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# FSMutableFileDataBuffer

A wrapper object for a data buffer.

```
class FSMutableFileDataBuffer
```

## Overview

This object provides a “zero-copy” buffer, for use when reading data from files.
By not requiring additional buffer copying, this object reduces the extension’s memory footprint and improves performance.
The `FSMutableFileDataBuffer` behaves similarly to a `uio` in the kernel.

## Topics

### Accessing buffer properties

[`withUnsafeMutableBytes(_:)`](/documentation/FSKit/FSMutableFileDataBuffer/withUnsafeMutableBytes(_:))

Performs the given closure with an unsafe pointer to the underlying bytes of the data buffer.

[`mutableBytes`](/documentation/FSKit/FSMutableFileDataBuffer/mutableBytes)

The byte data.

[`length`](/documentation/FSKit/FSMutableFileDataBuffer/length)

The data length of the buffer.


---

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