FromRawFd in std::os::fd - Rust (original) (raw)

Trait FromRawFd

1.66.0 · Source

pub trait FromRawFd {
    // Required method
    unsafe fn from_raw_fd(fd: RawFd) -> Self;
}

Expand description

A trait to express the ability to construct an object from a raw file descriptor.

1.1.0 · Source

Constructs a new instance of Self from the given raw file descriptor.

This function is typically used to consume ownership of the specified file descriptor. When used in this way, the returned object will take responsibility for closing it when the object goes out of scope.

However, consuming ownership is not strictly required. Use aFrom::from implementation for an API which strictly consumes ownership.

§Safety

The fd passed in must be an owned file descriptor; in particular, it must be open.

§Example

use std::fs::File;
#[cfg(any(unix, target_os = "wasi"))]
use std::os::fd::{FromRawFd, IntoRawFd, RawFd};

let f = File::open("foo.txt")?;
let raw_fd: RawFd = f.into_raw_fd();
// SAFETY: no other functions should call `from_raw_fd`, so there
// is only one owner for the file descriptor.
let f = unsafe { File::from_raw_fd(raw_fd) };

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.