Vendor in a purple-sys wrapper

This code comes from https://github.com/Flared/purple-icq/tree/master/src/purple

It is GPL-3 licensed

src/purple/connection/connections.rs

@@ -0,0 +1,45 @@
+use super::protocol_data::ProtocolData;
+use crate::purple::ffi::AsMutPtr;
+use crate::purple::Connection;
+use std::os::raw::c_void;
+
+pub struct Connections<T> {
+    protocol_datas: std::collections::HashSet<*mut ProtocolData<T>>,
+}
+
+impl<T> Connections<T> {
+    pub fn new() -> Self {
+        Self {
+            protocol_datas: Default::default(),
+        }
+    }
+
+    pub unsafe fn add(&mut self, connection: Connection, data: T) {
+        let account = connection.get_account();
+        let data_ptr = Box::new(ProtocolData::<T> {
+            account,
+            connection,
+            data,
+        });
+        let data_raw_ptr = Box::into_raw(data_ptr);
+        connection.set_protocol_data(data_raw_ptr as *mut c_void);
+        self.protocol_datas.insert(data_raw_ptr);
+    }
+
+    pub fn remove(&mut self, connection: Connection) {
+        let protocol_data_ptr = connection.get_protocol_data() as *mut ProtocolData<T>;
+        self.protocol_datas.remove(&protocol_data_ptr);
+        // Retake ownership of the protocol data to drop its data.
+        unsafe { Box::from_raw(protocol_data_ptr) };
+    }
+
+    pub fn get<'b, P>(&mut self, mut ptr: P) -> Option<&'b mut ProtocolData<T>>
+    where
+        P: AsMutPtr<PtrType = ProtocolData<T>>,
+    {
+        self.protocol_datas
+            .get(&ptr.as_mut_ptr())
+            .cloned()
+            .map(|p| unsafe { &mut *p })
+    }
+}