The Tor Browser: xpcom/glue/nsWeakReference.cpp@97036ab72558

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

     1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-

     2  *

     3  * This Source Code Form is subject to the terms of the Mozilla Public

     4  * License, v. 2.0. If a copy of the MPL was not distributed with this

     5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     7 // nsWeakReference.cpp

     9 #include "mozilla/Attributes.h"

    11 #include "nsWeakReference.h"

    12 #include "nsCOMPtr.h"

    14 class nsWeakReference MOZ_FINAL : public nsIWeakReference

    15   {

    16     public:

    17     // nsISupports...

    18       NS_DECL_ISUPPORTS

    20     // nsIWeakReference...

    21       NS_DECL_NSIWEAKREFERENCE

    23     private:

    24       friend class nsSupportsWeakReference;

    26       nsWeakReference( nsSupportsWeakReference* referent )

    27           : mReferent(referent)

    28           // ...I can only be constructed by an |nsSupportsWeakReference|

    29         {

    30           // nothing else to do here

    31         }

    33       ~nsWeakReference()

    34            // ...I will only be destroyed by calling |delete| myself.

    35         {

    36           if ( mReferent )

    37             mReferent->NoticeProxyDestruction();

    38         }

    40       void

    41       NoticeReferentDestruction()

    42           // ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.

    43         {

    44           mReferent = 0;

    45         }

    47       nsSupportsWeakReference*  mReferent;

    48   };

    50 nsresult

    51 nsQueryReferent::operator()( const nsIID& aIID, void** answer ) const

    52   {

    53     nsresult status;

    54     if ( mWeakPtr )

    55       {

    56         if ( NS_FAILED(status = mWeakPtr->QueryReferent(aIID, answer)) )

    57           *answer = 0;

    58       }

    59     else

    60       status = NS_ERROR_NULL_POINTER;

    62     if ( mErrorPtr )

    63       *mErrorPtr = status;

    64     return status;

    65   }

    67 NS_COM_GLUE nsIWeakReference*  // or else |already_AddRefed<nsIWeakReference>|

    68 NS_GetWeakReference( nsISupports* aInstancePtr, nsresult* aErrorPtr )

    69   {

    70     nsresult status;

    72     nsIWeakReference* result = nullptr;

    74     if ( aInstancePtr )

    75       {

    76         nsCOMPtr<nsISupportsWeakReference> factoryPtr = do_QueryInterface(aInstancePtr, &status);

    77         if ( factoryPtr )

    78           {

    79             status = factoryPtr->GetWeakReference(&result);

    80           }

    81         // else, |status| has already been set by |do_QueryInterface|

    82       }

    83     else

    84       status = NS_ERROR_NULL_POINTER;

    86     if ( aErrorPtr )

    87       *aErrorPtr = status;

    88     return result;

    89   }

    91 NS_COM_GLUE nsresult

    92 nsSupportsWeakReference::GetWeakReference( nsIWeakReference** aInstancePtr )

    93   {

    94     if ( !aInstancePtr )

    95       return NS_ERROR_NULL_POINTER;

    97     if ( !mProxy )

    98       mProxy = new nsWeakReference(this);

    99     *aInstancePtr = mProxy;

   101     nsresult status;

   102     if ( !*aInstancePtr )

   103       status = NS_ERROR_OUT_OF_MEMORY;

   104     else

   105       {

   106         NS_ADDREF(*aInstancePtr);

   107         status = NS_OK;

   108       }

   110     return status;

   111   }

   113 NS_IMPL_ISUPPORTS(nsWeakReference, nsIWeakReference)

   115 NS_IMETHODIMP

   116 nsWeakReference::QueryReferent( const nsIID& aIID, void** aInstancePtr )

   117   {

   118     return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) : NS_ERROR_NULL_POINTER;

   119   }

   121 void

   122 nsSupportsWeakReference::ClearWeakReferences()

   123 	{

   124 		if ( mProxy )

   125 			{

   126 				mProxy->NoticeReferentDestruction();

   127 				mProxy = 0;

   128 			}

   129 	}

The Tor Browser / file revision

xpcom/glue/nsWeakReference.cpp@97036ab72558

xpcom/glue/nsWeakReference.cpp