feat(c-api) Introduce the middleware (specifically metering) C API

Makefile

@@ -170,55 +170,55 @@ build-capi: build-capi-cranelift
 
 build-capi-singlepass:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,native,object-file,singlepass,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,native,object-file,singlepass,wasi,middlewares $(capi_default_features)
 
 build-capi-singlepass-jit:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,singlepass,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,singlepass,wasi,middlewares $(capi_default_features)
 
 build-capi-singlepass-native:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,native,singlepass,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,native,singlepass,wasi,middlewares $(capi_default_features)
 
 build-capi-singlepass-object-file:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,object-file,singlepass,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,object-file,singlepass,wasi,middlewares $(capi_default_features)
 
 build-capi-cranelift:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,native,object-file,cranelift,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,native,object-file,cranelift,wasi,middlewares $(capi_default_features)
 
 build-capi-cranelift-system-libffi:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,native,object-file,cranelift,wasi,system-libffi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,native,object-file,cranelift,wasi,middlewares,system-libffi $(capi_default_features)
 
 build-capi-cranelift-jit:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,cranelift,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,cranelift,wasi,middlewares $(capi_default_features)
 
 build-capi-cranelift-native:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,native,cranelift,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,native,cranelift,wasi,middlewares $(capi_default_features)
 
 build-capi-cranelift-object-file:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,native,object-file,cranelift,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,native,object-file,cranelift,wasi,middlewares $(capi_default_features)
 
 build-capi-llvm:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,native,object-file,llvm,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,native,object-file,llvm,wasi,middlewares $(capi_default_features)
 
 build-capi-llvm-jit:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,jit,llvm,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,jit,llvm,wasi,middlewares $(capi_default_features)
 
 build-capi-llvm-native:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,native,llvm,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,native,llvm,wasi,middlewares $(capi_default_features)
 
 build-capi-llvm-object-file:
 	cargo build --manifest-path lib/c-api/Cargo.toml --release \
-		--no-default-features --features deprecated,wat,object-file,llvm,wasi $(capi_default_features)
+		--no-default-features --features deprecated,wat,object-file,llvm,wasi,middlewares $(capi_default_features)
 
 # Headless (we include the minimal to be able to run)
 

lib/c-api/Cargo.toml

@@ -25,6 +25,7 @@ wasmer-engine = { version = "1.0.2", path = "../engine" }
 wasmer-engine-jit = { version = "1.0.2", path = "../engine-jit", optional = true }
 wasmer-engine-native = { version = "1.0.2", path = "../engine-native", optional = true }
 wasmer-engine-object-file = { version = "1.0.2", path = "../engine-object-file", optional = true }
+wasmer-middlewares = { version = "1.0.2", path = "../middlewares", optional = true }
 wasmer-wasi = { version = "1.0.2", path = "../wasi", optional = true }
 wasmer-types = { version = "1.0.2", path = "../wasmer-types" }
 enumset = "1.0"
@@ -50,10 +51,12 @@ default = [
     "cranelift",
     "jit",
     "wasi",
+    "middlewares",
 ]
 wat = ["wasmer/wat"]
 wasi = ["wasmer-wasi", "typetag", "serde"]
 engine = []
+middlewares = ["wasmer-middlewares"]
 deprecated = ["libffi"]
 jit = [
     "wasmer-engine-jit",

lib/c-api/build.rs

@@ -470,6 +470,7 @@ fn exclude_items_from_wasm_c_api(builder: Builder) -> Builder {
         .exclude_item("wasm_config_set_compiler")
         .exclude_item("wasm_config_set_engine")
         .exclude_item("wasm_config_set_target")
+        .exclude_item("wasm_config_push_middleware")
         .exclude_item("wasm_cpu_features_add")
         .exclude_item("wasm_cpu_features_delete")
         .exclude_item("wasm_cpu_features_new")
@@ -494,6 +495,8 @@ fn exclude_items_from_wasm_c_api(builder: Builder) -> Builder {
         .exclude_item("wasm_triple_t")
         .exclude_item("wasmer_compiler_t")
         .exclude_item("wasmer_engine_t")
+        .exclude_item("wasmer_metering_get_remaining_points")
+        .exclude_item("wasmer_metering_set_remaining_points")
         .exclude_item("wat2wasm")
 }
 

lib/c-api/src/lib.rs

@@ -41,5 +41,7 @@
 #[cfg(feature = "deprecated")]
 pub mod deprecated;
 pub mod error;
+#[cfg(feature = "middlewares")]
+pub mod metering;
 mod ordered_resolver;
 pub mod wasm_c_api;

lib/c-api/src/metering.rs

@@ -0,0 +1,73 @@
+// C API for metering.
+
+use super::wasm_c_api::instance::wasm_instance_t;
+use std::sync::Arc;
+use wasmer::wasmparser::Operator;
+use wasmer_middlewares::{
+    metering::{get_remaining_points, set_remaining_points, MeteringPoints},
+    Metering,
+};
+
+/// Opaque type representing a MeteringPoints.
+#[allow(non_camel_case_types)]
+pub struct wasmer_metering_points_t {
+    pub(crate) inner: MeteringPoints,
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_metering_points_value(
+    metering_points: &Box<wasmer_metering_points_t>,
+    exhausted: u64,
+) -> u64 {
+    match metering_points.inner {
+        MeteringPoints::Remaining(value) => value,
+        MeteringPoints::Exhausted => exhausted,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_metering_points_is_exhausted(
+    metering_points: &Box<wasmer_metering_points_t>,
+) -> bool {
+    matches!(metering_points.inner, MeteringPoints::Exhausted)
+}
+
+/// Opaque type representing a MeteringPoints.
+#[allow(non_camel_case_types)]
+pub struct wasmer_metering_t {
+    #[allow(dead_code)]
+    pub(crate) inner: Arc<Metering<fn(&Operator) -> u64>>,
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_metering_new(initial_limit: u64) -> Box<wasmer_metering_t> {
+    let cost_function = |operator: &Operator| -> u64 {
+        match operator {
+            Operator::I32Const { .. }
+            | Operator::I64Const { .. }
+            | Operator::F32Const { .. }
+            | Operator::F64Const { .. } => 0,
+            _ => 1,
+        }
+    };
+    Box::new(wasmer_metering_t {
+        inner: Arc::new(Metering::new(initial_limit, cost_function)),
+    })
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_metering_get_remaining_points(
+    instance: &wasm_instance_t,
+) -> Box<wasmer_metering_points_t> {
+    Box::new(wasmer_metering_points_t {
+        inner: get_remaining_points(&instance.inner),
+    })
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_metering_set_remaining_points(
+    instance: &wasm_instance_t,
+    new_limit: u64,
+) {
+    set_remaining_points(&instance.inner, new_limit);
+}

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

@@ -4,13 +4,19 @@ 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")]
 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! {

lib/c-api/wasmer.h

@@ -166,6 +166,13 @@ enum wasmer_value_tag
 typedef uint32_t wasmer_value_tag;
 #endif // __cplusplus
 
+typedef struct Box_wasmer_metering_points_t Box_wasmer_metering_points_t;
+
+/**
+ * Opaque type representing a MeteringPoints.
+ */
+typedef struct wasmer_metering_t wasmer_metering_t;
+
 typedef struct {
 
 } wasmer_module_t;
@@ -1296,6 +1303,13 @@ uint32_t wasmer_memory_length(const wasmer_memory_t *memory);
  */
 wasmer_result_t wasmer_memory_new(wasmer_memory_t **memory, wasmer_limits_t limits);
 
+wasmer_metering_t *wasmer_metering_new(uint64_t initial_limit);
+
+bool wasmer_metering_points_is_exhausted(const Box_wasmer_metering_points_t *metering_points);
+
+uint64_t wasmer_metering_points_value(const Box_wasmer_metering_points_t *metering_points,
+                                      uint64_t exhausted);
+
 /**
  * Deserialize the given serialized module.
  *

lib/c-api/wasmer.hh

@@ -112,6 +112,15 @@ enum class wasmer_value_tag : uint32_t {
   WASM_F64,
 };
 
+template<typename T = void>
+struct Box;
+
+/// Opaque type representing a MeteringPoints.
+struct wasmer_metering_points_t;
+
+/// Opaque type representing a MeteringPoints.
+struct wasmer_metering_t;
+
 struct wasmer_module_t {
 
 };
@@ -1060,6 +1069,13 @@ uint32_t wasmer_memory_length(const wasmer_memory_t *memory);
 /// ```
 wasmer_result_t wasmer_memory_new(wasmer_memory_t **memory, wasmer_limits_t limits);
 
+Box<wasmer_metering_t> wasmer_metering_new(uint64_t initial_limit);
+
+bool wasmer_metering_points_is_exhausted(const Box<wasmer_metering_points_t> *metering_points);
+
+uint64_t wasmer_metering_points_value(const Box<wasmer_metering_points_t> *metering_points,
+                                      uint64_t exhausted);
+
 /// Deserialize the given serialized module.
 ///
 /// Returns `wasmer_result_t::WASMER_OK` upon success.