vm: test for abort condition of current invocation

When a vm script aborted after a timeout/signal interruption, test
whether the local timeout/signal watchdog was responsible for
terminating the execution.

Without this, when a shorter timer from an outer `vm.run*` invocation
fires before an inner timeout, the inner timeout would throw an error
instead of the outer one, but because it did not witness the timeout
itself, it would assume the termination was the result of a signal
interruption.

PR-URL: #7373
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: addaleax

src/node_contextify.cc

@@ -836,14 +836,17 @@ class ContextifyScript : public BaseObject {
 
     Local<Value> result;
     bool timed_out = false;
+    bool received_signal = false;
     if (break_on_sigint && timeout != -1) {
       Watchdog wd(env->isolate(), timeout);
       SigintWatchdog swd(env->isolate());
       result = script->Run();
       timed_out = wd.HasTimedOut();
+      received_signal = swd.HasReceivedSignal();
     } else if (break_on_sigint) {
       SigintWatchdog swd(env->isolate());
       result = script->Run();
+      received_signal = swd.HasReceivedSignal();
     } else if (timeout != -1) {
       Watchdog wd(env->isolate(), timeout);
       result = script->Run();
@@ -852,14 +855,26 @@ class ContextifyScript : public BaseObject {
       result = script->Run();
     }
 
-    if (try_catch.HasCaught() && try_catch.HasTerminated()) {
-      env->isolate()->CancelTerminateExecution();
+    if (try_catch.HasCaught()) {
+      if (try_catch.HasTerminated())
+        env->isolate()->CancelTerminateExecution();
+
+      // It is possible that execution was terminated by another timeout in
+      // which this timeout is nested, so check whether one of the watchdogs
+      // from this invocation is responsible for termination.
       if (timed_out) {
         env->ThrowError("Script execution timed out.");
-      } else {
+      } else if (received_signal) {
         env->ThrowError("Script execution interrupted.");
       }
+
+      // If there was an exception thrown during script execution, re-throw it.
+      // If one of the above checks threw, re-throw the exception instead of
+      // letting try_catch catch it.
+      // If execution has been terminated, but not by one of the watchdogs from
+      // this invocation, this will re-throw a `null` value.
       try_catch.ReThrow();
+
       return false;
     }
 

src/node_watchdog.cc

@@ -99,7 +99,7 @@ void SigintWatchdog::Dispose() {
 
 
 SigintWatchdog::SigintWatchdog(v8::Isolate* isolate)
-    : isolate_(isolate), destroyed_(false) {
+    : isolate_(isolate), received_signal_(false), destroyed_(false) {
   // Register this watchdog with the global SIGINT/Ctrl+C listener.
   SigintWatchdogHelper::GetInstance()->Register(this);
   // Start the helper thread, if that has not already happened.
@@ -120,6 +120,7 @@ void SigintWatchdog::Destroy() {
 
 
 void SigintWatchdog::HandleSigint() {
+  received_signal_ = true;
   isolate_->TerminateExecution();
 }
 

src/node_watchdog.h

@@ -46,11 +46,13 @@ class SigintWatchdog {
     void Dispose();
 
     v8::Isolate* isolate() { return isolate_; }
+    bool HasReceivedSignal() { return received_signal_; }
     void HandleSigint();
   private:
     void Destroy();
 
     v8::Isolate* isolate_;
+    bool received_signal_;
     bool destroyed_;
 };
 

test/parallel/test-vm-timeout.js

@@ -32,3 +32,26 @@ assert.throws(function() {
   vm.runInNewContext('runInVM(10)', context, { timeout: 10000 });
   throw new Error('Test 5 failed');
 }, /Script execution timed out./);
+
+// Test 6: Nested vm timeouts, outer timeout is shorter and fires first.
+assert.throws(function() {
+  const context = {
+    runInVM: function(timeout) {
+      vm.runInNewContext('while(true) {}', context, { timeout: timeout });
+    }
+  };
+  vm.runInNewContext('runInVM(10000)', context, { timeout: 100 });
+  throw new Error('Test 6 failed');
+}, /Script execution timed out./);
+
+// Test 7: Nested vm timeouts, inner script throws an error.
+assert.throws(function() {
+  const context = {
+    runInVM: function(timeout) {
+      vm.runInNewContext('throw new Error(\'foobar\')', context, {
+        timeout: timeout
+      });
+    }
+  };
+  vm.runInNewContext('runInVM(10000)', context, { timeout: 100000 });
+}, /foobar/);