From efa9ba5892dd2ddc4953d456fa258bbb9aaab384 Mon Sep 17 00:00:00 2001
From: messense <messense@icloud.com>
Date: Sun, 19 Jul 2020 16:54:10 +0800
Subject: [PATCH] Throw exception when Rust code panics

---
 napi-derive/src/lib.rs             | 21 +++++++++++++++++++--
 test_module/__test__/throw.spec.js |  4 ++++
 test_module/src/lib.rs             |  5 +++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/napi-derive/src/lib.rs b/napi-derive/src/lib.rs
index 69b7d475..963f92bc 100644
--- a/napi-derive/src/lib.rs
+++ b/napi-derive/src/lib.rs
@@ -89,8 +89,9 @@ pub fn js_function(attr: TokenStream, input: TokenStream) -> TokenStream {
       use std::mem;
       use std::os::raw::c_char;
       use std::ptr;
+      use std::panic::{self, AssertUnwindSafe};
       use std::ffi::CString;
-      use napi::{JsUnknown, Env, Status, NapiValue, CallContext};
+      use napi::{JsUnknown, Env, Error, Status, NapiValue, CallContext};
       let mut argc = #arg_len_span as usize;
       let mut raw_args =
       unsafe { mem::MaybeUninit::<[napi::sys::napi_value; #arg_len_span as usize]>::uninit().assume_init() };
@@ -112,7 +113,23 @@ pub fn js_function(attr: TokenStream, input: TokenStream) -> TokenStream {
 
       let mut env = Env::from_raw(raw_env);
       let call_ctx = CallContext::new(&mut env, raw_this, &raw_args, #arg_len_span, argc as usize);
-      let result = call_ctx.and_then(|ctx| #new_fn_name(ctx));
+      let result = call_ctx.and_then(|ctx| {
+        match panic::catch_unwind(AssertUnwindSafe(move || #new_fn_name(ctx))) {
+          Ok(result) => result,
+          Err(e) => {
+            let message = {
+              if let Some(string) = e.downcast_ref::<String>() {
+                string.clone()
+              } else if let Some(string) = e.downcast_ref::<&str>() {
+                string.to_string()
+              } else {
+                format!("panic from Rust code: {:?}", e)
+              }
+            };
+            Err(Error { status: Status::GenericFailure, reason: message })
+          }
+        }
+      });
       has_error = has_error && result.is_err();
 
       match result {
diff --git a/test_module/__test__/throw.spec.js b/test_module/__test__/throw.spec.js
index 76a03546..461fbed4 100644
--- a/test_module/__test__/throw.spec.js
+++ b/test_module/__test__/throw.spec.js
@@ -14,3 +14,7 @@ test('should be able to throw error from native with reason', (t) => {
 test('should throw if argument type is not match', (t) => {
   t.throws(() => bindings.testThrowWithReason(2))
 })
+
+test('should throw if Rust code panic', (t) => {
+  t.throws(() => bindings.testThrowWithPanic())
+})
diff --git a/test_module/src/lib.rs b/test_module/src/lib.rs
index 88297dd5..88c9a900 100644
--- a/test_module/src/lib.rs
+++ b/test_module/src/lib.rs
@@ -86,3 +86,8 @@ fn test_throw_with_reason(ctx: CallContext) -> Result<JsUnknown> {
     reason.as_str()?.to_owned(),
   ))
 }
+
+#[js_function]
+pub fn test_throw_with_panic(_ctx: CallContext) -> Result<JsUnknown> {
+  panic!("don't panic.");
+}