feat(runtime-c-api) Add an API to update vm::Ctx.data.

This patch adds 2 functions for the runtime C API, respectively
`wasmer_instance_context_data_set` and
`wasmer_instance_context_data_get`. The goal is to modify the
`vm::Ctx.data` field in the `runtime-core` library.

This is required to pass dynamic data to imported functions for
instance.

lib/runtime-c-api/src/lib.rs

@@ -947,6 +947,17 @@ pub unsafe extern "C" fn wasmer_instance_exports(
     *exports = Box::into_raw(named_exports) as *mut wasmer_exports_t;
 }
 
+/// Sets the `data` field of the instance context. This context will be
+/// passed to all imported function for instance.
+#[no_mangle]
+pub extern "C" fn wasmer_instance_context_data_set(
+    instance: *mut wasmer_instance_t,
+    data_ptr: *mut c_void,
+) {
+    let instance_ref = unsafe { &mut *(instance as *mut Instance) };
+    instance_ref.context_mut().data = data_ptr;
+}
+
 pub struct NamedExports(Vec<NamedExport>);
 
 /// Frees the memory for the given exports
@@ -1350,6 +1361,15 @@ pub extern "C" fn wasmer_instance_context_memory(
     memory as *const Memory as *const wasmer_memory_t
 }
 
+/// Gets the `data` field within the context.
+#[no_mangle]
+pub extern "C" fn wasmer_instance_context_data_get(
+    ctx: *const wasmer_instance_context_t,
+) -> *mut c_void {
+    let ctx = unsafe { &*(ctx as *const Ctx) };
+    ctx.data
+}
+
 /// Gets the start pointer to the bytes within a Memory
 #[allow(clippy::cast_ptr_alignment)]
 #[no_mangle]

lib/runtime-c-api/wasmer.h

@@ -95,11 +95,11 @@ typedef struct {
 
 typedef struct {
 
-} wasmer_memory_t;
+} wasmer_instance_context_t;
 
 typedef struct {
 
-} wasmer_instance_context_t;
+} wasmer_memory_t;
 
 typedef struct {
 
@@ -382,6 +382,17 @@ wasmer_result_t wasmer_instance_call(wasmer_instance_t *instance,
                                      wasmer_value_t *results,
                                      int results_len);
 
+/**
+ * Gets the `data` field within the context.
+ */
+void *wasmer_instance_context_data_get(const wasmer_instance_context_t *ctx);
+
+/**
+ * Sets the `data` field of the instance context. This context will be
+ * passed to all imported function for instance.
+ */
+void wasmer_instance_context_data_set(wasmer_instance_t *instance, void *data_ptr);
+
 /**
  * Gets the memory within the context at the index `memory_idx`.
  * The index is always 0 until multiple memories are supported.

lib/runtime-c-api/wasmer.hh

@@ -90,11 +90,11 @@ struct wasmer_instance_t {
 
 };
 
-struct wasmer_memory_t {
+struct wasmer_instance_context_t {
 
 };
 
-struct wasmer_instance_context_t {
+struct wasmer_memory_t {
 
 };
 
@@ -307,6 +307,13 @@ wasmer_result_t wasmer_instance_call(wasmer_instance_t *instance,
                                      wasmer_value_t *results,
                                      int results_len);
 
+/// Gets the `data` field within the context.
+void *wasmer_instance_context_data_get(const wasmer_instance_context_t *ctx);
+
+/// Sets the `data` field of the instance context. This context will be
+/// passed to all imported function for instance.
+void wasmer_instance_context_data_set(wasmer_instance_t *instance, void *data_ptr);
+
 /// Gets the memory within the context at the index `memory_idx`.
 /// The index is always 0 until multiple memories are supported.
 const wasmer_memory_t *wasmer_instance_context_memory(const wasmer_instance_context_t *ctx,