System.IO.IOException when creating relationships multiple times

[twilker]

I get an IOException 'Entries cannot be opened multiple times in Update mode.' when I create a package part relationship, flush the package and again create a relationship. A similar issue was adressed in #24962, but not solved for this issue.

To reproduce it simply add the following unit test to the System.IO.Packaging.Tests project:

[Fact]
public void WriteRelationsTwice()
{
    FileInfo tempGuidFile = GetTempFileInfoWithExtension(".zip");

    using (Package package = Package.Open(tempGuidFile.FullName, FileMode.OpenOrCreate, FileAccess.ReadWrite))
    {
        //first part
        PackagePart packagePart = package.CreatePart(PackUriHelper.CreatePartUri(new Uri("MyFile1.xml", UriKind.Relative)),
                                                     System.Net.Mime.MediaTypeNames.Application.Octet);
        using (packagePart.GetStream(FileMode.Create))
        {
            //do stuff with stream - not necessary to reproduce bug
        }
        package.CreateRelationship(PackUriHelper.CreatePartUri(new Uri("MyFile1.xml", UriKind.Relative)),
                                   TargetMode.Internal, "http://my-fancy-relationship.com");

        package.Flush();

        //create second part after flush
        packagePart = package.CreatePart(PackUriHelper.CreatePartUri(new Uri("MyFile2.xml", UriKind.Relative)),
                                         System.Net.Mime.MediaTypeNames.Application.Octet);
        using (packagePart.GetStream(FileMode.Create))
        {
            //do stuff with stream - not necessary to reproduce bug
        }
        package.CreateRelationship(PackUriHelper.CreatePartUri(new Uri("MyFile2.xml", UriKind.Relative)),
                                   TargetMode.Internal, "http://my-fancy-relationship.com");
    }
}

A simple solution would be the to change the line
using (IgnoreFlushAndCloseStream s = new IgnoreFlushAndCloseStream(part.GetStream()))
in the method
private void WriteRelationshipPart(PackagePart part)
in the class
System.IO.Packaging.InternalRelationshipCollection
to the following lines:

using (Stream partStream = part.GetStream())
using (IgnoreFlushAndCloseStream s = new IgnoreFlushAndCloseStream(partStream))

[twilker]

Maybe this should be moved to the area-System.IO.Compression, as this is almost the same issue as the referenced issue in the description. I do not know how important that is.

[ahsonkhan]

cc @bartonjs - since you fixed https://github.com/dotnet/corefx/issues/26952, I am assuming you can help here as well :)

Does @Luciferius, proposed solution make sense?

[bartonjs]

Mighty big assumption there 😄.

It seems reasonable, and seems to solve the problem. I'm sort of wondering if the right answer is actually "get rid of IgnoreFlushAndCloseStream". It might have been a thing introduced to manage the zip library it was using in .NET Framework that doesn't make sense given that it now uses System.IO.Compression. (Looks like that was my thought when I got the previous bug load balanced to me, too 😄)

Though if we add this using we've effectively done that, so maybe adding a second using here is easier than figuring out if it's important to not flush?

@Luciferius Since you've already done all the leg work, do you want to just open a PR?

[twilker]

@bartonjs I will do that as soon as I can make the time for it ;-)