domains: port caeb677 from v0.10 to v0.12

caeb677
Do not abort the process if an error is thrown from within a domain,
an error handler is setup for the domain and
--abort-on-uncaught-exception was passed on the command line.

However, if an error is thrown from within the top-level domain's
error handler and --abort-on-uncaught-exception was passed on the
command line, make the process abort.

Fixes: #8877

Fixes: #8877
PR-URL: #25835
Reviewed-By: misterdjules - Julien Gilli <[email protected]>

Author: whitlockjc

lib/domain.js

@@ -77,6 +77,20 @@ Domain.prototype._disposed = undefined;
 // Called by process._fatalException in case an error was thrown.
 Domain.prototype._errorHandler = function errorHandler(er) {
   var caught = false;
+  var self = this;
+
+  function emitError() {
+    var handled = self.emit('error', er);
+
+    // Exit all domains on the stack.  Uncaught exceptions end the
+    // current tick and no domains should be left on the stack
+    // between ticks.
+    stack.length = 0;
+    exports.active = process.domain = null;
+
+    return handled;
+  }
+
   // ignore errors on disposed domains.
   //
   // XXX This is a bit stupid.  We should probably get rid of
@@ -89,38 +103,54 @@ Domain.prototype._errorHandler = function errorHandler(er) {
     er.domain = this;
     er.domainThrown = true;
   }
-  // wrap this in a try/catch so we don't get infinite throwing
-  try {
-    // One of three things will happen here.
-    //
-    // 1. There is a handler, caught = true
-    // 2. There is no handler, caught = false
-    // 3. It throws, caught = false
-    //
-    // If caught is false after this, then there's no need to exit()
-    // the domain, because we're going to crash the process anyway.
-    caught = this.emit('error', er);
 
-    // Exit all domains on the stack.  Uncaught exceptions end the
-    // current tick and no domains should be left on the stack
-    // between ticks.
-    stack.length = 0;
-    exports.active = process.domain = null;
-  } catch (er2) {
-    // The domain error handler threw!  oh no!
-    // See if another domain can catch THIS error,
-    // or else crash on the original one.
-    // If the user already exited it, then don't double-exit.
-    if (this === exports.active) {
-      stack.pop();
+  // The top-level domain-handler is handled separately.
+  //
+  // The reason is that if V8 was passed a command line option
+  // asking it to abort on an uncaught exception (currently
+  // "--abort-on-uncaught-exception"), we want an uncaught exception
+  // in the top-level domain error handler to make the
+  // process abort. Using try/catch here would always make V8 think
+  // 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 (stack.length) {
-      exports.active = process.domain = stack[stack.length - 1];
-      caught = process._fatalException(er2);
-    } else {
-      caught = false;
+  } else {
+    // wrap this in a try/catch so we don't get infinite throwing
+    try {
+      // One of three things will happen here.
+      //
+      // 1. There is a handler, caught = true
+      // 2. There is no handler, caught = false
+      // 3. It throws, caught = false
+      //
+      // If caught is false after this, then there's no need to exit()
+      // the domain, because we're going to crash the process anyway.
+      caught = emitError();
+    } catch (er2) {
+      // The domain error handler threw!  oh no!
+      // See if another domain can catch THIS error,
+      // or else crash on the original one.
+      // If the user already exited it, then don't double-exit.
+      if (this === exports.active) {
+        stack.pop();
+      }
+      if (stack.length) {
+        exports.active = process.domain = stack[stack.length - 1];
+        caught = process._fatalException(er2);
+      } else {
+        caught = false;
+      }
+      return caught;
     }
-    return caught;
   }
   return caught;
 };

src/env.h

@@ -86,6 +86,7 @@ namespace node {
   V(dev_string, "dev")                                                        \
   V(disposed_string, "_disposed")                                             \
   V(domain_string, "domain")                                                  \
+  V(emitting_top_level_domain_error_string, "_emittingTopLevelDomainError")   \
   V(exchange_string, "exchange")                                              \
   V(idle_string, "idle")                                                      \
   V(irq_string, "irq")                                                        \

src/node.cc

@@ -909,6 +909,33 @@ Local<Value> WinapiErrnoException(Isolate* isolate,
 #endif
 
 
+static bool IsDomainActive(const Environment* env) {
+  if (!env->using_domains()) {
+    return false;
+  }
+
+  Local<Array> domain_array = env->domain_array().As<Array>();
+  uint32_t domains_array_length = domain_array->Length();
+  if (domains_array_length == 0)
+    return false;
+
+  Local<Value> domain_v = domain_array->Get(0);
+  return !domain_v->IsNull();
+}
+
+
+bool ShouldAbortOnUncaughtException(v8::Isolate* isolate) {
+  Environment* env = Environment::GetCurrent(isolate);
+  Local<Object> process_object = env->process_object();
+  Local<String> emitting_top_level_domain_error_key =
+    env->emitting_top_level_domain_error_string();
+  bool isEmittingTopLevelDomainError =
+    process_object->Get(emitting_top_level_domain_error_key)->BooleanValue();
+
+  return !IsDomainActive(env) || isEmittingTopLevelDomainError;
+}
+
+
 void SetupDomainUse(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args.GetIsolate());
 
@@ -2772,6 +2799,9 @@ void SetupProcessObject(Environment* env,
 
   // pre-set _events object for faster emit checks
   process->Set(env->events_string(), Object::New(env->isolate()));
+
+  process->Set(env->emitting_top_level_domain_error_string(),
+               False(env->isolate()));
 }
 
 
@@ -3453,6 +3483,8 @@ void Init(int* argc,
   node_isolate = Isolate::New();
   Isolate::Scope isolate_scope(node_isolate);
 
+  node_isolate->SetAbortOnUncaughtException(ShouldAbortOnUncaughtException);
+
 #ifdef __POSIX__
   // Raise the open file descriptor limit.
   {  // NOLINT (whitespace/braces)

test/simple/test-domain-top-level-error-handler-throw.js

@@ -0,0 +1,74 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+/*
+ * The goal of this test is to make sure that when a top-level error
+ * handler throws an error following the handling of a previous error,
+ * the process reports the error message from the error thrown in the
+ * top-level error handler, not the one from the previous error.
+ */
+
+var domainErrHandlerExMessage = 'exception from domain error handler';
+var internalExMessage = 'You should NOT see me';
+
+if (process.argv[2] === 'child') {
+  var domain = require('domain');
+  var d = domain.create();
+
+  d.on('error', function() {
+    throw new Error(domainErrHandlerExMessage);
+  });
+
+  d.run(function doStuff() {
+    process.nextTick(function () {
+      throw new Error(internalExMessage);
+    });
+  });
+} else {
+  var fork = require('child_process').fork;
+  var assert = require('assert');
+
+  function test() {
+    var child = fork(process.argv[1], ['child'], {silent:true});
+    var gotDataFromStderr = false;
+    var stderrOutput = '';
+    if (child) {
+      child.stderr.on('data', function onStderrData(data) {
+        gotDataFromStderr = true;
+        stderrOutput += data.toString();
+      });
+
+      child.on('exit', function onChildExited(exitCode, signal) {
+        assert(gotDataFromStderr);
+        assert(stderrOutput.indexOf(domainErrHandlerExMessage) !== -1);
+        assert(stderrOutput.indexOf(internalExMessage) === -1);
+
+        var expectedExitCode = 7;
+        var expectedSignal = null;
+
+        assert.equal(exitCode, expectedExitCode);
+        assert.equal(signal, expectedSignal);
+      });
+    }
+  }
+
+  test();
+}