tor-browser

ScriptLoader.h (34337B)

---

/* -*- 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 mozilla_dom_ScriptLoader_h
#define mozilla_dom_ScriptLoader_h

#include "ModuleLoader.h"
#include "SharedScriptCache.h"
#include "js/TypeDecls.h"
#include "js/Utility.h"                     // JS::FreePolicy
#include "js/experimental/CompileScript.h"  // JS::FrontendContext
#include "js/loader/LoadedScript.h"
#include "js/loader/ModuleLoaderBase.h"
#include "js/loader/ScriptKind.h"
#include "js/loader/ScriptLoadRequest.h"
#include "js/loader/ScriptLoadRequestList.h"
#include "mozilla/CORSMode.h"
#include "mozilla/MaybeOneOf.h"
#include "mozilla/MozPromise.h"
#include "mozilla/dom/ScriptLoadContext.h"
#include "mozilla/dom/ScriptLoadRequestType.h"
#include "nsCOMArray.h"
#include "nsCOMPtr.h"
#include "nsCycleCollectionParticipant.h"
#include "nsILoadInfo.h"  // nsSecurityFlags
#include "nsINode.h"
#include "nsIObserver.h"
#include "nsIScriptElement.h"
#include "nsIScriptLoaderObserver.h"
#include "nsRefPtrHashtable.h"
#include "nsTArray.h"
#include "nsURIHashKey.h"

class nsCycleCollectionTraversalCallback;
class nsIChannel;
class nsIConsoleReportCollector;
class nsIContent;
class nsIIncrementalStreamLoader;
class nsIPrincipal;
class nsIScriptGlobalObject;
class nsITimer;
class nsIURI;

namespace JS {

class CompileOptions;

template <typename UnitT>
class SourceText;

namespace loader {

class LoadedScript;
class ModuleLoadRequest;
class ModuleScript;
class ScriptLoadRequest;

}  // namespace loader
}  // namespace JS

namespace mozilla {

class LazyLogModule;
union Utf8Unit;

namespace dom {

class AutoJSAPI;
class DocGroup;
class Document;
class ModuleLoader;
class SRICheckDataVerifier;
class SRIMetadata;
class ScriptLoadHandler;
class ScriptLoadContext;
class ScriptLoader;
class ScriptRequestProcessor;

enum class ReferrerPolicy : uint8_t;
enum class RequestPriority : uint8_t;

class AsyncCompileShutdownObserver final : public nsIObserver {
 ~AsyncCompileShutdownObserver() { Unregister(); }

public:
 explicit AsyncCompileShutdownObserver(ScriptLoader* aLoader)
     : mScriptLoader(aLoader) {}

 void OnShutdown();
 void Unregister();

 NS_DECL_ISUPPORTS
 NS_DECL_NSIOBSERVER

private:
 // Defined during registration in ScriptLoader constructor, and
 // cleared during destructor, ScriptLoader::Destroy() or Shutdown.
 ScriptLoader* mScriptLoader;
};

//////////////////////////////////////////////////////////////
// Script loader implementation
//////////////////////////////////////////////////////////////

class ScriptLoader final : public JS::loader::ScriptLoaderInterface {
 class MOZ_STACK_CLASS AutoCurrentScriptUpdater {
  public:
   AutoCurrentScriptUpdater(ScriptLoader* aScriptLoader,
                            nsIScriptElement* aCurrentScript)
       : mOldScript(aScriptLoader->mCurrentScript),
         mScriptLoader(aScriptLoader) {
     nsCOMPtr<nsINode> node = do_QueryInterface(aCurrentScript);
     mScriptLoader->mCurrentScript =
         node && !node->IsInShadowTree() ? aCurrentScript : nullptr;
   }

   ~AutoCurrentScriptUpdater() {
     mScriptLoader->mCurrentScript.swap(mOldScript);
   }

  private:
   nsCOMPtr<nsIScriptElement> mOldScript;
   ScriptLoader* mScriptLoader;
 };

 friend class JS::loader::ModuleLoadRequest;
 friend class ScriptRequestProcessor;
 friend class ModuleLoader;
 friend class ScriptLoadHandler;
 friend class AutoCurrentScriptUpdater;

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

 explicit ScriptLoader(Document* aDocument);

 NS_DECL_CYCLE_COLLECTING_ISUPPORTS_FINAL
 NS_DECL_CYCLE_COLLECTION_CLASS(ScriptLoader)

 /**
  * Called when the document that owns this script loader changes global. The
  * argument is null when the document is detached from a window.
  */
 void SetGlobalObject(nsIGlobalObject* aGlobalObject);

 /**
  * The loader maintains a weak reference to the document with
  * which it is initialized. This call forces the reference to
  * be dropped.
  */
 void DropDocumentReference();

 /**
  * Register this loader to the shared script cache.
  *
  * When the principal for the document for the loader is modified,
  * DeregisterFromCache and RegisterToCache should be called to reflect the
  * modification (See Document::SetPrincipals).
  */
 void RegisterToCache();

 /**
  * Deregister this loader from the shared script cache and
  * clear the cache data associated with this loader.
  */
 void DeregisterFromCache();

 // Methods for SharedScriptCache.
 nsIPrincipal* LoaderPrincipal() const;
 nsIPrincipal* PartitionedPrincipal() const;

 bool ShouldBypassCache() const;

 template <typename T>
 bool HasLoaded(const T& aKey) {
   // NOTE: ScriptLoader doesn't cache pending/loading requests, and
   //       this method is unsed.
   return false;
 }

 /**
  * Add an observer for all scripts loaded through this loader.
  *
  * @param aObserver observer for all script processing.
  */
 nsresult AddObserver(nsIScriptLoaderObserver* aObserver) {
   return mObservers.AppendObject(aObserver) ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
 }

 /**
  * Remove an observer.
  *
  * @param aObserver observer to be removed
  */
 void RemoveObserver(nsIScriptLoaderObserver* aObserver) {
   mObservers.RemoveObject(aObserver);
 }

 /**
  * Process a script element. This will include both loading the
  * source of the element if it is not inline and evaluating
  * the script itself.
  *
  * If the script is an inline script that can be executed immediately
  * (i.e. there are no other scripts pending) then ScriptAvailable
  * and ScriptEvaluated will be called before the function returns.
  *
  * If true is returned the script could not be executed immediately.
  * In this case ScriptAvailable is guaranteed to be called at a later
  * point (as well as possibly ScriptEvaluated).
  *
  * @param aElement    The element representing the script to be loaded and
  * evaluated.
  * @param aSourceText For inline non-trusted script, the source text after
  * application of the default Trusted Types policy, a void string otherwise.
  * See https://html.spec.whatwg.org/#prepare-the-script-element
  */
 bool ProcessScriptElement(nsIScriptElement* aElement,
                           const nsAString& aSourceText);

 /**
  * Gets the currently executing script. This is useful if you want to
  * generate a unique key based on the currently executing script.
  */
 nsIScriptElement* GetCurrentScript() { return mCurrentScript; }

 void ContinueParsingDocumentAfterCurrentScript() {
   MOZ_ASSERT(mCurrentScript);
   mContinueParsingDocumentAfterCurrentScript = true;
 }

 nsIScriptElement* GetCurrentParserInsertedScript() {
   return mCurrentParserInsertedScript;
 }

 /**
  * Whether the loader is enabled or not.
  * When disabled, processing of new script elements is disabled.
  * Any call to ProcessScriptElement() will return false. Note that
  * this DOES NOT disable currently loading or executing scripts.
  */
 bool GetEnabled() { return mEnabled; }

 void SetEnabled(bool aEnabled) {
   if (!mEnabled && aEnabled) {
     ProcessPendingRequestsAsync();
   }
   mEnabled = aEnabled;
 }

 ModuleLoader* GetModuleLoader() { return mModuleLoader; }

 void RegisterContentScriptModuleLoader(ModuleLoader* aLoader);
 void RegisterShadowRealmModuleLoader(ModuleLoader* aLoader);

 /**
  *  Check whether to speculatively OMT parse scripts as soon as
  *  they are fetched, even if not a parser blocking request.
  *  Controlled by
  *  dom.script_loader.external_scripts.speculative_omt_parse_enabled
  */
 bool SpeculativeOMTParsingEnabled() const {
   return mSpeculativeOMTParsingEnabled;
 }

 /**
  * Add/remove a blocker for parser-blocking scripts (and XSLT
  * scripts). Blockers will stop such scripts from executing, but not from
  * loading.
  */
 void AddParserBlockingScriptExecutionBlocker() {
   ++mParserBlockingBlockerCount;
 }

 void RemoveParserBlockingScriptExecutionBlocker() {
   if (!--mParserBlockingBlockerCount && ReadyToExecuteScripts()) {
     ProcessPendingRequestsAsync();
   }
 }

 /**
  * Add/remove a blocker for execution of all scripts.  Blockers will stop
  * scripts from executing, but not from loading.
  */
 void AddExecuteBlocker() { ++mBlockerCount; }

 void RemoveExecuteBlocker() {
   MOZ_ASSERT(mBlockerCount);
   if (!--mBlockerCount) {
     ProcessPendingRequestsAsync();
   }
 }

 /**
  * Convert the given buffer to a UTF-16 string.  If the buffer begins with a
  * BOM, it is interpreted as that encoding; otherwise the first of |aChannel|,
  * |aHintCharset|, or |aDocument| that provides a recognized encoding is used,
  * or Windows-1252 if none of them do.
  *
  * Encoding errors in the buffer are converted to replacement characters, so
  * allocation failure is the only way this function can fail.
  *
  * @param aChannel     Channel corresponding to the data. May be null.
  * @param aData        The data to convert
  * @param aLength      Length of the data
  * @param aHintCharset Character set hint (e.g., from a charset attribute).
  * @param aDocument    Document which the data is loaded for. May be null.
  * @param aBufOut      [out] fresh char16_t array containing data converted to
  *                     Unicode.
  * @param aLengthOut   [out] Length of array returned in aBufOut in number
  *                     of char16_t code units.
  */
 static nsresult ConvertToUTF16(nsIChannel* aChannel, const uint8_t* aData,
                                uint32_t aLength,
                                const nsAString& aHintCharset,
                                Document* aDocument,
                                UniquePtr<char16_t[], JS::FreePolicy>& aBufOut,
                                size_t& aLengthOut);

 /**
  * Convert the given buffer to a UTF-8 string.  If the buffer begins with a
  * BOM, it is interpreted as that encoding; otherwise the first of |aChannel|,
  * |aHintCharset|, or |aDocument| that provides a recognized encoding is used,
  * or Windows-1252 if none of them do.
  *
  * Encoding errors in the buffer are converted to replacement characters, so
  * allocation failure is the only way this function can fail.
  *
  * @param aChannel     Channel corresponding to the data. May be null.
  * @param aData        The data to convert
  * @param aLength      Length of the data
  * @param aHintCharset Character set hint (e.g., from a charset attribute).
  * @param aDocument    Document which the data is loaded for. May be null.
  * @param aBufOut      [out] fresh Utf8Unit array containing data converted to
  *                     Unicode.
  * @param aLengthOut   [out] Length of array returned in aBufOut in UTF-8 code
  *                     units (i.e. in bytes).
  */
 static nsresult ConvertToUTF8(nsIChannel* aChannel, const uint8_t* aData,
                               uint32_t aLength, const nsAString& aHintCharset,
                               Document* aDocument,
                               UniquePtr<Utf8Unit[], JS::FreePolicy>& aBufOut,
                               size_t& aLengthOut);

 /**
  * Handle the completion of a stream.  This is called by the
  * ScriptLoadHandler object which observes the IncrementalStreamLoader
  * loading the script. The streamed content is expected to be stored on the
  * aRequest argument.
  */
 nsresult OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
                           ScriptLoadRequest* aRequest,
                           nsresult aChannelStatus, nsresult aSRIStatus,
                           SRICheckDataVerifier* aSRIDataVerifier);

 /**
  * Returns wether any request is queued, and not executed yet.
  */
 bool HasPendingRequests() const;

 /**
  * Returns wether there are any dynamic module import requests pending.
  */
 bool HasPendingDynamicImports() const;

 /**
  * Processes any pending requests that are ready for processing.
  */
 void ProcessPendingRequests(bool aAllowBypassingParserBlocking = false);

 /**
  * Starts deferring deferred scripts and puts them in the mDeferredRequests
  * queue instead.
  */
 void BeginDeferringScripts();

 /**
  * Notifies the script loader that parsing is done.  If aTerminated is true,
  * this will drop any pending scripts that haven't run yet, otherwise it will
  * do nothing.
  */
 void ParsingComplete(bool aTerminated);

 /**
  * Notifies the script loader that the checkpoint to begin execution of defer
  * scripts has been reached. This is either the end of of the document parse
  * or the end of loading of parser-inserted stylesheets, whatever happens
  * last.
  *
  * Otherwise, it will stop deferring scripts and immediately processes the
  * mDeferredRequests queue.
  *
  * WARNING: This function will synchronously execute content scripts, so be
  * prepared that the world might change around you.
  */
 void DeferCheckpointReached();

 /**
  * Returns the number of pending scripts, deferred or not.
  */
 uint32_t HasPendingOrCurrentScripts() {
   return mCurrentScript || mParserBlockingRequest;
 }

 /**
  * Adds aURI to the preload list and starts loading it.
  *
  * @param aURI The URI of the external script.
  * @param aCharset The charset parameter for the script.
  * @param aType The type parameter for the script.
  * @param aCrossOrigin The crossorigin attribute for the script.
  *                     Void if not present.
  * @param aFetchPriority
  * <https://html.spec.whatwg.org/#the-script-element:attr-script-fetchpriority>.
  * @param aIntegrity The expect hash url, if avail, of the request

  * @param aScriptFromHead Whether or not the script was a child of head
  */
 void PreloadURI(nsIURI* aURI, const nsAString& aCharset,
                 const nsAString& aType, const nsAString& aCrossOrigin,
                 const nsAString& aNonce, const nsAString& aFetchPriority,
                 const nsAString& aIntegrity, bool aScriptFromHead,
                 bool aAsync, bool aDefer, bool aLinkPreload,
                 const ReferrerPolicy aReferrerPolicy,
                 uint64_t aEarlyHintPreloaderId);

 /**
  * Process a request that was deferred so that the script could be compiled
  * off thread.
  */
 nsresult ProcessOffThreadRequest(ScriptLoadRequest* aRequest);

 bool AddPendingChildLoader(ScriptLoader* aChild) {
   // XXX(Bug 1631371) Check if this should use a fallible operation as it
   // pretended earlier. Else, change the return type to void.
   mPendingChildLoaders.AppendElement(aChild);
   return true;
 }

 mozilla::dom::DocGroup* GetDocGroup() const;

 /**
  * Register the fact that we saw the load event, and that we need to perform
  * the caching at the next loop cycle unless new scripts are waiting in the
  * pipeline.
  */
 void LoadEventFired();

 /**
  * Destroy and prevent the ScriptLoader or the ScriptLoadRequests from owning
  * any references to the JSScript or to the Request which might be used for
  * caching.
  */
 void Destroy();

 /*
  * Get the currently active script. This is used as the initiating script when
  * executing timeout handler scripts.
  */
 static JS::loader::LoadedScript* GetActiveScript(JSContext* aCx);

 Document* GetDocument() const { return mDocument; }

 nsIURI* GetBaseURI() const override;

private:
 ~ScriptLoader();

 already_AddRefed<ScriptLoadRequest> CreateLoadRequest(
     JS::loader::ScriptKind aKind, nsIURI* aURI, nsIScriptElement* aElement,
     const nsAString& aScriptContent, nsIPrincipal* aTriggeringPrincipal,
     mozilla::CORSMode aCORSMode, const nsAString& aNonce,
     RequestPriority aRequestPriority, const SRIMetadata& aIntegrity,
     ReferrerPolicy aReferrerPolicy,
     JS::loader::ParserMetadata aParserMetadata,
     ScriptLoadRequestType aRequestType);

 /**
  * Helper function to lookup the cache entry and associate it to the
  * request if any.
  */
 void TryUseCache(
     ReferrerPolicy aReferrerPolicy, ScriptFetchOptions* aFetchOptions,
     nsIURI* aURI, ScriptLoadRequest* aRequest,
     nsIScriptElement* aElement = nullptr, const nsAString& aNonce = u""_ns,
     ScriptLoadRequestType aRequestType = ScriptLoadRequestType::External);

 /**
  * Helper function to notify network observers for cached request.
  */
 void EmulateNetworkEvents(ScriptLoadRequest* aRequest);

 void NotifyObserversForCachedScript(
     nsIURI* aURI, nsINode* aContext, nsIPrincipal* aTriggeringPrincipal,
     nsSecurityFlags aSecurityFlags, nsContentPolicyType aContentPolicyType,
     SubResourceNetworkMetadataHolder* aNetworkMetadata);

 /**
  * Unblocks the creator parser of the parser-blocking scripts.
  */
 void UnblockParser(ScriptLoadRequest* aParserBlockingRequest);

 /**
  * Asynchronously resumes the creator parser of the parser-blocking scripts.
  */
 void ContinueParserAsync(ScriptLoadRequest* aParserBlockingRequest);

 bool ProcessExternalScript(nsIScriptElement* aElement,
                            JS::loader::ScriptKind aScriptKind,
                            nsIContent* aScriptContent);

 bool ProcessInlineScript(nsIScriptElement* aElement,
                          JS::loader::ScriptKind aScriptKind,
                          const nsAString& aSourceText);

 enum class CacheBehavior : uint8_t {
   DoNothing,
   Insert,
   Evict,
 };

 CacheBehavior GetCacheBehavior(ScriptLoadRequest* aRequest);

 void TryCacheRequest(ScriptLoadRequest* aRequest);

 JS::loader::ScriptLoadRequest* LookupPreloadRequest(
     nsIScriptElement* aElement, JS::loader::ScriptKind aScriptKind,
     const SRIMetadata& aSRIMetadata);

 void GetSRIMetadata(const nsAString& aIntegrityAttr,
                     SRIMetadata* aMetadataOut);

 /**
  * Given a script element, get the referrer policy should be applied to load
  * requests.
  */
 ReferrerPolicy GetReferrerPolicy(nsIScriptElement* aElement);

 /**
  * Helper function to check the content policy for a given request.
  */
 nsresult CheckContentPolicy(nsIScriptElement* aElement,
                             const nsAString& aNonce,
                             ScriptLoadRequest* aRequest,
                             ScriptFetchOptions* aFetchOptions, nsIURI* aURI);

 /**
  * Helper function to determine whether an about: page loads a chrome: URI.
  * Please note that this function only returns true if:
  *   * the about: page uses a ContentPrincipal with scheme about:
  *   * the about: page is not linkable from content
  *     (e.g. the function will return false for about:blank or about:srcdoc)
  */
 static bool IsAboutPageLoadingChromeURI(ScriptLoadRequest* aRequest,
                                         Document* aDocument);

 /**
  * Start a load for aRequest's URI.
  */
 nsresult StartLoad(ScriptLoadRequest* aRequest,
                    const Maybe<nsAutoString>& aCharsetForPreload);
 /**
  * Start a load for a classic script URI.
  * Sets up the necessary security flags before calling StartLoadInternal.
  */
 nsresult StartClassicLoad(ScriptLoadRequest* aRequest,
                           const Maybe<nsAutoString>& aCharsetForPreload);

 static void PrepareCacheInfoChannel(nsIChannel* aChannel,
                                     ScriptLoadRequest* aRequest);

 static void PrepareRequestPriorityAndRequestDependencies(
     nsIChannel* aChannel, ScriptLoadRequest* aRequest);

 [[nodiscard]] static nsresult PrepareHttpRequestAndInitiatorType(
     nsIChannel* aChannel, ScriptLoadRequest* aRequest,
     const Maybe<nsAutoString>& aCharsetForPreload);

 [[nodiscard]] nsresult PrepareIncrementalStreamLoader(
     nsIIncrementalStreamLoader** aOutLoader, nsIChannel* aChannel,
     ScriptLoadRequest* aRequest);

 /**
  * Start a load for a script (module or classic) URI.
  *
  * aCharsetForPreload is only needed when this load is a preload (via
  * ScriptLoader::PreloadURI), because ScriptLoadRequest doesn't
  * have this information.
  */
 nsresult StartLoadInternal(ScriptLoadRequest* aRequest,
                            nsSecurityFlags securityFlags,
                            const Maybe<nsAutoString>& aCharsetForPreload);

 /**
  * Abort the current stream, and re-start with a new load request from scratch
  * without requesting any alternate data. Returns NS_BINDING_RETARGETED on
  * success, as this error code is used to abort the input stream.
  */
 nsresult RestartLoad(ScriptLoadRequest* aRequest);

 void HandleLoadError(ScriptLoadRequest* aRequest, nsresult aResult);

 void HandleLoadErrorAndProcessPendingRequests(ScriptLoadRequest* aRequest,
                                               nsresult aResult);

 /**
  * Process any pending requests asynchronously (i.e. off an event) if there
  * are any. Note that this is a no-op if there aren't any currently pending
  * requests.
  *
  * This function is virtual to allow cross-library calls to SetEnabled()
  */
 void ProcessPendingRequestsAsync();

 void ProcessPendingRequestsAsyncBypassParserBlocking();

 /**
  * If true, the loader is ready to execute parser-blocking scripts, and so are
  * all its ancestors.  If the loader itself is ready but some ancestor is not,
  * this function will add an execute blocker and ask the ancestor to remove it
  * once it becomes ready.
  */
 bool ReadyToExecuteParserBlockingScripts();

 /**
  * Return whether just this loader is ready to execute parser-blocking
  * scripts.
  */
 bool SelfReadyToExecuteParserBlockingScripts() {
   return ReadyToExecuteScripts() && !mParserBlockingBlockerCount;
 }

 /**
  * Return whether this loader is ready to execute scripts in general.
  */
 bool ReadyToExecuteScripts() { return mEnabled && !mBlockerCount; }

 nsresult VerifySRI(ScriptLoadRequest* aRequest,
                    nsIIncrementalStreamLoader* aLoader, nsresult aSRIStatus,
                    SRICheckDataVerifier* aSRIDataVerifier) const;

 nsresult SaveSRIHash(ScriptLoadRequest* aRequest,
                      SRICheckDataVerifier* aSRIDataVerifier) const;

 void ReportErrorToConsole(ScriptLoadRequest* aRequest,
                           nsresult aResult) const override;

 void ReportWarningToConsole(
     ScriptLoadRequest* aRequest, const char* aMessageName,
     const nsTArray<nsString>& aParams = nsTArray<nsString>()) const override;

 void ReportPreloadErrorsToConsole(ScriptLoadRequest* aRequest);

 nsIConsoleReportCollector* GetConsoleReportCollector() const override {
   return mReporter;
 }

 nsresult AttemptOffThreadScriptCompile(ScriptLoadRequest* aRequest,
                                        bool* aCouldCompileOut);

 nsresult CreateOffThreadTask(JSContext* aCx, ScriptLoadRequest* aRequest,
                              JS::CompileOptions& aOptions,
                              CompileOrDecodeTask** aCompileOrDecodeTask);

 nsresult ProcessRequest(ScriptLoadRequest* aRequest);
 nsresult CompileOffThreadOrProcessRequest(ScriptLoadRequest* aRequest);
 void FireScriptAvailable(nsresult aResult, ScriptLoadRequest* aRequest);
 // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
 MOZ_CAN_RUN_SCRIPT_BOUNDARY void FireScriptEvaluated(
     nsresult aResult, ScriptLoadRequest* aRequest);

 // Implements https://html.spec.whatwg.org/#execute-the-script-block
 nsresult EvaluateScriptElement(ScriptLoadRequest* aRequest);

 // Instantiate classic script from one of the following data:
 //   * text source
 //   * serialized stencil
 //   * cached stencil
 void InstantiateClassicScriptFromAny(
     JSContext* aCx, JS::CompileOptions& aCompileOptions,
     ScriptLoadRequest* aRequest, JS::MutableHandle<JSScript*> aScript,
     JS::Handle<JS::Value> aDebuggerPrivateValue,
     JS::Handle<JSScript*> aDebuggerIntroductionScript, ErrorResult& aRv);

 // Instantiate classic script from one of the following data:
 //   * text source
 //   * serialized stencil
 //
 // aStencilOut is set to the compiled stencil.
 void InstantiateClassicScriptFromMaybeEncodedSource(
     JSContext* aCx, JS::CompileOptions& aCompileOptions,
     ScriptLoadRequest* aRequest, JS::MutableHandle<JSScript*> aScript,
     JS::Handle<JS::Value> aDebuggerPrivateValue,
     JS::Handle<JSScript*> aDebuggerIntroductionScript, ErrorResult& aRv);

 // Instantiate classic script from the following data:
 //   * cached stencil
 void InstantiateClassicScriptFromCachedStencil(
     JSContext* aCx, JS::CompileOptions& aCompileOptions,
     ScriptLoadRequest* aRequest, JS::Stencil* aStencil,
     JS::MutableHandle<JSScript*> aScript,
     JS::Handle<JS::Value> aDebuggerPrivateValue,
     JS::Handle<JSScript*> aDebuggerIntroductionScript, ErrorResult& aRv);

 static nsCString& BytecodeMimeTypeFor(const ScriptLoadRequest* aRequest);
 static nsCString& BytecodeMimeTypeFor(
     const JS::loader::LoadedScript* aLoadedScript);

 // Queue the script load request for caching if we decided to cache it, or
 // cleanup the script load request fields otherwise.
 //
 // This method must be called after executing the script.
 nsresult MaybePrepareForDiskCacheAfterExecute(ScriptLoadRequest* aRequest,
                                               nsresult aRv);

 // Queue the top-level module load request for caching if we decided to cache
 // it, or cleanup the module load request fields otherwise.
 //
 // This method must be called after executing the script.
 nsresult MaybePrepareModuleForDiskCacheAfterExecute(
     ModuleLoadRequest* aRequest, nsresult aRv) override;

 // Implements https://html.spec.whatwg.org/#run-a-classic-script
 nsresult EvaluateScript(nsIGlobalObject* aGlobalObject,
                         ScriptLoadRequest* aRequest);

 /**
  * Register the script load request to be cached on the disk.
  *
  * The caller can call this at the same time instantiating the stencil,
  * and also start collecting delazifications.
  *
  * The cache handling will be performed when the page initialization ends.
  * The page initialization end is defined as being the time when the load
  * event got received, and when no more scripts are waiting to be executed.
  */
 void RegisterForDiskCache(ScriptLoadRequest* aRequest);

 /**
  * Check if all conditions are met, i-e that the onLoad event fired and that
  * no more script have to be processed.  If all conditions are met, queue an
  * event to perform the cache handling, which saves them to the necko cache.
  */
 void MaybeUpdateDiskCache() override;

 /**
  * Iterate over all scripts and save them to the necko cache.
  */
 void UpdateDiskCache();

public:
 /**
  * Encode the stencils and compress it.
  * aLoadedScript is used only for logging purpose, in order to allow
  * performing this off main thread.
  */
 static bool EncodeAndCompress(JS::FrontendContext* aFc,
                               const JS::loader::LoadedScript* aLoadedScript,
                               JS::Stencil* aStencil,
                               const JS::TranscodeBuffer& aSRI,
                               Vector<uint8_t>& aCompressed);

 /**
  * Save the serialized and maybe-compressed stencil to the necko cache.
  */
 static bool SaveToDiskCache(const JS::loader::LoadedScript* aLoadedScript,
                             const Vector<uint8_t>& aCompressed);

private:
 /**
  * Discard all disk-cache-related info for scripts queued for the disk cache.
  *
  * This should be used when the ScriptLoader is getting destroyed, or
  * when it hits any critical error.
  */
 void GiveUpDiskCaching();

 already_AddRefed<nsIGlobalObject> GetGlobalForRequest(
     ScriptLoadRequest* aRequest);

 already_AddRefed<nsIScriptGlobalObject> GetScriptGlobalObject();

 // Fill in CompileOptions, as well as produce the introducer script for
 // subsequent calls to UpdateDebuggerMetadata
 nsresult FillCompileOptionsForRequest(
     JSContext* aCx, ScriptLoadRequest* aRequest, JS::CompileOptions* aOptions,
     JS::MutableHandle<JSScript*> aIntroductionScript) override;

 uint32_t NumberOfProcessors();
 int32_t PhysicalSizeOfMemoryInGB();

 nsresult PrepareLoadedRequest(ScriptLoadRequest* aRequest,
                               nsIIncrementalStreamLoader* aLoader,
                               nsresult aStatus);

 void AddDeferRequest(ScriptLoadRequest* aRequest);
 void AddAsyncRequest(ScriptLoadRequest* aRequest);
 bool MaybeRemovedDeferRequests();

 bool ShouldApplyDelazifyStrategy(ScriptLoadRequest* aRequest);
 void ApplyDelazifyStrategy(JS::CompileOptions* aOptions);

 bool ShouldCompileOffThread(ScriptLoadRequest* aRequest);

 void MaybeMoveToLoadedList(ScriptLoadRequest* aRequest);

 bool IsBeforeFCP();

public:
 struct DiskCacheStrategy {
   bool mIsDisabled = false;
   bool mHasSourceLengthMin = false;
   bool mHasFetchCountMin = false;
   uint8_t mFetchCountMin = 0;
   size_t mSourceLengthMin = 0;
 };

 static DiskCacheStrategy GetDiskCacheStrategy();

private:
 // Check whether the request should be saved to the following or not:
 //   * in-memory cache as Stencil
 //   * necko alternative stream as Stencil XDR
 //
 // If the request is a non-top-level module request and it passed the
 // condition, it's stored into mDiskCacheableDependencyModules in order
 // to iterate over them later.
 void CalculateCacheFlag(ScriptLoadRequest* aRequest);

 void RunScriptWhenSafe(ScriptLoadRequest* aRequest);

 /**
  * Cancel and remove all outstanding load requests, including waiting for any
  * off thread compilations to finish.
  */
 void CancelAndClearScriptLoadRequests();

 Document* mDocument;  // [WEAK]
 nsCOMArray<nsIScriptLoaderObserver> mObservers;

 // The following lists maintains the list of requests for each phase and
 // situation.
 // Each request can be a part of at most one list.

 // Holds non-async, non-parser-created requests until it's evaluated or it
 // hits load error.
 JS::loader::ScriptLoadRequestList mNonAsyncExternalScriptInsertedRequests;

 // Holds async requests until it's loaded or it hits load error.
 // When they have been loaded they are moved to mLoadedAsyncRequests.
 JS::loader::ScriptLoadRequestList mLoadingAsyncRequests;

 // Holds async script requests and dynamic module import
 // requests, which are processed in the same way, until it's evaluated,
 // or it's passed to off-thread.
 JS::loader::ScriptLoadRequestList mLoadedAsyncRequests;

 // Holds non-async, parser-created, defer requests, until it's evaluated
 // or it hits load error.
 JS::loader::ScriptLoadRequestList mDeferRequests;

 // Holds parser-created XSLT requests, until it's evaluated or it hits
 // load error.
 JS::loader::ScriptLoadRequestList mXSLTRequests;

 RefPtr<ScriptLoadRequest> mParserBlockingRequest;

 // Holds requests which is passed to off-thread compilation.
 // When the off-thread compilation finishes, the request is added back to
 // the original list if any.
 JS::loader::ScriptLoadRequestList mOffThreadCompilingRequests;

 // Holds non-top-level module requests which passed disk caching conditions,
 // until it's queued to mDiskCacheQueue.
 //
 // TODO: Remove this and per-ScriptLoader caching queue (bug 1902951).
 JS::loader::ScriptLoadRequestList mDiskCacheableDependencyModules;

 // Holds already-evaluted requests' script that are holding a stencil which
 // has to be saved on the disk cache, until it's cached or the caching is
 // aborted.
 nsTArray<RefPtr<JS::loader::LoadedScript>> mDiskCacheQueue;

 // In mRequests, the additional information here is stored by the element.
 struct PreloadInfo {
   RefPtr<ScriptLoadRequest> mRequest;
   nsString mCharset;
 };

 friend void ImplCycleCollectionUnlink(ScriptLoader::PreloadInfo& aField);
 friend void ImplCycleCollectionTraverse(
     nsCycleCollectionTraversalCallback& aCallback,
     ScriptLoader::PreloadInfo& aField, const char* aName, uint32_t aFlags);

 struct PreloadRequestComparator {
   bool Equals(const PreloadInfo& aPi,
               ScriptLoadRequest* const& aRequest) const {
     return aRequest == aPi.mRequest;
   }
 };

 struct PreloadURIComparator {
   bool Equals(const PreloadInfo& aPi, nsIURI* const& aURI) const;
 };

 nsTArray<PreloadInfo> mPreloads;

 nsCOMPtr<nsIScriptElement> mCurrentScript;
 nsCOMPtr<nsIScriptElement> mCurrentParserInsertedScript;
 nsTArray<RefPtr<ScriptLoader>> mPendingChildLoaders;
 uint32_t mParserBlockingBlockerCount;
 uint32_t mBlockerCount;
 uint32_t mNumberOfProcessors;
 uint32_t mTotalFullParseSize;
 int32_t mPhysicalSizeOfMemory;
 bool mEnabled;
 bool mDeferEnabled;
 bool mSpeculativeOMTParsingEnabled;
 bool mDeferCheckpointReached;
 bool mBlockingDOMContentLoaded;
 bool mLoadEventFired;
 bool mGiveUpDiskCaching;
 bool mContinueParsingDocumentAfterCurrentScript;
 bool mHadFCPDoNotUseDirectly;

 TimeDuration mMainThreadParseTime;

 nsCOMPtr<nsIConsoleReportCollector> mReporter;

 // ShutdownObserver for off thread compilations
 RefPtr<AsyncCompileShutdownObserver> mShutdownObserver;

 RefPtr<ModuleLoader> mModuleLoader;
 nsTArray<RefPtr<ModuleLoader>> mWebExtModuleLoaders;
 nsTArray<RefPtr<ModuleLoader>> mShadowRealmModuleLoaders;

 RefPtr<SharedScriptCache> mCache;

 nsCOMPtr<nsITimer> mProcessPendingRequestsAsyncBypassParserBlocking;

 // Logging
public:
 static LazyLogModule gCspPRLog;
 static LazyLogModule gScriptLoaderLog;
};

class nsAutoScriptLoaderDisabler {
public:
 explicit nsAutoScriptLoaderDisabler(Document* aDoc);

 ~nsAutoScriptLoaderDisabler();

 bool mWasEnabled;
 RefPtr<ScriptLoader> mLoader;
};

}  // namespace dom
}  // namespace mozilla

#endif  // mozilla_dom_ScriptLoader_h