nsIScriptElement.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 nsIScriptElement_h___
#define nsIScriptElement_h___

#include "js/loader/ScriptKind.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/Assertions.h"
#include "mozilla/CORSMode.h"
#include "mozilla/dom/FromParser.h"
#include "nsCOMPtr.h"
#include "nsID.h"
#include "nsIScriptLoaderObserver.h"
#include "nsIWeakReferenceUtils.h"
#include "nsStringFwd.h"
#include "nscore.h"

// XXX Avoid including this here by moving function bodies to the cpp file
#include "nsIPrincipal.h"

class nsIContent;
class nsIParser;
class nsIPrincipal;
class nsIURI;

namespace mozilla::dom {
class Document;
enum class FetchPriority : uint8_t;
enum class ReferrerPolicy : uint8_t;
}  // namespace mozilla::dom

// Must be kept in sync with xpcom/rust/xpcom/src/interfaces/nonidl.rs
#define NS_ISCRIPTELEMENT_IID                        \
  {                                                  \
    0xe60fca9b, 0x1b96, 0x4e4e, {                    \
      0xa9, 0xb4, 0xdc, 0x98, 0x4f, 0x88, 0x3f, 0x9c \
    }                                                \
  }

/**
 * Internal interface implemented by script elements
 */
class nsIScriptElement : public nsIScriptLoaderObserver {
 public:
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISCRIPTELEMENT_IID)

  explicit nsIScriptElement(mozilla::dom::FromParser aFromParser)
      : mLineNumber(1),
        mColumnNumber(1),
        mAlreadyStarted(false),
        mMalformed(false),
        mDoneAddingChildren(aFromParser == mozilla::dom::NOT_FROM_PARSER ||
                            aFromParser == mozilla::dom::FROM_PARSER_FRAGMENT),
        mForceAsync(aFromParser == mozilla::dom::NOT_FROM_PARSER ||
                    aFromParser == mozilla::dom::FROM_PARSER_FRAGMENT),
        mFrozen(false),
        mDefer(false),
        mAsync(false),
        mExternal(false),
        mKind(JS::loader::ScriptKind::eClassic),
        mParserCreated(aFromParser == mozilla::dom::FROM_PARSER_FRAGMENT
                           ? mozilla::dom::NOT_FROM_PARSER
                           : aFromParser),
        // Fragment parser-created scripts (if executable)
        // behave like script-created scripts.
        mCreatorParser(nullptr) {}

  /**
   * Content type identifying the scripting language. Can be empty, in
   * which case javascript will be assumed.
   * Return false if type attribute is not found.
   */
  virtual bool GetScriptType(nsAString& type) = 0;

  /**
   * Location of script source text. Can return null, in which case
   * this is assumed to be an inline script element.
   */
  nsIURI* GetScriptURI() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mUri;
  }

  nsIPrincipal* GetScriptURITriggeringPrincipal() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mSrcTriggeringPrincipal;
  }

  /**
   * Script source text for inline script elements.
   */
  virtual void GetScriptText(nsAString& text) const = 0;

  virtual void GetScriptCharset(nsAString& charset) = 0;

  /**
   * Freezes the return values of the following methods so that subsequent
   * modifications to the attributes don't change execution behavior:
   *  - GetScriptIsModule()
   *  - GetScriptIsImportMap()
   *  - GetScriptDeferred()
   *  - GetScriptAsync()
   *  - GetScriptURI()
   *  - GetScriptExternal()
   */
  virtual void FreezeExecutionAttrs(const mozilla::dom::Document*) = 0;

  /**
   * Is the script a module script.
   */
  bool GetScriptIsModule() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mKind == JS::loader::ScriptKind::eModule;
  }

  /**
   * Is the script an import map.
   */
  bool GetScriptIsImportMap() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mKind == JS::loader::ScriptKind::eImportMap;
  }

  /**
   * Is the script deferred.
   */
  bool GetScriptDeferred() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mDefer;
  }

  /**
   * Is the script async.
   */
  bool GetScriptAsync() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mAsync;
  }

  /**
   * Is the script an external script?
   */
  bool GetScriptExternal() {
    MOZ_ASSERT(mFrozen, "Not ready for this call yet!");
    return mExternal;
  }

  /**
   * Returns how the element was created.
   */
  mozilla::dom::FromParser GetParserCreated() { return mParserCreated; }

  void SetScriptLineNumber(uint32_t aLineNumber) { mLineNumber = aLineNumber; }

  uint32_t GetScriptLineNumber() { return mLineNumber; }

  void SetScriptColumnNumber(uint32_t aColumnNumber) {
    mColumnNumber = aColumnNumber;
  }

  uint32_t GetScriptColumnNumber() { return mColumnNumber; }

  void SetIsMalformed() { mMalformed = true; }

  bool IsMalformed() { return mMalformed; }

  void PreventExecution() { mAlreadyStarted = true; }

  void LoseParserInsertedness() {
    mUri = nullptr;
    mCreatorParser = nullptr;
    mParserCreated = mozilla::dom::NOT_FROM_PARSER;
    mForceAsync = !GetAsyncState();

    // Reset state set by FreezeExecutionAttrs().
    mFrozen = false;
    mExternal = false;
    mAsync = false;
    mDefer = false;
    mKind = JS::loader::ScriptKind::eClassic;
  }

  void SetCreatorParser(nsIParser* aParser);

  /**
   * Unblocks the creator parser
   */
  void UnblockParser();

  /**
   * Attempts to resume parsing asynchronously
   */
  void ContinueParserAsync();

  /**
   * Informs the creator parser that the evaluation of this script is starting
   */
  void BeginEvaluating();

  /**
   * Informs the creator parser that the evaluation of this script is ending
   */
  void EndEvaluating();

  /**
   * Retrieves a pointer to the creator parser if this has one or null if not
   */
  already_AddRefed<nsIParser> GetCreatorParser();

  /**
   * This method is called when the parser finishes creating the script
   * element's children, if any are present.
   *
   * @return whether the parser will be blocked while this script is being
   *         loaded
   */
  bool AttemptToExecute() {
    mDoneAddingChildren = true;
    bool block = MaybeProcessScript();
    if (!mAlreadyStarted) {
      // Need to lose parser-insertedness here to allow another script to cause
      // execution later.
      LoseParserInsertedness();
    }
    return block;
  }

  /**
   * Get the CORS mode of the script element
   */
  virtual mozilla::CORSMode GetCORSMode() const {
    /* Default to no CORS */
    return mozilla::CORS_NONE;
  }

  /**
   * Get the fetch priority
   * (https://html.spec.whatwg.org/multipage/scripting.html#attr-script-fetchpriority)
   * of the script element.
   */
  virtual mozilla::dom::FetchPriority GetFetchPriority() const = 0;

  /**
   * Get referrer policy of the script element
   */
  virtual mozilla::dom::ReferrerPolicy GetReferrerPolicy();

  /**
   * Fire an error event
   */
  virtual nsresult FireErrorEvent() = 0;

 protected:
  /**
   * Processes the script if it's in the document-tree and links to or
   * contains a script. Once it has been evaluated there is no way to make it
   * reevaluate the script, you'll have to create a new element. This also means
   * that when adding a src attribute to an element that already contains an
   * inline script, the script referenced by the src attribute will not be
   * loaded.
   *
   * In order to be able to use multiple childNodes, or to use the
   * fallback mechanism of using both inline script and linked script you have
   * to add all attributes and childNodes before adding the element to the
   * document-tree.
   *
   * @return whether the parser will be blocked while this script is being
   *         loaded
   */
  virtual bool MaybeProcessScript() = 0;

  /**
   * Since we've removed the XPCOM interface to HTML elements, we need a way to
   * retreive async state from script elements without bringing the type in.
   */
  virtual bool GetAsyncState() = 0;

  /**
   * Allow implementing elements to avoid unnecessary QueryReferences.
   */
  virtual nsIContent* GetAsContent() = 0;

  /**
   * Determine whether this is a(n) classic/module/importmap script.
   */
  void DetermineKindFromType(const mozilla::dom::Document* aOwnerDoc);

  bool IsClassicNonAsyncDefer();

  /**
   * The start line number of the script.
   */
  uint32_t mLineNumber;

  /**
   * The start column number of the script.
   */
  uint32_t mColumnNumber;

  /**
   * The "already started" flag per HTML5.
   */
  bool mAlreadyStarted;

  /**
   * The script didn't have an end tag.
   */
  bool mMalformed;

  /**
   * False if parser-inserted but the parser hasn't triggered running yet.
   */
  bool mDoneAddingChildren;

  /**
   * If true, the .async property returns true instead of reflecting the
   * content attribute.
   */
  bool mForceAsync;

  /**
   * Whether src, defer and async are frozen.
   */
  bool mFrozen;

  /**
   * The effective deferredness.
   */
  bool mDefer;

  /**
   * The effective asyncness.
   */
  bool mAsync;

  /**
   * The effective externalness. A script can be external with mUri being null
   * if the src attribute contained an invalid URL string.
   */
  bool mExternal;

  /**
   * The effective script kind.
   */
  JS::loader::ScriptKind mKind;

  /**
   * Whether this element was parser-created.
   */
  mozilla::dom::FromParser mParserCreated;

  /**
   * The effective src (or null if no src).
   */
  nsCOMPtr<nsIURI> mUri;

  /**
   * The triggering principal for the src URL.
   */
  nsCOMPtr<nsIPrincipal> mSrcTriggeringPrincipal;

  /**
   * The creator parser of a non-defer, non-async parser-inserted script.
   */
  nsWeakPtr mCreatorParser;
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsIScriptElement, NS_ISCRIPTELEMENT_IID)

#endif  // nsIScriptElement_h___