---
page_type: sample
description: "Demonstrates how to attach contexts to instances, files, streams, and stream handles in your minifilter."
languages:
- cpp
products:
- windows
- windows-wdk
---

# Ctx File System Minifilter Drive

The Ctx minifilter is an example that demonstrates how to attach contexts to instances, files, streams, and stream handles in your minifilter.

## Universal Windows Driver Compliant

This sample builds a Universal Windows Driver. It uses only APIs and DDIs that are included in OneCoreUAP.

## Design and Operation

The *Ctx* minifilter demonstrates how to attach and remove contexts from instances, files, steams, and stream handles. *Ctx* attaches a context whenever one of these objects is created. While attaching a context to a file, the sample also creates a stream and stream handle context. All contexts are ultimately deleted by the filter manager using the callback function that the *Ctx* minifilter provides.

For more information on file system minifilter design, start with the [File System Minifilter Drivers](https://docs.microsoft.com/windows-hardware/drivers/ifs/file-system-minifilter-drivers) section in the Installable File Systems Design Guide.