The Tor Browser: netwerk/base/src/BackgroundFileSaver.h@6474c204b198 (annotated)

netwerk/base/src/BackgroundFileSaver.h@6474c204b198 (annotated)

netwerk/base/src/BackgroundFileSaver.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=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/. */
 /**
  * This file defines two implementations of the nsIBackgroundFileSaver
  * interface.  See the "test_backgroundfilesaver.js" file for usage examples.
  */
 #ifndef BackgroundFileSaver_h__
 #define BackgroundFileSaver_h__
 #include "mozilla/Mutex.h"
 #include "nsCOMArray.h"
 #include "nsCOMPtr.h"
 #include "nsNSSShutDown.h"
 #include "nsIAsyncOutputStream.h"
 #include "nsIBackgroundFileSaver.h"
 #include "nsIStreamListener.h"
 #include "nsStreamUtils.h"
 #include "ScopedNSSTypes.h"
 class nsIAsyncInputStream;
 class nsIThread;
 class nsIX509CertList;
 class PRLogModuleInfo;
 namespace mozilla {
 namespace net {
 class DigestOutputStream;
 ////////////////////////////////////////////////////////////////////////////////
 //// BackgroundFileSaver
 class BackgroundFileSaver : public nsIBackgroundFileSaver,
                             public nsNSSShutDownObject
 {
 public:
   NS_DECL_NSIBACKGROUNDFILESAVER
   BackgroundFileSaver();
   /**
    * Initializes the pipe and the worker thread on XPCOM construction.
    *
    * This is called automatically by the XPCOM infrastructure, and if this
    * fails, the factory will delete this object without returning a reference.
    */
   nsresult Init();
   /**
    * Used by nsNSSShutDownList to manage nsNSSShutDownObjects.
    */
   void virtualDestroyNSSReference();
   /**
    * Number of worker threads that are currently running.
    */
   static uint32_t sThreadCount;
   /**
    * Maximum number of worker threads reached during the current download session,
    * used for telemetry.
    *
    * When there are no more worker threads running, we consider the download
    * session finished, and this counter is reset.
    */
   static uint32_t sTelemetryMaxThreadCount;
 protected:
   virtual ~BackgroundFileSaver();
   static PRLogModuleInfo *prlog;
   /**
    * Helper function for managing NSS objects (mDigestContext).
    */
   void destructorSafeDestroyNSSReference();
   /**
    * Thread that constructed this object.
    */
   nsCOMPtr<nsIThread> mControlThread;
   /**
    * Thread to which the actual input/output is delegated.
    */
   nsCOMPtr<nsIThread> mWorkerThread;
   /**
    * Stream that receives data from derived classes.  The received data will be
    * available to the worker thread through mPipeInputStream. This is an
    * instance of nsPipeOutputStream, not BackgroundFileSaverOutputStream.
    */
   nsCOMPtr<nsIAsyncOutputStream> mPipeOutputStream;
   /**
    * Used during initialization, determines if the pipe is created with an
    * infinite buffer.  An infinite buffer is required if the derived class
    * implements nsIStreamListener, because this interface requires all the
    * provided data to be consumed synchronously.
    */
   virtual bool HasInfiniteBuffer() = 0;
   /**
    * Used by derived classes if they need to be called back while copying.
    */
   virtual nsAsyncCopyProgressFun GetProgressCallback() = 0;
   /**
    * Stream used by the worker thread to read the data to be saved.
    */
   nsCOMPtr<nsIAsyncInputStream> mPipeInputStream;
 private:
   friend class NotifyTargetChangeRunnable;
   /**
    * Matches the nsIBackgroundFileSaver::observer property.
    *
    * @remarks This is a strong reference so that JavaScript callers don't need
    *          to worry about keeping another reference to the observer.
    */
   nsCOMPtr<nsIBackgroundFileSaverObserver> mObserver;
   //////////////////////////////////////////////////////////////////////////////
   //// Shared state between control and worker threads
   /**
    * Protects the shared state between control and worker threads.  This mutex
    * is always locked for a very short time, never during input/output.
    */
   mozilla::Mutex mLock;
   /**
    * True if the worker thread is already waiting to process a change in state.
    */
   bool mWorkerThreadAttentionRequested;
   /**
    * True if the operation should finish as soon as possibile.
    */
   bool mFinishRequested;
   /**
    * True if the operation completed, with either success or failure.
    */
   bool mComplete;
   /**
    * Holds the current file saver status.  This is a success status while the
    * object is working correctly, and remains such if the operation completes
    * successfully.  This becomes an error status when an error occurs on the
    * worker thread, or when the operation is canceled.
    */
   nsresult mStatus;
   /**
    * True if we should append data to the initial target file, instead of
    * overwriting it.
    */
   bool mAppend;
   /**
    * This is set by the first SetTarget call on the control thread, and contains
    * the target file name that will be used by the worker thread, as soon as it
    * is possible to update mActualTarget and open the file.  This is null if no
    * target was ever assigned to this object.
    */
   nsCOMPtr<nsIFile> mInitialTarget;
   /**
    * This is set by the first SetTarget call on the control thread, and
    * indicates whether mInitialTarget should be kept as partially completed,
    * rather than deleted, if the operation fails or is canceled.
    */
   bool mInitialTargetKeepPartial;
   /**
    * This is set by subsequent SetTarget calls on the control thread, and
    * contains the new target file name to which the worker thread will move the
    * target file, as soon as it can be done.  This is null if SetTarget was
    * called only once, or no target was ever assigned to this object.
    *
    * The target file can be renamed multiple times, though only the most recent
    * rename is guaranteed to be processed by the worker thread.
    */
   nsCOMPtr<nsIFile> mRenamedTarget;
   /**
    * This is set by subsequent SetTarget calls on the control thread, and
    * indicates whether mRenamedTarget should be kept as partially completed,
    * rather than deleted, if the operation fails or is canceled.
    */
   bool mRenamedTargetKeepPartial;
   /**
    * While NS_AsyncCopy is in progress, allows canceling it.  Null otherwise.
    * This is read by both threads but only written by the worker thread.
    */
   nsCOMPtr<nsISupports> mAsyncCopyContext;
   /**
    * The SHA 256 hash in raw bytes of the downloaded file. This is written
    * by the worker thread but can be read on the main thread.
    */
   nsAutoCString mSha256;
   /**
    * Whether or not to compute the hash. Must be set on the main thread before
    * setTarget is called.
    */
   bool mSha256Enabled;
   /**
    * Store the signature info.
    */
   nsCOMArray<nsIX509CertList> mSignatureInfo;
   /**
    * Whether or not to extract the signature. Must be set on the main thread
    * before setTarget is called.
    */
   bool mSignatureInfoEnabled;
   //////////////////////////////////////////////////////////////////////////////
   //// State handled exclusively by the worker thread
   /**
    * Current target file associated to the input and output streams.
    */
   nsCOMPtr<nsIFile> mActualTarget;
   /**
    * Indicates whether mActualTarget should be kept as partially completed,
    * rather than deleted, if the operation fails or is canceled.
    */
   bool mActualTargetKeepPartial;
   /**
    * Used to calculate the file hash. This keeps state across file renames and
    * is lazily initialized in ProcessStateChange.
    */
   ScopedPK11Context mDigestContext;
   //////////////////////////////////////////////////////////////////////////////
   //// Private methods
   /**
    * Called when NS_AsyncCopy completes.
    *
    * @param aClosure
    *        Populated with a raw pointer to the BackgroundFileSaver object.
    * @param aStatus
    *        Success or failure status specified when the copy was interrupted.
    */
   static void AsyncCopyCallback(void *aClosure, nsresult aStatus);
   /**
    * Called on the control thread after state changes, to ensure that the worker
    * thread will process the state change appropriately.
    *
    * @param aShouldInterruptCopy
    *        If true, the current NS_AsyncCopy, if any, is canceled.
    */
   nsresult GetWorkerThreadAttention(bool aShouldInterruptCopy);
   /**
    * Event called on the worker thread to begin processing a state change.
    */
   nsresult ProcessAttention();
   /**
    * Called by ProcessAttention to execute the operations corresponding to the
    * state change.  If this results in an error, ProcessAttention will force the
    * entire operation to be aborted.
    */
   nsresult ProcessStateChange();
   /**
    * Returns true if completion conditions are met on the worker thread.  The
    * first time this happens, posts the completion event to the control thread.
    */
   bool CheckCompletion();
   /**
    * Event called on the control thread to indicate that file contents will now
    * be saved to the specified file.
    */
   nsresult NotifyTargetChange(nsIFile *aTarget);
   /**
    * Event called on the control thread to send the final notification.
    */
   nsresult NotifySaveComplete();
   /**
    * Verifies the signature of the binary at the specified file path and stores
    * the signature data in mSignatureInfo. We extract only X.509 certificates,
    * since that is what Google's Safebrowsing protocol specifies.
    */
   nsresult ExtractSignatureInfo(const nsAString& filePath);
 };
 ////////////////////////////////////////////////////////////////////////////////
 //// BackgroundFileSaverOutputStream
 class BackgroundFileSaverOutputStream : public BackgroundFileSaver
                                       , public nsIAsyncOutputStream
                                       , public nsIOutputStreamCallback
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIOUTPUTSTREAM
   NS_DECL_NSIASYNCOUTPUTSTREAM
   NS_DECL_NSIOUTPUTSTREAMCALLBACK
   BackgroundFileSaverOutputStream();
 protected:
   virtual bool HasInfiniteBuffer() MOZ_OVERRIDE;
   virtual nsAsyncCopyProgressFun GetProgressCallback() MOZ_OVERRIDE;
 private:
   ~BackgroundFileSaverOutputStream();
   /**
    * Original callback provided to our AsyncWait wrapper.
    */
   nsCOMPtr<nsIOutputStreamCallback> mAsyncWaitCallback;
 };
 ////////////////////////////////////////////////////////////////////////////////
 //// BackgroundFileSaverStreamListener. This class is instantiated by
 // nsExternalHelperAppService, DownloadCore.jsm, and possibly others.
 class BackgroundFileSaverStreamListener : public BackgroundFileSaver
                                         , public nsIStreamListener
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIREQUESTOBSERVER
   NS_DECL_NSISTREAMLISTENER
   BackgroundFileSaverStreamListener();
 protected:
   virtual bool HasInfiniteBuffer() MOZ_OVERRIDE;
   virtual nsAsyncCopyProgressFun GetProgressCallback() MOZ_OVERRIDE;
 private:
   ~BackgroundFileSaverStreamListener();
   /**
    * Protects the state related to whether the request should be suspended.
    */
   mozilla::Mutex mSuspensionLock;
   /**
    * Whether we should suspend the request because we received too much data.
    */
   bool mReceivedTooMuchData;
   /**
    * Request for which we received too much data.  This is populated when
    * mReceivedTooMuchData becomes true for the first time.
    */
   nsCOMPtr<nsIRequest> mRequest;
   /**
    * Whether mRequest is currently suspended.
    */
   bool mRequestSuspended;
   /**
    * Called while NS_AsyncCopy is copying data.
    */
   static void AsyncCopyProgressCallback(void *aClosure, uint32_t aCount);
   /**
    * Called on the control thread to suspend or resume the request.
    */
   nsresult NotifySuspendOrResume();
 };
 // A wrapper around nsIOutputStream, so that we can compute hashes on the
 // stream without copying and without polluting pristine NSS code with XPCOM
 // interfaces.
 class DigestOutputStream : public nsNSSShutDownObject,
                            public nsIOutputStream
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIOUTPUTSTREAM
   // Constructor. Neither parameter may be null. The caller owns both.
   DigestOutputStream(nsIOutputStream* outputStream, PK11Context* aContext);
   ~DigestOutputStream();
   // We don't own any NSS objects here, so no need to clean up
   void virtualDestroyNSSReference() { }
 private:
   // Calls to write are passed to this stream.
   nsCOMPtr<nsIOutputStream> mOutputStream;
   // Digest context used to compute the hash, owned by the caller.
   PK11Context* mDigestContext;
   // Don't accidentally copy construct.
   DigestOutputStream(const DigestOutputStream& d);
 };
 } // namespace net
 } // namespace mozilla
 #endif

The Tor Browser / annotate

netwerk/base/src/BackgroundFileSaver.h@6474c204b198 (annotated)

netwerk/base/src/BackgroundFileSaver.h