Expose TrapCode::Interrupt on epoch based interruption (#4105)

Author: saulecabrera

crates/cranelift/src/func_environ.rs

@@ -593,7 +593,7 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
         // The reason is that one can construct a "zip-bomb-like"
         // program with exponential-in-program-size runtime, with no
         // backedges (loops), by building a tree of function calls: f0
-        // calls f1 ten tims, f1 calls f2 ten times, etc. E.g., nine
+        // calls f1 ten times, f1 calls f2 ten times, etc. E.g., nine
         // levels of this yields a billion function calls with no
         // backedges. So we can't do checks only at backedges.
         //

crates/wasmtime/src/store.rs

@@ -1856,7 +1856,14 @@ unsafe impl<T> wasmtime_runtime::Store for StoreInner<T> {
 
     fn new_epoch(&mut self) -> Result<u64, anyhow::Error> {
         return match &self.epoch_deadline_behavior {
-            &EpochDeadline::Trap => Err(anyhow::Error::new(EpochDeadlineError)),
+            &EpochDeadline::Trap => {
+                let trap = Trap::new_wasm(
+                    None,
+                    wasmtime_environ::TrapCode::Interrupt,
+                    wasmtime_runtime::Backtrace::new(),
+                );
+                Err(anyhow::Error::from(trap))
+            }
             #[cfg(feature = "async")]
             &EpochDeadline::YieldAndExtendDeadline { delta } => {
                 // Do the async yield. May return a trap if future was
@@ -1870,17 +1877,6 @@ unsafe impl<T> wasmtime_runtime::Store for StoreInner<T> {
                 Ok(self.get_epoch_deadline())
             }
         };
-
-        #[derive(Debug)]
-        struct EpochDeadlineError;
-
-        impl fmt::Display for EpochDeadlineError {
-            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                f.write_str("epoch deadline reached during execution")
-            }
-        }
-
-        impl std::error::Error for EpochDeadlineError {}
     }
 }
 

examples/interrupt.rs

@@ -29,7 +29,7 @@ fn main() -> Result<()> {
     let trap = run.call(&mut store, ()).unwrap_err();
 
     println!("trap received...");
-    assert!(trap.to_string().contains("epoch deadline reached"));
+    assert!(trap.trap_code().unwrap() == TrapCode::Interrupt);
 
     Ok(())
 }

tests/all/cli_tests.rs

@@ -175,7 +175,7 @@ fn timeout_in_start() -> Result<()> {
     assert_eq!(output.stdout, b"");
     let stderr = String::from_utf8_lossy(&output.stderr);
     assert!(
-        stderr.contains("epoch deadline reached during execution"),
+        stderr.contains("wasm trap: interrupt"),
         "bad stderr: {}",
         stderr
     );
@@ -196,7 +196,7 @@ fn timeout_in_invoke() -> Result<()> {
     assert_eq!(output.stdout, b"");
     let stderr = String::from_utf8_lossy(&output.stderr);
     assert!(
-        stderr.contains("epoch deadline reached during execution"),
+        stderr.contains("wasm trap: interrupt"),
         "bad stderr: {}",
         stderr
     );

tests/all/iloop.rs

@@ -33,7 +33,7 @@ fn loops_interruptable() -> anyhow::Result<()> {
     store.engine().increment_epoch();
     let trap = iloop.call(&mut store, ()).unwrap_err();
     assert!(
-        trap.to_string().contains("epoch deadline reached"),
+        trap.trap_code().unwrap() == TrapCode::Interrupt,
         "bad message: {}",
         trap
     );
@@ -50,7 +50,7 @@ fn functions_interruptable() -> anyhow::Result<()> {
     store.engine().increment_epoch();
     let trap = iloop.call(&mut store, ()).unwrap_err();
     assert!(
-        trap.to_string().contains("epoch deadline reached"),
+        trap.trap_code().unwrap() == TrapCode::Interrupt,
         "{}",
         trap.to_string()
     );
@@ -103,7 +103,7 @@ fn loop_interrupt_from_afar() -> anyhow::Result<()> {
     thread.join().unwrap();
     assert!(HITS.load(SeqCst) > NUM_HITS);
     assert!(
-        trap.to_string().contains("epoch deadline reached"),
+        trap.trap_code().unwrap() == TrapCode::Interrupt,
         "bad message: {}",
         trap.to_string()
     );
@@ -143,7 +143,7 @@ fn function_interrupt_from_afar() -> anyhow::Result<()> {
     thread.join().unwrap();
     assert!(HITS.load(SeqCst) > NUM_HITS);
     assert!(
-        trap.to_string().contains("epoch deadline reached"),
+        trap.trap_code().unwrap() == TrapCode::Interrupt,
         "bad message: {}",
         trap.to_string()
     );