ScriptLoadRequest.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#ifndef js_loader_ScriptLoadRequest_h
#define js_loader_ScriptLoadRequest_h

#include "js/AllocPolicy.h"
#include "js/RootingAPI.h"
#include "js/SourceText.h"
#include "js/TypeDecls.h"
#include "mozilla/Atomics.h"
#include "mozilla/Assertions.h"
#include "mozilla/CORSMode.h"
#include "mozilla/dom/SRIMetadata.h"
#include "mozilla/dom/ReferrerPolicyBinding.h"
#include "mozilla/LinkedList.h"
#include "mozilla/Maybe.h"
#include "mozilla/MaybeOneOf.h"
#include "mozilla/PreloaderBase.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/Utf8.h"  // mozilla::Utf8Unit
#include "mozilla/Variant.h"
#include "mozilla/Vector.h"
#include "nsCOMPtr.h"
#include "nsCycleCollectionParticipant.h"
#include "nsIGlobalObject.h"
#include "ScriptKind.h"
#include "nsIScriptElement.h"

class nsICacheInfoChannel;

namespace mozilla::dom {

class ScriptLoadContext;
class WorkerLoadContext;
class WorkletLoadContext;

}  // namespace mozilla::dom

namespace mozilla::loader {
class ComponentLoadContext;
}  // namespace mozilla::loader

namespace JS {
class OffThreadToken;

namespace loader {

using Utf8Unit = mozilla::Utf8Unit;

class LoadContextBase;
class ModuleLoadRequest;
class ScriptLoadRequestList;

/*
 * ScriptFetchOptions loosely corresponds to HTML's "script fetch options",
 * https://html.spec.whatwg.org/multipage/webappapis.html#script-fetch-options
 * with the exception of the following properties:
 *   cryptographic nonce
 *      The cryptographic nonce metadata used for the initial fetch and for
 *      fetching any imported modules. As this is populated by a DOM element,
 *      this is implemented via mozilla::dom::Element as the field
 *      mElement. The default value is an empty string, and is indicated
 *      when this field is a nullptr. Nonce is not represented on the dom
 *      side as per bug 1374612.
 *   parser metadata
 *      The parser metadata used for the initial fetch and for fetching any
 *      imported modules. This is populated from a mozilla::dom::Element and is
 *      handled by the field mElement. The default value is an empty string,
 *      and is indicated when this field is a nullptr.
 *   integrity metadata
 *      The integrity metadata used for the initial fetch. This is
 *      implemented in ScriptLoadRequest, as it changes for every
 *      ScriptLoadRequest.
 *
 * In the case of classic scripts without dynamic import, this object is
 * used once. For modules, this object is propogated throughout the module
 * tree. If there is a dynamically imported module in any type of script,
 * the ScriptFetchOptions object will be propogated from its importer.
 */

class ScriptFetchOptions {
  ~ScriptFetchOptions();

 public:
  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(ScriptFetchOptions)
  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ScriptFetchOptions)

  ScriptFetchOptions(mozilla::CORSMode aCORSMode,
                     enum mozilla::dom::ReferrerPolicy aReferrerPolicy,
                     nsIPrincipal* aTriggeringPrincipal,
                     mozilla::dom::Element* aElement = nullptr);

  /*
   *  The credentials mode used for the initial fetch (for module scripts)
   *  and for fetching any imported modules (for both module scripts and
   *  classic scripts)
   */
  const mozilla::CORSMode mCORSMode;

  /*
   *  The referrer policy used for the initial fetch and for fetching any
   *  imported modules
   */
  const enum mozilla::dom::ReferrerPolicy mReferrerPolicy;

  /*
   *  Used to determine CSP and if we are on the About page.
   *  Only used in DOM content scripts.
   *  TODO: Move to ScriptLoadContext
   */
  nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
  /*
   *  Represents fields populated by DOM elements (nonce, parser metadata)
   *  Leave this field as a nullptr for any fetch that requires the
   *  default classic script options.
   *  (https://html.spec.whatwg.org/multipage/webappapis.html#default-classic-script-fetch-options)
   *  TODO: extract necessary fields rather than passing this object
   */
  nsCOMPtr<mozilla::dom::Element> mElement;
};

/*
 * ScriptLoadRequest
 *
 * ScriptLoadRequest is a generic representation of a JavaScript script that
 * will be loaded by a Script/Module loader. This representation is used by the
 * DOM ScriptLoader and will be used by workers and MOZJSComponentLoader.
 *
 * The ScriptLoadRequest contains information about the kind of script (classic
 * or module), the URI, and the ScriptFetchOptions associated with the script.
 * It is responsible for holding the script data once the fetch is complete, or
 * if the request is cached, the bytecode.
 *
 * Relationship to ScriptLoadContext:
 *
 * ScriptLoadRequest and ScriptLoadContexts have a circular pointer.  A
 * ScriptLoadContext augments the loading of a ScriptLoadRequest by providing
 * additional information regarding the loading and evaluation behavior (see
 * the ScriptLoadContext class for details).  In terms of responsibility,
 * the ScriptLoadRequest represents "What" is being loaded, and the
 * ScriptLoadContext represents "How".
 *
 * TODO: see if we can use it in the jsshell script loader. We need to either
 * remove ISUPPORTS or find a way to encorporate that in the jsshell. We would
 * then only have one implementation of the script loader, and it would be
 * tested whenever jsshell tests are run. This would mean finding another way to
 * create ScriptLoadRequest lists.
 *
 */

class ScriptLoadRequest
    : public nsISupports,
      private mozilla::LinkedListElement<ScriptLoadRequest> {
  using super = LinkedListElement<ScriptLoadRequest>;

  // Allow LinkedListElement<ScriptLoadRequest> to cast us to itself as needed.
  friend class mozilla::LinkedListElement<ScriptLoadRequest>;
  friend class ScriptLoadRequestList;

 protected:
  virtual ~ScriptLoadRequest();

 public:
  using SRIMetadata = mozilla::dom::SRIMetadata;
  ScriptLoadRequest(ScriptKind aKind, nsIURI* aURI,
                    ScriptFetchOptions* aFetchOptions,
                    const SRIMetadata& aIntegrity, nsIURI* aReferrer,
                    LoadContextBase* aContext);

  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ScriptLoadRequest)

  using super::getNext;
  using super::isInList;

  template <typename T>
  using VariantType = mozilla::VariantType<T>;

  template <typename... Ts>
  using Variant = mozilla::Variant<Ts...>;

  template <typename T, typename D = JS::DeletePolicy<T>>
  using UniquePtr = mozilla::UniquePtr<T, D>;

  using MaybeSourceText =
      mozilla::MaybeOneOf<JS::SourceText<char16_t>, JS::SourceText<Utf8Unit>>;

  bool IsModuleRequest() const { return mKind == ScriptKind::eModule; }
  bool IsImportMapRequest() const { return mKind == ScriptKind::eImportMap; }

  ModuleLoadRequest* AsModuleRequest();
  const ModuleLoadRequest* AsModuleRequest() const;

  virtual bool IsTopLevel() const { return true; };

  virtual void Cancel();

  virtual void SetReady();

  enum class State : uint8_t {
    Fetching,
    Compiling,
    LoadingImports,
    Ready,
    Canceled
  };

  bool IsFetching() const { return mState == State::Fetching; }
  bool IsCompiling() const { return mState == State::Compiling; }
  bool IsLoadingImports() const { return mState == State::LoadingImports; }

  bool IsReadyToRun() const {
    return mState == State::Ready || mState == State::Canceled;
  }

  bool IsCanceled() const { return mState == State::Canceled; }

  // Type of data provided by the nsChannel.
  enum class DataType : uint8_t { eUnknown, eTextSource, eBytecode };

  bool IsUnknownDataType() const { return mDataType == DataType::eUnknown; }
  bool IsTextSource() const { return mDataType == DataType::eTextSource; }
  bool IsSource() const { return IsTextSource(); }

  void SetUnknownDataType() {
    mDataType = DataType::eUnknown;
    mScriptData.reset();
  }

  bool IsUTF8ParsingEnabled();

  void SetTextSource() {
    MOZ_ASSERT(IsUnknownDataType());
    mDataType = DataType::eTextSource;
    if (IsUTF8ParsingEnabled()) {
      mScriptData.emplace(VariantType<ScriptTextBuffer<Utf8Unit>>());
    } else {
      mScriptData.emplace(VariantType<ScriptTextBuffer<char16_t>>());
    }
  }

  // Use a vector backed by the JS allocator for script text so that contents
  // can be transferred in constant time to the JS engine, not copied in linear
  // time.
  template <typename Unit>
  using ScriptTextBuffer = mozilla::Vector<Unit, 0, js::MallocAllocPolicy>;

  bool IsUTF16Text() const {
    return mScriptData->is<ScriptTextBuffer<char16_t>>();
  }
  bool IsUTF8Text() const {
    return mScriptData->is<ScriptTextBuffer<Utf8Unit>>();
  }

  template <typename Unit>
  const ScriptTextBuffer<Unit>& ScriptText() const {
    MOZ_ASSERT(IsTextSource());
    return mScriptData->as<ScriptTextBuffer<Unit>>();
  }
  template <typename Unit>
  ScriptTextBuffer<Unit>& ScriptText() {
    MOZ_ASSERT(IsTextSource());
    return mScriptData->as<ScriptTextBuffer<Unit>>();
  }

  size_t ScriptTextLength() const {
    MOZ_ASSERT(IsTextSource());
    return IsUTF16Text() ? ScriptText<char16_t>().length()
                         : ScriptText<Utf8Unit>().length();
  }

  // Get source text.  On success |aMaybeSource| will contain either UTF-8 or
  // UTF-16 source; on failure it will remain in its initial state.
  nsresult GetScriptSource(JSContext* aCx, MaybeSourceText* aMaybeSource);

  void ClearScriptText() {
    MOZ_ASSERT(IsTextSource());
    return IsUTF16Text() ? ScriptText<char16_t>().clearAndFree()
                         : ScriptText<Utf8Unit>().clearAndFree();
  }

  enum mozilla::dom::ReferrerPolicy ReferrerPolicy() const {
    return mFetchOptions->mReferrerPolicy;
  }

  nsIPrincipal* TriggeringPrincipal() const {
    return mFetchOptions->mTriggeringPrincipal;
  }

  void ClearScriptSource();

  void MarkForBytecodeEncoding(JSScript* aScript);

  bool IsMarkedForBytecodeEncoding() const;

  bool IsBytecode() const { return mDataType == DataType::eBytecode; }

  void SetBytecode();

  mozilla::CORSMode CORSMode() const { return mFetchOptions->mCORSMode; }

  void DropBytecodeCacheReferences();

  bool HasLoadContext() const { return mLoadContext; }
  bool HasScriptLoadContext() const;
  bool HasWorkerLoadContext() const;

  mozilla::dom::ScriptLoadContext* GetScriptLoadContext();

  mozilla::loader::ComponentLoadContext* GetComponentLoadContext();

  mozilla::dom::WorkerLoadContext* GetWorkerLoadContext();

  mozilla::dom::WorkletLoadContext* GetWorkletLoadContext();

  const ScriptKind mKind;  // Whether this is a classic script or a module
                           // script.

  State mState;           // Are we still waiting for a load to complete?
  bool mFetchSourceOnly;  // Request source, not cached bytecode.
  DataType mDataType;     // Does this contain Source or Bytecode?
  RefPtr<ScriptFetchOptions> mFetchOptions;
  const SRIMetadata mIntegrity;
  const nsCOMPtr<nsIURI> mReferrer;
  mozilla::Maybe<nsString>
      mSourceMapURL;  // Holds source map url for loaded scripts

  // Holds script source data for non-inline scripts.
  mozilla::Maybe<
      Variant<ScriptTextBuffer<char16_t>, ScriptTextBuffer<Utf8Unit>>>
      mScriptData;

  // The length of script source text, set when reading completes. This is used
  // since mScriptData is cleared when the source is passed to the JS engine.
  size_t mScriptTextLength;

  // Holds the SRI serialized hash and the script bytecode for non-inline
  // scripts. The data is laid out according to ScriptBytecodeDataLayout
  // or, if compression is enabled, ScriptBytecodeCompressedDataLayout.
  mozilla::Vector<uint8_t> mScriptBytecode;
  uint32_t mBytecodeOffset;  // Offset of the bytecode in mScriptBytecode

  const nsCOMPtr<nsIURI> mURI;
  nsCOMPtr<nsIPrincipal> mOriginPrincipal;

  // Keep the URI's filename alive during off thread parsing.
  // Also used by workers to report on errors while loading, and used by
  // worklets as the file name in compile options.
  nsAutoCString mURL;

  // The base URL used for resolving relative module imports.
  nsCOMPtr<nsIURI> mBaseURL;

  // Holds the top-level JSScript that corresponds to the current source, once
  // it is parsed, and planned to be saved in the bytecode cache.
  //
  // NOTE: This field is not used for ModuleLoadRequest.
  //       See ModuleLoadRequest::mIsMarkedForBytecodeEncoding.
  JS::Heap<JSScript*> mScriptForBytecodeEncoding;

  // Holds the Cache information, which is used to register the bytecode
  // on the cache entry, such that we can load it the next time.
  nsCOMPtr<nsICacheInfoChannel> mCacheInfo;

  // LoadContext for augmenting the load depending on the loading
  // context (DOM, Worker, etc.)
  RefPtr<LoadContextBase> mLoadContext;
};

class ScriptLoadRequestList : private mozilla::LinkedList<ScriptLoadRequest> {
  using super = mozilla::LinkedList<ScriptLoadRequest>;

 public:
  ~ScriptLoadRequestList();

  void CancelRequestsAndClear();

#ifdef DEBUG
  bool Contains(ScriptLoadRequest* aElem) const;
#endif  // DEBUG

  using super::getFirst;
  using super::isEmpty;

  void AppendElement(ScriptLoadRequest* aElem) {
    MOZ_ASSERT(!aElem->isInList());
    NS_ADDREF(aElem);
    insertBack(aElem);
  }

  already_AddRefed<ScriptLoadRequest> Steal(ScriptLoadRequest* aElem) {
    aElem->removeFrom(*this);
    return dont_AddRef(aElem);
  }

  already_AddRefed<ScriptLoadRequest> StealFirst() {
    MOZ_ASSERT(!isEmpty());
    return Steal(getFirst());
  }

  void Remove(ScriptLoadRequest* aElem) {
    aElem->removeFrom(*this);
    NS_RELEASE(aElem);
  }
};

inline void ImplCycleCollectionUnlink(ScriptLoadRequestList& aField) {
  while (!aField.isEmpty()) {
    RefPtr<ScriptLoadRequest> first = aField.StealFirst();
  }
}

inline void ImplCycleCollectionTraverse(
    nsCycleCollectionTraversalCallback& aCallback,
    ScriptLoadRequestList& aField, const char* aName, uint32_t aFlags) {
  for (ScriptLoadRequest* request = aField.getFirst(); request;
       request = request->getNext()) {
    CycleCollectionNoteChild(aCallback, request, aName, aFlags);
  }
}

}  // namespace loader
}  // namespace JS

#endif  // js_loader_ScriptLoadRequest_h