Initial commit of C API for metering and middleware.

lib/c-api/src/wasm_c_api/engine.rs

@@ -4,6 +4,8 @@ use crate::error::{update_last_error, CApiError};
 use cfg_if::cfg_if;
 use std::sync::Arc;
 use wasmer::Engine;
+#[cfg(feature = "middlewares")]
+use wasmer_compiler::ModuleMiddleware;
 #[cfg(feature = "jit")]
 use wasmer_engine_jit::JIT;
 #[cfg(feature = "native")]
@@ -11,6 +13,10 @@ use wasmer_engine_native::Native;
 #[cfg(feature = "object-file")]
 use wasmer_engine_object_file::ObjectFile;
 
+#[cfg(feature = "middlewares")]
+#[cfg(not(feature = "compiler"))]
+compile_error!("middlewares features requires compilers feature");
+
 /// Kind of compilers that can be used by the engines.
 ///
 /// This is a Wasmer-specific type with Wasmer-specific functions for
@@ -86,6 +92,16 @@ impl Default for wasmer_engine_t {
     }
 }
 
+/// Opaque representing a middleware.
+///
+#[cfg(feature = "middlewares")]
+#[derive(Debug)]
+#[repr(C)]
+#[allow(non_camel_case_types)]
+pub struct wasmer_module_middleware_t {
+    pub(super) inner: Arc<dyn ModuleMiddleware>,
+}
+
 /// A configuration holds the compiler and the engine used by the store.
 ///
 /// cbindgen:ignore
@@ -96,6 +112,8 @@ pub struct wasm_config_t {
     #[cfg(feature = "compiler")]
     compiler: wasmer_compiler_t,
     pub(super) target: Option<Box<wasm_target_t>>,
+    #[cfg(feature = "middlewares")]
+    pub(super) middlewares: Vec<wasmer_module_middleware_t>,
 }
 
 /// Create a new default Wasmer configuration.
@@ -246,6 +264,16 @@ pub extern "C" fn wasm_config_set_engine(config: &mut wasm_config_t, engine: was
     config.engine = engine;
 }
 
+// TODO: documentation
+#[cfg(feature = "middlewares")]
+#[no_mangle]
+pub extern "C" fn wasm_config_push_middleware(
+    config: &mut wasm_config_t,
+    middleware: Box<wasmer_module_middleware_t>,
+) {
+    config.middlewares.push(*middleware);
+}
+
 /// An engine is used by the store to drive the compilation and the
 /// execution of a WebAssembly module.
 ///
@@ -311,7 +339,7 @@ cfg_if! {
         /// cbindgen:ignore
         #[no_mangle]
         pub extern "C" fn wasm_engine_new() -> Box<wasm_engine_t> {
-            let mut compiler_config: Box<dyn CompilerConfig> = get_default_compiler_config();
+            let compiler_config: Box<dyn CompilerConfig> = get_default_compiler_config();
             let engine: Arc<dyn Engine + Send + Sync> = Arc::new(Native::new(compiler_config).engine());
             Box::new(wasm_engine_t { inner: engine })
         }
@@ -448,6 +476,14 @@ pub extern "C" fn wasm_engine_new_with_config(
                 },
             };
 
+            cfg_if! {
+                if #[cfg(feature = "middlewares")] {
+                    for middleware in config.middlewares {
+                        compiler_config.push_middleware(middleware.inner);
+                    }
+                }
+            }
+
             let inner: Arc<dyn Engine + Send + Sync> = match config.engine {
                 wasmer_engine_t::JIT => {
                     cfg_if! {