fix initialization of tinygo programs (#118)

* fix: ensure Go programs built with tinygo >= 0.35.0 run

WASI programs built by tinygo have to be written with a `main` function, even if it's empty.
Starting from tinygo >= 0.35.0, the `main` function calls the WASI process exit function,
which is handled by wasmtime as an Error.

We must check if this error can be converted into a WASI exit
error and, if the exit code is 0, we can ignore it. Otherwise the waPC initialization
will fail.

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

* wasmtime-provider: tag patch release

- fix: tinygo 0.35.0 programs do not run

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

---------

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

Author: flavio

crates/wasmtime-provider/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "wasmtime-provider"
-version = "2.3.0"
+version = "2.3.1"
 authors = [
   "Kevin Hoffman <alothien@gmail.com>",
   "Jarrod Overson <jsoverson@gmail.com>",
@@ -72,6 +72,7 @@ async-trait = { version = "0.1", optional = true }
 tokio = { version = "1", optional = true, default-features = false, features = [
   "rt",
 ] }
+tracing = "0.1"
 
 [dev-dependencies]
 wapc-codec = { path = "../wapc-codec" }

crates/wasmtime-provider/src/errors.rs

@@ -10,7 +10,7 @@ pub(crate) type Result<T> = std::result::Result<T, Error>;
 pub enum Error {
   /// Wasmtime initialization failed
   #[error("Initialization failed: {0}")]
-  InitializationFailed(Box<dyn std::error::Error + Send + Sync>),
+  InitializationFailed(String),
 
   /// Wasmtime initialization failed
   #[error("Initialization failed: {0} init interrupted, execution deadline exceeded")]

crates/wasmtime-provider/src/provider.rs

@@ -2,6 +2,7 @@ use std::sync::Arc;
 
 use log::{error, info};
 use parking_lot::RwLock;
+use tracing::trace;
 #[cfg(feature = "wasi")]
 use wapc::WasiParams;
 use wapc::{wapc_functions, ModuleState, WebAssemblyEngineProvider};
@@ -248,6 +249,7 @@ impl WebAssemblyEngineProvider for WasmtimeEngineProvider {
 impl WasmtimeEngineProvider {
   fn initialize(&mut self) -> Result<()> {
     for starter in wapc_functions::REQUIRED_STARTS.iter() {
+      trace!(function = starter, "calling init function");
       if let Some(deadlines) = &self.epoch_deadlines {
         // the deadline counter must be set before invoking the wasm function
         self.store.set_epoch_deadline(deadlines.wapc_init);
@@ -265,17 +267,34 @@ impl WasmtimeEngineProvider {
         // generic `anyhow::Error` that doesn't allow nice handling of
         // errors
         let starter_func: TypedFunc<(), ()> = engine_inner.instance.read().get_typed_func(&mut self.store, starter)?;
-        starter_func.call(&mut self.store, ()).map_err(|err| {
+
+        if let Err(err) = starter_func.call(&mut self.store, ()) {
+          trace!(function = starter, ?err, "handling error returned by init function");
           if let Some(trap) = err.downcast_ref::<wasmtime::Trap>() {
             if matches!(trap, wasmtime::Trap::Interrupt) {
-              Error::InitializationFailedTimeout((*starter).to_owned())
-            } else {
-              Error::InitializationFailed(err.into())
+              return Err(Error::InitializationFailedTimeout((*starter).to_owned()));
             }
-          } else {
-            Error::InitializationFailed(err.into())
+            return Err(Error::InitializationFailed(err.to_string()));
           }
-        })?;
+
+          // WASI programs built by tinygo have to be written with a `main` function, even if it's empty.
+          // Starting from tinygo >= 0.35.0, the `main` function calls the WASI process exit function,
+          // which is handled by wasmtime as an Error.
+          //
+          // We must check if this error can be converted into a WASI exit
+          // error and, if the exit code is 0, we can ignore it. Otherwise the waPC initialization
+          // will fail.
+          #[cfg(feature = "wasi")]
+          if let Some(exit_err) = err.downcast_ref::<wasi_common::I32Exit>() {
+            if exit_err.0 != 0 {
+              return Err(Error::InitializationFailed(err.to_string()));
+            }
+            trace!("ignoring successful exit trap generated by WASI");
+            continue;
+          }
+
+          return Err(Error::InitializationFailed(err.to_string()));
+        };
       }
     }
     Ok(())

crates/wasmtime-provider/src/provider_async.rs

@@ -4,6 +4,7 @@ use log::{error, info};
 
 use async_trait::async_trait;
 use parking_lot::RwLock;
+use tracing::trace;
 #[cfg(feature = "wasi")]
 use wapc::WasiParams;
 use wapc::{wapc_functions, ModuleStateAsync, WebAssemblyEngineProviderAsync};
@@ -322,17 +323,34 @@ impl WasmtimeEngineProviderAsync {
         // generic `anyhow::Error` that doesn't allow nice handling of
         // errors
         let starter_func: TypedFunc<(), ()> = engine_inner.instance.read().get_typed_func(&mut self.store, starter)?;
-        starter_func.call_async(&mut self.store, ()).await.map_err(|err| {
+
+        if let Err(err) = starter_func.call_async(&mut self.store, ()).await {
+          trace!(function = starter, ?err, "handling error returned by init function");
           if let Some(trap) = err.downcast_ref::<wasmtime::Trap>() {
             if matches!(trap, wasmtime::Trap::Interrupt) {
-              Error::InitializationFailedTimeout((*starter).to_owned())
-            } else {
-              Error::InitializationFailed(err.into())
+              return Err(Error::InitializationFailedTimeout((*starter).to_owned()));
             }
-          } else {
-            Error::InitializationFailed(err.into())
+            return Err(Error::InitializationFailed(err.to_string()));
           }
-        })?;
+
+          // WASI programs built by tinygo have to be written with a `main` function, even if it's empty.
+          // Starting from tinygo >= 0.35.0, the `main` function calls the WASI process exit function,
+          // which is handled by wasmtime as an Error.
+          //
+          // We must check if this error can be converted into a WASI exit
+          // error and, if the exit code is 0, we can ignore it. Otherwise the waPC initialization
+          // will fail.
+          #[cfg(feature = "wasi")]
+          if let Some(exit_err) = err.downcast_ref::<wasi_common::I32Exit>() {
+            if exit_err.0 != 0 {
+              return Err(Error::InitializationFailed(err.to_string()));
+            }
+            trace!("ignoring successful exit trap generated by WASI");
+            continue;
+          }
+
+          return Err(Error::InitializationFailed(err.to_string()));
+        };
       }
     }
     Ok(())