void applyDiffToFile(string deltaPath, string relativeFilePath, string workingDirectory)
        {
            var inputFile   = Path.Combine(deltaPath, relativeFilePath);
            var finalTarget = Path.Combine(workingDirectory, Regex.Replace(relativeFilePath, @".diff$", ""));

            var tempTargetFile = Path.GetTempFileName();

            // NB: Zero-length diffs indicate the file hasn't actually changed
            if (new FileInfo(inputFile).Length == 0)
            {
                this.Log().Info("{0} exists unchanged, skipping", relativeFilePath);
                return;
            }

            if (relativeFilePath.EndsWith(".diff", StringComparison.InvariantCultureIgnoreCase))
            {
                using (var of = File.OpenWrite(tempTargetFile))
                    using (var inf = File.OpenRead(finalTarget)) {
                        this.Log().Info("Applying Diff to {0}", relativeFilePath);
                        BinaryPatchUtility.Apply(inf, () => File.OpenRead(inputFile), of);
                    }

                try {
                    verifyPatchedFile(relativeFilePath, inputFile, tempTargetFile);
                } catch (Exception) {
                    File.Delete(tempTargetFile);
                    throw;
                }
            }
            else
            {
                using (var of = File.OpenWrite(tempTargetFile))
                    using (var inf = File.OpenRead(inputFile)) {
                        this.Log().Info("Adding new file: {0}", relativeFilePath);
                        inf.CopyTo(of);
                    }
            }

            if (File.Exists(finalTarget))
            {
                File.Delete(finalTarget);
            }

            var targetPath = Directory.GetParent(finalTarget);

            if (!targetPath.Exists)
            {
                targetPath.Create();
            }

            File.Move(tempTargetFile, finalTarget);
        }
        void createDeltaForSingleFile(FileInfo targetFile, DirectoryInfo workingDirectory, Dictionary <string, string> baseFileListing)
        {
            // NB: There are three cases here that we'll handle:
            //
            // 1. Exists only in new => leave it alone, we'll use it directly.
            // 2. Exists in both old and new => write a dummy file so we know
            //    to keep it.
            // 3. Exists in old but changed in new => create a delta file
            //
            // The fourth case of "Exists only in old => delete it in new"
            // is handled when we apply the delta package
            var relativePath = targetFile.FullName.Replace(workingDirectory.FullName, "");

            if (!baseFileListing.ContainsKey(relativePath))
            {
                this.Log().Info("{0} not found in base package, marking as new", relativePath);
                return;
            }

            var oldData = File.ReadAllBytes(baseFileListing[relativePath]);
            var newData = File.ReadAllBytes(targetFile.FullName);

            if (bytesAreIdentical(oldData, newData))
            {
                this.Log().Info("{0} hasn't changed, writing dummy file", relativePath);

                File.Create(targetFile.FullName + ".diff").Dispose();
                File.Create(targetFile.FullName + ".shasum").Dispose();
                targetFile.Delete();
                return;
            }

            this.Log().Info("Delta patching {0} => {1}", baseFileListing[relativePath], targetFile.FullName);
            using (var of = File.Create(targetFile.FullName + ".diff")) {
                BinaryPatchUtility.Create(oldData, newData, of);

                var rl = ReleaseEntry.GenerateFromFile(new MemoryStream(newData), targetFile.Name + ".shasum");
                File.WriteAllText(targetFile.FullName + ".shasum", rl.EntryAsString, Encoding.UTF8);
                targetFile.Delete();
            }
        }