private void UpdateCommentOnly()

in src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs [2884:2952]
54 lines of code
6 McCabe index (conditional complexity)

		private void UpdateCommentOnly()
		{
			long baseLength = baseStream_.Length;

			Stream updateFile;

			if (archiveStorage_.UpdateMode == FileUpdateMode.Safe)
			{
				updateFile = archiveStorage_.MakeTemporaryCopy(baseStream_);

				baseStream_.Dispose();
				baseStream_ = null;
			}
			else
			{
				if (archiveStorage_.UpdateMode == FileUpdateMode.Direct)
				{
					// TODO: archiveStorage wasnt originally intended for this use.
					// Need to revisit this to tidy up handling as archive storage currently doesnt
					// handle the original stream well.
					// The problem is when using an existing zip archive with an in memory archive storage.
					// The open stream wont support writing but the memory storage should open the same file not an in memory one.

					// Need to tidy up the archive storage interface and contract basically.
					baseStream_ = archiveStorage_.OpenForDirectUpdate(baseStream_);
					updateFile = baseStream_;
				}
				else
				{
					baseStream_.Dispose();
					baseStream_ = null;
					updateFile = new FileStream(Name, FileMode.Open, FileAccess.ReadWrite);
				}
			}

			try
			{
				long locatedCentralDirOffset =
					ZipFormat.LocateBlockWithSignature(updateFile, ZipConstants.EndOfCentralDirectorySignature,
						baseLength, ZipConstants.EndOfCentralRecordBaseSize, 0xffff);
				if (locatedCentralDirOffset < 0)
				{
					throw new ZipException("Cannot find central directory");
				}

				const int CentralHeaderCommentSizeOffset = 16;
				updateFile.Position += CentralHeaderCommentSizeOffset;

				byte[] rawComment = newComment_.RawComment;

				updateFile.WriteLEShort(rawComment.Length);
				updateFile.Write(rawComment, 0, rawComment.Length);
				updateFile.SetLength(updateFile.Position);
			}
			finally
			{
				if(updateFile != baseStream_)
					updateFile.Dispose();
			}

			if (archiveStorage_.UpdateMode == FileUpdateMode.Safe)
			{
				Reopen(archiveStorage_.ConvertTemporaryToFinal());
			}
			else
			{
				ReadEntries();
			}
		}