From 0e145f89a698a6743be3459b72ca87b91f96a971 Mon Sep 17 00:00:00 2001
From: Kevin Mehall <km@kevinmehall.net>
Date: Sat, 1 Feb 2025 19:42:37 -0700
Subject: [PATCH] Switch to rustix for netlink bind/recvfrom

---
 Cargo.toml                          |  1 -
 src/platform/linux_usbfs/hotplug.rs | 78 +++++++++--------------------
 2 files changed, 24 insertions(+), 55 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 1d57c47..b0afabd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,7 +23,6 @@ futures-lite = "1.13.0"
 
 [target.'cfg(any(target_os="linux", target_os="android"))'.dependencies]
 rustix = { version = "1.0.1", features = ["fs", "event", "net"] }
-libc = "0.2.155"
 
 [target.'cfg(target_os="windows")'.dependencies]
 windows-sys = { version = "0.59.0", features = ["Win32_Devices_Usb", "Win32_Devices_DeviceAndDriverInstallation", "Win32_Foundation", "Win32_Devices_Properties", "Win32_Storage_FileSystem", "Win32_Security", "Win32_System_IO", "Win32_System_Registry", "Win32_System_Com"] }
diff --git a/src/platform/linux_usbfs/hotplug.rs b/src/platform/linux_usbfs/hotplug.rs
index a2d4814..28ddc04 100644
--- a/src/platform/linux_usbfs/hotplug.rs
+++ b/src/platform/linux_usbfs/hotplug.rs
@@ -1,16 +1,14 @@
-use libc::{sockaddr, sockaddr_nl, socklen_t, AF_NETLINK, MSG_DONTWAIT};
 use log::{error, trace, warn};
 use rustix::{
-    fd::{AsFd, AsRawFd, OwnedFd},
-    net::{netlink, socket_with, AddressFamily, SocketFlags, SocketType},
-};
-use std::{
-    io::ErrorKind,
-    mem,
-    os::{raw::c_void, unix::prelude::BorrowedFd},
-    path::Path,
-    task::Poll,
+    fd::{AsFd, OwnedFd},
+    io::Errno,
+    net::{
+        bind,
+        netlink::{self, SocketAddrNetlink},
+        recvfrom, socket_with, AddressFamily, RecvFlags, SocketFlags, SocketType,
+    },
 };
+use std::{mem::MaybeUninit, os::unix::prelude::BorrowedFd, path::Path, task::Poll};
 
 use crate::{hotplug::HotplugEvent, Error};
 
@@ -31,23 +29,7 @@ impl LinuxHotplugWatch {
             SocketFlags::CLOEXEC,
             Some(netlink::KOBJECT_UEVENT),
         )?;
-
-        unsafe {
-            // rustix doesn't support netlink yet (pending https://github.com/bytecodealliance/rustix/pull/1004)
-            // so use libc for now.
-            let mut addr: sockaddr_nl = mem::zeroed();
-            addr.nl_family = AF_NETLINK as u16;
-            addr.nl_groups = UDEV_MULTICAST_GROUP;
-            let r = libc::bind(
-                fd.as_raw_fd(),
-                &addr as *const sockaddr_nl as *const sockaddr,
-                mem::size_of_val(&addr) as socklen_t,
-            );
-            if r != 0 {
-                return Err(Error::last_os_error());
-            }
-        }
-
+        bind(&fd, &SocketAddrNetlink::new(0, UDEV_MULTICAST_GROUP))?;
         Ok(LinuxHotplugWatch {
             fd: Async::new(fd)?,
         })
@@ -67,40 +49,28 @@ impl LinuxHotplugWatch {
 }
 
 fn try_receive_event(fd: BorrowedFd) -> Option<HotplugEvent> {
-    let mut buf = [0; 8192];
+    let mut buf = [MaybeUninit::uninit(); 8192];
 
-    let received = unsafe {
-        let mut addr: sockaddr_nl = mem::zeroed();
-        let mut addrlen: socklen_t = mem::size_of_val(&addr) as socklen_t;
-        let r = libc::recvfrom(
-            fd.as_raw_fd(),
-            buf.as_mut_ptr() as *mut c_void,
-            buf.len(),
-            MSG_DONTWAIT,
-            &mut addr as *mut sockaddr_nl as *mut sockaddr,
-            &mut addrlen,
-        );
-        if r >= 0 {
-            Ok((r as usize, addr.nl_groups))
-        } else {
-            Err(Error::last_os_error())
+    let (data, src) = match recvfrom(fd, &mut buf, RecvFlags::DONTWAIT) {
+        Ok(((buf, _), _, src)) => (buf, src),
+        Err(Errno::AGAIN | Errno::INTR) => return None,
+        Err(e) => {
+            error!("udev netlink socket recvfrom failed with {e}");
+            return None;
         }
     };
 
-    match received {
-        // udev messages will normally be sent to a multicast group, which only
-        // root can send to. Reject unicast messages that may be from anywhere.
-        Ok((size, groups)) if groups == UDEV_MULTICAST_GROUP => parse_packet(&buf[..size]),
-        Ok((_, src)) => {
+    // udev messages will normally be sent to a multicast group, which only
+    // root can send to. Reject unicast messages that may be from anywhere.
+    match src.map(SocketAddrNetlink::try_from).transpose() {
+        Ok(Some(nl)) if nl.groups() == UDEV_MULTICAST_GROUP => {}
+        src => {
             warn!("udev netlink socket received message from {src:?}");
-            None
-        }
-        Err(e) if e.kind() == ErrorKind::WouldBlock => None,
-        Err(e) => {
-            error!("udev netlink socket recvfrom failed with {e}");
-            None
+            return None;
         }
     }
+
+    parse_packet(data)
 }
 
 fn parse_packet(buf: &[u8]) -> Option<HotplugEvent> {