Fix reusable connection message

Author: plule

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
 ### Fixed
 
 - Documentation example fixes
+- Fix the polled message being unsafely clonable
 
 ## [0.2.0] - 2024-03-25
 

src/connection.rs

@@ -1,4 +1,4 @@
-use std::{ffi::CString, mem};
+use std::{ffi::CString, marker::PhantomData, mem};
 
 use ::leap_sys::*;
 
@@ -9,10 +9,6 @@ use crate::*;
 #[doc = " @since 3.0.0"]
 pub struct Connection {
     handle: LEAP_CONNECTION,
-    // Each call to call() invalidates the connection message pointer,
-    // and it is distroy on the connection drop.
-    // Only distribute non mutable references of this one.
-    connection_message: Option<ConnectionMessage>,
 }
 
 impl Drop for Connection {
@@ -45,7 +41,6 @@ impl Connection {
 
         Ok(Self {
             handle: leap_connection,
-            connection_message: None,
         })
     }
 
@@ -97,17 +92,13 @@ impl Connection {
     #[doc = " times out, this method will return eLeapRS_Timeout. The evt pointer will reference a"]
     #[doc = " message of type eLeapEventType_None."]
     #[doc = " @since 3.0.0"]
-    pub fn poll(&mut self, timeout: u32) -> Result<&ConnectionMessage, Error> {
-        // The code after will invalidate it.
-        self.connection_message = None;
+    pub fn poll(&mut self, timeout: u32) -> Result<ConnectionMessage, Error> {
         let mut msg: LEAP_CONNECTION_MESSAGE;
         unsafe {
             msg = mem::zeroed();
             leap_try(LeapPollConnection(self.handle, timeout, &mut msg))?;
         }
-        self.connection_message = Some(ConnectionMessage(msg));
-
-        Ok(self.connection_message.as_ref().unwrap())
+        Ok(ConnectionMessage(msg, PhantomData))
     }
 
     #[doc = " Retrieves a list of Ultraleap Tracking camera devices currently attached to the system."]

src/connection_message.rs

@@ -1,3 +1,5 @@
+use std::marker::PhantomData;
+
 use derive_deref::Deref;
 use leap_sys::LEAP_CONNECTION_MESSAGE;
 
@@ -7,9 +9,13 @@ use crate::event::EventRef;
 #[doc = " Set by calling LeapPollConnection()."]
 #[doc = " @since 3.0.0"]
 #[derive(Deref, Clone, Copy)]
-pub struct ConnectionMessage(pub(crate) LEAP_CONNECTION_MESSAGE);
+pub struct ConnectionMessage<'a>(
+    pub(crate) LEAP_CONNECTION_MESSAGE,
+    /// Holds a lifetime to invalidate previous messages
+    pub(crate) PhantomData<&'a ()>,
+);
 
-impl ConnectionMessage {
+impl ConnectionMessage<'_> {
     #[doc = " A pointer to the event data for the current type of message. @since 3.0.0"]
     pub fn event(&self) -> EventRef {
         (self.type_, &self.__bindgen_anon_1).into()