Scan Logic

This document describes the scanning logic implemented in the Xdows Security Scan Page (targeting developers).

Feature Overview

Offers four virus-scanning modes: Quick, Full, File, and Folder, with support for multi-engine parallel scanning and asynchronous streaming UI updates.

Input	Output
Scan Mode + User Path + Engine Toggles	Real-time progress, threat list, statistics, log entries

Sequence Overview

Engine Priority

async function scanFile(path: string): Promise<string | null> {
  if (useSouXiao)        return await souXiaoScan(path);
  if (useLocal)          return await localScan(path, deep, extra);
  if (useJiSuSafeAXMode) return await AXScan(path);
  if (useCloud)          return await cloudScan(path);
  if (useCzkCloud)       return await czkCloudScan(path, apiKey);
  return null;                                       // safe
}

Enumeration Strategy

Mode	Scope	Key Implementation
Quick	Critical system folders + executable extensions	EnumerateQuickScanFiles()
Full	All local drives	SafeEnumerateFiles() skips inaccessible nodes
File	Single file	PickSingleFileAsync()
Folder	Recursive directory	SafeEnumerateFolder() uses stack + try-catch

State Machine

State	Trigger	UI Indication
Idle	Initial / Scan finished	Buttons enabled, radar stopped
Running	StartScanAsync	Buttons disabled, radar spinning
Paused	OnPauseScanClick	Radar paused, resume button shown
Canceled	token.Cancel()	Status shows "Scan canceled"

Exception & Cancellation

catch (OperationCanceledException)
{
    StatusText.Text = "Scan canceled";
}
catch (Exception ex)
{
    LogText.AddNewLog(4, "Security - Failed", ex.Message);
}

Note

Exceptions affect only the current file; the queue continues.

Performance & Threading

Item	Strategy
Concurrency	One Task.Run(...) per file, loop delays 1 ms
UI Refresh	DispatcherQueue.TryEnqueue ensures thread safety
I/O Blocking	SafeEnumerate* patterns pre-catch permission issues

Log Format

Level	Module	Event	Details
1	Security - StartScan	Use LocalScan-DeepScan CloudScan
1	Security - ScanFile	C:\Windows\notepad.exe
1	Security - Find	MEMZUAC.Cloud.VirusFile

FAQ

How to add a new scan engine?

1. Register a toggle in settings.
2. Read the toggle inside StartScanAsync.
3. Append if (useNewEngine) result = await NewScanAsync(path); in the engine chain.
4. Update the "Engine Priority" section of this doc.

Why does the UI stay responsive during large scans?

All heavy work runs on the ThreadPool; UI updates are marshaled via DispatcherQueue.

Need incremental scanning?

Cache LastScanTime and compare with LastWriteTime during enumeration to skip unchanged files.