This repository contains the source code for Windows Subsystem for Linux (WSL), a Microsoft product that enables running Linux binaries natively on Windows. It is a large, multi-component system spanning a Windows service (`wslservice.exe`), a Docker-compatible container CLI (`wslc.exe`), a WinRT SDK (`Microsoft.WSL.Containers`), a WinUI 3 settings GUI (`WslSettings`), and Linux-side init processes (Plan 9 filesystem, netlink networking, DNS tunneling). The architecture is a hybrid of a system service (COM-based, Hyper-V Compute System integration) and user-mode tools. Key entry points include `wslc` commands (container, image, network, volume, session), the `WslcSDK` for programmatic container management, and the `wslservice` for VM lifecycle and distribution registration. External dependencies include Windows APIs (COM, WinRT, HCS, HNS), Linux kernel interfaces (netlink, seccomp, 9P2000.L), and third-party libraries (nlohmann/json, Microsoft.GSL, wil, Boost.Beast). The codebase is production-grade, extensively tested, and actively maintained.
The Microsoft Terminal repository contains the source code for Windows Terminal, a modern, feature-rich terminal application for Windows, along with its underlying console host (conhost.exe). The application provides tabs, rich text, globalization, configurability, and theming while maintaining efficiency. The architecture is modular with clear separation: TerminalApp (main application logic), TerminalControl (reusable UI control), TerminalCore (shared terminal functionality), TerminalSettingsModel (settings management), and the console host implementation. Key entry points include src/cascadia/WindowsTerminal/main.cpp for the terminal application and src/host/ for the console host. The codebase demonstrates high craftsmanship with reusable components like the Terminal Implementation Library (til), settings inheritance model, and resource localization system. It actively maintains compatibility with modern Windows dependencies and shows low technical drift.
The Windows App SDK (formerly Project Reunion) is a Microsoft platform SDK for building modern Windows desktop applications. It provides a unified set of WinRT APIs and runtime components that bridge Win32 and UWP development, enabling features like app lifecycle management (single-instance, file/protocol activation), dynamic package dependencies (resolving framework packages at runtime), rich notifications (toast, push, badge), resource management via MRT Core (PRI files with qualifier-based selection), deployment APIs (package sets, validation), environment variable management, OAuth 2.0 authentication, and interop wrappers for storage pickers and camera capture. The architecture is modular: each feature area is implemented as a separate C++/WinRT component (DLL) that can be consumed individually via NuGet packages. The SDK supports both packaged (MSIX) and unpackaged (self-contained) apps, with a bootstrap DLL that initializes the runtime and hooks into the Windows package graph via Detours. Key entry points include MddBootstrapInitialize2 for runtime initialization, the WindowsAppRuntime DLL for COM class factories, and individual component APIs like AppNotificationManager, PushNotificationManager, and PackageDependency. External dependencies include the Windows SDK, C++/WinRT projections, the Windows Implementation Libraries (WIL), and Microsoft Detours for API interception. Data flows involve inter-process communication through shared memory (for activation redirection), named pipes (for OAuth callbacks), and COM out-of-process servers (for push notification long-running tasks). The codebase is heavily instrumented with TraceLogging telemetry and uses feature flags (TerminalVelocity) to gate experimental APIs.
Win2D is a production-grade Windows Runtime 2D graphics library that wraps Direct2D, DirectWrite, Direct3D, and WIC into a WinRT API for use in UWP and WinUI3 applications. It provides immediate-mode GPU-accelerated rendering through XAML controls (CanvasControl, CanvasAnimatedControl, CanvasSwapChainPanel), drawing sessions, brushes, geometries, text layout and analysis, SVG documents, printing, and over 70 image effects. The library is packaged as a NuGet package (Microsoft.Graphics.Win2D) and supports C#, C++/CX, C++/WinRT, and VB.NET consumers. Architecturally, Win2D is a WinRT component implemented in C++/WinRT with a DLL entry point (module.cpp) that registers activation factories and telemetry. The core rendering logic lives in winrt/lib/, organized by subsystem: drawing (CanvasDrawingSession, DeviceContextPool), effects (generated wrappers and custom pixel shader support), text (DirectWrite wrappers), geometry, brushes, SVG, printing, and XAML controls. A code generation tool (tools/codegen) produces IDL and effect implementations from XML definitions, ensuring consistency across the large effect surface. The library relies on external dependencies including Direct2D, DirectWrite, Direct3D 11, Windows Imaging Component (WIC), and the Windows App SDK (for WinUI3). Key entry points for developers are the XAML controls (CanvasControl, CanvasAnimatedControl) which provide CreateResources and Draw events, and the CanvasDrawingSession which exposes all drawing operations. The library also includes extensive interop interfaces (ICanvasImageInterop, ICanvasResourceWrapperNative) for integrating with native Direct2D code. Testing is comprehensive, with internal C++ unit tests using mocks/stubs, external integration tests with real devices, and managed C# tests.