First thoughts on porting to Mono

I’ve known about Mono since its inception, but a few months ago I really became interested as support for C# 2.0 and WinForms 2.0 was announced. I played around with some code and was pretty impressed at how easy it was to get stuff compiled and running. This weekend I made a concerted effort to tackle something more complex, getting Fragment Sync compiled and running. I’ve read you can simply use Mono with the managed executable and not have to deal with compiling source code, but Fragment Sync does quite a bit of interop with unmanaged code so that really wasn’t an option.

I first attempted to import all the source files into MonoDevelop (commenting out win32 specific stuff), but this proved problematic when it came to resources. I tried a ton of different things, but could not get MonoDevelop to properly compile in the app’s resources. I then read you can just open the Visual Studio solution with MonoDevelop; this proved to be effortless and resolved the compilation issue with resources.

After a successful compiled, I had some issues getting a window up. There was an issue loading the application icon. This seems to be an issue with using Vista-compatible icons (where the 256×256 sized bitmap, is an embedded png). I changed the icon to null for a few forms to resolve this; which involves the following line in the form designer code:

this.Icon = ((System.Drawing.Icon)(resources.GetObject("$this.Icon")));

The final and most serious issue I encountered was with Fragment Sync’s Rijndael encryption code. You can find the issue described in detail here. Note the issue will pop up when using CryptoStream as well, since CryptoStream simply abstracts the calls to the underlying Transform methods of ICryptoTransform. The trick here is to always check that you can reuse the transform. With Microsoft’s implementation you can, with Mono you can’t. So you have to recreate the transform object.

if (!decryptor.CanReuseTransform)
    decryptor = rij.CreateDecryptor();

With these issues resolved I could get things up and running.

fragment sync running on mono in opensuse

Obviously things don’t look pretty, but I think this is a good starting point to work from to get Linux support for Fragment Sync.

I should mention I did consider using Gtk# and redoing the Fragment Sync user interfaces, but I found Gtk’s design methodology unbearable… let’s just say I’m not a fan of packing widgets into containers.

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