Broken Excel fail generated when writing to not seekable stream

[aboryczko]

Hi,

I've tried to use this library to stream Excel files on the fly via ASP.NET Core. My use case prohibits me with caching it in memory and I end up using the raw HTTP response stream. The file generated seems ok at first, but when I load it with Excel it tries to repair it and without any data loss the file is opened.
The only difference between a correct file and the broken one is that the underlying ZIP file has the general purpose bit flag set to (bit 3).
I know that this is more of an Excel issue but did anyone have any luck working around that?

[aboryczko]

I guess it's not totaly Excel related because I've exchanged the SharpCompress library for the .NET internal compression implementation and my generated files work correctly.

[aboryczko]

so there is an error in the compression library that adds some strange bytes in the middle of the content every N bytes. I will go continue this thread there.

[aboryczko]

@salvois if it would be ok with you I could create a PR that would replace SharpCompress with the built-in .NET Core implementation and bumped it to v2.0. It worked fine for me.

[salvois]

Hi @aboryczko , last time I checked, the built-in compressor in .NET failed to produce a ZIP64 with content larger that 4 GiB considered valid by Excel. It refused to open it altogether. If this is still the case, unfortunately I cannot switch the underlying compression library.
Have you tried this too?
Thanks,
Salvl

[Erior]

Would be nice if you can try out the 0.32.1 release of sharpcompress, that was linked to this issue

[salvois]

Hi @Erior ,
many thanks for pointing that out and for your help, I will try it next week!
Salvo

[salvois]

Hi @aboryczko , @Erior ,
the issue seems to be solved using SharpCompress 0.32.1.
I have just released LargeXlsx 1.5.1 with the updated dependency.
Please have a try and let me know.
Thanks for your contribution!
Salvo

[aboryczko]

Thanks everyone, I can also confirm that the issue has been resolved :)