RelationshipErrorHandlerFactory fails with "Data at the root level is invalid"

[Muppets]

Using RelationshipErrorHandlerFactory.Rewrite with an output that is shorter than the original URI causes the output XML to be malformed in this Word document.

        static void Main(string[] args)
        {
            var doc = WordprocessingDocument.Open("BrokenURI.docx", isEditable: true, new OpenSettings
            {
                RelationshipErrorHandlerFactory = _ => new RemoveMalformedHyperlinksRelationshipErrorHandler(),
            });
        }

        private sealed class RemoveMalformedHyperlinksRelationshipErrorHandler : RelationshipErrorHandler
        {
            // Works
            //public override string Rewrite(Uri partUri, string id, string uri) => $"https://error{new string('r', uri.Length)}";

            // Fails with "Data at the root level is invalid"
            public override string Rewrite(Uri partUri, string id, string uri) => $"https://error";
        }

When the above is run on a Word document with the following document.xml.rels:

<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
	<Relationship Id="rId8" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/fontTable" Target="fontTable.xml"/>
	<Relationship Id="rId3" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/settings" Target="settings.xml"/>
	<Relationship Id="rId7" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/hyperlink" Target="mailto:test@test.com;%20test2@test.com;%252test3@test.com;%20test3@test.com;%20test4@test.com;%20test5@test.com?subject=Unsubscribe%20Request&amp;body=Please%20unsubscribe%20me%20from%20all%20future%20communications" TargetMode="External"/>
	<Relationship Id="rId2" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/>
	<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/numbering" Target="numbering.xml"/>
	<Relationship Id="rId6" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/endnotes" Target="endnotes.xml"/>
	<Relationship Id="rId5" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/footnotes" Target="footnotes.xml"/>
	<Relationship Id="rId4" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/webSettings" Target="webSettings.xml"/>
	<Relationship Id="rId9" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme" Target="theme/theme1.xml"/>
</Relationships>

It fails with "Data at the root level is invalid. Line 12, position 17." and has produced the following in the output document:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
  <Relationship Id="rId8" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/fontTable" Target="fontTable.xml" />
  <Relationship Id="rId3" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/settings" Target="settings.xml" />
  <Relationship Id="rId7" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/hyperlink" Target="https://error" TargetMode="External" />
  <Relationship Id="rId2" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml" />
  <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/numbering" Target="numbering.xml" />
  <Relationship Id="rId6" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/endnotes" Target="endnotes.xml" />
  <Relationship Id="rId5" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/footnotes" Target="footnotes.xml" />
  <Relationship Id="rId4" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/webSettings" Target="webSettings.xml" />
  <Relationship Id="rId9" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme" Target="theme/theme1.xml" />
</Relationships>l"/><Relationship Id="rId9" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme" Target="theme/theme1.xml"/></Relationships>

As you can see, the end part of the XML has now been malformed. This is probably a buffer issue with the shorter string being returned from the Rewrite method. I've seen this in a few places when working with the Package classes.

Extending the Rewrite output to match the length of the original URI resolves the issue:

public override string Rewrite(Uri partUri, string id, string uri) => $"https://error{new string('r', uri.Length)}";

Information

• .NET Target: .NET Core
• DocumentFormat.OpenXml Version: 2.12.1

Please see example console app with sample Word document repo'ing the issue:

https://github.com/Muppets/RelationshipErrorHandlerFactoryTest

Observed

Exception thrown: System.Xml.XmlException: 'Data at the root level is invalid. Line 12, position 17.'

Expected

Invalid URI is replaced with https://error

Just as a footnote, I'm loving the new RelationshipErrorHandlerFactory support added recently, great work! 🎉

[Muppets]

Update on this. Turns out my hack to resolve the issue comes with a glaring issue.

public override string Rewrite(Uri partUri, string id, string uri) => $"https://error{new string('r', uri.Length)}";

If the output produced is over 265 characters, it blows up with:

System.InvalidOperationException: Provided URI was invalid after rewriting malformed relationship URI
   at DocumentFormat.OpenXml.Packaging.RelationshipErrorHandler.ValidateLink(PackagePart part, XElement child)
   at DocumentFormat.OpenXml.Packaging.RelationshipErrorHandler.WalkRelationships(PackagePart part)
   at DocumentFormat.OpenXml.Packaging.RelationshipErrorHandler.Handle(Package package)
   at DocumentFormat.OpenXml.Packaging.OpenXmlPackage.Load()
   at DocumentFormat.OpenXml.Packaging.OpenXmlPackage.OpenCore(String path, Boolean readWriteMode)
   at DocumentFormat.OpenXml.Packaging.WordprocessingDocument.Open(String path, Boolean isEditable, OpenSettings openSettings)

[twsouthwick]

Oh good catch on the bufferring! Probably need to set the stream to 0 before writing it.

I'm fairly busy right now, but will happily review PRs!

As for your workaround - just subract the length of the new string part. Didn't realize there was a length limit there

[Muppets]

@twsouthwick Just wanted to give a big thank you for helping get that fix in and the speed you got it rolled out on Nuget. Kudos to you sir! ❤️