domains: fix handling of uncaught exceptions

Fix node exiting due to an exception being thrown rather than emitting
an 'uncaughtException' event on the process object when:
1. no error handler is set on the domain within which an error is thrown
2. an 'uncaughtException' event listener is set on the process

Also fix an issue where the process would not abort in the proper
function call if an error is thrown within a domain with no error
handler and --abort-on-uncaught-exception is used.

Fixes #3607 and #3653.

PR: #3885
PR-URL: #3885
Reviewed-By: James M Snell <[email protected]>

Author: Julien Gilli

lib/domain.js

@@ -45,19 +45,20 @@ Object.defineProperty(process, 'domain', {
 // between js and c++ w/o much overhead
 var _domain_flag = {};
 
+// it's possible to enter one domain while already inside
+// another one.  the stack is each entered domain.
+var stack = [];
+exports._stack = stack;
+
 // let the process know we're using domains
-process._setupDomainUse(_domain, _domain_flag);
+process._setupDomainUse(_domain, _domain_flag, stack);
 
 exports.Domain = Domain;
 
 exports.create = exports.createDomain = function() {
   return new Domain();
 };
 
-// it's possible to enter one domain while already inside
-// another one.  the stack is each entered domain.
-var stack = [];
-exports._stack = stack;
 // the active domain is always the one that we're currently in.
 exports.active = null;
 
@@ -114,14 +115,20 @@ Domain.prototype._errorHandler = function errorHandler(er) {
   // that these exceptions are caught, and thus would prevent it from
   // aborting in these cases.
   if (stack.length === 1) {
-    try {
-      // Set the _emittingTopLevelDomainError so that we know that, even
-      // if technically the top-level domain is still active, it would
-      // be ok to abort on an uncaught exception at this point
-      process._emittingTopLevelDomainError = true;
-      caught = emitError();
-    } finally {
-      process._emittingTopLevelDomainError = false;
+    // If there's no error handler, do not emit an 'error' event
+    // as this would throw an error, make the process exit, and thus
+    // prevent the process 'uncaughtException' event from being emitted
+    // if a listener is set.
+    if (EventEmitter.listenerCount(self, 'error') > 0) {
+      try {
+        // Set the _emittingTopLevelDomainError so that we know that, even
+        // if technically the top-level domain is still active, it would
+        // be ok to abort on an uncaught exception at this point
+        process._emittingTopLevelDomainError = true;
+        caught = emitError();
+      } finally {
+        process._emittingTopLevelDomainError = false;
+      }
     }
   } else {
     // wrap this in a try/catch so we don't get infinite throwing

src/env.h

@@ -258,6 +258,7 @@ namespace node {
   V(buffer_constructor_function, v8::Function)                                \
   V(context, v8::Context)                                                     \
   V(domain_array, v8::Array)                                                  \
+  V(domains_stack_array, v8::Array)                                           \
   V(fs_stats_constructor_function, v8::Function)                              \
   V(gc_info_callback_function, v8::Function)                                  \
   V(module_load_list_array, v8::Array)                                        \

src/node.cc

@@ -910,19 +910,53 @@ Local<Value> WinapiErrnoException(Isolate* isolate,
 }
 #endif
 
+static bool DomainHasErrorHandler(const Environment* env,
+                                  const Local<Object>& domain) {
+  HandleScope scope(env->isolate());
 
-static bool IsDomainActive(const Environment* env) {
-  if (!env->using_domains()) {
+  Local<Value> domain_event_listeners_v = domain->Get(env->events_string());
+  if (!domain_event_listeners_v->IsObject())
     return false;
-  }
 
-  Local<Array> domain_array = env->domain_array().As<Array>();
-  uint32_t domains_array_length = domain_array->Length();
-  if (domains_array_length == 0)
+  Local<Object> domain_event_listeners_o =
+      domain_event_listeners_v.As<Object>();
+
+  Local<Value> domain_error_listeners_v =
+      domain_event_listeners_o->Get(env->error_string());
+
+  if (domain_error_listeners_v->IsFunction() ||
+      (domain_error_listeners_v->IsArray() &&
+      domain_error_listeners_v.As<Array>()->Length() > 0))
+    return true;
+
+  return false;
+}
+
+static bool TopDomainHasErrorHandler(const Environment* env) {
+  HandleScope scope(env->isolate());
+
+  if (!env->using_domains())
     return false;
 
-  Local<Value> domain_v = domain_array->Get(0);
-  return !domain_v->IsNull();
+  Local<Array> domains_stack_array = env->domains_stack_array().As<Array>();
+  if (domains_stack_array->Length() == 0)
+    return false;
+
+  uint32_t domains_stack_length = domains_stack_array->Length();
+  if (domains_stack_length == 0)
+    return false;
+
+  Local<Value> top_domain_v =
+      domains_stack_array->Get(domains_stack_length - 1);
+
+  if (!top_domain_v->IsObject())
+    return false;
+
+  Local<Object> top_domain = top_domain_v.As<Object>();
+  if (DomainHasErrorHandler(env, top_domain))
+    return true;
+
+  return false;
 }
 
 
@@ -934,7 +968,7 @@ bool ShouldAbortOnUncaughtException(v8::Isolate* isolate) {
   bool isEmittingTopLevelDomainError =
     process_object->Get(emitting_top_level_domain_error_key)->BooleanValue();
 
-  return !IsDomainActive(env) || isEmittingTopLevelDomainError;
+  return isEmittingTopLevelDomainError || !TopDomainHasErrorHandler(env);
 }
 
 
@@ -962,8 +996,10 @@ void SetupDomainUse(const FunctionCallbackInfo<Value>& args) {
 
   assert(args[0]->IsArray());
   assert(args[1]->IsObject());
+  assert(args[2]->IsArray());
 
   env->set_domain_array(args[0].As<Array>());
+  env->set_domains_stack_array(args[2].As<Array>());
 
   Local<Object> domain_flag_obj = args[1].As<Object>();
   Environment::DomainFlag* domain_flag = env->domain_flag();

test/common.js

@@ -347,3 +347,37 @@ exports.busyLoop = function busyLoop(time) {
     ;
   }
 };
+
+// Returns true if the exit code "exitCode" and/or signal name "signal"
+// represent the exit code and/or signal name of a node process that aborted,
+// false otherwise.
+exports.nodeProcessAborted = function nodeProcessAborted(exitCode, signal) {
+  // Depending on the compiler used, node will exit with either
+  // exit code 132 (SIGILL), 133 (SIGTRAP) or 134 (SIGABRT).
+  var expectedExitCodes = [132, 133, 134];
+
+  // On platforms using KSH as the default shell (like SmartOS),
+  // when a process aborts, KSH exits with an exit code that is
+  // greater than 256, and thus the exit code emitted with the 'exit'
+  // event is null and the signal is set to either SIGILL, SIGTRAP,
+  // or SIGABRT (depending on the compiler).
+  var expectedSignals = ['SIGILL', 'SIGTRAP', 'SIGABRT'];
+
+  // On Windows, v8's base::OS::Abort triggers an access violation,
+  // which corresponds to exit code 3221225477 (0xC0000005)
+  if (process.platform === 'win32')
+    expectedExitCodes = [3221225477];
+
+  // When using --abort-on-uncaught-exception, V8 will use
+  // base::OS::Abort to terminate the process.
+  // Depending on the compiler used, the shell or other aspects of
+  // the platform used to build the node binary, this will actually
+  // make V8 exit by aborting or by raising a signal. In any case,
+  // one of them (exit code or signal) needs to be set to one of
+  // the expected exit codes or signals.
+  if (signal !== null) {
+    return expectedSignals.indexOf(signal) > -1;
+  } else {
+    return expectedExitCodes.indexOf(exitCode) > -1;
+  }
+};