VPatch.net is a port of Koen van de Sande's differential patching program "VPatch" to the .NET framework. The original program is provided by the author at his site as well as is bundled with the Nullsoft Scriptable Install System for making small delta patches. It allows C# (and other .NET code, as far as I'm aware) to make use of the algorithm both as a patch generator and as a patch applier.

I needed a way to do delta patches when experimenting with my own patcher GUI, as the existing GUIs for creating deployable patches are either expensive with draconic licensing or underdeveloped. Remembering VPatch from reading NSIS documentation, and that the C# version of bsdiff depended on GPL code, I decided to port the BSD-licensed VPatch algorithm to .NET and release it under a similar license.

This .NET port aims to make the creation and application of delta patches trivial, which should be useful for applying application updates or potentially synchronizing complex game states that have run amok.

While VPatch.net is developed with SharpDevelop, the project files should be openable in Visual Studio. You may, additionally, drop the source code files in to a project in an existing solution and build it; there are no special requirements other than patch creation code depends on System.LINQ.

Patch application code does not have this requirement so that component should be safe to use on .NET 2.0 which is pre-installed on all Windows Vista and 7 machines, and updated XP machines.

NConsoler.dll is under the Mozilla Public License 1.1, the rest of these files are under the BSD license just like the original VPatch code.

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                           -=* VPatch *=-
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 Copyright (C) 2001-2005 Koen van de Sande / Van de Sande Productions
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 Website: http://www.tibed.net/vpatch

 This software is provided 'as-is', without any express or implied
 warranty.  In no event will the authors be held liable for any damages
 arising from the use of this software.

 Permission is granted to anyone to use this software for any purpose,
 including commercial applications, and to alter it and redistribute it
 freely, subject to the following restrictions:

 1. The origin of this software must not be misrepresented; you must not
    claim that you wrote the original software. If you use this software
    in a product, an acknowledgment in the product documentation would be
    appreciated but is not required.
 2. Altered source versions must be plainly marked as such, and must not be
    misrepresented as being the original software.
 3. This notice may not be removed or altered from any source distribution.
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Ported to C# 2012 Joshua Cearley

Headers in the .cs files will be updated as time permits.

• VPatch.net files created with the Data.Formatter.PatFormatter class are compatible with the original vpatch, and in turn are compatible with NSIS scripts.

• Takes approximately twice as much RAM as the original C version, from some simple tests.
• Not compatible with VPatch's .dat format if they contain more than one file, only the first file is read.
• Filetimes are recorded when creating patches but are ignored when applying them. If maintaining file time stamps becomes important I'll look in to fixing that.
• May throw exceptions here and there. Those will be stamped out as use cases can be formed around them.