fix(c-api) Move the middleware API into the unstable module.

lib/c-api/src/wasm_c_api/unstable/middlewares/metering.rs

@@ -0,0 +1,73 @@
+// C API for metering.
+
+use super::super::super::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: &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: &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/unstable/middlewares/mod.rs

@@ -0,0 +1 @@
+pub mod metering;

lib/c-api/src/wasm_c_api/unstable/mod.rs

@@ -1,3 +1,5 @@
 pub mod engine;
+#[cfg(feature = "middlewares")]
+pub mod middlewares;
 pub mod module;
 pub mod target_lexicon;