---
title: mbuf_leadingspace
framework: Kernel
role: symbol
role_heading: Function
platforms: [macOS 10.4+]
path: kernel/1535767-mbuf_leadingspace
---

# mbuf_leadingspace

## Declaration

```occ
size_t mbuf_leadingspace(const mbuf_t mbuf);
```

## Parameters

- `mbuf`: The mbuf.

## Return Value

Return Value The number of unused bytes at the start of the mbuf.

## Discussion

Discussion Determines the space available in the mbuf proceeding the current data.