vm: add support for import.meta to Module

Fixes: https://github.com/nodejs/node/issues/18570

PR-URL: https://github.com/nodejs/node/pull/19277
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/doc/api/vm.md b/doc/api/vm.md
index c729ef5999..ed7be81776 100644
--- a/doc/api/vm.md
+++ b/doc/api/vm.md
@@ -167,9 +167,49 @@ const contextifiedSandbox = vm.createContext({ secret: 42 });
     in stack traces produced by this Module.
   * `columnOffset` {integer} Spcifies the column number offset that is displayed
     in stack traces produced by this Module.
+  * `initalizeImportMeta` {Function} Called during evaluation of this Module to
+    initialize the `import.meta`. This function has the signature `(meta,
+    module)`, where `meta` is the `import.meta` object in the Module, and
+    `module` is this `vm.Module` object.
 
 Creates a new ES `Module` object.
 
+*Note*: Properties assigned to the `import.meta` object that are objects may
+allow the Module to access information outside the specified `context`, if the
+object is created in the top level context. Use `vm.runInContext()` to create
+objects in a specific context.
+
+```js
+const vm = require('vm');
+
+const contextifiedSandbox = vm.createContext({ secret: 42 });
+
+(async () => {
+  const module = new vm.Module(
+    'Object.getPrototypeOf(import.meta.prop).secret = secret;',
+    {
+      initializeImportMeta(meta) {
+        // Note: this object is created in the top context. As such,
+        // Object.getPrototypeOf(import.meta.prop) points to the
+        // Object.prototype in the top context rather than that in
+        // the sandbox.
+        meta.prop = {};
+      }
+    });
+  // Since module has no dependencies, the linker function will never be called.
+  await module.link(() => {});
+  module.initialize();
+  await module.evaluate();
+
+  // Now, Object.prototype.secret will be equal to 42.
+  //
+  // To fix this problem, replace
+  //     meta.prop = {};
+  // above with
+  //     meta.prop = vm.runInContext('{}', contextifiedSandbox);
+})();
+```
+
 ### module.dependencySpecifiers
 
 * {string[]}