/origin.sigs and the individual signature streams.

With this, MSO can open the signed file again (while previously it just
declared the file corrupted), though it still declares the signature
invalid.

Change-Id: I199ad96bb91e7ce03fdf1f10f9500db4e05bb5c1

xmlsecurity/inc/xmlsecurity/xmlsignaturehelper.hxx

@@ -187,7 +187,10 @@ public:
     void ExportSignatureRelations(css::uno::Reference<css::embed::XStorage> xStorage, int nSignatureCount);
     /// Given that xSignatureStorage is an OOXML _xmlsignatures storage, create and write a new signature.
     bool CreateAndWriteOOXMLSignature(css::uno::Reference<css::embed::XStorage> xRootStorage, css::uno::Reference<css::embed::XStorage> xSignatureStorage, int nSignatureIndex);
+    /// Similar to CreateAndWriteOOXMLSignature(), but used to write the signature to the persistent storage, not the temporary one.
     void ExportOOXMLSignature(css::uno::Reference<css::embed::XStorage> xRootStorage, css::uno::Reference<css::embed::XStorage> xSignatureStorage, const SignatureInformation& rInformation, int nSignatureIndex);
+    /// Given that xStorage is an OOXML root storage, advertise signatures in its [Content_Types].xml stream.
+    void ExportSignatureContentTypes(css::uno::Reference<css::embed::XStorage> xStorage, int nSignatureCount);
 };
 
 #endif // INCLUDED_XMLSECURITY_INC_XMLSECURITY_XMLSIGNATUREHELPER_HXX

xmlsecurity/source/dialogs/digitalsignaturesdialog.cxx

@@ -416,6 +416,7 @@ IMPL_LINK_NOARG_TYPED(DigitalSignaturesDialog, OKButtonHdl, Button*, void)
     {
         // OOXML
         size_t nSignatureCount = maCurrentSignatureInformations.size();
+        maSignatureHelper.ExportSignatureContentTypes(mxStore, nSignatureCount);
         maSignatureHelper.ExportSignatureRelations(aStreamHelper.xSignatureStorage, nSignatureCount);
 
         for (size_t i = 0; i < nSignatureCount; ++i)

xmlsecurity/source/helper/xmlsignaturehelper.cxx

@@ -513,6 +513,51 @@ void XMLSignatureHelper::ExportSignatureRelations(css::uno::Reference<css::embed
     xTransact->commit();
 }
 
+void XMLSignatureHelper::ExportSignatureContentTypes(css::uno::Reference<css::embed::XStorage> xStorage, int nSignatureCount)
+{
+    sal_Int32 nOpenMode = embed::ElementModes::READWRITE;
+    uno::Reference<io::XStream> xStream(xStorage->openStreamElement("[Content_Types].xml", nOpenMode), uno::UNO_QUERY);
+    uno::Reference<io::XInputStream> xInputStream = xStream->getInputStream();
+    uno::Sequence< uno::Sequence<beans::StringPair> > aContentTypeInfo = comphelper::OFOPXMLHelper::ReadContentTypeSequence(xInputStream, mxCtx);
+    if (aContentTypeInfo.getLength() < 2)
+    {
+        SAL_WARN("xmlsecurity.helper", "no defaults or overrides in aContentTypeInfo");
+        return;
+    }
+
+    // Append sigs to defaults, if it's not there already.
+    uno::Sequence<beans::StringPair>& rDefaults = aContentTypeInfo[0];
+    auto it = std::find_if(rDefaults.begin(), rDefaults.end(), [](const beans::StringPair& rPair)
+    {
+        return rPair.First == "sigs";
+    });
+    if (it == rDefaults.end())
+    {
+        auto aDefaults = comphelper::sequenceToContainer< std::vector<beans::StringPair> >(rDefaults);
+        aDefaults.push_back(beans::StringPair("sigs", "application/vnd.openxmlformats-package.digital-signature-origin"));
+        rDefaults = comphelper::containerToSequence(aDefaults);
+    }
+
+    // Remove existing signature overrides.
+    uno::Sequence<beans::StringPair>& rOverrides = aContentTypeInfo[1];
+    auto aOverrides = comphelper::sequenceToContainer< std::vector<beans::StringPair> >(rOverrides);
+    aOverrides.erase(std::remove_if(aOverrides.begin(), aOverrides.end(), [](const beans::StringPair& rPair)
+    {
+        return rPair.First.startsWith("/_xmlsignatures/sig");
+    }), aOverrides.end());
+
+    // Add our signature overrides.
+    for (int i = 1; i <= nSignatureCount; ++i)
+        aOverrides.push_back(beans::StringPair("/_xmlsignatures/sig" + OUString::number(i) + ".xml", "application/vnd.openxmlformats-package.digital-signature-xmlsignature+xml"));
+
+    rOverrides = comphelper::containerToSequence(aOverrides);
+    uno::Reference<io::XOutputStream> xOutputStream = xStream->getOutputStream();
+    uno::Reference <io::XTruncate> xTruncate(xOutputStream, uno::UNO_QUERY);
+    xTruncate->truncate();
+    comphelper::OFOPXMLHelper::WriteContentSequence(xOutputStream, rDefaults, rOverrides, mxCtx);
+    uno::Reference<embed::XTransactedObject> xTransact(xStorage, uno::UNO_QUERY);
+    xTransact->commit();
+}
 bool XMLSignatureHelper::CreateAndWriteOOXMLSignature(uno::Reference<embed::XStorage> xRootStorage, uno::Reference<embed::XStorage> xSignatureStorage, int nSignatureIndex)
 {
     sal_Int32 nOpenMode = embed::ElementModes::READWRITE;