Merge #616

616: runtime-c-api: create the import object separately from instance instantiation  r=bjfish a=YaronWittenstein

Creating an `import object` separately from the `wasmer` instance, let's us build the import object incrementally and support the use-case of having import functions (a.k.a `vmcalls`) implemented in 2 programming languages (Rust and Golang for example) and consumed by the same `wasmer` instance.

Co-authored-by: Yaron Wittenstein <[email protected]>
Co-authored-by: Brandon Fish <[email protected]>

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

@@ -10,9 +10,10 @@ use crate::{
 };
 use libc::c_uint;
 use std::{ffi::c_void, ptr, slice, sync::Arc};
-use wasmer_runtime::Module;
+use wasmer_runtime::{Global, Memory, Module, Table};
 use wasmer_runtime_core::{
     export::{Context, Export, FuncPointer},
+    import::ImportObject,
     module::ImportName,
     types::{FuncSig, Type},
 };
@@ -25,6 +26,9 @@ pub struct wasmer_import_t {
     pub value: wasmer_import_export_value,
 }
 
+#[repr(C)]
+pub struct wasmer_import_object_t;
+
 #[repr(C)]
 #[derive(Clone)]
 pub struct wasmer_import_func_t;
@@ -37,6 +41,83 @@ pub struct wasmer_import_descriptor_t;
 #[derive(Clone)]
 pub struct wasmer_import_descriptors_t;
 
+/// Creates a new empty import object.
+/// See also `wasmer_import_object_append`
+#[allow(clippy::cast_ptr_alignment)]
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_import_object_new() -> *mut wasmer_import_object_t {
+    let import_object = Box::new(ImportObject::new());
+
+    Box::into_raw(import_object) as *mut wasmer_import_object_t
+}
+
+/// Extends an existing import object with new imports
+#[allow(clippy::cast_ptr_alignment)]
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_import_object_extend(
+    import_object: *mut wasmer_import_object_t,
+    imports: *mut wasmer_import_t,
+    imports_len: c_uint,
+) -> wasmer_result_t {
+    let import_object: &mut ImportObject = &mut *(import_object as *mut ImportObject);
+
+    let mut extensions: Vec<(String, String, Export)> = Vec::new();
+
+    let imports: &[wasmer_import_t] = slice::from_raw_parts(imports, imports_len as usize);
+    for import in imports {
+        let module_name = slice::from_raw_parts(
+            import.module_name.bytes,
+            import.module_name.bytes_len as usize,
+        );
+        let module_name = if let Ok(s) = std::str::from_utf8(module_name) {
+            s
+        } else {
+            update_last_error(CApiError {
+                msg: "error converting module name to string".to_string(),
+            });
+            return wasmer_result_t::WASMER_ERROR;
+        };
+        let import_name = slice::from_raw_parts(
+            import.import_name.bytes,
+            import.import_name.bytes_len as usize,
+        );
+        let import_name = if let Ok(s) = std::str::from_utf8(import_name) {
+            s
+        } else {
+            update_last_error(CApiError {
+                msg: "error converting import_name to string".to_string(),
+            });
+            return wasmer_result_t::WASMER_ERROR;
+        };
+
+        let export = match import.tag {
+            wasmer_import_export_kind::WASM_MEMORY => {
+                let mem = import.value.memory as *mut Memory;
+                Export::Memory((&*mem).clone())
+            }
+            wasmer_import_export_kind::WASM_FUNCTION => {
+                let func_export = import.value.func as *mut Export;
+                (&*func_export).clone()
+            }
+            wasmer_import_export_kind::WASM_GLOBAL => {
+                let global = import.value.global as *mut Global;
+                Export::Global((&*global).clone())
+            }
+            wasmer_import_export_kind::WASM_TABLE => {
+                let table = import.value.table as *mut Table;
+                Export::Table((&*table).clone())
+            }
+        };
+
+        let extension = (module_name.to_string(), import_name.to_string(), export);
+        extensions.push(extension)
+    }
+
+    import_object.extend(extensions);
+
+    return wasmer_result_t::WASMER_OK;
+}
+
 /// Gets import descriptors for the given module
 ///
 /// The caller owns the object and should call `wasmer_import_descriptors_destroy` to free it.
@@ -352,6 +433,14 @@ pub extern "C" fn wasmer_import_func_destroy(func: *mut wasmer_import_func_t) {
     }
 }
 
+/// Frees memory of the given ImportObject
+#[no_mangle]
+pub extern "C" fn wasmer_import_object_destroy(import_object: *mut wasmer_import_object_t) {
+    if !import_object.is_null() {
+        unsafe { Box::from_raw(import_object as *mut ImportObject) };
+    }
+}
+
 struct NamedImportDescriptor {
     module: String,
     name: String,

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

@@ -3,15 +3,19 @@
 use crate::{
     error::{update_last_error, CApiError},
     export::{wasmer_exports_t, wasmer_import_export_kind, NamedExport, NamedExports},
-    import::wasmer_import_t,
+    import::{wasmer_import_object_t, wasmer_import_t},
     memory::wasmer_memory_t,
+    module::wasmer_module_t,
     value::{wasmer_value, wasmer_value_t, wasmer_value_tag},
     wasmer_result_t,
 };
 use libc::{c_char, c_int, c_void};
 use std::{collections::HashMap, ffi::CStr, slice};
-use wasmer_runtime::{Ctx, Global, ImportObject, Instance, Memory, Table, Value};
-use wasmer_runtime_core::{export::Export, import::Namespace};
+use wasmer_runtime::{Ctx, Global, Instance, Memory, Module, Table, Value};
+use wasmer_runtime_core::{
+    export::Export,
+    import::{ImportObject, Namespace},
+};
 
 #[repr(C)]
 pub struct wasmer_instance_t;
@@ -108,6 +112,32 @@ pub unsafe extern "C" fn wasmer_instantiate(
     wasmer_result_t::WASMER_OK
 }
 
+/// Given:
+/// * A prepared `wasmer` import-object
+/// * A compiled wasmer module
+///
+/// Instantiates a wasmer instance
+#[no_mangle]
+pub unsafe extern "C" fn wasmer_module_import_instantiate(
+    instance: *mut *mut wasmer_instance_t,
+    module: *const wasmer_module_t,
+    import_object: *const wasmer_import_object_t,
+) -> wasmer_result_t {
+    let import_object: &ImportObject = &*(import_object as *const ImportObject);
+    let module: &Module = &*(module as *const Module);
+
+    let new_instance: Instance = match module.instantiate(import_object) {
+        Ok(instance) => instance,
+        Err(error) => {
+            update_last_error(error);
+            return wasmer_result_t::WASMER_ERROR;
+        }
+    };
+    *instance = Box::into_raw(Box::new(new_instance)) as *mut wasmer_instance_t;
+
+    return wasmer_result_t::WASMER_OK;
+}
+
 /// Extracts the instance's context and returns it.
 #[allow(clippy::cast_ptr_alignment)]
 #[no_mangle]

lib/runtime-c-api/tests/.gitignore

@@ -24,3 +24,4 @@ test-module-serialize
 test-tables
 test-validate
 test-context
+test-module-import-instantiate

lib/runtime-c-api/tests/CMakeLists.txt

@@ -15,6 +15,7 @@ add_executable(test-module-serialize test-module-serialize.c)
 add_executable(test-tables test-tables.c)
 add_executable(test-validate test-validate.c)
 add_executable(test-context test-context.c)
+add_executable(test-module-import-instantiate test-module-import-instantiate.c)
 
 find_library(
         WASMER_LIB NAMES libwasmer_runtime_c_api.dylib libwasmer_runtime_c_api.so libwasmer_runtime_c_api.dll
@@ -92,3 +93,7 @@ add_test(test-validate test-validate)
 target_link_libraries(test-context general ${WASMER_LIB})
 target_compile_options(test-context PRIVATE ${COMPILER_OPTIONS})
 add_test(test-context test-context)
+
+target_link_libraries(test-module-import-instantiate general ${WASMER_LIB})
+target_compile_options(test-module-import-instantiate PRIVATE ${COMPILER_OPTIONS})
+add_test(test-module-import-instantiate test-module-import-instantiate)

lib/runtime-c-api/tests/assets/inc.wast

@@ -1,7 +1,12 @@
 (module
   (func $inc (import "env" "inc"))
+  (func $mul (import "env" "mul"))
   (func $get (import "env" "get") (result i32))
 
   (func (export "inc_and_get") (result i32)
       call $inc
+      call $get)
+
+  (func (export "mul_and_get") (result i32)
+      call $mul
       call $get))

lib/runtime-c-api/tests/test-context.c

@@ -34,6 +34,11 @@ void inc_counter(wasmer_instance_context_t *ctx) {
     data->value = data->value + data->amount;
 }
 
+void mul_counter(wasmer_instance_context_t *ctx) {
+    counter_data* data = (counter_data*)wasmer_instance_context_data_get(ctx);
+    data->value = data->value * data->amount;
+}
+
 int32_t get_counter(wasmer_instance_context_t *ctx) {
     counter_data* data = (counter_data*)wasmer_instance_context_data_get(ctx);
     return data->value;
@@ -90,21 +95,27 @@ int main()
     wasmer_import_func_t *inc_func = wasmer_import_func_new((void (*)(void *)) inc_counter, inc_params_sig, 0, inc_returns_sig, 0);
     wasmer_import_t inc_import = create_import("env", "inc", inc_func);
 
+    wasmer_value_tag mul_params_sig[] = {};
+    wasmer_value_tag mul_returns_sig[] = {};
+    wasmer_import_func_t *mul_func = wasmer_import_func_new((void (*)(void *)) mul_counter, mul_params_sig, 0, mul_returns_sig, 0);
+    wasmer_import_t mul_import = create_import("env", "mul", mul_func);
+
     wasmer_value_tag get_params_sig[] = {};
     wasmer_value_tag get_returns_sig[] = {WASM_I32};
     wasmer_import_func_t *get_func = wasmer_import_func_new((void (*)(void *)) get_counter, get_params_sig, 0, get_returns_sig, 1);
     wasmer_import_t get_import = create_import("env", "get", get_func);
 
-    wasmer_import_t imports[] = {inc_import, get_import};
+    wasmer_import_t imports[] = {inc_import, mul_import, get_import};
 
     // Read the wasm file
     wasm_file_t wasm_file = read_wasm_file("assets/inc.wasm");
 
     // Instantiate instance
     printf("Instantiating\n");
     wasmer_instance_t *instance = NULL;
-    wasmer_result_t compile_result = wasmer_instantiate(&instance, wasm_file.bytes, wasm_file.bytes_len, imports, 2);
-    printf("Compile result:  %d\n", compile_result);
+    wasmer_result_t instantiate_res = wasmer_instantiate(&instance, wasm_file.bytes, wasm_file.bytes_len, imports, 3);
+    printf("Compile result:  %d\n", instantiate_res);
+    assert(instantiate_res == WASMER_OK);
 
     // Init counter
     counter_data *counter = init_counter(2, 5);