1 files changed, 574 insertions, 0 deletions
diff --git a/js/src/shell/ModuleLoader.cpp b/js/src/shell/ModuleLoader.cpp
new file mode 100644
index 0000000000..8127787d53
--- /dev/null
+++ b/js/src/shell/ModuleLoader.cpp
@@ -0,0 +1,574 @@
+/* -*- 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 "NamespaceImports.h"
+
+#include "js/Modules.h"
+#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(HandleLinearString path) {
+  return StringStartsWith(path, JavaScriptScheme);
+}
+
+static JSString* ExtractJavaScriptURLSource(JSContext* cx,
+                                            HandleLinearString 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, PinAtom);
+  if (!loadPathStr) {
+    return false;
+  }
+
+  MOZ_ASSERT(IsAbsolutePath(loadPathStr));
+
+  char16_t sep = PathSeparator;
+  pathSeparatorStr = AtomizeChars(cx, &sep, 1);
+  if (!pathSeparatorStr) {
+    return false;
+  }
+
+  JSRuntime* rt = cx->runtime();
+  JS::SetModuleResolveHook(rt, ModuleLoader::ResolveImportedModule);
+  JS::SetModuleMetadataHook(rt, ModuleLoader::GetImportMetaProperties);
+  JS::SetModuleDynamicImportHook(rt, ModuleLoader::ImportModuleDynamically);
+
+  return true;
+}
+
+// static
+JSObject* ModuleLoader::ResolveImportedModule(
+    JSContext* cx, JS::HandleValue referencingPrivate,
+    JS::HandleString specifier) {
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->resolveImportedModule(cx, referencingPrivate,
+                                                  specifier);
+}
+
+// static
+bool ModuleLoader::GetImportMetaProperties(JSContext* cx,
+                                           JS::HandleValue privateValue,
+                                           JS::HandleObject metaObject) {
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->populateImportMeta(cx, privateValue, metaObject);
+}
+
+// static
+bool ModuleLoader::ImportModuleDynamically(JSContext* cx,
+                                           JS::HandleValue referencingPrivate,
+                                           JS::HandleString specifier,
+                                           JS::HandleObject promise) {
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->dynamicImport(cx, referencingPrivate, specifier,
+                                          promise);
+}
+
+bool ModuleLoader::loadRootModule(JSContext* cx, HandleString path) {
+  RootedValue rval(cx);
+  if (!loadAndExecute(cx, path, &rval)) {
+    return false;
+  }
+
+  if (cx->options().topLevelAwait()) {
+    RootedObject evaluationPromise(cx, &rval.toObject());
+    if (evaluationPromise == nullptr) {
+      return false;
+    }
+
+    return JS::ThrowOnModuleEvaluationFailure(cx, evaluationPromise);
+  }
+  return true;
+}
+
+bool ModuleLoader::registerTestModule(JSContext* cx, HandleString specifier,
+                                      HandleModuleObject module) {
+  RootedLinearString path(cx, resolve(cx, specifier, UndefinedHandleValue));
+  if (!path) {
+    return false;
+  }
+
+  path = normalizePath(cx, path);
+  if (!path) {
+    return false;
+  }
+
+  return addModuleToRegistry(cx, path, module);
+}
+
+bool ModuleLoader::loadAndExecute(JSContext* cx, HandleString path,
+                                  MutableHandleValue rval) {
+  RootedObject module(cx, loadAndParse(cx, path));
+  if (!module) {
+    return false;
+  }
+
+  if (!JS::ModuleInstantiate(cx, module)) {
+    return false;
+  }
+
+  return JS::ModuleEvaluate(cx, module, rval);
+}
+
+JSObject* ModuleLoader::resolveImportedModule(
+    JSContext* cx, JS::HandleValue referencingPrivate,
+    JS::HandleString specifier) {
+  RootedLinearString path(cx, resolve(cx, specifier, referencingPrivate));
+  if (!path) {
+    return nullptr;
+  }
+
+  return loadAndParse(cx, path);
+}
+
+bool ModuleLoader::populateImportMeta(JSContext* cx,
+                                      JS::HandleValue privateValue,
+                                      JS::HandleObject metaObject) {
+  RootedLinearString 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));
+  return JS_DefineProperty(cx, metaObject, "url", pathValue, JSPROP_ENUMERATE);
+}
+
+bool ModuleLoader::dynamicImport(JSContext* cx,
+                                 JS::HandleValue referencingPrivate,
+                                 JS::HandleString specifier,
+                                 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 specifierValue(cx, StringValue(specifier));
+  RootedValue promiseValue(cx, ObjectValue(*promise));
+  RootedObject closure(cx, JS_NewPlainObject(cx));
+  if (!closure ||
+      !JS_DefineProperty(cx, closure, "referencingPrivate", referencingPrivate,
+                         JSPROP_ENUMERATE) ||
+      !JS_DefineProperty(cx, closure, "specifier", specifierValue,
+                         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 specifierValue(cx);
+  RootedValue promiseValue(cx);
+  if (!JS_GetProperty(cx, closure, "referencingPrivate", &referencingPrivate) ||
+      !JS_GetProperty(cx, closure, "specifier", &specifierValue) ||
+      !JS_GetProperty(cx, closure, "promise", &promiseValue)) {
+    return false;
+  }
+
+  RootedString specifier(cx, specifierValue.toString());
+  RootedObject promise(cx, &promiseValue.toObject());
+
+  ShellContext* scx = GetShellContext(cx);
+  return scx->moduleLoader->doDynamicImport(cx, referencingPrivate, specifier,
+                                            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::HandleString specifier,
+                                   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, specifier, promise, &rval);
+  if (cx->options().topLevelAwait()) {
+    JSObject* evaluationObject = ok ? &rval.toObject() : nullptr;
+    RootedObject evaluationPromise(cx, evaluationObject);
+    return JS::FinishDynamicModuleImport(
+        cx, evaluationPromise, referencingPrivate, specifier, promise);
+  }
+  JS::DynamicImportStatus status =
+      ok ? JS::DynamicImportStatus::Ok : JS::DynamicImportStatus::Failed;
+  return JS::FinishDynamicModuleImport_NoTLA(cx, status, referencingPrivate,
+                                             specifier, promise);
+}
+
+bool ModuleLoader::tryDynamicImport(JSContext* cx,
+                                    JS::HandleValue referencingPrivate,
+                                    JS::HandleString specifier,
+                                    JS::HandleObject promise,
+                                    JS::MutableHandleValue rval) {
+  RootedLinearString path(cx, resolve(cx, specifier, referencingPrivate));
+  if (!path) {
+    return false;
+  }
+
+  return loadAndExecute(cx, path, rval);
+}
+
+JSLinearString* ModuleLoader::resolve(JSContext* cx, HandleString nameArg,
+                                      HandleValue referencingInfo) {
+  if (nameArg->length() == 0) {
+    JS_ReportErrorASCII(cx, "Invalid module specifier");
+    return nullptr;
+  }
+
+  RootedLinearString name(cx, JS_EnsureLinearString(cx, nameArg));
+  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;
+    }
+
+    RootedLinearString 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;
+  }
+
+  return JS_EnsureLinearString(cx, result);
+}
+
+JSObject* ModuleLoader::loadAndParse(JSContext* cx, HandleString pathArg) {
+  RootedLinearString 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 stableChars(cx);
+  if (!stableChars.initTwoByte(cx, source)) {
+    return nullptr;
+  }
+
+  const char16_t* chars = stableChars.twoByteRange().begin().get();
+  JS::SourceText<char16_t> srcBuf;
+  if (!srcBuf.init(cx, chars, source->length(),
+                   JS::SourceOwnership::Borrowed)) {
+    return nullptr;
+  }
+
+  module = JS::CompileModule(cx, options, srcBuf);
+  if (!module) {
+    return nullptr;
+  }
+
+  RootedObject info(cx, 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,
+                                            HandleLinearString pathArg) {
+  RootedLinearString 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.
+  RootedLinearString 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);
+  size_t lastSep = 0;
+  while (lastSep < path->length()) {
+    int32_t i = IndexOf(path, PathSeparator, lastSep);
+    if (i < 0) {
+      i = path->length();
+    }
+
+    RootedLinearString 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;
+    }
+  }
+
+  RootedLinearString 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, HandleLinearString path) {
+  if (IsJavaScriptURL(path)) {
+    return ExtractJavaScriptURLSource(cx, path);
+  }
+
+  RootedString resolvedPath(cx, ResolvePath(cx, path, RootRelative));
+  if (!resolvedPath) {
+    return nullptr;
+  }
+
+  return FileAsString(cx, resolvedPath);
+}