auto attachment from runInContext

Not recommended for multiple runs on the same context.
nodejs · TimothyGu · Jul 14, 2017 · Jul 14, 2017 · Jul 15, 2017 · Jul 17, 2017
commit fc7d4085bba9ce4a7a9defd038ff168f4854143f
diff --git a/lib/vm.js b/lib/vm.js
@@ -23,6 +23,13 @@
 
 const binding = process.binding('contextify');
 const Script = binding.ContextifyScript;
+const { contextAttached, attachContext, detachContext } = (() => {
+  try {
+    return require('inspector');
+  } catch (err) {
+    return {};
+  }
+})();
 
 // The binding provides a few useful primitives:
 // - Script(code, { filename = "evalmachine.anonymous",
@@ -46,11 +53,23 @@ Script.prototype.runInThisContext = function(options) {
 };
 
 Script.prototype.runInContext = function(contextifiedSandbox, options) {
-  if (options && options.breakOnSigint && process._events.SIGINT) {
-    return sigintHandlersWrap(realRunInContext, this,
-                              [contextifiedSandbox, options]);
-  } else {
-    return realRunInContext.call(this, contextifiedSandbox, options);
+  const needToAttach = contextAttached &&
+                       !(options && options.doNotInformInspector) &&
+                       !contextAttached(contextifiedSandbox);
+  if (needToAttach) {
+    attachContext(contextifiedSandbox);
+  }
+  try {
+    if (options && options.breakOnSigint && process._events.SIGINT) {
+      return sigintHandlersWrap(realRunInContext, this,
+                                [contextifiedSandbox, options]);
+    } else {
+      return realRunInContext.call(this, contextifiedSandbox, options);
+    }
+  } finally {
+    if (needToAttach) {
+      detachContext(contextifiedSandbox);
+    }
   }
 };
 

diff --git a/test/inspector/test-inspector-contexts-js.js b/test/inspector/test-inspector-contexts-js.js
@@ -10,7 +10,7 @@ const {
   contextAttached
 } = require('inspector');
 const { promisify } = require('util');
-const { createContext } = require('vm');
+const { createContext, runInContext } = require('vm');
 
 common.crashOnUnhandledRejection();
 
@@ -97,6 +97,43 @@ async function main() {
       await eventPromise;
       assert.strictEqual(contextAttached(sandbox), false);
     }
+
+    // Re-attaching contextified sandbox.
+    {
+      const VM_CONTEXT_NAME = 'New VM Context';
+      const VM_CONTEXT_ORIGIN = 'https://nodejs.org/api/vm.html';
+
+      const eventPromise = fires(once('Runtime.executionContextCreated'));
+      attachContext(sandbox, {
+        name: VM_CONTEXT_NAME,
+        origin: VM_CONTEXT_ORIGIN
+      });
+      vmContext = (await eventPromise).params.context;
+      assert.strictEqual(vmContext.name, VM_CONTEXT_NAME);
+      assert.strictEqual(vmContext.origin, VM_CONTEXT_ORIGIN);
+      assert.strictEqual(vmContext.auxData.isDefault, false);
+      assert.strictEqual(contextAttached(sandbox), true);
+    }
+
+    // Evaluating expressions in the specified context.
+    {
+      const { result } = await post('Runtime.evaluate', {
+        expression: 'propInSandbox++',
+        contextId: vmContext.id
+      });
+      assert.strictEqual(result.type, 'number');
+      assert.strictEqual(result.value, 43);
+      assert.strictEqual(sandbox.propInSandbox, 44);
+    }
+
+    // Detach context.
+    {
+      const eventPromise = fires(once('Runtime.executionContextDestroyed'));
+      detachContext(sandbox);
+      const destroyedId = (await eventPromise).params.executionContextId;
+      assert.strictEqual(destroyedId, vmContext.id);
+      assert.strictEqual(contextAttached(sandbox), false);
+    }
   }
 
   // Default context names.
@@ -124,6 +161,56 @@ async function main() {
     }
   }
 
+  // Automatic attachment from vm.runInContext.
+  {
+    const sandbox = {
+      propInSandbox: 42
+    };
+    createContext(sandbox);
+    {
+      const createdPromise = fires(once('Runtime.executionContextCreated'));
+      const destroyedPromise = fires(once('Runtime.executionContextDestroyed'));
+      const result = runInContext('propInSandbox++', sandbox);
+      assert.strictEqual(result, 42);
+      assert.strictEqual(sandbox.propInSandbox, 43);
+      await createdPromise;
+      await destroyedPromise;
+      assert.strictEqual(contextAttached(sandbox), false);
+    }
+
+    // doNotInformInspector
+    {
+      const createdPromise =
+          neverFires(once('Runteme.executionContextCreated'));
+      const destroyedPromise =
+          neverFires(once('Runtime.executionContextDestroyed'));
+      const result = runInContext('propInSandbox++', sandbox, {
+        doNotInformInspector: true
+      });
+      assert.strictEqual(result, 43);
+      assert.strictEqual(sandbox.propInSandbox, 44);
+      await createdPromise;
+      await destroyedPromise;
+      assert.strictEqual(contextAttached(sandbox), false);
+    }
+
+    // Do not try to attach or detach when sandbox is already attached.
+    attachContext(sandbox);
+    {
+      const createdPromise =
+          neverFires(once('Runtime.executionContextCreated'));
+      const destroyedPromise =
+          neverFires(once('Runtime.executionContextDestroyed'));
+      const result = runInContext('propInSandbox++', sandbox);
+      assert.strictEqual(result, 44);
+      assert.strictEqual(sandbox.propInSandbox, 45);
+      await createdPromise;
+      await destroyedPromise;
+      assert.strictEqual(contextAttached(sandbox), true);
+    }
+    detachContext(sandbox);
+  }
+
   session.disconnect();
 }