feat(plugin): add API version compatibility check for native plugins (#1237)

Author: Sclock

pumpkin-api-macros/src/lib.rs

@@ -80,6 +80,9 @@ pub fn plugin_impl(_attr: TokenStream, item: TokenStream) -> TokenStream {
             description: env!("CARGO_PKG_DESCRIPTION"),
         };
 
+        #[unsafe(no_mangle)]
+        pub static PUMPKIN_API_VERSION: u32 = pumpkin::plugin::PLUGIN_API_VERSION;
+
         #input_struct
 
         impl pumpkin::plugin::Plugin for #struct_ident {

pumpkin/src/plugin/loader/mod.rs

@@ -56,4 +56,17 @@ pub enum LoaderError {
 
     #[error("Invalid loader data")]
     InvalidLoaderData,
+
+    #[error(
+        "Plugin was built for an incompatible API version. Please rebuild it against this Pumpkin build."
+    )]
+    ApiVersionMissing,
+
+    #[error(
+        "Plugin API version mismatch (plugin {plugin_version}, server {server_version}). Please rebuild it against this Pumpkin build."
+    )]
+    ApiVersionMismatch {
+        plugin_version: u32,
+        server_version: u32,
+    },
 }

pumpkin/src/plugin/loader/native.rs

@@ -2,7 +2,10 @@ use std::any::Any;
 
 use libloading::Library;
 
-use crate::plugin::loader::{PluginLoadFuture, PluginUnloadFuture};
+use crate::plugin::{
+    PLUGIN_API_VERSION,
+    loader::{PluginLoadFuture, PluginUnloadFuture},
+};
 
 use super::{LoaderError, Path, Plugin, PluginLoader, PluginMetadata};
 
@@ -16,6 +19,21 @@ impl PluginLoader for NativePluginLoader {
             let library = unsafe { Library::new(&path) }
                 .map_err(|e| LoaderError::LibraryLoad(e.to_string()))?;
 
+            // Ensure this plugin was built against a compatible Pumpkin plugin API version
+            let plugin_api_version = unsafe {
+                match library.get::<*const u32>(b"PUMPKIN_API_VERSION") {
+                    Ok(symbol) => **symbol,
+                    Err(_) => return Err(LoaderError::ApiVersionMissing),
+                }
+            };
+
+            if plugin_api_version != PLUGIN_API_VERSION {
+                return Err(LoaderError::ApiVersionMismatch {
+                    plugin_version: plugin_api_version,
+                    server_version: PLUGIN_API_VERSION,
+                });
+            }
+
             // 2. Extract Metadata (METADATA)
             let metadata = unsafe {
                 &**library

pumpkin/src/plugin/mod.rs

@@ -18,6 +18,10 @@ pub use api::*;
 
 pub type BoxFuture<'a, T> = Pin<Box<dyn Future<Output = T> + Send + 'a>>;
 
+/// Bump this whenever the public plugin API or any event layout changes in a way
+/// that makes old binary plugins incompatible.
+pub const PLUGIN_API_VERSION: u32 = 2;
+
 /// A trait for handling events dynamically.
 ///
 /// This trait allows for handling events of any type that implements the `Event` trait.