Get byte array for ZipArchive in C#

Question

I'm trying to write code to remove the _MAXOSX folder from a zip archive if it exists (breaks validation further down the line if it exists).

The code must return a byte[] and not the ZipArchive itself. The code I currently have is:

var fileBytes = uploadController.FileBytes;
if (stripMacOSXFolder && uploadController.FileName.EndsWith(".zip", StringComparison.CurrentCultureIgnoreCase))
{
    try
    {
        using (var data = new MemoryStream(fileBytes))
        using (var archive = new ZipArchive(data, ZipArchiveMode.Update))
        {
            var osx = archive.Entries.SingleOrDefault(c =>
                c.FullName.Equals("__MACOSX/", StringComparison.CurrentCultureIgnoreCase));
            if (osx != null)
            {
                osx.Delete();
                // SET fileBytes to archive byte[]
            }
        }
    }
    catch (Exception)
    {
        return new ObjectReturnMethodResult<UploadedFileV2>("Uploaded zip appears to be invalid.");
    }
}

It's not clear to me once I've deleted the entry how I set fileBytes to the byte array of the updated ZipArchive.

Answer 1

The docs for Update mode state:

When you set the mode to Update, the underlying file or stream must support reading, writing, and seeking. The content of the entire archive is held in memory, and no data is written to the underlying file or stream until the archive is disposed.

It seems that you will need to obtain the updates bytes after the ZipArchive has been disposed of:

using (var data = new MemoryStream(fileBytes))
{
    using (var archive = new ZipArchive(data, ZipArchiveMode.Update))
    {
        var osx = archive.Entries.SingleOrDefault(c =>
            c.FullName.Equals("__MACOSX/", StringComparison.CurrentCultureIgnoreCase));
        if (osx != null)
        {
            osx.Delete();
        }
    }
    fileBytes = data.ToArray();
}