Support checking the execution limit exceeded error.

lib/middleware-common/src/metering.rs

@@ -34,6 +34,9 @@ impl Metering {
     }
 }
 
+#[derive(Copy, Clone, Debug)]
+pub struct ExecutionLimitExceededError;
+
 impl FunctionMiddleware for Metering {
     type Error = String;
     fn feed_event<'a, 'b: 'a>(
@@ -93,9 +96,8 @@ impl FunctionMiddleware for Metering {
                         }));
                         sink.push(Event::Internal(InternalEvent::Breakpoint(Box::new(
                             move |ctx| {
-                                eprintln!("execution limit reached");
                                 unsafe {
-                                    (ctx.throw)();
+                                    (ctx.throw)(Box::new(ExecutionLimitExceededError));
                                 }
                             },
                         ))));
@@ -251,6 +253,7 @@ mod tests {
 
     #[test]
     fn test_traps_after_costly_call() {
+        use wasmer_runtime_core::error::RuntimeError;
         let wasm_binary = wat2wasm(WAT).unwrap();
 
         let limit = 100u64;
@@ -265,8 +268,13 @@ mod tests {
         let add_to: Func<(i32, i32), i32> = instance.func("add_to").unwrap();
         let result = add_to.call(10_000_000, 4);
 
-        // verify it errors
+        let err = result.unwrap_err();
-        assert_eq!(result.is_err(), true); // TODO assert that the trap is caused by PointsExausted
+        match err {
+            RuntimeError::Error { data } => {
+                assert!(data.downcast_ref::<ExecutionLimitExceededError>().is_some());
+            },
+            _ => unreachable!(),
+        }
 
         // verify is uses the correct number of points
         assert_eq!(get_points_used(&instance), 109); // Used points will be slightly more than `limit` because of the way we do gas checking.

lib/runtime-core/src/codegen.rs

@@ -8,6 +8,7 @@ use crate::{
     types::{FuncIndex, FuncSig, SigIndex},
 };
 use smallvec::SmallVec;
+use std::any::Any;
 use std::fmt;
 use std::fmt::Debug;
 use std::marker::PhantomData;
@@ -43,7 +44,7 @@ impl fmt::Debug for InternalEvent {
 }
 
 pub struct BkptInfo {
-    pub throw: unsafe extern "C" fn() -> !,
+    pub throw: unsafe fn(Box<dyn Any>) -> !,
 }
 
 pub trait ModuleCodeGenerator<FCG: FunctionCodeGenerator<E>, RM: RunnableModule, E: Debug> {

lib/singlepass-backend/src/protect_unix.rs

@@ -128,11 +128,12 @@ pub fn call_protected<T>(f: impl FnOnce() -> T) -> Result<T, CallProtError> {
     }
 }
 
-pub unsafe extern "C" fn throw() -> ! {
+pub unsafe fn throw(payload: Box<dyn Any>) -> ! {
     let jmp_buf = SETJMP_BUFFER.with(|buf| buf.get());
     if *jmp_buf == [0; SETJMP_BUFFER_LEN] {
         ::std::process::abort();
     }
+    TRAP_EARLY_DATA.with(|cell| cell.replace(Some(payload)));
     longjmp(jmp_buf as *mut ::nix::libc::c_void, 0xffff);
 }
 

src/bin/wasmer.rs

@@ -33,6 +33,7 @@ use wasmer_runtime_core::{
 use wasmer_singlepass_backend::ModuleCodeGenerator as SinglePassMCG;
 #[cfg(feature = "wasi")]
 use wasmer_wasi;
+use wasmer_middleware_common::metering::Metering;
 
 // stub module to make conditional compilation happy
 #[cfg(not(feature = "wasi"))]