1 files changed, 672 insertions, 0 deletions
diff --git a/js/src/shell/ModuleLoader.cpp b/js/src/shell/ModuleLoader.cpp
new file mode 100644
index 0000000000..5b22a6d3f0
--- /dev/null
+++ b/js/src/shell/ModuleLoader.cpp
@@ -0,0 +1,672 @@
+/* -*- Mode: javascript; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4
+ * -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "shell/ModuleLoader.h"
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/TextUtils.h"
+
+#include "jsapi.h"
+#include "NamespaceImports.h"
+
+#include "builtin/TestingUtility.h"  // js::CreateScriptPrivate
+#include "js/Conversions.h"
+#include "js/MapAndSet.h"
+#include "js/Modules.h"
+#include "js/PropertyAndElement.h"  // JS_DefineProperty, JS_GetProperty
+#include "js/SourceText.h"
+#include "js/StableStringChars.h"
+#include "shell/jsshell.h"
+#include "shell/OSObject.h"
+#include "shell/StringUtils.h"
+#include "util/Text.h"
+#include "vm/JSAtom.h"
+#include "vm/JSContext.h"
+#include "vm/StringType.h"
+
+using namespace js;
+using namespace js::shell;
+
+static constexpr char16_t JavaScriptScheme[] = u"javascript:";
+
+static bool IsJavaScriptURL(Handle<JSLinearString*> path) {
+  return StringStartsWith(path, JavaScriptScheme);
+}
+
+static JSString* ExtractJavaScriptURLSource(JSContext* cx,
+                                            Handle<JSLinearString*> path) {
+  MOZ_ASSERT(IsJavaScriptURL(path));
+
+  const size_t schemeLength = js_strlen(JavaScriptScheme);
+  return SubString(cx, path, schemeLength);
+}
+
+bool ModuleLoader::init(JSContext* cx, HandleString loadPath) {
+  loadPathStr = AtomizeString(cx, loadPath);
+  if (!loadPathStr || !PinAtom(cx, loadPathStr)) {
+    return false;
+  }
+
+  MOZ_ASSERT(IsAbsolutePath(loadPathStr));
+
+  char16_t sep = PathSeparator;
+  pathSeparatorStr = AtomizeChars(cx, &sep, 1);
+  if (!pathSeparatorStr || !PinAtom(cx, pathSeparatorStr)) {
+    return false;
+  }
+
+  JSRuntime* rt = cx->runtime();
+  JS::SetModuleResolveHook(rt, ModuleLoader::ResolveImportedModule);
+  JS::SetModuleMetadataHook(rt, ModuleLoader::GetImportMetaProperties);
+  JS::SetModuleDynamicImportHook(rt, ModuleLoader::ImportModuleDynamically);
+
+  JS::ImportAssertionVector assertions;
+  MOZ_ALWAYS_TRUE(assertions.reserve(1));
+  assertions.infallibleAppend(JS::ImportAssertion::Type);
+  JS::SetSupportedImportAssertions(rt, assertions);
+
+  return true;
+}
+
+// static
+JSObject* ModuleLoader::ResolveImportedModule(
+    JSContext* cx, JS::HandleValue referencingPrivate,
+    JS::HandleObject moduleRequest) {
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->resolveImportedModule(cx, referencingPrivate,
+                                                  moduleRequest);
+}
+
+// static
+bool ModuleLoader::GetImportMetaProperties(JSContext* cx,
+                                           JS::HandleValue privateValue,
+                                           JS::HandleObject metaObject) {
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->populateImportMeta(cx, privateValue, metaObject);
+}
+
+bool ModuleLoader::ImportMetaResolve(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+  RootedValue modulePrivate(
+      cx, js::GetFunctionNativeReserved(&args.callee(), ModulePrivateSlot));
+
+  // https://html.spec.whatwg.org/#hostgetimportmetaproperties
+  // Step 4.1. Set specifier to ? ToString(specifier).
+  //
+  // https://tc39.es/ecma262/#sec-tostring
+  RootedValue v(cx, args.get(ImportMetaResolveSpecifierArg));
+  RootedString specifier(cx, JS::ToString(cx, v));
+  if (!specifier) {
+    return false;
+  }
+
+  // Step 4.2, 4.3 are implemented in importMetaResolve.
+  ShellContext* scx = GetShellContext(cx);
+  RootedString url(cx);
+  if (!scx->moduleLoader->importMetaResolve(cx, modulePrivate, specifier,
+                                            &url)) {
+    return false;
+  }
+
+  // Step 4.4. Return the serialization of url.
+  args.rval().setString(url);
+  return true;
+}
+
+// static
+bool ModuleLoader::ImportModuleDynamically(JSContext* cx,
+                                           JS::HandleValue referencingPrivate,
+                                           JS::HandleObject moduleRequest,
+                                           JS::HandleObject promise) {
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->dynamicImport(cx, referencingPrivate, moduleRequest,
+                                          promise);
+}
+
+// static
+bool ModuleLoader::GetSupportedImportAssertions(
+    JSContext* cx, JS::ImportAssertionVector& values) {
+  MOZ_ASSERT(values.empty());
+
+  if (!values.reserve(1)) {
+    ReportOutOfMemory(cx);
+    return false;
+  }
+
+  values.infallibleAppend(JS::ImportAssertion::Type);
+
+  return true;
+}
+
+bool ModuleLoader::loadRootModule(JSContext* cx, HandleString path) {
+  RootedValue rval(cx);
+  if (!loadAndExecute(cx, path, &rval)) {
+    return false;
+  }
+
+  RootedObject evaluationPromise(cx, &rval.toObject());
+  if (evaluationPromise == nullptr) {
+    return false;
+  }
+
+  return JS::ThrowOnModuleEvaluationFailure(cx, evaluationPromise);
+}
+
+bool ModuleLoader::registerTestModule(JSContext* cx, HandleObject moduleRequest,
+                                      Handle<ModuleObject*> module) {
+  Rooted<JSLinearString*> path(
+      cx, resolve(cx, moduleRequest, UndefinedHandleValue));
+  if (!path) {
+    return false;
+  }
+
+  path = normalizePath(cx, path);
+  if (!path) {
+    return false;
+  }
+
+  return addModuleToRegistry(cx, path, module);
+}
+
+void ModuleLoader::clearModules(JSContext* cx) {
+  Handle<GlobalObject*> global = cx->global();
+  global->setReservedSlot(GlobalAppSlotModuleRegistry, UndefinedValue());
+}
+
+bool ModuleLoader::loadAndExecute(JSContext* cx, HandleString path,
+                                  MutableHandleValue rval) {
+  RootedObject module(cx, loadAndParse(cx, path));
+  if (!module) {
+    return false;
+  }
+
+  if (!JS::ModuleLink(cx, module)) {
+    return false;
+  }
+
+  return JS::ModuleEvaluate(cx, module, rval);
+}
+
+JSObject* ModuleLoader::resolveImportedModule(
+    JSContext* cx, JS::HandleValue referencingPrivate,
+    JS::HandleObject moduleRequest) {
+  Rooted<JSLinearString*> path(cx,
+                               resolve(cx, moduleRequest, referencingPrivate));
+  if (!path) {
+    return nullptr;
+  }
+
+  return loadAndParse(cx, path);
+}
+
+bool ModuleLoader::populateImportMeta(JSContext* cx,
+                                      JS::HandleValue privateValue,
+                                      JS::HandleObject metaObject) {
+  Rooted<JSLinearString*> path(cx);
+  if (!privateValue.isUndefined()) {
+    if (!getScriptPath(cx, privateValue, &path)) {
+      return false;
+    }
+  }
+
+  if (!path) {
+    path = NewStringCopyZ<CanGC>(cx, "(unknown)");
+    if (!path) {
+      return false;
+    }
+  }
+
+  RootedValue pathValue(cx, StringValue(path));
+  if (!JS_DefineProperty(cx, metaObject, "url", pathValue, JSPROP_ENUMERATE)) {
+    return false;
+  }
+
+  JSFunction* resolveFunc = js::DefineFunctionWithReserved(
+      cx, metaObject, "resolve", ImportMetaResolve, ImportMetaResolveNumArgs,
+      JSPROP_ENUMERATE);
+  if (!resolveFunc) {
+    return false;
+  }
+
+  RootedObject resolveFuncObj(cx, JS_GetFunctionObject(resolveFunc));
+  js::SetFunctionNativeReserved(resolveFuncObj, ModulePrivateSlot,
+                                privateValue);
+
+  return true;
+}
+
+bool ModuleLoader::importMetaResolve(JSContext* cx,
+                                     JS::Handle<JS::Value> referencingPrivate,
+                                     JS::Handle<JSString*> specifier,
+                                     JS::MutableHandle<JSString*> urlOut) {
+  Rooted<JSLinearString*> path(cx, resolve(cx, specifier, referencingPrivate));
+  if (!path) {
+    return false;
+  }
+
+  urlOut.set(path);
+  return true;
+}
+
+bool ModuleLoader::dynamicImport(JSContext* cx,
+                                 JS::HandleValue referencingPrivate,
+                                 JS::HandleObject moduleRequest,
+                                 JS::HandleObject promise) {
+  // To make this more realistic, use a promise to delay the import and make it
+  // happen asynchronously. This method packages up the arguments and creates a
+  // resolved promise, which on fullfillment calls doDynamicImport with the
+  // original arguments.
+
+  MOZ_ASSERT(promise);
+  RootedValue moduleRequestValue(cx, ObjectValue(*moduleRequest));
+  RootedValue promiseValue(cx, ObjectValue(*promise));
+  RootedObject closure(cx, JS_NewObjectWithGivenProto(cx, nullptr, nullptr));
+  if (!closure ||
+      !JS_DefineProperty(cx, closure, "referencingPrivate", referencingPrivate,
+                         JSPROP_ENUMERATE) ||
+      !JS_DefineProperty(cx, closure, "moduleRequest", moduleRequestValue,
+                         JSPROP_ENUMERATE) ||
+      !JS_DefineProperty(cx, closure, "promise", promiseValue,
+                         JSPROP_ENUMERATE)) {
+    return false;
+  }
+
+  RootedFunction onResolved(
+      cx, NewNativeFunction(cx, DynamicImportDelayFulfilled, 1, nullptr));
+  if (!onResolved) {
+    return false;
+  }
+
+  RootedFunction onRejected(
+      cx, NewNativeFunction(cx, DynamicImportDelayRejected, 1, nullptr));
+  if (!onRejected) {
+    return false;
+  }
+
+  RootedObject delayPromise(cx);
+  RootedValue closureValue(cx, ObjectValue(*closure));
+  delayPromise = PromiseObject::unforgeableResolve(cx, closureValue);
+  if (!delayPromise) {
+    return false;
+  }
+
+  return JS::AddPromiseReactions(cx, delayPromise, onResolved, onRejected);
+}
+
+bool ModuleLoader::DynamicImportDelayFulfilled(JSContext* cx, unsigned argc,
+                                               Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+  RootedObject closure(cx, &args[0].toObject());
+
+  RootedValue referencingPrivate(cx);
+  RootedValue moduleRequestValue(cx);
+  RootedValue promiseValue(cx);
+  if (!JS_GetProperty(cx, closure, "referencingPrivate", &referencingPrivate) ||
+      !JS_GetProperty(cx, closure, "moduleRequest", &moduleRequestValue) ||
+      !JS_GetProperty(cx, closure, "promise", &promiseValue)) {
+    return false;
+  }
+
+  RootedObject moduleRequest(cx, &moduleRequestValue.toObject());
+  RootedObject promise(cx, &promiseValue.toObject());
+
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->doDynamicImport(cx, referencingPrivate,
+                                            moduleRequest, promise);
+}
+
+bool ModuleLoader::DynamicImportDelayRejected(JSContext* cx, unsigned argc,
+                                              Value* vp) {
+  MOZ_CRASH("This promise should never be rejected");
+}
+
+bool ModuleLoader::doDynamicImport(JSContext* cx,
+                                   JS::HandleValue referencingPrivate,
+                                   JS::HandleObject moduleRequest,
+                                   JS::HandleObject promise) {
+  // Exceptions during dynamic import are handled by calling
+  // FinishDynamicModuleImport with a pending exception on the context.
+  RootedValue rval(cx);
+  bool ok =
+      tryDynamicImport(cx, referencingPrivate, moduleRequest, promise, &rval);
+  JSObject* evaluationObject = ok ? &rval.toObject() : nullptr;
+  RootedObject evaluationPromise(cx, evaluationObject);
+  return JS::FinishDynamicModuleImport(
+      cx, evaluationPromise, referencingPrivate, moduleRequest, promise);
+}
+
+bool ModuleLoader::tryDynamicImport(JSContext* cx,
+                                    JS::HandleValue referencingPrivate,
+                                    JS::HandleObject moduleRequest,
+                                    JS::HandleObject promise,
+                                    JS::MutableHandleValue rval) {
+  Rooted<JSLinearString*> path(cx,
+                               resolve(cx, moduleRequest, referencingPrivate));
+  if (!path) {
+    return false;
+  }
+
+  return loadAndExecute(cx, path, rval);
+}
+
+JSLinearString* ModuleLoader::resolve(JSContext* cx,
+                                      HandleObject moduleRequestArg,
+                                      HandleValue referencingInfo) {
+  ModuleRequestObject* moduleRequest =
+      &moduleRequestArg->as<ModuleRequestObject>();
+  if (moduleRequest->specifier()->length() == 0) {
+    JS_ReportErrorASCII(cx, "Invalid module specifier");
+    return nullptr;
+  }
+
+  Rooted<JSLinearString*> name(
+      cx, JS_EnsureLinearString(cx, moduleRequest->specifier()));
+  if (!name) {
+    return nullptr;
+  }
+
+  return resolve(cx, name, referencingInfo);
+}
+
+JSLinearString* ModuleLoader::resolve(JSContext* cx, HandleString specifier,
+                                      HandleValue referencingInfo) {
+  Rooted<JSLinearString*> name(cx, JS_EnsureLinearString(cx, specifier));
+  if (!name) {
+    return nullptr;
+  }
+
+  if (IsJavaScriptURL(name) || IsAbsolutePath(name)) {
+    return name;
+  }
+
+  // Treat |name| as a relative path if it starts with either "./" or "../".
+  bool isRelative =
+      StringStartsWith(name, u"./") || StringStartsWith(name, u"../")
+#ifdef XP_WIN
+      || StringStartsWith(name, u".\\") || StringStartsWith(name, u"..\\")
+#endif
+      ;
+
+  RootedString path(cx, loadPathStr);
+
+  if (isRelative) {
+    if (referencingInfo.isUndefined()) {
+      JS_ReportErrorASCII(cx, "No referencing module for relative import");
+      return nullptr;
+    }
+
+    Rooted<JSLinearString*> refPath(cx);
+    if (!getScriptPath(cx, referencingInfo, &refPath)) {
+      return nullptr;
+    }
+
+    if (!refPath) {
+      JS_ReportErrorASCII(cx, "No path set for referencing module");
+      return nullptr;
+    }
+
+    int32_t sepIndex = LastIndexOf(refPath, u'/');
+#ifdef XP_WIN
+    sepIndex = std::max(sepIndex, LastIndexOf(refPath, u'\\'));
+#endif
+    if (sepIndex >= 0) {
+      path = SubString(cx, refPath, 0, sepIndex);
+      if (!path) {
+        return nullptr;
+      }
+    }
+  }
+
+  RootedString result(cx);
+  RootedString pathSep(cx, pathSeparatorStr);
+  result = JS_ConcatStrings(cx, path, pathSep);
+  if (!result) {
+    return nullptr;
+  }
+
+  result = JS_ConcatStrings(cx, result, name);
+  if (!result) {
+    return nullptr;
+  }
+
+  Rooted<JSLinearString*> linear(cx, JS_EnsureLinearString(cx, result));
+  if (!linear) {
+    return nullptr;
+  }
+  return normalizePath(cx, linear);
+}
+
+JSObject* ModuleLoader::loadAndParse(JSContext* cx, HandleString pathArg) {
+  Rooted<JSLinearString*> path(cx, JS_EnsureLinearString(cx, pathArg));
+  if (!path) {
+    return nullptr;
+  }
+
+  path = normalizePath(cx, path);
+  if (!path) {
+    return nullptr;
+  }
+
+  RootedObject module(cx);
+  if (!lookupModuleInRegistry(cx, path, &module)) {
+    return nullptr;
+  }
+
+  if (module) {
+    return module;
+  }
+
+  UniqueChars filename = JS_EncodeStringToLatin1(cx, path);
+  if (!filename) {
+    return nullptr;
+  }
+
+  JS::CompileOptions options(cx);
+  options.setFileAndLine(filename.get(), 1);
+
+  RootedString source(cx, fetchSource(cx, path));
+  if (!source) {
+    return nullptr;
+  }
+
+  JS::AutoStableStringChars linearChars(cx);
+  if (!linearChars.initTwoByte(cx, source)) {
+    return nullptr;
+  }
+
+  JS::SourceText<char16_t> srcBuf;
+  if (!srcBuf.initMaybeBorrowed(cx, linearChars)) {
+    return nullptr;
+  }
+
+  module = JS::CompileModule(cx, options, srcBuf);
+  if (!module) {
+    return nullptr;
+  }
+
+  RootedObject info(cx, js::CreateScriptPrivate(cx, path));
+  if (!info) {
+    return nullptr;
+  }
+
+  JS::SetModulePrivate(module, ObjectValue(*info));
+
+  if (!addModuleToRegistry(cx, path, module)) {
+    return nullptr;
+  }
+
+  return module;
+}
+
+bool ModuleLoader::lookupModuleInRegistry(JSContext* cx, HandleString path,
+                                          MutableHandleObject moduleOut) {
+  moduleOut.set(nullptr);
+
+  RootedObject registry(cx, getOrCreateModuleRegistry(cx));
+  if (!registry) {
+    return false;
+  }
+
+  RootedValue pathValue(cx, StringValue(path));
+  RootedValue moduleValue(cx);
+  if (!JS::MapGet(cx, registry, pathValue, &moduleValue)) {
+    return false;
+  }
+
+  if (!moduleValue.isUndefined()) {
+    moduleOut.set(&moduleValue.toObject());
+  }
+
+  return true;
+}
+
+bool ModuleLoader::addModuleToRegistry(JSContext* cx, HandleString path,
+                                       HandleObject module) {
+  RootedObject registry(cx, getOrCreateModuleRegistry(cx));
+  if (!registry) {
+    return false;
+  }
+
+  RootedValue pathValue(cx, StringValue(path));
+  RootedValue moduleValue(cx, ObjectValue(*module));
+  return JS::MapSet(cx, registry, pathValue, moduleValue);
+}
+
+JSObject* ModuleLoader::getOrCreateModuleRegistry(JSContext* cx) {
+  Handle<GlobalObject*> global = cx->global();
+  RootedValue value(cx, global->getReservedSlot(GlobalAppSlotModuleRegistry));
+  if (!value.isUndefined()) {
+    return &value.toObject();
+  }
+
+  JSObject* registry = JS::NewMapObject(cx);
+  if (!registry) {
+    return nullptr;
+  }
+
+  global->setReservedSlot(GlobalAppSlotModuleRegistry, ObjectValue(*registry));
+  return registry;
+}
+
+bool ModuleLoader::getScriptPath(JSContext* cx, HandleValue privateValue,
+                                 MutableHandle<JSLinearString*> pathOut) {
+  pathOut.set(nullptr);
+
+  RootedObject infoObj(cx, &privateValue.toObject());
+  RootedValue pathValue(cx);
+  if (!JS_GetProperty(cx, infoObj, "path", &pathValue)) {
+    return false;
+  }
+
+  if (pathValue.isUndefined()) {
+    return true;
+  }
+
+  RootedString path(cx, pathValue.toString());
+  pathOut.set(JS_EnsureLinearString(cx, path));
+  return pathOut;
+}
+
+JSLinearString* ModuleLoader::normalizePath(JSContext* cx,
+                                            Handle<JSLinearString*> pathArg) {
+  Rooted<JSLinearString*> path(cx, pathArg);
+
+  if (IsJavaScriptURL(path)) {
+    return path;
+  }
+
+#ifdef XP_WIN
+  // Replace all forward slashes with backward slashes.
+  path = ReplaceCharGlobally(cx, path, u'/', PathSeparator);
+  if (!path) {
+    return nullptr;
+  }
+
+  // Remove the drive letter, if present.
+  Rooted<JSLinearString*> drive(cx);
+  if (path->length() > 2 && mozilla::IsAsciiAlpha(CharAt(path, 0)) &&
+      CharAt(path, 1) == u':' && CharAt(path, 2) == u'\\') {
+    drive = SubString(cx, path, 0, 2);
+    path = SubString(cx, path, 2);
+    if (!drive || !path) {
+      return nullptr;
+    }
+  }
+#endif  // XP_WIN
+
+  // Normalize the path by removing redundant path components.
+  Rooted<GCVector<JSLinearString*>> components(cx, cx);
+  size_t lastSep = 0;
+  while (lastSep < path->length()) {
+    int32_t i = IndexOf(path, PathSeparator, lastSep);
+    if (i < 0) {
+      i = path->length();
+    }
+
+    Rooted<JSLinearString*> part(cx, SubString(cx, path, lastSep, i));
+    if (!part) {
+      return nullptr;
+    }
+
+    lastSep = i + 1;
+
+    // Remove "." when preceded by a path component.
+    if (StringEquals(part, u".") && !components.empty()) {
+      continue;
+    }
+
+    if (StringEquals(part, u"..") && !components.empty()) {
+      // Replace "./.." with "..".
+      if (StringEquals(components.back(), u".")) {
+        components.back() = part;
+        continue;
+      }
+
+      // When preceded by a non-empty path component, remove ".." and the
+      // preceding component, unless the preceding component is also "..".
+      if (!StringEquals(components.back(), u"") &&
+          !StringEquals(components.back(), u"..")) {
+        components.popBack();
+        continue;
+      }
+    }
+
+    if (!components.append(part)) {
+      return nullptr;
+    }
+  }
+
+  Rooted<JSLinearString*> pathSep(cx, pathSeparatorStr);
+  RootedString normalized(cx, JoinStrings(cx, components, pathSep));
+  if (!normalized) {
+    return nullptr;
+  }
+
+#ifdef XP_WIN
+  if (drive) {
+    normalized = JS_ConcatStrings(cx, drive, normalized);
+    if (!normalized) {
+      return nullptr;
+    }
+  }
+#endif
+
+  return JS_EnsureLinearString(cx, normalized);
+}
+
+JSString* ModuleLoader::fetchSource(JSContext* cx,
+                                    Handle<JSLinearString*> path) {
+  if (IsJavaScriptURL(path)) {
+    return ExtractJavaScriptURLSource(cx, path);
+  }
+
+  RootedString resolvedPath(cx, ResolvePath(cx, path, RootRelative));
+  if (!resolvedPath) {
+    return nullptr;
+  }
+
+  return FileAsString(cx, resolvedPath);
+}