Replace &mut with & where we're not modifying the struct's state.

Cargo.toml

@@ -10,6 +10,10 @@ readme = "README.md"
 repository = "https://github.com/rust-netlink/netlink-sys"
 description = "netlink sockets, with optional integration with tokio"
 
+# When running the examples against a local version of `netlink-sys`
+# [patch.crates-io]
+# netlink-sys = { path = "." }
+
 [dependencies]
 bytes = "1.8"
 libc = "0.2.164"

examples/audit_events_async_std.rs

@@ -31,7 +31,7 @@ const AUDIT_STATUS_PID: u32 = 4;
 #[async_std::main]
 async fn main() {
     let kernel_unicast: SocketAddr = SocketAddr::new(0, 0);
-    let mut socket = SmolSocket::new(NETLINK_AUDIT).unwrap();
+    let socket = SmolSocket::new(NETLINK_AUDIT).unwrap();
 
     let mut status = StatusMessage::new();
     status.enabled = 1;

examples/audit_events_tokio.rs

@@ -31,7 +31,7 @@ const AUDIT_STATUS_PID: u32 = 4;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let kernel_unicast: SocketAddr = SocketAddr::new(0, 0);
-    let mut socket = TokioSocket::new(NETLINK_AUDIT).unwrap();
+    let socket = TokioSocket::new(NETLINK_AUDIT).unwrap();
 
     let mut status = StatusMessage::new();
     status.enabled = 1;

src/async_socket.rs

@@ -20,14 +20,14 @@ pub trait AsyncSocket: Sized + Unpin {
 
     /// Polling wrapper for [`Socket::send`]
     fn poll_send(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &[u8],
     ) -> Poll<io::Result<usize>>;
 
     /// Polling wrapper for [`Socket::send_to`]
     fn poll_send_to(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &[u8],
         addr: &SocketAddr,
@@ -38,7 +38,7 @@ pub trait AsyncSocket: Sized + Unpin {
     /// Passes 0 for flags, and ignores the returned length (the buffer will
     /// have advanced by the amount read).
     fn poll_recv<B>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &mut B,
     ) -> Poll<io::Result<()>>
@@ -50,7 +50,7 @@ pub trait AsyncSocket: Sized + Unpin {
     /// Passes 0 for flags, and ignores the returned length - just returns the
     /// address (the buffer will have advanced by the amount read).
     fn poll_recv_from<B>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &mut B,
     ) -> Poll<io::Result<SocketAddr>>
@@ -62,7 +62,7 @@ pub trait AsyncSocket: Sized + Unpin {
     /// Passes 0 for flags, and ignores the returned length - just returns the
     /// address (the buffer will have advanced by the amount read).
     fn poll_recv_from_full(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
     ) -> Poll<io::Result<(Vec<u8>, SocketAddr)>>;
 }

src/async_socket_ext.rs

@@ -13,14 +13,14 @@ use crate::{AsyncSocket, SocketAddr};
 ///
 /// Provides awaitable variants of the poll functions from [`AsyncSocket`].
 pub trait AsyncSocketExt: AsyncSocket {
-    /// `async fn send(&mut self, buf: &[u8]) -> io::Result<usize>`
-    fn send<'a, 'b>(&'a mut self, buf: &'b [u8]) -> PollSend<'a, 'b, Self> {
+    /// `async fn send(&self, buf: &[u8]) -> io::Result<usize>`
+    fn send<'a, 'b>(&'a self, buf: &'b [u8]) -> PollSend<'a, 'b, Self> {
         PollSend { socket: self, buf }
     }
 
-    /// `async fn send(&mut self, buf: &[u8]) -> io::Result<usize>`
+    /// `async fn send(&self, buf: &[u8]) -> io::Result<usize>`
     fn send_to<'a, 'b>(
-        &'a mut self,
+        &'a self,
         buf: &'b [u8],
         addr: &'b SocketAddr,
     ) -> PollSendTo<'a, 'b, Self> {
@@ -31,20 +31,17 @@ pub trait AsyncSocketExt: AsyncSocket {
         }
     }
 
-    /// `async fn recv<B>(&mut self, buf: &mut [u8]) -> io::Result<()>`
-    fn recv<'a, 'b, B>(
-        &'a mut self,
-        buf: &'b mut B,
-    ) -> PollRecv<'a, 'b, Self, B>
+    /// `async fn recv<B>(&self, buf: &mut [u8]) -> io::Result<()>`
+    fn recv<'a, 'b, B>(&'a self, buf: &'b mut B) -> PollRecv<'a, 'b, Self, B>
     where
         B: bytes::BufMut,
     {
         PollRecv { socket: self, buf }
     }
 
-    /// `async fn recv<B>(&mut self, buf: &mut [u8]) -> io::Result<SocketAddr>`
+    /// `async fn recv<B>(&self, buf: &mut [u8]) -> io::Result<SocketAddr>`
     fn recv_from<'a, 'b, B>(
-        &'a mut self,
+        &'a self,
         buf: &'b mut B,
     ) -> PollRecvFrom<'a, 'b, Self, B>
     where
@@ -53,17 +50,17 @@ pub trait AsyncSocketExt: AsyncSocket {
         PollRecvFrom { socket: self, buf }
     }
 
-    /// `async fn recrecv_from_full(&mut self) -> io::Result<(Vec<u8>,
+    /// `async fn recrecv_from_full(&self) -> io::Result<(Vec<u8>,
     /// SocketAddr)>`
-    fn recv_from_full(&mut self) -> PollRecvFromFull<'_, Self> {
+    fn recv_from_full(&self) -> PollRecvFromFull<'_, Self> {
         PollRecvFromFull { socket: self }
     }
 }
 
 impl<S: AsyncSocket> AsyncSocketExt for S {}
 
 pub struct PollSend<'a, 'b, S> {
-    socket: &'a mut S,
+    socket: &'a S,
     buf: &'b [u8],
 }
 
@@ -80,7 +77,7 @@ where
 }
 
 pub struct PollSendTo<'a, 'b, S> {
-    socket: &'a mut S,
+    socket: &'a S,
     buf: &'b [u8],
     addr: &'b SocketAddr,
 }
@@ -98,7 +95,7 @@ where
 }
 
 pub struct PollRecv<'a, 'b, S, B> {
-    socket: &'a mut S,
+    socket: &'a S,
     buf: &'b mut B,
 }
 
@@ -116,7 +113,7 @@ where
 }
 
 pub struct PollRecvFrom<'a, 'b, S, B> {
-    socket: &'a mut S,
+    socket: &'a S,
     buf: &'b mut B,
 }
 
@@ -134,7 +131,7 @@ where
 }
 
 pub struct PollRecvFromFull<'a, S> {
-    socket: &'a mut S,
+    socket: &'a S,
 }
 
 impl<S> Future for PollRecvFromFull<'_, S>

src/smol.rs

@@ -42,12 +42,12 @@ impl AsFd for SmolSocket {
 // replicate this in these poll functions:
 impl SmolSocket {
     fn poll_write_with<F, R>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         mut op: F,
     ) -> Poll<io::Result<R>>
     where
-        F: FnMut(&mut Self) -> io::Result<R>,
+        F: FnMut(&Self) -> io::Result<R>,
     {
         loop {
             match op(self) {
@@ -60,12 +60,12 @@ impl SmolSocket {
     }
 
     fn poll_read_with<F, R>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         mut op: F,
     ) -> Poll<io::Result<R>>
     where
-        F: FnMut(&mut Self) -> io::Result<R>,
+        F: FnMut(&Self) -> io::Result<R>,
     {
         loop {
             match op(self) {
@@ -94,54 +94,54 @@ impl AsyncSocket for SmolSocket {
     }
 
     fn poll_send(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &[u8],
     ) -> Poll<io::Result<usize>> {
-        self.poll_write_with(cx, |this| this.socket_mut().send(buf, 0))
+        self.poll_write_with(cx, |this| this.socket_ref().send(buf, 0))
     }
 
     fn poll_send_to(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &[u8],
         addr: &SocketAddr,
     ) -> Poll<io::Result<usize>> {
-        self.poll_write_with(cx, |this| this.socket_mut().send_to(buf, addr, 0))
+        self.poll_write_with(cx, |this| this.socket_ref().send_to(buf, addr, 0))
     }
 
     fn poll_recv<B>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &mut B,
     ) -> Poll<io::Result<()>>
     where
         B: bytes::BufMut,
     {
         self.poll_read_with(cx, |this| {
-            this.socket_mut().recv(buf, 0).map(|_len| ())
+            this.socket_ref().recv(buf, 0).map(|_len| ())
         })
     }
 
     fn poll_recv_from<B>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &mut B,
     ) -> Poll<io::Result<SocketAddr>>
     where
         B: bytes::BufMut,
     {
         self.poll_read_with(cx, |this| {
-            let x = this.socket_mut().recv_from(buf, 0);
+            let x = this.socket_ref().recv_from(buf, 0);
             trace!("poll_recv_from: {:?}", x);
             x.map(|(_len, addr)| addr)
         })
     }
 
     fn poll_recv_from_full(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
     ) -> Poll<io::Result<(Vec<u8>, SocketAddr)>> {
-        self.poll_read_with(cx, |this| this.socket_mut().recv_from_full())
+        self.poll_read_with(cx, |this| this.socket_ref().recv_from_full())
     }
 }

src/socket.rs

@@ -410,7 +410,7 @@ impl Socket {
         Ok(res as usize)
     }
 
-    pub fn set_pktinfo(&mut self, value: bool) -> Result<()> {
+    pub fn set_pktinfo(&self, value: bool) -> Result<()> {
         let value: libc::c_int = value.into();
         setsockopt(
             self.as_raw_fd(),
@@ -429,7 +429,7 @@ impl Socket {
         Ok(res == 1)
     }
 
-    pub fn add_membership(&mut self, group: u32) -> Result<()> {
+    pub fn add_membership(&self, group: u32) -> Result<()> {
         setsockopt(
             self.as_raw_fd(),
             libc::SOL_NETLINK,
@@ -438,7 +438,7 @@ impl Socket {
         )
     }
 
-    pub fn drop_membership(&mut self, group: u32) -> Result<()> {
+    pub fn drop_membership(&self, group: u32) -> Result<()> {
         setsockopt(
             self.as_raw_fd(),
             libc::SOL_NETLINK,
@@ -457,7 +457,7 @@ impl Socket {
     /// `NETLINK_BROADCAST_ERROR` (since Linux 2.6.30). When not set,
     /// `netlink_broadcast()` only reports `ESRCH` errors and silently
     /// ignore `NOBUFS` errors.
-    pub fn set_broadcast_error(&mut self, value: bool) -> Result<()> {
+    pub fn set_broadcast_error(&self, value: bool) -> Result<()> {
         let value: libc::c_int = value.into();
         setsockopt(
             self.as_raw_fd(),
@@ -478,7 +478,7 @@ impl Socket {
 
     /// `NETLINK_NO_ENOBUFS` (since Linux 2.6.30). This flag can be used by
     /// unicast and broadcast listeners to avoid receiving `ENOBUFS` errors.
-    pub fn set_no_enobufs(&mut self, value: bool) -> Result<()> {
+    pub fn set_no_enobufs(&self, value: bool) -> Result<()> {
         let value: libc::c_int = value.into();
         setsockopt(
             self.as_raw_fd(),
@@ -502,7 +502,7 @@ impl Socket {
     /// have an nsid assigned into the network namespace where the socket
     /// has been opened. The nsid is sent to user space via an ancillary
     /// data.
-    pub fn set_listen_all_namespaces(&mut self, value: bool) -> Result<()> {
+    pub fn set_listen_all_namespaces(&self, value: bool) -> Result<()> {
         let value: libc::c_int = value.into();
         setsockopt(
             self.as_raw_fd(),
@@ -527,7 +527,7 @@ impl Socket {
     /// The netlink message header is still included, so the user can
     /// guess from the sequence  number which message triggered the
     /// acknowledgment.
-    pub fn set_cap_ack(&mut self, value: bool) -> Result<()> {
+    pub fn set_cap_ack(&self, value: bool) -> Result<()> {
         let value: libc::c_int = value.into();
         setsockopt(
             self.as_raw_fd(),
@@ -549,7 +549,7 @@ impl Socket {
     /// `NETLINK_EXT_ACK`
     /// Extended ACK controls reporting of additional error/warning TLVs in
     /// NLMSG_ERROR and NLMSG_DONE messages.
-    pub fn set_ext_ack(&mut self, value: bool) -> Result<()> {
+    pub fn set_ext_ack(&self, value: bool) -> Result<()> {
         let value: libc::c_int = value.into();
         setsockopt(
             self.as_raw_fd(),
@@ -697,7 +697,7 @@ mod test {
 
     #[test]
     fn options() {
-        let mut sock = Socket::new(NETLINK_ROUTE).unwrap();
+        let sock = Socket::new(NETLINK_ROUTE).unwrap();
 
         sock.set_cap_ack(true).unwrap();
         assert!(sock.get_cap_ack().unwrap());

src/tokio.rs

@@ -46,7 +46,7 @@ impl AsyncSocket for TokioSocket {
     }
 
     fn poll_send(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &[u8],
     ) -> Poll<io::Result<usize>> {
@@ -66,7 +66,7 @@ impl AsyncSocket for TokioSocket {
     }
 
     fn poll_send_to(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &[u8],
         addr: &SocketAddr,
@@ -82,7 +82,7 @@ impl AsyncSocket for TokioSocket {
     }
 
     fn poll_recv<B>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &mut B,
     ) -> Poll<io::Result<()>>
@@ -104,7 +104,7 @@ impl AsyncSocket for TokioSocket {
     }
 
     fn poll_recv_from<B>(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
         buf: &mut B,
     ) -> Poll<io::Result<SocketAddr>>
@@ -130,7 +130,7 @@ impl AsyncSocket for TokioSocket {
     }
 
     fn poll_recv_from_full(
-        &mut self,
+        &self,
         cx: &mut Context<'_>,
     ) -> Poll<io::Result<(Vec<u8>, SocketAddr)>> {
         loop {