fix(c-api) Cherry-pick manually from https://github.com/wasmerio/wasmer/pull/1657.

lib/c-api/src/wasm_c_api/externals/function.rs

@@ -60,8 +60,11 @@ pub unsafe extern "C" fn wasm_func_new(
             num_rets
         ];
 
-        let _traps = callback(processed_args.as_ptr(), results.as_mut_ptr());
-        // TODO: do something with `traps`
+        let trap = callback(processed_args.as_ptr(), results.as_mut_ptr());
+        if !trap.is_null() {
+            let trap: Box<wasm_trap_t> = Box::from_raw(trap);
+            RuntimeError::raise(Box::new(trap.inner));
+        }
 
         let processed_results = results
             .into_iter()
@@ -134,7 +137,7 @@ pub unsafe extern "C" fn wasm_func_call(
     func: &wasm_func_t,
     args: *const wasm_val_t,
     results: *mut wasm_val_t,
-) -> Option<NonNull<wasm_trap_t>> {
+) -> Option<Box<wasm_trap_t>> {
     let num_params = func.inner.ty().params().len();
     let params: Vec<Val> = (0..num_params)
         .map(|i| (&(*args.add(i))).try_into())
@@ -149,7 +152,7 @@ pub unsafe extern "C" fn wasm_func_call(
             }
             None
         }
-        Err(e) => Some(NonNull::new_unchecked(Box::into_raw(Box::new(e)) as _)),
+        Err(e) => Some(Box::new(e.into())),
     }
 }
 

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

@@ -36,6 +36,37 @@ macro_rules! wasm_declare_vec {
                 pub data: *mut [<wasm_ $name _t>],
             }
 
+            impl<'a> From<Vec<[<wasm_ $name _t>]>> for [<wasm_ $name _vec_t>] {
+                fn from(other: Vec<[<wasm_ $name _t>]>) -> Self {
+                    let mut boxed_slice = other.into_boxed_slice();
+                    let size = boxed_slice.len();
+                    let data = boxed_slice.as_mut_ptr();
+                    ::std::mem::forget(boxed_slice);
+                    Self {
+                        size,
+                        data,
+                    }
+                }
+            }
+
+            impl<'a, T: Into<[<wasm_ $name _t>]> + Clone> From<&'a [T]> for [<wasm_ $name _vec_t>] {
+                fn from(other: &'a [T]) -> Self {
+                    let size = other.len();
+                    let mut copied_data = other
+                        .iter()
+                        .cloned()
+                        .map(Into::into)
+                        .collect::<Vec<[<wasm_ $name _t>]>>()
+                        .into_boxed_slice();
+                    let data = copied_data.as_mut_ptr();
+                    ::std::mem::forget(copied_data);
+                    Self {
+                        size,
+                        data,
+                    }
+                }
+            }
+
             impl [<wasm_ $name _vec_t>] {
                 pub unsafe fn into_slice(&self) -> Option<&[[<wasm_ $name _t>]]>{
                     if self.data.is_null() {

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

@@ -1,51 +1,59 @@
-use super::types::wasm_byte_vec_t;
-use std::mem;
-use std::ptr::NonNull;
+use super::store::wasm_store_t;
+use super::types::{wasm_byte_vec_t, wasm_frame_t, wasm_frame_vec_t, wasm_message_t};
 use wasmer::RuntimeError;
 
 // opaque type which is a `RuntimeError`
 /// cbindgen:ignore
 #[allow(non_camel_case_types)]
-pub struct wasm_trap_t {}
+pub struct wasm_trap_t {
+    pub(crate) inner: RuntimeError,
+}
 
-/// cbindgen:ignore
-#[no_mangle]
-pub unsafe extern "C" fn wasm_trap_delete(trap: Option<NonNull<wasm_trap_t>>) {
-    if let Some(t_inner) = trap {
-        let _ = Box::from_raw(t_inner.cast::<RuntimeError>().as_ptr());
+impl From<RuntimeError> for wasm_trap_t {
+    fn from(other: RuntimeError) -> Self {
+        Self { inner: other }
     }
 }
 
 /// cbindgen:ignore
 #[no_mangle]
-pub unsafe extern "C" fn wasm_trap_message(
-    trap: *const wasm_trap_t,
-    out_ptr: *mut wasm_byte_vec_t,
-) {
-    let re = &*(trap as *const RuntimeError);
-    // this code assumes no nul bytes appear in the message
-    let mut message = format!("{}\0", re);
-    message.shrink_to_fit();
+pub unsafe extern "C" fn wasm_trap_new(
+    _store: &mut wasm_store_t,
+    message: &wasm_message_t,
+) -> Option<Box<wasm_trap_t>> {
+    let message_bytes: &[u8] = message.into_slice()?;
+    let message_str = c_try!(std::str::from_utf8(message_bytes));
+    let runtime_error = RuntimeError::new(message_str);
+    let trap = runtime_error.into();
 
-    // TODO use `String::into_raw_parts` when it gets stabilized
-    (*out_ptr).size = message.as_bytes().len();
-    (*out_ptr).data = message.as_mut_ptr();
-    mem::forget(message);
+    Some(Box::new(trap))
 }
 
-// in trap/RuntimeError we need to store
-// 1. message
-// 2. origin (frame); frame contains:
-//    1. func index
-//    2. func offset
-//    3. module offset
-//    4. which instance this was apart of
+/// cbindgen:ignore
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_delete(_trap: Option<Box<wasm_trap_t>>) {}
 
-/*#[no_mangle]
-pub unsafe extern "C" fn wasm_trap_trace(trap: *const wasm_trap_t, out_ptr: *mut wasm_frame_vec_t) {
-    let re = &*(trap as *const RuntimeError);
-    todo!()
-}*/
+/// cbindgen:ignore
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_message(trap: &wasm_trap_t, out_ptr: &mut wasm_byte_vec_t) {
+    let message = trap.inner.message();
+    let byte_vec: wasm_byte_vec_t = message.into_bytes().into();
+    out_ptr.size = byte_vec.size;
+    out_ptr.data = byte_vec.data;
+}
 
-//wasm_declare_ref!(trap);
-//wasm_declare_ref!(foreign);
+/// cbindgen:ignore
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_origin(trap: &wasm_trap_t) -> Option<Box<wasm_frame_t>> {
+    trap.inner.trace().first().map(Into::into).map(Box::new)
+}
+
+/// cbindgen:ignore
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_trace(trap: &wasm_trap_t, out_ptr: &mut wasm_frame_vec_t) {
+    let frames = trap.inner.trace();
+    let frame_vec: wasm_frame_vec_t = frames.into();
+
+    out_ptr.size = frame_vec.size;
+    out_ptr.data = frame_vec.data;
+}

lib/c-api/src/wasm_c_api/types/frame.rs

@@ -0,0 +1,51 @@
+use super::super::instance::wasm_instance_t;
+use wasmer::FrameInfo;
+
+#[derive(Debug, Clone)]
+#[repr(C)]
+pub struct wasm_frame_t {
+    info: FrameInfo,
+}
+
+impl<'a> From<&'a FrameInfo> for wasm_frame_t {
+    fn from(other: &'a FrameInfo) -> Self {
+        other.clone().into()
+    }
+}
+
+impl From<FrameInfo> for wasm_frame_t {
+    fn from(other: FrameInfo) -> Self {
+        Self { info: other }
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_copy(frame: &wasm_frame_t) -> Box<wasm_frame_t> {
+    Box::new(frame.clone())
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_delete(_frame: Option<Box<wasm_frame_t>>) {}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_instance(frame: &wasm_frame_t) -> *const wasm_instance_t {
+    //todo!("wasm_frame_instance")
+    std::ptr::null()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_func_index(frame: &wasm_frame_t) -> u32 {
+    frame.info.func_index()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_func_offset(frame: &wasm_frame_t) -> usize {
+    frame.info.func_offset()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_module_offset(frame: &wasm_frame_t) -> usize {
+    frame.info.module_offset()
+}
+
+wasm_declare_vec!(frame);

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

@@ -1,5 +1,6 @@
 mod export;
 mod extern_;
+mod frame;
 mod function;
 mod global;
 mod import;
@@ -10,6 +11,7 @@ mod value;
 
 pub use export::*;
 pub use extern_::*;
+pub use frame::*;
 pub use function::*;
 pub use global::*;
 pub use import::*;
@@ -23,12 +25,6 @@ pub type wasm_byte_t = u8;
 
 wasm_declare_vec!(byte);
 
-#[derive(Debug)]
-#[repr(C)]
-pub struct wasm_frame_t {}
-
-wasm_declare_vec!(frame);
-
 /// cbindgen:ignore
 #[allow(non_camel_case_types)]
 pub type wasm_name_t = wasm_byte_vec_t;
@@ -37,3 +33,7 @@ pub type wasm_name_t = wasm_byte_vec_t;
 /// cbindgen:ignore
 #[allow(non_camel_case_types)]
 pub struct wasm_ref_t;
+
+/// cbindgen:ignore
+#[allow(non_camel_case_types)]
+pub type wasm_message_t = wasm_byte_vec_t;