Secure Delete .Net

Secure Delete .Net

文章链接：http://www.codeproject.com/KB/miscctrl/SecureDeleteDotNet.aspx?azid=86

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下载 ：Download SecureDelete.zip - 124.16 KB

 

 We can use a Task to get all of the directory details since Directory.GetDirectories can be quite slow when there are lots of directories to retrieve (e.g. C:\Windows) 

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var task = Task.Factory.StartNew(() =>
{
	List<string> directoryDetails = new List<string>();
	foreach (string directory in Directory.GetDirectories(startPath))
	{
		directoryDetails.Add(directory);
	}
	return directoryDetails;
});

Task failed = task.ContinueWith(t => HandleTaskError(t.Exception),
	TaskContinuationOptions.OnlyOnFaulted);

Task ok = task.ContinueWith(t => 
	PopulateTree(t.Result, startPath, node), TaskContinuationOptions.OnlyOnRanToCompletion);

Loading the files contained within the directory is also contained in a Task

The method GetFilesFromDirectory starts a new task that calls Directory.GetFiles and generates an ExplorerFileInfo instance for each found file.

For each file retrieved, it checks the cache of 'Known File Types' for a file Icon and file type description. If one isn't found, it calls the APISHGetFileInfo to retrieve the information. It then passes a list of ExplorerFileInfo instances to LoadFilesToList 

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private void LoadFilesToList(List<ExplorerFileInfo> files)
{
	try
	{
		this.filesList.Items.Clear();
		this.filesList.BeginUpdate();

		ListViewItem[] viewItems = new ListViewItem[files.Count];

		for (int i = 0; i < viewItems.Length; ++i)
		{
			ExplorerFileInfo file = files[i];
			string[] items = new string[]{ file.Name, file.FileSize,
				file.FileTypeDescription, file.LastWriteTime.ToString()};

			ListViewItem listItem = new ListViewItem(items, file.Extension);
			listItem.Name = file.FullName;
			listItem.SubItems[1].Tag = file.Length;

			viewItems[i] = listItem;
		}

		this.filesList.Items.AddRange(viewItems);
	}
	finally                
	{
		this.filesList.EndUpdate();
	}            
}

There are a couple of things to note in LoadFilesToList.

• Use of BeginUpdate and EndUpdate. Really helps with performance, but I don't see enough people using them
• Building up a list of items and adding to the ListView using AddRange. This is much quicker than adding to the ListView within the loop via the Items.Add method.

Try browsing to a location that has a large number of files in (many thousand) - performance should still be acceptable.

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if (Program.AskQuestion(Resources.DeletionPrompt) == DialogResult.Yes)
{
	// Check here to show a message before starting a thread
	if (!FileCleaner.CheckForDeleteProgram())
	{
		Program.ShowError(Resources.DeletionProgramNotFound);
		return;
	}

	List<string> filesToDelete = new List<string>();
	foreach (ListViewItem item in this.selectedFilesList.Items)
	{
		filesToDelete.Add(item.Name);
	}

	progressWindow.Begin(0, filesToDelete.Count);

	// Starts the deletion process on the worker thread and displays the progress
	// of the operation
	DeletionStartArguments arguments = new DeletionStartArguments(filesToDelete, UserOptions.Current.NumberOfPasses);
	this.deletionWorker.RunWorkerAsync(arguments);

	progressWindow.ShowDialog(this);
}

 

using (Process p = new Process())
{
	p.StartInfo.FileName = Resources.DeletionProgram;
	p.StartInfo.Arguments = string.Format("-p {0} -q \"{1}\"", passes, fileName);
	p.StartInfo.CreateNoWindow = true;
	p.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
	p.StartInfo.UseShellExecute = false;
	p.StartInfo.RedirectStandardOutput = true;
	p.Start();

	string output = p.StandardOutput.ReadToEnd();
	p.WaitForExit();

	fileDeleted = !File.Exists(fileName);

	if (UserOptions.Current.LogOperations)
	{
		log.Info(output);
		log.Info(string.Format(Resources.FileDeletionStatus, fileName, fileDeleted.ToString()));
	}
}