Merge #381

381: Hook up error propagation r=lachlansneff a=lachlansneff

You can now retrieve the error from a panicking or error-returning imported function.

Example:

```rust
#[derive(Debug)]
struct ExitCode {
    code: i32,
}

fn do_panic(_ctx: &mut Ctx) -> Result<i32, ExitCode> {
    Err(ExitCode { code: 42 })
}

// This wasm functions calls `do_panic`.
let foo: Func<(), i32> = instance.func(...)?;

let result = foo.call();

println!("result: {:?}", result);

if let Err(RuntimeError::Error { data }) = result {
    if let Ok(exit_code) = data.downcast::<ExitCode>() {
        println!("exit code: {:?}", exit_code);
    }
}
```

outputs:

```
result: Err(unknown error)
exit code: ExitCode { code: 42 }
```

Co-authored-by: Lachlan Sneff <lachlan.sneff@gmail.com>

CHANGELOG.md

@@ -5,6 +5,7 @@ All PRs to the Wasmer repository must add to this file.
 Blocks of changes will separated by version increments.
 
 ## **[Unreleased]**
+- [#381](https://github.com/wasmerio/wasmer/pull/381) Allow retrieving propagated user errors.
 - [#379](https://github.com/wasmerio/wasmer/pull/379) Fix small return types from imported functions.
 - [#371](https://github.com/wasmerio/wasmer/pull/371) Add more Debug impl for WASI types
 - [#368](https://github.com/wasmerio/wasmer/pull/368) Fix issue with write buffering

lib/clif-backend/src/signal/mod.rs

@@ -27,6 +27,11 @@ thread_local! {
     pub static TRAP_EARLY_DATA: Cell<Option<Box<dyn Any>>> = Cell::new(None);
 }
 
+pub enum CallProtError {
+    Trap(WasmTrapInfo),
+    Error(Box<dyn Any>),
+}
+
 pub struct Caller {
     handler_data: HandlerData,
     trampolines: Arc<Trampolines>,
@@ -59,7 +64,8 @@ impl RunnableModule for Caller {
             func: NonNull<vm::Func>,
             args: *const u64,
             rets: *mut u64,
-            _trap_info: *mut WasmTrapInfo,
+            trap_info: *mut WasmTrapInfo,
+            user_error: *mut Option<Box<dyn Any>>,
             invoke_env: Option<NonNull<c_void>>,
         ) -> bool {
             let handler_data = &*invoke_env.unwrap().cast().as_ptr();
@@ -68,14 +74,22 @@ impl RunnableModule for Caller {
             let res = call_protected(handler_data, || {
                 // Leap of faith.
                 trampoline(ctx, func, args, rets);
-            })
-            .is_ok();
+            });
 
             // the trampoline is called from C on windows
             #[cfg(target_os = "windows")]
-            let res = call_protected(handler_data, trampoline, ctx, func, args, rets).is_ok();
+            let res = call_protected(handler_data, trampoline, ctx, func, args, rets);
 
-            res
+            match res {
+                Err(err) => {
+                    match err {
+                        CallProtError::Trap(info) => *trap_info = info,
+                        CallProtError::Error(data) => *user_error = Some(data),
+                    }
+                    false
+                }
+                Ok(()) => true,
+            }
         }
 
         let trampoline = self

lib/clif-backend/src/signal/unix.rs

@@ -10,7 +10,7 @@
 //! unless you have memory unsafety elsewhere in your code.
 //!
 use crate::relocation::{TrapCode, TrapData};
-use crate::signal::HandlerData;
+use crate::signal::{CallProtError, HandlerData};
 use libc::{c_int, c_void, siginfo_t};
 use nix::sys::signal::{
     sigaction, SaFlags, SigAction, SigHandler, SigSet, Signal, SIGBUS, SIGFPE, SIGILL, SIGSEGV,
@@ -18,7 +18,7 @@ use nix::sys::signal::{
 use std::cell::{Cell, UnsafeCell};
 use std::ptr;
 use std::sync::Once;
-use wasmer_runtime_core::error::{RuntimeError, RuntimeResult};
+use wasmer_runtime_core::typed_func::WasmTrapInfo;
 
 extern "C" fn signal_trap_handler(
     signum: ::nix::libc::c_int,
@@ -62,7 +62,10 @@ pub unsafe fn trigger_trap() -> ! {
     longjmp(jmp_buf as *mut c_void, 0)
 }
 
-pub fn call_protected<T>(handler_data: &HandlerData, f: impl FnOnce() -> T) -> RuntimeResult<T> {
+pub fn call_protected<T>(
+    handler_data: &HandlerData,
+    f: impl FnOnce() -> T,
+) -> Result<T, CallProtError> {
     unsafe {
         let jmp_buf = SETJMP_BUFFER.with(|buf| buf.get());
         let prev_jmp_buf = *jmp_buf;
@@ -76,7 +79,7 @@ pub fn call_protected<T>(handler_data: &HandlerData, f: impl FnOnce() -> T) -> R
             *jmp_buf = prev_jmp_buf;
 
             if let Some(data) = super::TRAP_EARLY_DATA.with(|cell| cell.replace(None)) {
-                Err(RuntimeError::Error { data })
+                Err(CallProtError::Error(data))
             } else {
                 let (faulting_addr, inst_ptr) = CAUGHT_ADDRESSES.with(|cell| cell.get());
 
@@ -85,33 +88,18 @@ pub fn call_protected<T>(handler_data: &HandlerData, f: impl FnOnce() -> T) -> R
                     srcloc: _,
                 }) = handler_data.lookup(inst_ptr)
                 {
-                    Err(match Signal::from_c_int(signum) {
+                    Err(CallProtError::Trap(match Signal::from_c_int(signum) {
                         Ok(SIGILL) => match trapcode {
-                            TrapCode::BadSignature => RuntimeError::Trap {
-                                msg: "incorrect call_indirect signature".into(),
-                            },
-                            TrapCode::IndirectCallToNull => RuntimeError::Trap {
-                                msg: "indirect call to null".into(),
-                            },
-                            TrapCode::HeapOutOfBounds => RuntimeError::Trap {
-                                msg: "memory out-of-bounds access".into(),
-                            },
-                            TrapCode::TableOutOfBounds => RuntimeError::Trap {
-                                msg: "table out-of-bounds access".into(),
-                            },
-                            _ => RuntimeError::Trap {
-                                msg: "unknown trap".into(),
-                            },
-                        },
-                        Ok(SIGSEGV) | Ok(SIGBUS) => RuntimeError::Trap {
-                            msg: "memory out-of-bounds access".into(),
-                        },
-                        Ok(SIGFPE) => RuntimeError::Trap {
-                            msg: "illegal arithmetic operation".into(),
+                            TrapCode::BadSignature => WasmTrapInfo::IncorrectCallIndirectSignature,
+                            TrapCode::IndirectCallToNull => WasmTrapInfo::CallIndirectOOB,
+                            TrapCode::HeapOutOfBounds => WasmTrapInfo::MemoryOutOfBounds,
+                            TrapCode::TableOutOfBounds => WasmTrapInfo::CallIndirectOOB,
+                            _ => WasmTrapInfo::Unknown,
                         },
+                        Ok(SIGSEGV) | Ok(SIGBUS) => WasmTrapInfo::MemoryOutOfBounds,
+                        Ok(SIGFPE) => WasmTrapInfo::IllegalArithmetic,
                         _ => unimplemented!(),
-                    }
-                    .into())
+                    }))
                 } else {
                     let signal = match Signal::from_c_int(signum) {
                         Ok(SIGFPE) => "floating-point exception",
@@ -122,10 +110,8 @@ pub fn call_protected<T>(handler_data: &HandlerData, f: impl FnOnce() -> T) -> R
                         _ => "unkown trapped signal",
                     };
                     // When the trap-handler is fully implemented, this will return more information.
-                    Err(RuntimeError::Trap {
-                        msg: format!("unknown trap at {:p} - {}", faulting_addr, signal).into(),
-                    }
-                    .into())
+                    let s = format!("unknown trap at {:p} - {}", faulting_addr, signal);
+                    Err(CallProtError::Error(Box::new(s)))
                 }
             }
         } else {

lib/clif-backend/src/signal/windows.rs

@@ -1,10 +1,11 @@
 use crate::relocation::{TrapCode, TrapData};
-use crate::signal::HandlerData;
+use crate::signal::{CallProtError, HandlerData};
 use crate::trampoline::Trampoline;
 use std::cell::Cell;
 use std::ffi::c_void;
 use std::ptr::{self, NonNull};
 use wasmer_runtime_core::error::{RuntimeError, RuntimeResult};
+use wasmer_runtime_core::typed_func::WasmTrapInfo;
 use wasmer_runtime_core::vm::Ctx;
 use wasmer_runtime_core::vm::Func;
 use wasmer_win_exception_handler::CallProtectedData;
@@ -28,7 +29,7 @@ pub fn call_protected(
     func: NonNull<Func>,
     param_vec: *const u64,
     return_vec: *mut u64,
-) -> RuntimeResult<()> {
+) -> Result<(), CallProtError> {
     // TODO: trap early
     // user code error
     //    if let Some(msg) = super::TRAP_EARLY_DATA.with(|cell| cell.replace(None)) {
@@ -52,38 +53,22 @@ pub fn call_protected(
         srcloc: _,
     }) = handler_data.lookup(instruction_pointer as _)
     {
-        Err(match signum as DWORD {
-            EXCEPTION_ACCESS_VIOLATION => RuntimeError::Trap {
-                msg: "memory out-of-bounds access".into(),
-            },
+        Err(CallProtError::Trap(match signum as DWORD {
+            EXCEPTION_ACCESS_VIOLATION => WasmTrapInfo::MemoryOutOfBounds,
             EXCEPTION_ILLEGAL_INSTRUCTION => match trapcode {
-                TrapCode::BadSignature => RuntimeError::Trap {
-                    msg: "incorrect call_indirect signature".into(),
-                },
-                TrapCode::IndirectCallToNull => RuntimeError::Trap {
-                    msg: "indirect call to null".into(),
-                },
-                TrapCode::HeapOutOfBounds => RuntimeError::Trap {
-                    msg: "memory out-of-bounds access".into(),
-                },
-                TrapCode::TableOutOfBounds => RuntimeError::Trap {
-                    msg: "table out-of-bounds access".into(),
-                },
-                _ => RuntimeError::Trap {
-                    msg: "unknown trap".into(),
-                },
-            },
-            EXCEPTION_STACK_OVERFLOW => RuntimeError::Trap {
-                msg: "stack overflow trap".into(),
-            },
-            EXCEPTION_INT_DIVIDE_BY_ZERO | EXCEPTION_INT_OVERFLOW => RuntimeError::Trap {
-                msg: "illegal arithmetic operation".into(),
-            },
-            _ => RuntimeError::Trap {
-                msg: "unknown trap".into(),
+                TrapCode::BadSignature => WasmTrapInfo::IncorrectCallIndirectSignature,
+                TrapCode::IndirectCallToNull => WasmTrapInfo::CallIndirectOOB,
+                TrapCode::HeapOutOfBounds => WasmTrapInfo::MemoryOutOfBounds,
+                TrapCode::TableOutOfBounds => WasmTrapInfo::CallIndirectOOB,
+                TrapCode::UnreachableCodeReached => WasmTrapInfo::Unreachable,
+                _ => WasmTrapInfo::Unknown,
             },
+            EXCEPTION_STACK_OVERFLOW => WasmTrapInfo::Unknown,
+            EXCEPTION_INT_DIVIDE_BY_ZERO | EXCEPTION_INT_OVERFLOW => {
+                WasmTrapInfo::IllegalArithmetic
             }
-        .into())
+            _ => WasmTrapInfo::Unknown,
+        }))
     } else {
         let signal = match signum as DWORD {
             EXCEPTION_FLT_DENORMAL_OPERAND
@@ -98,10 +83,9 @@ pub fn call_protected(
             _ => "unkown trapped signal",
         };
 
-        Err(RuntimeError::Trap {
-            msg: format!("unknown trap at {} - {}", exception_address, signal).into(),
-        }
-        .into())
+        let s = format!("unknown trap at {} - {}", exception_address, signal);
+
+        Err(CallProtError::Error(Box::new(s)))
     }
 }
 

lib/llvm-backend/build.rs

@@ -213,6 +213,8 @@ fn main() {
 
     println!("cargo:rustc-link-lib=static=llvm-backend");
     println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=cpp/object_loader.cpp");
+    println!("cargo:rerun-if-changed=cpp/object_loader.hh");
 
     // Enable "nightly" cfg if the current compiler is nightly.
     if rustc_version::version_meta().unwrap().channel == rustc_version::Channel::Nightly {

lib/llvm-backend/cpp/object_loader.hh

@@ -43,6 +43,11 @@ typedef struct
     visit_fde_t visit_fde;
 } callbacks_t;
 
+typedef struct
+{
+    size_t data, vtable;
+} box_any_t;
+
 struct WasmException
 {
   public:
@@ -61,7 +66,7 @@ struct UncatchableException : WasmException
 struct UserException : UncatchableException
 {
   public:
-    UserException(size_t data, size_t vtable) : data(data), vtable(vtable) {}
+    UserException(size_t data, size_t vtable) : error_data({ data, vtable }) {}
 
     virtual std::string description() const noexcept override
     {
@@ -69,7 +74,7 @@ struct UserException : UncatchableException
     }
 
     // The parts of a `Box<dyn Any>`.
-    size_t data, vtable;
+    box_any_t error_data;
 };
 
 struct WasmTrap : UncatchableException
@@ -194,6 +199,7 @@ extern "C"
         void *params,
         void *results,
         WasmTrap::Type *trap_out,
+        box_any_t *user_error,
         void *invoke_env) throw()
     {
         try
@@ -206,6 +212,11 @@ extern "C"
             *trap_out = e.type;
             return false;
         }
+        catch (const UserException &e)
+        {
+            *user_error = e.error_data;
+            return false;
+        }
         catch (const WasmException &e)
         {
             *trap_out = WasmTrap::Type::Unknown;

lib/llvm-backend/src/backend.rs

@@ -93,6 +93,7 @@ extern "C" {
         params: *const u64,
         results: *mut u64,
         trap_out: *mut WasmTrapInfo,
+        user_error: *mut Option<Box<dyn Any>>,
         invoke_env: Option<NonNull<c_void>>,
     ) -> bool;
 }

lib/runtime-core/src/error.rs

@@ -137,15 +137,13 @@ impl std::fmt::Display for RuntimeError {
                 write!(f, "WebAssembly trap occured during runtime: {}", msg)
             }
             RuntimeError::Error { data } => {
-                let msg = if let Some(s) = data.downcast_ref::<String>() {
-                    s
+                if let Some(s) = data.downcast_ref::<String>() {
+                    write!(f, "\"{}\"", s)
                 } else if let Some(s) = data.downcast_ref::<&str>() {
-                    s
+                    write!(f, "\"{}\"", s)
                 } else {
-                    "user-defined, opaque"
-                };
-
-                write!(f, "{}", msg)
+                    write!(f, "unknown error")
+                }
             }
         }
     }

lib/runtime-core/src/instance.rs

@@ -528,6 +528,7 @@ fn call_func_with_index(
 
     let run_wasm = |result_space: *mut u64| unsafe {
         let mut trap_info = WasmTrapInfo::Unknown;
+        let mut user_error = None;
 
         let success = invoke(
             trampoline,
@@ -536,16 +537,21 @@ fn call_func_with_index(
             raw_args.as_ptr(),
             result_space,
             &mut trap_info,
+            &mut user_error,
             invoke_env,
         );
 
         if success {
             Ok(())
+        } else {
+            if let Some(data) = user_error {
+                Err(RuntimeError::Error { data })
             } else {
                 Err(RuntimeError::Trap {
                     msg: trap_info.to_string().into(),
                 })
             }
+        }
     };
 
     let raw_to_value = |raw, ty| match ty {

lib/runtime-core/src/typed_func.rs

@@ -58,6 +58,7 @@ pub type Invoke = unsafe extern "C" fn(
     *const u64,
     *mut u64,
     *mut WasmTrapInfo,
+    *mut Option<Box<dyn Any>>,
     Option<NonNull<c_void>>,
 ) -> bool;
 
@@ -104,7 +105,7 @@ pub trait WasmTypeList {
         f: NonNull<vm::Func>,
         wasm: Wasm,
         ctx: *mut Ctx,
-    ) -> Result<Rets, WasmTrapInfo>
+    ) -> Result<Rets, RuntimeError>
     where
         Rets: WasmTypeList;
 }
@@ -213,6 +214,35 @@ where
     }
 }
 
+impl WasmTypeList for Infallible {
+    type CStruct = Infallible;
+    type RetArray = [u64; 0];
+    fn from_ret_array(_: Self::RetArray) -> Self {
+        unreachable!()
+    }
+    fn empty_ret_array() -> Self::RetArray {
+        unreachable!()
+    }
+    fn from_c_struct(_: Self::CStruct) -> Self {
+        unreachable!()
+    }
+    fn into_c_struct(self) -> Self::CStruct {
+        unreachable!()
+    }
+    fn types() -> &'static [Type] {
+        &[]
+    }
+    #[allow(non_snake_case)]
+    unsafe fn call<Rets: WasmTypeList>(
+        self,
+        _: NonNull<vm::Func>,
+        _: Wasm,
+        _: *mut Ctx,
+    ) -> Result<Rets, RuntimeError> {
+        unreachable!()
+    }
+}
+
 impl<A: WasmExternType> WasmTypeList for (A,) {
     type CStruct = S1<A>;
     type RetArray = [u64; 1];
@@ -242,11 +272,12 @@ impl<A: WasmExternType> WasmTypeList for (A,) {
         f: NonNull<vm::Func>,
         wasm: Wasm,
         ctx: *mut Ctx,
-    ) -> Result<Rets, WasmTrapInfo> {
+    ) -> Result<Rets, RuntimeError> {
         let (a,) = self;
         let args = [a.to_native().to_bits()];
         let mut rets = Rets::empty_ret_array();
         let mut trap = WasmTrapInfo::Unknown;
+        let mut user_error = None;
 
         if (wasm.invoke)(
             wasm.trampoline,
@@ -255,11 +286,18 @@ impl<A: WasmExternType> WasmTypeList for (A,) {
             args.as_ptr(),
             rets.as_mut().as_mut_ptr(),
             &mut trap,
+            &mut user_error,
             wasm.invoke_env,
         ) {
             Ok(Rets::from_ret_array(rets))
         } else {
-            Err(trap)
+            if let Some(data) = user_error {
+                Err(RuntimeError::Error { data })
+            } else {
+                Err(RuntimeError::Trap {
+                    msg: trap.to_string().into(),
+                })
+            }
         }
     }
 }
@@ -269,11 +307,7 @@ where
     Rets: WasmTypeList,
 {
     pub fn call(&self, a: A) -> Result<Rets, RuntimeError> {
-        unsafe { <A as WasmTypeList>::call(a, self.f, self.inner, self.ctx) }.map_err(|e| {
-            RuntimeError::Trap {
-                msg: e.to_string().into(),
-            }
-        })
+        unsafe { <A as WasmTypeList>::call(a, self.f, self.inner, self.ctx) }
     }
 }
 
@@ -307,17 +341,22 @@ macro_rules! impl_traits {
                 &[$( $x::Native::TYPE, )*]
             }
             #[allow(non_snake_case)]
-            unsafe fn call<Rets: WasmTypeList>(self, f: NonNull<vm::Func>, wasm: Wasm, ctx: *mut Ctx) -> Result<Rets, WasmTrapInfo> {
+            unsafe fn call<Rets: WasmTypeList>(self, f: NonNull<vm::Func>, wasm: Wasm, ctx: *mut Ctx) -> Result<Rets, RuntimeError> {
                 #[allow(unused_parens)]
                 let ( $( $x ),* ) = self;
                 let args = [ $( $x.to_native().to_bits() ),* ];
                 let mut rets = Rets::empty_ret_array();
                 let mut trap = WasmTrapInfo::Unknown;
+                let mut user_error = None;
 
-                if (wasm.invoke)(wasm.trampoline, ctx, f, args.as_ptr(), rets.as_mut().as_mut_ptr(), &mut trap, wasm.invoke_env) {
+                if (wasm.invoke)(wasm.trampoline, ctx, f, args.as_ptr(), rets.as_mut().as_mut_ptr(), &mut trap, &mut user_error, wasm.invoke_env) {
                     Ok(Rets::from_ret_array(rets))
                 } else {
-                    Err(trap)
+                    if let Some(data) = user_error {
+                        Err(RuntimeError::Error { data })
+                    } else {
+                        Err(RuntimeError::Trap { msg: trap.to_string().into() })
+                    }
                 }
             }
         }
@@ -359,11 +398,7 @@ macro_rules! impl_traits {
             #[allow(non_snake_case)]
             pub fn call(&self, $( $x: $x, )* ) -> Result<Rets, RuntimeError> {
                 #[allow(unused_parens)]
-                unsafe { <( $( $x ),* ) as WasmTypeList>::call(( $($x),* ), self.f, self.inner, self.ctx) }.map_err(|e| {
-                    RuntimeError::Trap {
-                        msg: e.to_string().into(),
-                    }
-                })
+                unsafe { <( $( $x ),* ) as WasmTypeList>::call(( $($x),* ), self.f, self.inner, self.ctx) }
             }
         }
     };

lib/runtime/examples/call.rs

@@ -1,4 +1,4 @@
-use wasmer_runtime::{compile, error, imports, Ctx, Func, Value};
+use wasmer_runtime::{compile, error, error::RuntimeError, imports, Ctx, Func, Value};
 
 use wabt::wat2wasm;
 
@@ -7,6 +7,8 @@ static WAT: &'static str = r#"
       (type (;0;) (func (result i32)))
       (import "env" "do_panic" (func $do_panic (type 0)))
       (func $dbz (result i32)
+        call $do_panic
+        drop
         i32.const 42
         i32.const 0
         i32.div_u
@@ -34,8 +36,13 @@ fn foobar(_ctx: &mut Ctx) -> i32 {
     42
 }
 
-fn do_panic(_ctx: &mut Ctx) -> Result<i32, String> {
-    Err("error".to_string())
+#[derive(Debug)]
+struct ExitCode {
+    code: i32,
+}
+
+fn do_panic(_ctx: &mut Ctx) -> Result<i32, ExitCode> {
+    Err(ExitCode { code: 42 })
 }
 
 fn main() -> Result<(), error::Error> {
@@ -63,5 +70,11 @@ fn main() -> Result<(), error::Error> {
 
     println!("result: {:?}", result);
 
+    if let Err(RuntimeError::Error { data }) = result {
+        if let Ok(exit_code) = data.downcast::<ExitCode>() {
+            println!("exit code: {:?}", exit_code);
+        }
+    }
+
     Ok(())
 }

lib/runtime/tests/error_propagation.rs

@@ -0,0 +1,49 @@
+#[test]
+fn error_propagation() {
+    use std::convert::Infallible;
+    use wabt::wat2wasm;
+    use wasmer_runtime::{compile, error::RuntimeError, imports, Ctx, Func};
+
+    static WAT: &'static str = r#"
+        (module
+        (type (;0;) (func))
+        (import "env" "ret_err" (func $ret_err (type 0)))
+        (func $call_panic
+            call $ret_err
+        )
+        (export "call_err" (func $call_panic))
+        )
+    "#;
+
+    #[derive(Debug)]
+    struct ExitCode {
+        code: i32,
+    }
+
+    fn ret_err(_ctx: &mut Ctx) -> Result<Infallible, ExitCode> {
+        Err(ExitCode { code: 42 })
+    }
+
+    let wasm = wat2wasm(WAT).unwrap();
+
+    let module = compile(&wasm).unwrap();
+
+    let instance = module
+        .instantiate(&imports! {
+          "env" => {
+              "ret_err" => Func::new(ret_err),
+          },
+        })
+        .unwrap();
+
+    let foo: Func<(), ()> = instance.func("call_err").unwrap();
+
+    let result = foo.call();
+
+    if let Err(RuntimeError::Error { data }) = result {
+        let exit_code = data.downcast::<ExitCode>().unwrap();
+        assert_eq!(exit_code.code, 42);
+    } else {
+        panic!("didn't return RuntimeError::Error")
+    }
+}

lib/singlepass-backend/src/codegen_x64.rs

@@ -205,7 +205,8 @@ impl RunnableModule for X64ExecutionContext {
             func: NonNull<vm::Func>,
             args: *const u64,
             rets: *mut u64,
-            _trap_info: *mut WasmTrapInfo,
+            trap_info: *mut WasmTrapInfo,
+            user_error: *mut Option<Box<dyn Any>>,
             num_params_plus_one: Option<NonNull<c_void>>,
         ) -> bool {
             let args = ::std::slice::from_raw_parts(
@@ -227,7 +228,13 @@ impl RunnableModule for X64ExecutionContext {
                     }
                     true
                 }
-                Err(_) => false,
+                Err(err) => {
+                    match err {
+                        protect_unix::CallProtError::Trap(info) => *trap_info = info,
+                        protect_unix::CallProtError::Error(data) => *user_error = Some(data),
+                    }
+                    false
+                }
             }
         }
 

lib/singlepass-backend/src/protect_unix.rs

@@ -17,7 +17,7 @@ use std::any::Any;
 use std::cell::{Cell, UnsafeCell};
 use std::ptr;
 use std::sync::Once;
-use wasmer_runtime_core::error::{RuntimeError, RuntimeResult};
+use wasmer_runtime_core::typed_func::WasmTrapInfo;
 
 extern "C" fn signal_trap_handler(
     signum: ::nix::libc::c_int,
@@ -62,7 +62,12 @@ pub unsafe fn trigger_trap() -> ! {
     longjmp(jmp_buf as *mut c_void, 0)
 }
 
-pub fn call_protected<T>(f: impl FnOnce() -> T) -> RuntimeResult<T> {
+pub enum CallProtError {
+    Trap(WasmTrapInfo),
+    Error(Box<dyn Any>),
+}
+
+pub fn call_protected<T>(f: impl FnOnce() -> T) -> Result<T, CallProtError> {
     unsafe {
         let jmp_buf = SETJMP_BUFFER.with(|buf| buf.get());
         let prev_jmp_buf = *jmp_buf;
@@ -76,23 +81,24 @@ pub fn call_protected<T>(f: impl FnOnce() -> T) -> RuntimeResult<T> {
             *jmp_buf = prev_jmp_buf;
 
             if let Some(data) = TRAP_EARLY_DATA.with(|cell| cell.replace(None)) {
-                Err(RuntimeError::Error { data })
+                Err(CallProtError::Error(data))
             } else {
-                let (faulting_addr, _inst_ptr) = CAUGHT_ADDRESSES.with(|cell| cell.get());
+                // let (faulting_addr, _inst_ptr) = CAUGHT_ADDRESSES.with(|cell| cell.get());
 
-                let signal = match Signal::from_c_int(signum) {
-                    Ok(SIGFPE) => "floating-point exception",
-                    Ok(SIGILL) => "illegal instruction",
-                    Ok(SIGSEGV) => "segmentation violation",
-                    Ok(SIGBUS) => "bus error",
-                    Err(_) => "error while getting the Signal",
-                    _ => "unkown trapped signal",
-                };
-                // When the trap-handler is fully implemented, this will return more information.
-                Err(RuntimeError::Trap {
-                    msg: format!("unknown trap at {:p} - {}", faulting_addr, signal).into(),
-                }
-                .into())
+                // let signal = match Signal::from_c_int(signum) {
+                //     Ok(SIGFPE) => "floating-point exception",
+                //     Ok(SIGILL) => "illegal instruction",
+                //     Ok(SIGSEGV) => "segmentation violation",
+                //     Ok(SIGBUS) => "bus error",
+                //     Err(_) => "error while getting the Signal",
+                //     _ => "unkown trapped signal",
+                // };
+                // // When the trap-handler is fully implemented, this will return more information.
+                // Err(RuntimeError::Trap {
+                //     msg: format!("unknown trap at {:p} - {}", faulting_addr, signal).into(),
+                // }
+                // .into())
+                Err(CallProtError::Trap(WasmTrapInfo::Unknown))
             }
         } else {
             let ret = f(); // TODO: Switch stack?

lib/wasi/src/syscalls/mod.rs

@@ -13,6 +13,7 @@ use crate::{
 };
 use rand::{thread_rng, Rng};
 use std::cell::Cell;
+use std::convert::Infallible;
 use std::io::{self, Read, Seek, Write};
 use wasmer_runtime_core::{debug, memory::Memory, vm::Ctx};
 
@@ -1431,7 +1432,7 @@ pub fn poll_oneoff(
     debug!("wasi::poll_oneoff");
     unimplemented!()
 }
-pub fn proc_exit(ctx: &mut Ctx, code: __wasi_exitcode_t) -> Result<(), ExitCode> {
+pub fn proc_exit(ctx: &mut Ctx, code: __wasi_exitcode_t) -> Result<Infallible, ExitCode> {
     debug!("wasi::proc_exit, {}", code);
     Err(ExitCode { code })
 }