# CMSG_LEN

- **Language:** C
- **Kind:** constant
- **Source:** https://github.com/tmux/tmux/blob/3b929f332aafa7f1080eacc31feb11ffbb1d1841/compat.h#L202
- **Page:** https://libtmux.org/en/tmux/3.2a/reference/c-define-compat-h-cmsg_len/

```c
#define CMSG_LEN(len) (CMSG_ALIGN(sizeof(struct cmsghdr)) + (len))
```

## Referenced declarations

- [`CMSG_ALIGN`](/en/tmux/3.2a/reference/c-define-compat-h-cmsg_align/) (constant)