Merge pull request #3813 from wasmerio/better-errors

Better errors

lib/api/Cargo.toml

@@ -31,6 +31,7 @@ bytes = "1"
 # - Optional shared dependencies.
 wat = { version = "1.0", optional = true }
 tracing = { version = "0.1", optional = true }
+rustc-demangle = "0.1"
 
 # Dependencies and Development Dependencies for `sys`.
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]

lib/api/src/errors.rs

@@ -1,8 +1,35 @@
 #[cfg(feature = "js")]
-pub use crate::js::errors::{LinkError, RuntimeError};
+use crate::js::trap::Trap;
+use std::fmt;
+use std::sync::Arc;
 use thiserror::Error;
+use wasmer_types::{FrameInfo, TrapCode};
 #[cfg(feature = "sys")]
-pub use wasmer_compiler::{LinkError, RuntimeError};
+use wasmer_vm::Trap;
+
+use wasmer_types::ImportError;
+
+/// The WebAssembly.LinkError object indicates an error during
+/// module instantiation (besides traps from the start function).
+///
+/// This is based on the [link error][link-error] API.
+///
+/// [link-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/LinkError
+#[derive(Debug)]
+#[cfg_attr(feature = "std", derive(Error))]
+#[cfg_attr(feature = "std", error("Link error: {0}"))]
+pub enum LinkError {
+    /// An error occurred when checking the import types.
+    #[cfg_attr(feature = "std", error("Error while importing {0:?}.{1:?}: {2}"))]
+    Import(String, String, ImportError),
+
+    /// A trap ocurred during linking.
+    #[cfg_attr(feature = "std", error("RuntimeError occurred during linking: {0}"))]
+    Trap(#[source] RuntimeError),
+    /// Insufficient resources available for linking.
+    #[cfg_attr(feature = "std", error("Insufficient resources: {0}"))]
+    Resource(String),
+}
 
 /// An error while instantiating a module.
 ///
@@ -38,3 +65,199 @@ pub enum InstantiationError {
     #[cfg_attr(feature = "std", error("incorrect OS or architecture"))]
     DifferentArchOS,
 }
+
+/// A struct representing an aborted instruction execution, with a message
+/// indicating the cause.
+#[derive(Clone)]
+pub struct RuntimeError {
+    pub(crate) inner: Arc<RuntimeErrorInner>,
+}
+
+#[derive(Debug)]
+struct RuntimeStringError {
+    details: String,
+}
+
+impl RuntimeStringError {
+    fn new(msg: String) -> RuntimeStringError {
+        RuntimeStringError { details: msg }
+    }
+}
+
+impl fmt::Display for RuntimeStringError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.details)
+    }
+}
+
+impl std::error::Error for RuntimeStringError {
+    fn description(&self) -> &str {
+        &self.details
+    }
+}
+
+pub(crate) struct RuntimeErrorInner {
+    /// The source error
+    pub(crate) source: Trap,
+    /// The trap code (if any)
+    trap_code: Option<TrapCode>,
+    /// The reconstructed Wasm trace (from the native trace and the `GlobalFrameInfo`).
+    wasm_trace: Vec<FrameInfo>,
+}
+
+impl RuntimeError {
+    /// Creates a new generic `RuntimeError` with the given `message`.
+    ///
+    /// # Example
+    /// ```
+    /// let trap = wasmer::RuntimeError::new("unexpected error");
+    /// assert_eq!("unexpected error", trap.message());
+    /// ```
+    pub fn new<I: Into<String>>(message: I) -> Self {
+        let msg = message.into();
+        let source = RuntimeStringError::new(msg);
+        Self::user(Box::new(source))
+    }
+
+    /// Creates `RuntimeError` from an error and a WasmTrace
+    ///
+    /// # Example
+    /// ```ignore
+    /// let wasm_trace = vec![wasmer_types::FrameInfo::new(
+    ///   "my_module".to_string(),
+    ///   0,
+    ///   Some("my_function".to_string()),
+    ///   0.into(),
+    ///   2.into()
+    /// )];
+    /// let trap = wasmer::RuntimeError::new_from_source(my_error, wasm_trace, None);
+    /// assert_eq!("unexpected error", trap.message());
+    /// ```
+    pub fn new_from_source(
+        source: Trap,
+        wasm_trace: Vec<FrameInfo>,
+        trap_code: Option<TrapCode>,
+    ) -> Self {
+        // println!("CREATING ERROR FROM TRAP {}", source);
+        Self {
+            inner: Arc::new(RuntimeErrorInner {
+                source,
+                wasm_trace,
+                trap_code,
+            }),
+        }
+    }
+
+    /// Creates a custom user Error.
+    ///
+    /// This error object can be passed through Wasm frames and later retrieved
+    /// using the `downcast` method.
+    pub fn user(error: Box<dyn std::error::Error + Send + Sync>) -> Self {
+        match error.downcast::<Self>() {
+            Ok(err) => *err,
+            Err(error) => error.into(),
+        }
+    }
+
+    /// Returns a reference the `message` stored in `Trap`.
+    pub fn message(&self) -> String {
+        if let Some(trap_code) = self.inner.trap_code {
+            trap_code.message().to_string()
+        } else {
+            self.inner.source.to_string()
+        }
+    }
+
+    /// Returns a list of function frames in WebAssembly code that led to this
+    /// trap happening.
+    pub fn trace(&self) -> &[FrameInfo] {
+        &self.inner.wasm_trace
+    }
+
+    /// Returns trap code, if it's a Trap
+    pub fn to_trap(self) -> Option<TrapCode> {
+        self.inner.trap_code
+    }
+
+    // /// Returns trap code, if it's a Trap
+    // pub fn to_source(self) -> &'static Trap {
+    //     &self.inner.as_ref().source
+    // }
+
+    /// Attempts to downcast the `RuntimeError` to a concrete type.
+    pub fn downcast<T: std::error::Error + 'static>(self) -> Result<T, Self> {
+        match Arc::try_unwrap(self.inner) {
+            Ok(inner) if inner.source.is::<T>() => Ok(inner.source.downcast::<T>().unwrap()),
+            Ok(inner) => Err(Self {
+                inner: Arc::new(inner),
+            }),
+            Err(inner) => Err(Self { inner }),
+        }
+    }
+
+    /// Attempts to downcast the `RuntimeError` to a concrete type.
+    pub fn downcast_ref<T: std::error::Error + 'static>(&self) -> Option<&T> {
+        self.inner.as_ref().source.downcast_ref::<T>()
+    }
+
+    /// Returns true if the `RuntimeError` is the same as T
+    pub fn is<T: std::error::Error + 'static>(&self) -> bool {
+        self.inner.source.is::<T>()
+    }
+}
+
+impl fmt::Debug for RuntimeError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RuntimeError")
+            .field("source", &self.inner.source)
+            .field("wasm_trace", &self.inner.wasm_trace)
+            .finish()
+    }
+}
+
+impl fmt::Display for RuntimeError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "RuntimeError: {}", self.message())?;
+        let trace = self.trace();
+        if trace.is_empty() {
+            return Ok(());
+        }
+        for frame in self.trace().iter() {
+            let name = frame.module_name();
+            let func_index = frame.func_index();
+            writeln!(f)?;
+            write!(f, "    at ")?;
+            match frame.function_name() {
+                Some(name) => match rustc_demangle::try_demangle(name) {
+                    Ok(name) => write!(f, "{}", name)?,
+                    Err(_) => write!(f, "{}", name)?,
+                },
+                None => write!(f, "<unnamed>")?,
+            }
+            write!(
+                f,
+                " ({}[{}]:0x{:x})",
+                name,
+                func_index,
+                frame.module_offset()
+            )?;
+        }
+        Ok(())
+    }
+}
+
+impl std::error::Error for RuntimeError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        self.inner.source.source()
+    }
+}
+
+impl From<Box<dyn std::error::Error + Send + Sync>> for RuntimeError {
+    fn from(error: Box<dyn std::error::Error + Send + Sync>) -> Self {
+        match error.downcast::<Self>() {
+            // The error is already a RuntimeError, we return it directly
+            Ok(runtime_error) => *runtime_error,
+            Err(error) => Trap::user(error).into(),
+        }
+    }
+}

lib/api/src/js/errors.rs

@@ -1,27 +1,28 @@
-use crate::js::lib::std::string::String;
-pub use crate::js::trap::RuntimeError;
-#[cfg(feature = "std")]
-use thiserror::Error;
-use wasmer_types::ImportError;
+use crate::js::trap::Trap;
+use crate::RuntimeError;
+use wasm_bindgen::prelude::*;
 
-/// The WebAssembly.LinkError object indicates an error during
-/// module instantiation (besides traps from the start function).
-///
-/// This is based on the [link error][link-error] API.
-///
-/// [link-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/LinkError
-#[derive(Debug)]
-#[cfg_attr(feature = "std", derive(Error))]
-#[cfg_attr(feature = "std", error("Link error: {0}"))]
-pub enum LinkError {
-    /// An error occurred when checking the import types.
-    #[cfg_attr(feature = "std", error("Error while importing {0:?}.{1:?}: {2}"))]
-    Import(String, String, ImportError),
+impl From<Trap> for RuntimeError {
+    fn from(trap: Trap) -> Self {
+        if trap.is::<RuntimeError>() {
+            return trap.downcast::<RuntimeError>().unwrap();
+        }
+        let wasm_trace = vec![];
+        let trap_code = None;
+        // let (wasm_trace, trap_code) = wasmer_compiler::get_trace_and_trapcode(&trap);
+        RuntimeError::new_from_source(trap, wasm_trace, trap_code)
+    }
+}
+
+impl From<RuntimeError> for JsValue {
+    fn from(_err: RuntimeError) -> Self {
+        // err.inner.source.into()
+        unimplemented!();
+    }
+}
 
-    /// A trap ocurred during linking.
-    #[cfg_attr(feature = "std", error("RuntimeError occurred during linking: {0}"))]
-    Trap(#[source] RuntimeError),
-    /// Insufficient resources available for linking.
-    #[cfg_attr(feature = "std", error("Insufficient resources: {0}"))]
-    Resource(String),
+pub(crate) fn raise(error: Box<dyn std::error::Error + Send + Sync>) -> ! {
+    let error = Trap::user(error);
+    let js_error: JsValue = error.into();
+    wasm_bindgen::throw_val(js_error)
 }

lib/api/src/js/externals/function.rs

@@ -394,10 +394,10 @@ macro_rules! impl_host_function {
                             Ok(Ok(result)) => return result.into_c_struct(&mut store),
                             #[allow(deprecated)]
                             #[cfg(feature = "std")]
-                            Ok(Err(trap)) => RuntimeError::raise(Box::new(trap)),
+                            Ok(Err(trap)) => crate::js::errors::raise(Box::new(trap)),
                             #[cfg(feature = "core")]
                             #[allow(deprecated)]
-                            Ok(Err(trap)) => RuntimeError::raise(Box::new(trap)),
+                            Ok(Err(trap)) => crate::js::errors::raise(Box::new(trap)),
                             Err(_panic) => unimplemented!(),
                         }
                     }
@@ -442,10 +442,10 @@ macro_rules! impl_host_function {
                             Ok(Ok(result)) => return result.into_c_struct(&mut store),
                             #[cfg(feature = "std")]
                             #[allow(deprecated)]
-                            Ok(Err(trap)) => RuntimeError::raise(Box::new(trap)),
+                            Ok(Err(trap)) => crate::js::errors::raise(Box::new(trap)),
                             #[cfg(feature = "core")]
                             #[allow(deprecated)]
-                            Ok(Err(trap)) => RuntimeError::raise(Box::new(trap)),
+                            Ok(Err(trap)) => crate::js::errors::raise(Box::new(trap)),
                             Err(_panic) => unimplemented!(),
                         }
                     }

lib/api/src/js/mod.rs

@@ -34,7 +34,7 @@ pub(crate) mod module;
 #[cfg(feature = "wasm-types-polyfill")]
 mod module_info_polyfill;
 pub(crate) mod store;
-mod trap;
+pub(crate) mod trap;
 pub(crate) mod typed_function;
 pub(crate) mod vm;
 mod wasm_bindgen_polyfill;