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---
page_type: sample
description: "Demonstrates how to attach contexts to instances, files, streams, and stream handles in your minifilter."
languages:
- cpp
products:
- windows
---
<!---
name: Ctx File System Minifilter Driver
platform: WDM
language: cpp
category: FileSystem
description: Demonstrates how to attach contexts to instances, files, streams, and stream handles in your minifilter.
samplefwlink: http://go.microsoft.com/fwlink/p/?LinkId=617648
--->
# 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](http://msdn.microsoft.com/en-us/library/windows/hardware/ff540402) section in the Installable File Systems Design Guide.
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