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Add os::unix::net::SocketAddr::from_path #93239

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56 changes: 48 additions & 8 deletions library/std/src/os/unix/net/addr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use crate::ffi::OsStr;
use crate::os::unix::ffi::OsStrExt;
use crate::path::Path;
use crate::sys::cvt;
use crate::{ascii, fmt, io, iter, mem};
use crate::{ascii, fmt, io, mem, ptr};

// FIXME(#43348): Make libc adapt #[doc(cfg(...))] so we don't need these fake definitions here?
#[cfg(not(unix))]
Expand All @@ -22,8 +22,9 @@ fn sun_path_offset(addr: &libc::sockaddr_un) -> usize {
path - base
}

pub(super) unsafe fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
let mut addr: libc::sockaddr_un = mem::zeroed();
pub(super) fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
// SAFETY: All zeros is a valid representation for `sockaddr_un`.
let mut addr: libc::sockaddr_un = unsafe { mem::zeroed() };
addr.sun_family = libc::AF_UNIX as libc::sa_family_t;

let bytes = path.as_os_str().as_bytes();
Expand All @@ -41,11 +42,13 @@ pub(super) unsafe fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un,
&"path must be shorter than SUN_LEN",
));
}
for (dst, src) in iter::zip(&mut addr.sun_path, bytes) {
*dst = *src as libc::c_char;
}
// null byte for pathname addresses is already there because we zeroed the
// struct
// SAFETY: `bytes` and `addr.sun_path` are not overlapping and
// both point to valid memory.
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Perhaps add "we checked path is not too long"

// NOTE: We zeroed the memory above, so the path is already null
// terminated.
unsafe {
ptr::copy_nonoverlapping(bytes.as_ptr(), addr.sun_path.as_mut_ptr().cast(), bytes.len())
};

let mut len = sun_path_offset(&addr) + bytes.len();
match bytes.get(0) {
Expand Down Expand Up @@ -127,6 +130,43 @@ impl SocketAddr {
Ok(SocketAddr { addr, len })
}

/// Constructs a `SockAddr` with the family `AF_UNIX` and the provided path.
///
/// # Errors
///
/// Returns an error if the path is longer than `SUN_LEN` or if it contains
/// NULL bytes.
///
/// # Examples
///
/// ```
/// #![feature(unix_socket_creation)]
/// use std::os::unix::net::SocketAddr;
/// use std::path::Path;
///
/// # fn main() -> std::io::Result<()> {
/// let address = SocketAddr::from_path("/path/to/socket")?;
/// assert_eq!(address.as_pathname(), Some(Path::new("/path/to/socket")));
/// # Ok(())
/// # }
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/// ```
///
/// Creating a `SocketAddr` with a NULL byte results in an error.
///
/// ```
/// #![feature(unix_socket_creation)]
/// use std::os::unix::net::SocketAddr;
///
/// assert!(SocketAddr::from_path("/path/with/\0/bytes").is_err());
/// ```
#[unstable(feature = "unix_socket_creation", issue = "93423")]
pub fn from_path<P>(path: P) -> io::Result<SocketAddr>
where
P: AsRef<Path>,
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{
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sockaddr_un(path.as_ref()).map(|(addr, len)| SocketAddr { addr, len })
}

/// Returns `true` if the address is unnamed.
///
/// # Examples
Expand Down