The Tor Browser: docshell/shistory/src/nsSHistory.cpp@97036ab72558 (annotated)

docshell/shistory/src/nsSHistory.cpp@97036ab72558 (annotated)

docshell/shistory/src/nsSHistory.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

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.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  *
  * 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/. */
 // Local Includes
 #include "nsSHistory.h"
 #include <algorithm>
 // Helper Classes
 #include "mozilla/Preferences.h"
 // Interfaces Needed
 #include "nsILayoutHistoryState.h"
 #include "nsIDocShell.h"
 #include "nsIDocShellLoadInfo.h"
 #include "nsISHContainer.h"
 #include "nsIDocShellTreeItem.h"
 #include "nsIURI.h"
 #include "nsIContentViewer.h"
 #include "nsICacheService.h"
 #include "nsIObserverService.h"
 #include "prclist.h"
 #include "mozilla/Services.h"
 #include "nsTArray.h"
 #include "nsCOMArray.h"
 #include "nsDocShell.h"
 #include "mozilla/Attributes.h"
 #include "nsISHEntry.h"
 #include "nsISHTransaction.h"
 #include "nsISHistoryListener.h"
 #include "nsComponentManagerUtils.h"
 // For calculating max history entries and max cachable contentviewers
 #include "prsystem.h"
 #include "mozilla/MathAlgorithms.h"
 using namespace mozilla;
 #define PREF_SHISTORY_SIZE "browser.sessionhistory.max_entries"
 #define PREF_SHISTORY_MAX_TOTAL_VIEWERS "browser.sessionhistory.max_total_viewers"
 static const char* kObservedPrefs[] = {
   PREF_SHISTORY_SIZE,
   PREF_SHISTORY_MAX_TOTAL_VIEWERS,
   nullptr
 };
 static int32_t  gHistoryMaxSize = 50;
 // Max viewers allowed per SHistory objects
 static const int32_t  gHistoryMaxViewers = 3;
 // List of all SHistory objects, used for content viewer cache eviction
 static PRCList gSHistoryList;
 // Max viewers allowed total, across all SHistory objects - negative default
 // means we will calculate how many viewers to cache based on total memory
 int32_t nsSHistory::sHistoryMaxTotalViewers = -1;
 // A counter that is used to be able to know the order in which
 // entries were touched, so that we can evict older entries first.
 static uint32_t gTouchCounter = 0;
 #ifdef PR_LOGGING
 static PRLogModuleInfo*
 GetSHistoryLog()
 {
   static PRLogModuleInfo *sLog;
   if (!sLog)
     sLog = PR_NewLogModule("nsSHistory");
   return sLog;
 }
 #define LOG(format) PR_LOG(GetSHistoryLog(), PR_LOG_DEBUG, format)
 // This macro makes it easier to print a log message which includes a URI's
 // spec.  Example use:
 //
 //  nsIURI *uri = [...];
 //  LOG_SPEC(("The URI is %s.", _spec), uri);
 //
 #define LOG_SPEC(format, uri)                              \
   PR_BEGIN_MACRO                                           \
     if (PR_LOG_TEST(GetSHistoryLog(), PR_LOG_DEBUG)) {     \
       nsAutoCString _specStr(NS_LITERAL_CSTRING("(null)"));\
       if (uri) {                                           \
         uri->GetSpec(_specStr);                            \
       }                                                    \
       const char* _spec = _specStr.get();                  \
       LOG(format);                                         \
     }                                                      \
   PR_END_MACRO
 // This macro makes it easy to log a message including an SHEntry's URI.
 // For example:
 //
 //  nsCOMPtr<nsISHEntry> shentry = [...];
 //  LOG_SHENTRY_SPEC(("shentry %p has uri %s.", shentry.get(), _spec), shentry);
 //
 #define LOG_SHENTRY_SPEC(format, shentry)                  \
   PR_BEGIN_MACRO                                           \
     if (PR_LOG_TEST(GetSHistoryLog(), PR_LOG_DEBUG)) {     \
       nsCOMPtr<nsIURI> uri;                                \
       shentry->GetURI(getter_AddRefs(uri));                \
       LOG_SPEC(format, uri);                               \
     }                                                      \
   PR_END_MACRO
 #else // !PR_LOGGING
 #define LOG(format)
 #define LOG_SPEC(format, uri)
 #define LOG_SHENTRY_SPEC(format, shentry)
 #endif // PR_LOGGING
 // Iterates over all registered session history listeners.
 #define ITERATE_LISTENERS(body)                            \
   PR_BEGIN_MACRO                                           \
   {                                                        \
     nsAutoTObserverArray<nsWeakPtr, 2>::EndLimitedIterator \
       iter(mListeners);                                    \
     while (iter.HasMore()) {                               \
       nsCOMPtr<nsISHistoryListener> listener =             \
         do_QueryReferent(iter.GetNext());                  \
       if (listener) {                                      \
         body                                               \
       }                                                    \
     }                                                      \
   }                                                        \
   PR_END_MACRO
 // Calls a given method on all registered session history listeners.
 #define NOTIFY_LISTENERS(method, args)                     \
   ITERATE_LISTENERS(                                       \
     listener->method args;                                 \
   );
 // Calls a given method on all registered session history listeners.
 // Listeners may return 'false' to cancel an action so make sure that we
 // set the return value to 'false' if one of the listeners wants to cancel.
 #define NOTIFY_LISTENERS_CANCELABLE(method, retval, args)  \
   PR_BEGIN_MACRO                                           \
   {                                                        \
     bool canceled = false;                                 \
     retval = true;                                         \
     ITERATE_LISTENERS(                                     \
       listener->method args;                               \
       if (!retval) {                                       \
         canceled = true;                                   \
       }                                                    \
     );                                                     \
     if (canceled) {                                        \
       retval = false;                                      \
     }                                                      \
   }                                                        \
   PR_END_MACRO
 enum HistCmd{
   HIST_CMD_BACK,
   HIST_CMD_FORWARD,
   HIST_CMD_GOTOINDEX,
   HIST_CMD_RELOAD
 } ;
 //*****************************************************************************
 //***      nsSHistoryObserver
 //*****************************************************************************
 class nsSHistoryObserver MOZ_FINAL : public nsIObserver
 {
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIOBSERVER
   nsSHistoryObserver() {}
 protected:
   ~nsSHistoryObserver() {}
 };
 static nsSHistoryObserver* gObserver = nullptr;
 NS_IMPL_ISUPPORTS(nsSHistoryObserver, nsIObserver)
 NS_IMETHODIMP
 nsSHistoryObserver::Observe(nsISupports *aSubject, const char *aTopic,
                             const char16_t *aData)
 {
   if (!strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID)) {
     nsSHistory::UpdatePrefs();
     nsSHistory::GloballyEvictContentViewers();
   } else if (!strcmp(aTopic, NS_CACHESERVICE_EMPTYCACHE_TOPIC_ID) ||
              !strcmp(aTopic, "memory-pressure")) {
     nsSHistory::GloballyEvictAllContentViewers();
   }
   return NS_OK;
 }
 namespace {
 already_AddRefed<nsIContentViewer>
 GetContentViewerForTransaction(nsISHTransaction *aTrans)
 {
   nsCOMPtr<nsISHEntry> entry;
   aTrans->GetSHEntry(getter_AddRefs(entry));
   if (!entry) {
     return nullptr;
   }
   nsCOMPtr<nsISHEntry> ownerEntry;
   nsCOMPtr<nsIContentViewer> viewer;
   entry->GetAnyContentViewer(getter_AddRefs(ownerEntry),
                              getter_AddRefs(viewer));
   return viewer.forget();
 }
 void
 EvictContentViewerForTransaction(nsISHTransaction *aTrans)
 {
   nsCOMPtr<nsISHEntry> entry;
   aTrans->GetSHEntry(getter_AddRefs(entry));
   nsCOMPtr<nsIContentViewer> viewer;
   nsCOMPtr<nsISHEntry> ownerEntry;
   entry->GetAnyContentViewer(getter_AddRefs(ownerEntry),
                              getter_AddRefs(viewer));
   if (viewer) {
     NS_ASSERTION(ownerEntry,
                  "Content viewer exists but its SHEntry is null");
     LOG_SHENTRY_SPEC(("Evicting content viewer 0x%p for "
                       "owning SHEntry 0x%p at %s.",
                       viewer.get(), ownerEntry.get(), _spec), ownerEntry);
     // Drop the presentation state before destroying the viewer, so that
     // document teardown is able to correctly persist the state.
     ownerEntry->SetContentViewer(nullptr);
     ownerEntry->SyncPresentationState();
     viewer->Destroy();
   }
 }
 } // anonymous namespace
 //*****************************************************************************
 //***    nsSHistory: Object Management
 //*****************************************************************************
 nsSHistory::nsSHistory() : mListRoot(nullptr), mIndex(-1), mLength(0), mRequestedIndex(-1)
 {
   // Add this new SHistory object to the list
   PR_APPEND_LINK(this, &gSHistoryList);
 }
 nsSHistory::~nsSHistory()
 {
   // Remove this SHistory object from the list
   PR_REMOVE_LINK(this);
 }
 //*****************************************************************************
 //    nsSHistory: nsISupports
 //*****************************************************************************
 NS_IMPL_ADDREF(nsSHistory)
 NS_IMPL_RELEASE(nsSHistory)
 NS_INTERFACE_MAP_BEGIN(nsSHistory)
    NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsISHistory)
    NS_INTERFACE_MAP_ENTRY(nsISHistory)
    NS_INTERFACE_MAP_ENTRY(nsIWebNavigation)
    NS_INTERFACE_MAP_ENTRY(nsISHistoryInternal)
 NS_INTERFACE_MAP_END
 //*****************************************************************************
 //    nsSHistory: nsISHistory
 //*****************************************************************************
 // static
 uint32_t
 nsSHistory::CalcMaxTotalViewers()
 {
   // Calculate an estimate of how many ContentViewers we should cache based
   // on RAM.  This assumes that the average ContentViewer is 4MB (conservative)
   // and caps the max at 8 ContentViewers
   //
   // TODO: Should we split the cache memory betw. ContentViewer caching and
   // nsCacheService?
   //
   // RAM      ContentViewers
   // -----------------------
   // 32   Mb       0
   // 64   Mb       1
   // 128  Mb       2
   // 256  Mb       3
   // 512  Mb       5
   // 1024 Mb       8
   // 2048 Mb       8
   // 4096 Mb       8
   uint64_t bytes = PR_GetPhysicalMemorySize();
   if (bytes == 0)
     return 0;
   // Conversion from unsigned int64_t to double doesn't work on all platforms.
   // We need to truncate the value at INT64_MAX to make sure we don't
   // overflow.
   if (bytes > INT64_MAX)
     bytes = INT64_MAX;
   double kBytesD = (double)(bytes >> 10);
   // This is essentially the same calculation as for nsCacheService,
   // except that we divide the final memory calculation by 4, since
   // we assume each ContentViewer takes on average 4MB
   uint32_t viewers = 0;
   double x = std::log(kBytesD)/std::log(2.0) - 14;
   if (x > 0) {
     viewers    = (uint32_t)(x * x - x + 2.001); // add .001 for rounding
     viewers   /= 4;
   }
   // Cap it off at 8 max
   if (viewers > 8) {
     viewers = 8;
   }
   return viewers;
 }
 // static
 void
 nsSHistory::UpdatePrefs()
 {
   Preferences::GetInt(PREF_SHISTORY_SIZE, &gHistoryMaxSize);
   Preferences::GetInt(PREF_SHISTORY_MAX_TOTAL_VIEWERS,
                       &sHistoryMaxTotalViewers);
   // If the pref is negative, that means we calculate how many viewers
   // we think we should cache, based on total memory
   if (sHistoryMaxTotalViewers < 0) {
     sHistoryMaxTotalViewers = CalcMaxTotalViewers();
   }
 }
 // static
 nsresult
 nsSHistory::Startup()
 {
   UpdatePrefs();
   // The goal of this is to unbreak users who have inadvertently set their
   // session history size to less than the default value.
   int32_t defaultHistoryMaxSize =
     Preferences::GetDefaultInt(PREF_SHISTORY_SIZE, 50);
   if (gHistoryMaxSize < defaultHistoryMaxSize) {
     gHistoryMaxSize = defaultHistoryMaxSize;
   }
   // Allow the user to override the max total number of cached viewers,
   // but keep the per SHistory cached viewer limit constant
   if (!gObserver) {
     gObserver = new nsSHistoryObserver();
     NS_ADDREF(gObserver);
     Preferences::AddStrongObservers(gObserver, kObservedPrefs);
     nsCOMPtr<nsIObserverService> obsSvc =
       mozilla::services::GetObserverService();
     if (obsSvc) {
       // Observe empty-cache notifications so tahat clearing the disk/memory
       // cache will also evict all content viewers.
       obsSvc->AddObserver(gObserver,
                           NS_CACHESERVICE_EMPTYCACHE_TOPIC_ID, false);
       // Same for memory-pressure notifications
       obsSvc->AddObserver(gObserver, "memory-pressure", false);
     }
   }
   // Initialize the global list of all SHistory objects
   PR_INIT_CLIST(&gSHistoryList);
   return NS_OK;
 }
 // static
 void
 nsSHistory::Shutdown()
 {
   if (gObserver) {
     Preferences::RemoveObservers(gObserver, kObservedPrefs);
     nsCOMPtr<nsIObserverService> obsSvc =
       mozilla::services::GetObserverService();
     if (obsSvc) {
       obsSvc->RemoveObserver(gObserver, NS_CACHESERVICE_EMPTYCACHE_TOPIC_ID);
       obsSvc->RemoveObserver(gObserver, "memory-pressure");
     }
     NS_RELEASE(gObserver);
   }
 }
 /* Add an entry to the History list at mIndex and
  * increment the index to point to the new entry
  */
 NS_IMETHODIMP
 nsSHistory::AddEntry(nsISHEntry * aSHEntry, bool aPersist)
 {
   NS_ENSURE_ARG(aSHEntry);
   nsCOMPtr<nsISHTransaction> currentTxn;
   if(mListRoot)
     GetTransactionAtIndex(mIndex, getter_AddRefs(currentTxn));
   bool currentPersist = true;
   if(currentTxn)
     currentTxn->GetPersist(&currentPersist);
   int32_t currentIndex = mIndex;
   if(!currentPersist)
   {
     NOTIFY_LISTENERS(OnHistoryReplaceEntry, (currentIndex));
     NS_ENSURE_SUCCESS(currentTxn->SetSHEntry(aSHEntry),NS_ERROR_FAILURE);
     currentTxn->SetPersist(aPersist);
     return NS_OK;
   }
   nsCOMPtr<nsISHTransaction> txn(do_CreateInstance(NS_SHTRANSACTION_CONTRACTID));
   NS_ENSURE_TRUE(txn, NS_ERROR_FAILURE);
   nsCOMPtr<nsIURI> uri;
   aSHEntry->GetURI(getter_AddRefs(uri));
   NOTIFY_LISTENERS(OnHistoryNewEntry, (uri));
   // If a listener has changed mIndex, we need to get currentTxn again,
   // otherwise we'll be left at an inconsistent state (see bug 320742)
   if (currentIndex != mIndex) {
     GetTransactionAtIndex(mIndex, getter_AddRefs(currentTxn));
   }
   // Set the ShEntry and parent for the transaction. setting the
   // parent will properly set the parent child relationship
   txn->SetPersist(aPersist);
   NS_ENSURE_SUCCESS(txn->Create(aSHEntry, currentTxn), NS_ERROR_FAILURE);
   // A little tricky math here...  Basically when adding an object regardless of
   // what the length was before, it should always be set back to the current and
   // lop off the forward.
   mLength = (++mIndex + 1);
   // If this is the very first transaction, initialize the list
   if(!mListRoot)
     mListRoot = txn;
   // Purge History list if it is too long
   if ((gHistoryMaxSize >= 0) && (mLength > gHistoryMaxSize))
     PurgeHistory(mLength-gHistoryMaxSize);
   RemoveDynEntries(mIndex - 1, mIndex);
   return NS_OK;
 }
 /* Get size of the history list */
 NS_IMETHODIMP
 nsSHistory::GetCount(int32_t * aResult)
 {
   NS_ENSURE_ARG_POINTER(aResult);
   *aResult = mLength;
   return NS_OK;
 }
 /* Get index of the history list */
 NS_IMETHODIMP
 nsSHistory::GetIndex(int32_t * aResult)
 {
   NS_PRECONDITION(aResult, "null out param?");
   *aResult = mIndex;
   return NS_OK;
 }
 /* Get the requestedIndex */
 NS_IMETHODIMP
 nsSHistory::GetRequestedIndex(int32_t * aResult)
 {
   NS_PRECONDITION(aResult, "null out param?");
   *aResult = mRequestedIndex;
   return NS_OK;
 }
 /* Get the entry at a given index */
 NS_IMETHODIMP
 nsSHistory::GetEntryAtIndex(int32_t aIndex, bool aModifyIndex, nsISHEntry** aResult)
 {
   nsresult rv;
   nsCOMPtr<nsISHTransaction> txn;
   /* GetTransactionAtIndex ensures aResult is valid and validates aIndex */
   rv = GetTransactionAtIndex(aIndex, getter_AddRefs(txn));
   if (NS_SUCCEEDED(rv) && txn) {
     //Get the Entry from the transaction
     rv = txn->GetSHEntry(aResult);
     if (NS_SUCCEEDED(rv) && (*aResult)) {
       // Set mIndex to the requested index, if asked to do so..
       if (aModifyIndex) {
         mIndex = aIndex;
       }
     } //entry
   }  //Transaction
   return rv;
 }
 /* Get the transaction at a given index */
 NS_IMETHODIMP
 nsSHistory::GetTransactionAtIndex(int32_t aIndex, nsISHTransaction ** aResult)
 {
   nsresult rv;
   NS_ENSURE_ARG_POINTER(aResult);
   if ((mLength <= 0) || (aIndex < 0) || (aIndex >= mLength))
     return NS_ERROR_FAILURE;
   if (!mListRoot)
     return NS_ERROR_FAILURE;
   if (aIndex == 0)
   {
     *aResult = mListRoot;
     NS_ADDREF(*aResult);
     return NS_OK;
   }
   int32_t   cnt=0;
   nsCOMPtr<nsISHTransaction>  tempPtr;
   rv = GetRootTransaction(getter_AddRefs(tempPtr));
   if (NS_FAILED(rv) || !tempPtr)
     return NS_ERROR_FAILURE;
   while(1) {
     nsCOMPtr<nsISHTransaction> ptr;
     rv = tempPtr->GetNext(getter_AddRefs(ptr));
     if (NS_SUCCEEDED(rv) && ptr) {
       cnt++;
       if (cnt == aIndex) {
         *aResult = ptr;
         NS_ADDREF(*aResult);
         break;
       }
       else {
         tempPtr = ptr;
         continue;
       }
     }  //NS_SUCCEEDED
     else
       return NS_ERROR_FAILURE;
   }  // while
   return NS_OK;
 }
 /* Get the index of a given entry */
 NS_IMETHODIMP
 nsSHistory::GetIndexOfEntry(nsISHEntry* aSHEntry, int32_t* aResult) {
   NS_ENSURE_ARG(aSHEntry);
   NS_ENSURE_ARG_POINTER(aResult);
   *aResult = -1;
   if (mLength <= 0) {
     return NS_ERROR_FAILURE;
   }
   nsCOMPtr<nsISHTransaction> currentTxn;
   int32_t cnt = 0;
   nsresult rv = GetRootTransaction(getter_AddRefs(currentTxn));
   if (NS_FAILED(rv) || !currentTxn) {
     return NS_ERROR_FAILURE;
   }
   while (true) {
     nsCOMPtr<nsISHEntry> entry;
     rv = currentTxn->GetSHEntry(getter_AddRefs(entry));
     if (NS_FAILED(rv) || !entry) {
       return NS_ERROR_FAILURE;
     }
     if (aSHEntry == entry) {
       *aResult = cnt;
       break;
     }
     rv = currentTxn->GetNext(getter_AddRefs(currentTxn));
     if (NS_FAILED(rv) || !currentTxn) {
       return NS_ERROR_FAILURE;
     }
     cnt++;
   }
   return NS_OK;
 }
 #ifdef DEBUG
 nsresult
 nsSHistory::PrintHistory()
 {
   nsCOMPtr<nsISHTransaction>   txn;
   int32_t index = 0;
   nsresult rv;
   if (!mListRoot)
     return NS_ERROR_FAILURE;
   txn = mListRoot;
   while (1) {
     if (!txn)
       break;
     nsCOMPtr<nsISHEntry>  entry;
     rv = txn->GetSHEntry(getter_AddRefs(entry));
     if (NS_FAILED(rv) && !entry)
       return NS_ERROR_FAILURE;
     nsCOMPtr<nsILayoutHistoryState> layoutHistoryState;
     nsCOMPtr<nsIURI>  uri;
     nsXPIDLString title;
     entry->GetLayoutHistoryState(getter_AddRefs(layoutHistoryState));
     entry->GetURI(getter_AddRefs(uri));
     entry->GetTitle(getter_Copies(title));
 #if 0
     nsAutoCString url;
     if (uri)
      uri->GetSpec(url);
     printf("**** SH Transaction #%d, Entry = %x\n", index, entry.get());
     printf("\t\t URL = %s\n", url.get());
     printf("\t\t Title = %s\n", NS_LossyConvertUTF16toASCII(title).get());
     printf("\t\t layout History Data = %x\n", layoutHistoryState.get());
 #endif
     nsCOMPtr<nsISHTransaction> next;
     rv = txn->GetNext(getter_AddRefs(next));
     if (NS_SUCCEEDED(rv) && next) {
       txn = next;
       index++;
       continue;
     }
     else
       break;
   }
   return NS_OK;
 }
 #endif
 NS_IMETHODIMP
 nsSHistory::GetRootTransaction(nsISHTransaction ** aResult)
 {
   NS_ENSURE_ARG_POINTER(aResult);
   *aResult=mListRoot;
   NS_IF_ADDREF(*aResult);
   return NS_OK;
 }
 /* Get the max size of the history list */
 NS_IMETHODIMP
 nsSHistory::GetMaxLength(int32_t * aResult)
 {
   NS_ENSURE_ARG_POINTER(aResult);
   *aResult = gHistoryMaxSize;
   return NS_OK;
 }
 /* Set the max size of the history list */
 NS_IMETHODIMP
 nsSHistory::SetMaxLength(int32_t aMaxSize)
 {
   if (aMaxSize < 0)
     return NS_ERROR_ILLEGAL_VALUE;
   gHistoryMaxSize = aMaxSize;
   if (mLength > aMaxSize)
     PurgeHistory(mLength-aMaxSize);
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::PurgeHistory(int32_t aEntries)
 {
   if (mLength <= 0 || aEntries <= 0)
     return NS_ERROR_FAILURE;
   aEntries = std::min(aEntries, mLength);
   bool purgeHistory = true;
   NOTIFY_LISTENERS_CANCELABLE(OnHistoryPurge, purgeHistory,
                               (aEntries, &purgeHistory));
   if (!purgeHistory) {
     // Listener asked us not to purge
     return NS_SUCCESS_LOSS_OF_INSIGNIFICANT_DATA;
   }
   int32_t cnt = 0;
   while (cnt < aEntries) {
     nsCOMPtr<nsISHTransaction> nextTxn;
     if (mListRoot) {
       mListRoot->GetNext(getter_AddRefs(nextTxn));
       mListRoot->SetNext(nullptr);
     }
     mListRoot = nextTxn;
     if (mListRoot) {
       mListRoot->SetPrev(nullptr);
     }
     cnt++;
   }
   mLength -= cnt;
   mIndex -= cnt;
   // Now if we were not at the end of the history, mIndex could have
   // become far too negative.  If so, just set it to -1.
   if (mIndex < -1) {
     mIndex = -1;
   }
   if (mRootDocShell)
     mRootDocShell->HistoryPurged(cnt);
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::AddSHistoryListener(nsISHistoryListener * aListener)
 {
   NS_ENSURE_ARG_POINTER(aListener);
   // Check if the listener supports Weak Reference. This is a must.
   // This listener functionality is used by embedders and we want to
   // have the right ownership with who ever listens to SHistory
   nsWeakPtr listener = do_GetWeakReference(aListener);
   if (!listener) return NS_ERROR_FAILURE;
   return mListeners.AppendElementUnlessExists(listener) ?
     NS_OK : NS_ERROR_OUT_OF_MEMORY;
 }
 NS_IMETHODIMP
 nsSHistory::RemoveSHistoryListener(nsISHistoryListener * aListener)
 {
   // Make sure the listener that wants to be removed is the
   // one we have in store.
   nsWeakPtr listener = do_GetWeakReference(aListener);
   mListeners.RemoveElement(listener);
   return NS_OK;
 }
 /* Replace an entry in the History list at a particular index.
  * Do not update index or count.
  */
 NS_IMETHODIMP
 nsSHistory::ReplaceEntry(int32_t aIndex, nsISHEntry * aReplaceEntry)
 {
   NS_ENSURE_ARG(aReplaceEntry);
   nsresult rv;
   nsCOMPtr<nsISHTransaction> currentTxn;
   if (!mListRoot) // Session History is not initialised.
     return NS_ERROR_FAILURE;
   rv = GetTransactionAtIndex(aIndex, getter_AddRefs(currentTxn));
   if(currentTxn)
   {
     NOTIFY_LISTENERS(OnHistoryReplaceEntry, (aIndex));
     // Set the replacement entry in the transaction
     rv = currentTxn->SetSHEntry(aReplaceEntry);
     rv = currentTxn->SetPersist(true);
   }
   return rv;
 }
 NS_IMETHODIMP
 nsSHistory::NotifyOnHistoryReload(nsIURI* aReloadURI, uint32_t aReloadFlags,
                                   bool* aCanReload)
 {
   NOTIFY_LISTENERS_CANCELABLE(OnHistoryReload, *aCanReload,
                               (aReloadURI, aReloadFlags, aCanReload));
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::EvictOutOfRangeContentViewers(int32_t aIndex)
 {
   // Check our per SHistory object limit in the currently navigated SHistory
   EvictOutOfRangeWindowContentViewers(aIndex);
   // Check our total limit across all SHistory objects
   GloballyEvictContentViewers();
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::EvictAllContentViewers()
 {
   // XXXbz we don't actually do a good job of evicting things as we should, so
   // we might have viewers quite far from mIndex.  So just evict everything.
   nsCOMPtr<nsISHTransaction> trans = mListRoot;
   while (trans) {
     EvictContentViewerForTransaction(trans);
     nsISHTransaction *temp = trans;
     temp->GetNext(getter_AddRefs(trans));
   }
   return NS_OK;
 }
 //*****************************************************************************
 //    nsSHistory: nsIWebNavigation
 //*****************************************************************************
 NS_IMETHODIMP
 nsSHistory::GetCanGoBack(bool * aCanGoBack)
 {
   NS_ENSURE_ARG_POINTER(aCanGoBack);
   *aCanGoBack = false;
   int32_t index = -1;
   NS_ENSURE_SUCCESS(GetIndex(&index), NS_ERROR_FAILURE);
   if(index > 0)
      *aCanGoBack = true;
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GetCanGoForward(bool * aCanGoForward)
 {
   NS_ENSURE_ARG_POINTER(aCanGoForward);
   *aCanGoForward = false;
   int32_t index = -1;
   int32_t count = -1;
   NS_ENSURE_SUCCESS(GetIndex(&index), NS_ERROR_FAILURE);
   NS_ENSURE_SUCCESS(GetCount(&count), NS_ERROR_FAILURE);
   if((index >= 0) && (index < (count - 1)))
     *aCanGoForward = true;
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GoBack()
 {
   bool canGoBack = false;
   GetCanGoBack(&canGoBack);
   if (!canGoBack)  // Can't go back
     return NS_ERROR_UNEXPECTED;
   return LoadEntry(mIndex-1, nsIDocShellLoadInfo::loadHistory, HIST_CMD_BACK);
 }
 NS_IMETHODIMP
 nsSHistory::GoForward()
 {
   bool canGoForward = false;
   GetCanGoForward(&canGoForward);
   if (!canGoForward)  // Can't go forward
     return NS_ERROR_UNEXPECTED;
   return LoadEntry(mIndex+1, nsIDocShellLoadInfo::loadHistory, HIST_CMD_FORWARD);
 }
 NS_IMETHODIMP
 nsSHistory::Reload(uint32_t aReloadFlags)
 {
   nsDocShellInfoLoadType loadType;
   if (aReloadFlags & nsIWebNavigation::LOAD_FLAGS_BYPASS_PROXY &&
       aReloadFlags & nsIWebNavigation::LOAD_FLAGS_BYPASS_CACHE)
   {
     loadType = nsIDocShellLoadInfo::loadReloadBypassProxyAndCache;
   }
   else if (aReloadFlags & nsIWebNavigation::LOAD_FLAGS_BYPASS_PROXY)
   {
     loadType = nsIDocShellLoadInfo::loadReloadBypassProxy;
   }
   else if (aReloadFlags & nsIWebNavigation::LOAD_FLAGS_BYPASS_CACHE)
   {
     loadType = nsIDocShellLoadInfo::loadReloadBypassCache;
   }
   else if (aReloadFlags & nsIWebNavigation::LOAD_FLAGS_CHARSET_CHANGE)
   {
     loadType = nsIDocShellLoadInfo::loadReloadCharsetChange;
   }
   else if (aReloadFlags & nsIWebNavigation::LOAD_FLAGS_ALLOW_MIXED_CONTENT)
   {
     loadType = nsIDocShellLoadInfo::loadReloadMixedContent;
   }
   else
   {
     loadType = nsIDocShellLoadInfo::loadReloadNormal;
   }
   // We are reloading. Send Reload notifications.
   // nsDocShellLoadFlagType is not public, where as nsIWebNavigation
   // is public. So send the reload notifications with the
   // nsIWebNavigation flags.
   bool canNavigate = true;
   nsCOMPtr<nsIURI> currentURI;
   GetCurrentURI(getter_AddRefs(currentURI));
   NOTIFY_LISTENERS_CANCELABLE(OnHistoryReload, canNavigate,
                               (currentURI, aReloadFlags, &canNavigate));
   if (!canNavigate)
     return NS_OK;
   return LoadEntry(mIndex, loadType, HIST_CMD_RELOAD);
 }
 NS_IMETHODIMP
 nsSHistory::ReloadCurrentEntry()
 {
   // Notify listeners
   bool canNavigate = true;
   nsCOMPtr<nsIURI> currentURI;
   GetCurrentURI(getter_AddRefs(currentURI));
   NOTIFY_LISTENERS_CANCELABLE(OnHistoryGotoIndex, canNavigate,
                               (mIndex, currentURI, &canNavigate));
   if (!canNavigate)
     return NS_OK;
   return LoadEntry(mIndex, nsIDocShellLoadInfo::loadHistory, HIST_CMD_RELOAD);
 }
 void
 nsSHistory::EvictOutOfRangeWindowContentViewers(int32_t aIndex)
 {
   // XXX rename method to EvictContentViewersExceptAroundIndex, or something.
   // We need to release all content viewers that are no longer in the range
   //
   //  aIndex - gHistoryMaxViewers to aIndex + gHistoryMaxViewers
   //
   // to ensure that this SHistory object isn't responsible for more than
   // gHistoryMaxViewers content viewers.  But our job is complicated by the
   // fact that two transactions which are related by either hash navigations or
   // history.pushState will have the same content viewer.
   //
   // To illustrate the issue, suppose gHistoryMaxViewers = 3 and we have four
   // linked transactions in our history.  Suppose we then add a new content
   // viewer and call into this function.  So the history looks like:
   //
   //   A A A A B
   //     +     *
   //
   // where the letters are content viewers and + and * denote the beginning and
   // end of the range aIndex +/- gHistoryMaxViewers.
   //
   // Although one copy of the content viewer A exists outside the range, we
   // don't want to evict A, because it has other copies in range!
   //
   // We therefore adjust our eviction strategy to read:
   //
   //   Evict each content viewer outside the range aIndex -/+
   //   gHistoryMaxViewers, unless that content viewer also appears within the
   //   range.
   //
   // (Note that it's entirely legal to have two copies of one content viewer
   // separated by a different content viewer -- call pushState twice, go back
   // once, and refresh -- so we can't rely on identical viewers only appearing
   // adjacent to one another.)
   if (aIndex < 0) {
     return;
   }
   NS_ENSURE_TRUE_VOID(aIndex < mLength);
   // Calculate the range that's safe from eviction.
   int32_t startSafeIndex = std::max(0, aIndex - gHistoryMaxViewers);
   int32_t endSafeIndex = std::min(mLength, aIndex + gHistoryMaxViewers);
   LOG(("EvictOutOfRangeWindowContentViewers(index=%d), "
        "mLength=%d. Safe range [%d, %d]",
        aIndex, mLength, startSafeIndex, endSafeIndex));
   // The content viewers in range aIndex -/+ gHistoryMaxViewers will not be
   // evicted.  Collect a set of them so we don't accidentally evict one of them
   // if it appears outside this range.
   nsCOMArray<nsIContentViewer> safeViewers;
   nsCOMPtr<nsISHTransaction> trans;
   GetTransactionAtIndex(startSafeIndex, getter_AddRefs(trans));
   for (int32_t i = startSafeIndex; trans && i <= endSafeIndex; i++) {
     nsCOMPtr<nsIContentViewer> viewer = GetContentViewerForTransaction(trans);
     safeViewers.AppendObject(viewer);
     nsISHTransaction *temp = trans;
     temp->GetNext(getter_AddRefs(trans));
   }
   // Walk the SHistory list and evict any content viewers that aren't safe.
   GetTransactionAtIndex(0, getter_AddRefs(trans));
   while (trans) {
     nsCOMPtr<nsIContentViewer> viewer = GetContentViewerForTransaction(trans);
     if (safeViewers.IndexOf(viewer) == -1) {
       EvictContentViewerForTransaction(trans);
     }
     nsISHTransaction *temp = trans;
     temp->GetNext(getter_AddRefs(trans));
   }
 }
 namespace {
 class TransactionAndDistance
 {
 public:
   TransactionAndDistance(nsISHTransaction *aTrans, uint32_t aDist)
     : mTransaction(aTrans)
     , mDistance(aDist)
   {
     mViewer = GetContentViewerForTransaction(aTrans);
     NS_ASSERTION(mViewer, "Transaction should have a content viewer");
     nsCOMPtr<nsISHEntry> shentry;
     mTransaction->GetSHEntry(getter_AddRefs(shentry));
     nsCOMPtr<nsISHEntryInternal> shentryInternal = do_QueryInterface(shentry);
     if (shentryInternal) {
       shentryInternal->GetLastTouched(&mLastTouched);
     } else {
       NS_WARNING("Can't cast to nsISHEntryInternal?");
       mLastTouched = 0;
     }
   }
   bool operator<(const TransactionAndDistance &aOther) const
   {
     // Compare distances first, and fall back to last-accessed times.
     if (aOther.mDistance != this->mDistance) {
       return this->mDistance < aOther.mDistance;
     }
     return this->mLastTouched < aOther.mLastTouched;
   }
   bool operator==(const TransactionAndDistance &aOther) const
   {
     // This is a little silly; we need == so the default comaprator can be
     // instantiated, but this function is never actually called when we sort
     // the list of TransactionAndDistance objects.
     return aOther.mDistance == this->mDistance &&
            aOther.mLastTouched == this->mLastTouched;
   }
   nsCOMPtr<nsISHTransaction> mTransaction;
   nsCOMPtr<nsIContentViewer> mViewer;
   uint32_t mLastTouched;
   int32_t mDistance;
 };
 } // anonymous namespace
 //static
 void
 nsSHistory::GloballyEvictContentViewers()
 {
   // First, collect from each SHistory object the transactions which have a
   // cached content viewer.  Associate with each transaction its distance from
   // its SHistory's current index.
   nsTArray<TransactionAndDistance> transactions;
   nsSHistory *shist = static_cast<nsSHistory*>(PR_LIST_HEAD(&gSHistoryList));
   while (shist != &gSHistoryList) {
     // Maintain a list of the transactions which have viewers and belong to
     // this particular shist object.  We'll add this list to the global list,
     // |transactions|, eventually.
     nsTArray<TransactionAndDistance> shTransactions;
     // Content viewers are likely to exist only within shist->mIndex -/+
     // gHistoryMaxViewers, so only search within that range.
     //
     // A content viewer might exist outside that range due to either:
     //
     //   * history.pushState or hash navigations, in which case a copy of the
     //     content viewer should exist within the range, or
     //
     //   * bugs which cause us not to call nsSHistory::EvictContentViewers()
     //     often enough.  Once we do call EvictContentViewers() for the
     //     SHistory object in question, we'll do a full search of its history
     //     and evict the out-of-range content viewers, so we don't bother here.
     //
     int32_t startIndex = std::max(0, shist->mIndex - gHistoryMaxViewers);
     int32_t endIndex = std::min(shist->mLength - 1,
                               shist->mIndex + gHistoryMaxViewers);
     nsCOMPtr<nsISHTransaction> trans;
     shist->GetTransactionAtIndex(startIndex, getter_AddRefs(trans));
     for (int32_t i = startIndex; trans && i <= endIndex; i++) {
       nsCOMPtr<nsIContentViewer> contentViewer =
         GetContentViewerForTransaction(trans);
       if (contentViewer) {
         // Because one content viewer might belong to multiple SHEntries, we
         // have to search through shTransactions to see if we already know
         // about this content viewer.  If we find the viewer, update its
         // distance from the SHistory's index and continue.
         bool found = false;
         for (uint32_t j = 0; j < shTransactions.Length(); j++) {
           TransactionAndDistance &container = shTransactions[j];
           if (container.mViewer == contentViewer) {
             container.mDistance = std::min(container.mDistance, DeprecatedAbs(i - shist->mIndex));
             found = true;
             break;
           }
         }
         // If we didn't find a TransactionAndDistance for this content viewer, make a new
         // one.
         if (!found) {
           TransactionAndDistance container(trans, DeprecatedAbs(i - shist->mIndex));
           shTransactions.AppendElement(container);
         }
       }
       nsISHTransaction *temp = trans;
       temp->GetNext(getter_AddRefs(trans));
     }
     // We've found all the transactions belonging to shist which have viewers.
     // Add those transactions to our global list and move on.
     transactions.AppendElements(shTransactions);
     shist = static_cast<nsSHistory*>(PR_NEXT_LINK(shist));
   }
   // We now have collected all cached content viewers.  First check that we
   // have enough that we actually need to evict some.
   if ((int32_t)transactions.Length() <= sHistoryMaxTotalViewers) {
     return;
   }
   // If we need to evict, sort our list of transactions and evict the largest
   // ones.  (We could of course get better algorithmic complexity here by using
   // a heap or something more clever.  But sHistoryMaxTotalViewers isn't large,
   // so let's not worry about it.)
   transactions.Sort();
   for (int32_t i = transactions.Length() - 1;
        i >= sHistoryMaxTotalViewers; --i) {
     EvictContentViewerForTransaction(transactions[i].mTransaction);
   }
 }
 nsresult
 nsSHistory::EvictExpiredContentViewerForEntry(nsIBFCacheEntry *aEntry)
 {
   int32_t startIndex = std::max(0, mIndex - gHistoryMaxViewers);
   int32_t endIndex = std::min(mLength - 1,
                             mIndex + gHistoryMaxViewers);
   nsCOMPtr<nsISHTransaction> trans;
   GetTransactionAtIndex(startIndex, getter_AddRefs(trans));
   int32_t i;
   for (i = startIndex; trans && i <= endIndex; ++i) {
     nsCOMPtr<nsISHEntry> entry;
     trans->GetSHEntry(getter_AddRefs(entry));
     // Does entry have the same BFCacheEntry as the argument to this method?
     if (entry->HasBFCacheEntry(aEntry)) {
       break;
     }
     nsISHTransaction *temp = trans;
     temp->GetNext(getter_AddRefs(trans));
   }
   if (i > endIndex)
     return NS_OK;
   if (i == mIndex) {
     NS_WARNING("How did the current SHEntry expire?");
     return NS_OK;
   }
   EvictContentViewerForTransaction(trans);
   return NS_OK;
 }
 // Evicts all content viewers in all history objects.  This is very
 // inefficient, because it requires a linear search through all SHistory
 // objects for each viewer to be evicted.  However, this method is called
 // infrequently -- only when the disk or memory cache is cleared.
 //static
 void
 nsSHistory::GloballyEvictAllContentViewers()
 {
   int32_t maxViewers = sHistoryMaxTotalViewers;
   sHistoryMaxTotalViewers = 0;
   GloballyEvictContentViewers();
   sHistoryMaxTotalViewers = maxViewers;
 }
 void GetDynamicChildren(nsISHContainer* aContainer,
                         nsTArray<uint64_t>& aDocshellIDs,
                         bool aOnlyTopLevelDynamic)
 {
   int32_t count = 0;
   aContainer->GetChildCount(&count);
   for (int32_t i = 0; i < count; ++i) {
     nsCOMPtr<nsISHEntry> child;
     aContainer->GetChildAt(i, getter_AddRefs(child));
     if (child) {
       bool dynAdded = false;
       child->IsDynamicallyAdded(&dynAdded);
       if (dynAdded) {
         uint64_t docshellID = 0;
         child->GetDocshellID(&docshellID);
         aDocshellIDs.AppendElement(docshellID);
       }
       if (!dynAdded || !aOnlyTopLevelDynamic) {
         nsCOMPtr<nsISHContainer> childAsContainer = do_QueryInterface(child);
         if (childAsContainer) {
           GetDynamicChildren(childAsContainer, aDocshellIDs,
                              aOnlyTopLevelDynamic);
         }
       }
     }
   }
 }
 bool
 RemoveFromSessionHistoryContainer(nsISHContainer* aContainer,
                                   nsTArray<uint64_t>& aDocshellIDs)
 {
   nsCOMPtr<nsISHEntry> root = do_QueryInterface(aContainer);
   NS_ENSURE_TRUE(root, false);
   bool didRemove = false;
   int32_t childCount = 0;
   aContainer->GetChildCount(&childCount);
   for (int32_t i = childCount - 1; i >= 0; --i) {
     nsCOMPtr<nsISHEntry> child;
     aContainer->GetChildAt(i, getter_AddRefs(child));
     if (child) {
       uint64_t docshelldID = 0;
       child->GetDocshellID(&docshelldID);
       if (aDocshellIDs.Contains(docshelldID)) {
         didRemove = true;
         aContainer->RemoveChild(child);
       } else {
         nsCOMPtr<nsISHContainer> container = do_QueryInterface(child);
         if (container) {
           bool childRemoved =
             RemoveFromSessionHistoryContainer(container, aDocshellIDs);
           if (childRemoved) {
             didRemove = true;
           }
         }
       }
     }
   }
   return didRemove;
 }
 bool RemoveChildEntries(nsISHistory* aHistory, int32_t aIndex,
                           nsTArray<uint64_t>& aEntryIDs)
 {
   nsCOMPtr<nsISHEntry> rootHE;
   aHistory->GetEntryAtIndex(aIndex, false, getter_AddRefs(rootHE));
   nsCOMPtr<nsISHContainer> root = do_QueryInterface(rootHE);
   return root ? RemoveFromSessionHistoryContainer(root, aEntryIDs) : false;
 }
 bool IsSameTree(nsISHEntry* aEntry1, nsISHEntry* aEntry2)
 {
   if (!aEntry1 && !aEntry2) {
     return true;
   }
   if ((!aEntry1 && aEntry2) || (aEntry1 && !aEntry2)) {
     return false;
   }
   uint32_t id1, id2;
   aEntry1->GetID(&id1);
   aEntry2->GetID(&id2);
   if (id1 != id2) {
     return false;
   }
   nsCOMPtr<nsISHContainer> container1 = do_QueryInterface(aEntry1);
   nsCOMPtr<nsISHContainer> container2 = do_QueryInterface(aEntry2);
   int32_t count1, count2;
   container1->GetChildCount(&count1);
   container2->GetChildCount(&count2);
   // We allow null entries in the end of the child list.
   int32_t count = std::max(count1, count2);
   for (int32_t i = 0; i < count; ++i) {
     nsCOMPtr<nsISHEntry> child1, child2;
     container1->GetChildAt(i, getter_AddRefs(child1));
     container2->GetChildAt(i, getter_AddRefs(child2));
     if (!IsSameTree(child1, child2)) {
       return false;
     }
   }
   return true;
 }
 bool
 nsSHistory::RemoveDuplicate(int32_t aIndex, bool aKeepNext)
 {
   NS_ASSERTION(aIndex >= 0, "aIndex must be >= 0!");
   NS_ASSERTION(aIndex != 0 || aKeepNext,
                "If we're removing index 0 we must be keeping the next");
   NS_ASSERTION(aIndex != mIndex, "Shouldn't remove mIndex!");
   int32_t compareIndex = aKeepNext ? aIndex + 1 : aIndex - 1;
   nsCOMPtr<nsISHEntry> root1, root2;
   GetEntryAtIndex(aIndex, false, getter_AddRefs(root1));
   GetEntryAtIndex(compareIndex, false, getter_AddRefs(root2));
   if (IsSameTree(root1, root2)) {
     nsCOMPtr<nsISHTransaction> txToRemove, txToKeep, txNext, txPrev;
     GetTransactionAtIndex(aIndex, getter_AddRefs(txToRemove));
     GetTransactionAtIndex(compareIndex, getter_AddRefs(txToKeep));
     NS_ENSURE_TRUE(txToRemove, false);
     NS_ENSURE_TRUE(txToKeep, false);
     txToRemove->GetNext(getter_AddRefs(txNext));
     txToRemove->GetPrev(getter_AddRefs(txPrev));
     txToRemove->SetNext(nullptr);
     txToRemove->SetPrev(nullptr);
     if (aKeepNext) {
       if (txPrev) {
         txPrev->SetNext(txToKeep);
       } else {
         txToKeep->SetPrev(nullptr);
       }
     } else {
       txToKeep->SetNext(txNext);
     }
     if (aIndex == 0 && aKeepNext) {
       NS_ASSERTION(txToRemove == mListRoot,
                    "Transaction at index 0 should be mListRoot!");
       // We're removing the very first session history transaction!
       mListRoot = txToKeep;
     }
     if (mRootDocShell) {
       static_cast<nsDocShell*>(mRootDocShell)->HistoryTransactionRemoved(aIndex);
     }
     // Adjust our indices to reflect the removed transaction
     if (mIndex > aIndex) {
       mIndex = mIndex - 1;
     }
     // NB: If the transaction we are removing is the transaction currently
     // being navigated to (mRequestedIndex) then we adjust the index
     // only if we're not keeping the next entry (because if we are keeping
     // the next entry (because the current is a duplicate of the next), then
     // that entry slides into the spot that we're currently pointing to.
     // We don't do this adjustment for mIndex because mIndex cannot equal
     // aIndex.
     // NB: We don't need to guard on mRequestedIndex being nonzero here,
     // because either they're strictly greater than aIndex which is at least
     // zero, or they are equal to aIndex in which case aKeepNext must be true
     // if aIndex is zero.
     if (mRequestedIndex > aIndex || (mRequestedIndex == aIndex && !aKeepNext)) {
       mRequestedIndex = mRequestedIndex - 1;
     }
     --mLength;
     return true;
   }
   return false;
 }
 NS_IMETHODIMP_(void)
 nsSHistory::RemoveEntries(nsTArray<uint64_t>& aIDs, int32_t aStartIndex)
 {
   int32_t index = aStartIndex;
   while(index >= 0 && RemoveChildEntries(this, --index, aIDs));
   int32_t minIndex = index;
   index = aStartIndex;
   while(index >= 0 && RemoveChildEntries(this, index++, aIDs));
   // We need to remove duplicate nsSHEntry trees.
   bool didRemove = false;
   while (index > minIndex) {
     if (index != mIndex) {
       didRemove = RemoveDuplicate(index, index < mIndex) || didRemove;
     }
     --index;
   }
   if (didRemove && mRootDocShell) {
     nsRefPtr<nsIRunnable> ev =
       NS_NewRunnableMethod(static_cast<nsDocShell*>(mRootDocShell),
                            &nsDocShell::FireDummyOnLocationChange);
     NS_DispatchToCurrentThread(ev);
   }
 }
 void
 nsSHistory::RemoveDynEntries(int32_t aOldIndex, int32_t aNewIndex)
 {
   // Search for the entries which are in the current index,
   // but not in the new one.
   nsCOMPtr<nsISHEntry> originalSH;
   GetEntryAtIndex(aOldIndex, false, getter_AddRefs(originalSH));
   nsCOMPtr<nsISHContainer> originalContainer = do_QueryInterface(originalSH);
   nsAutoTArray<uint64_t, 16> toBeRemovedEntries;
   if (originalContainer) {
     nsTArray<uint64_t> originalDynDocShellIDs;
     GetDynamicChildren(originalContainer, originalDynDocShellIDs, true);
     if (originalDynDocShellIDs.Length()) {
       nsCOMPtr<nsISHEntry> currentSH;
       GetEntryAtIndex(aNewIndex, false, getter_AddRefs(currentSH));
       nsCOMPtr<nsISHContainer> newContainer = do_QueryInterface(currentSH);
       if (newContainer) {
         nsTArray<uint64_t> newDynDocShellIDs;
         GetDynamicChildren(newContainer, newDynDocShellIDs, false);
         for (uint32_t i = 0; i < originalDynDocShellIDs.Length(); ++i) {
           if (!newDynDocShellIDs.Contains(originalDynDocShellIDs[i])) {
             toBeRemovedEntries.AppendElement(originalDynDocShellIDs[i]);
           }
         }
       }
     }
   }
   if (toBeRemovedEntries.Length()) {
     RemoveEntries(toBeRemovedEntries, aOldIndex);
   }
 }
 NS_IMETHODIMP
 nsSHistory::UpdateIndex()
 {
   // Update the actual index with the right value.
   if (mIndex != mRequestedIndex && mRequestedIndex != -1) {
     RemoveDynEntries(mIndex, mRequestedIndex);
     mIndex = mRequestedIndex;
   }
   mRequestedIndex = -1;
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::Stop(uint32_t aStopFlags)
 {
   //Not implemented
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GetDocument(nsIDOMDocument** aDocument)
 {
   // Not implemented
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GetCurrentURI(nsIURI** aResultURI)
 {
   NS_ENSURE_ARG_POINTER(aResultURI);
   nsresult rv;
   nsCOMPtr<nsISHEntry> currentEntry;
   rv = GetEntryAtIndex(mIndex, false, getter_AddRefs(currentEntry));
   if (NS_FAILED(rv) && !currentEntry) return rv;
   rv = currentEntry->GetURI(aResultURI);
   return rv;
 }
 NS_IMETHODIMP
 nsSHistory::GetReferringURI(nsIURI** aURI)
 {
   *aURI = nullptr;
   // Not implemented
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::SetSessionHistory(nsISHistory* aSessionHistory)
 {
   // Not implemented
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GetSessionHistory(nsISHistory** aSessionHistory)
 {
   // Not implemented
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::LoadURIWithBase(const char16_t* aURI,
                             uint32_t aLoadFlags,
                             nsIURI* aReferringURI,
                             nsIInputStream* aPostStream,
                             nsIInputStream* aExtraHeaderStream,
                             nsIURI* aBaseURI)
 {
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::LoadURI(const char16_t* aURI,
                     uint32_t aLoadFlags,
                     nsIURI* aReferringURI,
                     nsIInputStream* aPostStream,
                     nsIInputStream* aExtraHeaderStream)
 {
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GotoIndex(int32_t aIndex)
 {
   return LoadEntry(aIndex, nsIDocShellLoadInfo::loadHistory, HIST_CMD_GOTOINDEX);
 }
 nsresult
 nsSHistory::LoadNextPossibleEntry(int32_t aNewIndex, long aLoadType, uint32_t aHistCmd)
 {
   mRequestedIndex = -1;
   if (aNewIndex < mIndex) {
     return LoadEntry(aNewIndex - 1, aLoadType, aHistCmd);
   }
   if (aNewIndex > mIndex) {
     return LoadEntry(aNewIndex + 1, aLoadType, aHistCmd);
   }
   return NS_ERROR_FAILURE;
 }
 NS_IMETHODIMP
 nsSHistory::LoadEntry(int32_t aIndex, long aLoadType, uint32_t aHistCmd)
 {
   nsCOMPtr<nsIDocShell> docShell;
   // Keep note of requested history index in mRequestedIndex.
   mRequestedIndex = aIndex;
   nsCOMPtr<nsISHEntry> prevEntry;
   GetEntryAtIndex(mIndex, false, getter_AddRefs(prevEntry));
   nsCOMPtr<nsISHEntry> nextEntry;
   GetEntryAtIndex(mRequestedIndex, false, getter_AddRefs(nextEntry));
   if (!nextEntry || !prevEntry) {
     mRequestedIndex = -1;
     return NS_ERROR_FAILURE;
   }
   // Remember that this entry is getting loaded at this point in the sequence
   nsCOMPtr<nsISHEntryInternal> entryInternal = do_QueryInterface(nextEntry);
   if (entryInternal) {
     entryInternal->SetLastTouched(++gTouchCounter);
   }
   // Send appropriate listener notifications
   bool canNavigate = true;
   // Get the uri for the entry we are about to visit
   nsCOMPtr<nsIURI> nextURI;
   nextEntry->GetURI(getter_AddRefs(nextURI));
   if (aHistCmd == HIST_CMD_BACK) {
     // We are going back one entry. Send GoBack notifications
     NOTIFY_LISTENERS_CANCELABLE(OnHistoryGoBack, canNavigate,
                                 (nextURI, &canNavigate));
   } else if (aHistCmd == HIST_CMD_FORWARD) {
     // We are going forward. Send GoForward notification
     NOTIFY_LISTENERS_CANCELABLE(OnHistoryGoForward, canNavigate,
                                 (nextURI, &canNavigate));
   } else if (aHistCmd == HIST_CMD_GOTOINDEX) {
     // We are going somewhere else. This is not reload either
     NOTIFY_LISTENERS_CANCELABLE(OnHistoryGotoIndex, canNavigate,
                                 (aIndex, nextURI, &canNavigate));
   }
   if (!canNavigate) {
     // If the listener asked us not to proceed with
     // the operation, simply return.
     mRequestedIndex = -1;
     return NS_OK;  // XXX Maybe I can return some other error code?
   }
   nsCOMPtr<nsIURI> nexturi;
   int32_t pCount=0, nCount=0;
   nsCOMPtr<nsISHContainer> prevAsContainer(do_QueryInterface(prevEntry));
   nsCOMPtr<nsISHContainer> nextAsContainer(do_QueryInterface(nextEntry));
   if (prevAsContainer && nextAsContainer) {
     prevAsContainer->GetChildCount(&pCount);
     nextAsContainer->GetChildCount(&nCount);
   }
   nsCOMPtr<nsIDocShellLoadInfo> loadInfo;
   if (mRequestedIndex == mIndex) {
     // Possibly a reload case
     docShell = mRootDocShell;
   }
   else {
     // Going back or forward.
     if ((pCount > 0) && (nCount > 0)) {
       /* THis is a subframe navigation. Go find
        * the docshell in which load should happen
        */
       bool frameFound = false;
       nsresult rv = CompareFrames(prevEntry, nextEntry, mRootDocShell, aLoadType, &frameFound);
       if (!frameFound) {
         // We did not successfully find the subframe in which
         // the new url was to be loaded. Go further in the history.
         return LoadNextPossibleEntry(aIndex, aLoadType, aHistCmd);
       }
       return rv;
     }   // (pCount >0)
     else {
       // Loading top level page.
       uint32_t prevID = 0;
       uint32_t nextID = 0;
       prevEntry->GetID(&prevID);
       nextEntry->GetID(&nextID);
       if (prevID == nextID) {
         // Try harder to find something new to load.
         // This may happen for example if some page removed iframes dynamically.
         return LoadNextPossibleEntry(aIndex, aLoadType, aHistCmd);
       }
       docShell = mRootDocShell;
     }
   }
   if (!docShell) {
     // we did not successfully go to the proper index.
     // return error.
     mRequestedIndex = -1;
     return NS_ERROR_FAILURE;
   }
   // Start the load on the appropriate docshell
   return InitiateLoad(nextEntry, docShell, aLoadType);
 }
 nsresult
 nsSHistory::CompareFrames(nsISHEntry * aPrevEntry, nsISHEntry * aNextEntry, nsIDocShell * aParent, long aLoadType, bool * aIsFrameFound)
 {
   if (!aPrevEntry || !aNextEntry || !aParent)
     return NS_ERROR_FAILURE;
   // We should be comparing only entries which were created for the
   // same docshell. This is here to just prevent anything strange happening.
   // This check could be possibly an assertion.
   uint64_t prevdID, nextdID;
   aPrevEntry->GetDocshellID(&prevdID);
   aNextEntry->GetDocshellID(&nextdID);
   NS_ENSURE_STATE(prevdID == nextdID);
   nsresult result = NS_OK;
   uint32_t prevID, nextID;
   aPrevEntry->GetID(&prevID);
   aNextEntry->GetID(&nextID);
   // Check the IDs to verify if the pages are different.
   if (prevID != nextID) {
     if (aIsFrameFound)
       *aIsFrameFound = true;
     // Set the Subframe flag of the entry to indicate that
     // it is subframe navigation
     aNextEntry->SetIsSubFrame(true);
     InitiateLoad(aNextEntry, aParent, aLoadType);
     return NS_OK;
   }
   /* The root entries are the same, so compare any child frames */
   int32_t pcnt=0, ncnt=0, dsCount=0;
   nsCOMPtr<nsISHContainer>  prevContainer(do_QueryInterface(aPrevEntry));
   nsCOMPtr<nsISHContainer>  nextContainer(do_QueryInterface(aNextEntry));
   if (!aParent)
     return NS_ERROR_FAILURE;
   if (!prevContainer || !nextContainer)
     return NS_ERROR_FAILURE;
   prevContainer->GetChildCount(&pcnt);
   nextContainer->GetChildCount(&ncnt);
   aParent->GetChildCount(&dsCount);
   // Create an array for child docshells.
   nsCOMArray<nsIDocShell> docshells;
   for (int32_t i = 0; i < dsCount; ++i) {
     nsCOMPtr<nsIDocShellTreeItem> treeItem;
     aParent->GetChildAt(i, getter_AddRefs(treeItem));
     nsCOMPtr<nsIDocShell> shell = do_QueryInterface(treeItem);
     if (shell) {
       docshells.AppendObject(shell);
     }
   }
   // Search for something to load next.
   for (int32_t i = 0; i < ncnt; ++i) {
     // First get an entry which may cause a new page to be loaded.
     nsCOMPtr<nsISHEntry> nChild;
     nextContainer->GetChildAt(i, getter_AddRefs(nChild));
     if (!nChild) {
       continue;
     }
     uint64_t docshellID = 0;
     nChild->GetDocshellID(&docshellID);
     // Then find the associated docshell.
     nsIDocShell* dsChild = nullptr;
     int32_t count = docshells.Count();
     for (int32_t j = 0; j < count; ++j) {
       uint64_t shellID = 0;
       nsIDocShell* shell = docshells[j];
       shell->GetHistoryID(&shellID);
       if (shellID == docshellID) {
         dsChild = shell;
         break;
       }
     }
     if (!dsChild) {
       continue;
     }
     // Then look at the previous entries to see if there was
     // an entry for the docshell.
     nsCOMPtr<nsISHEntry> pChild;
     for (int32_t k = 0; k < pcnt; ++k) {
       nsCOMPtr<nsISHEntry> child;
       prevContainer->GetChildAt(k, getter_AddRefs(child));
       if (child) {
         uint64_t dID = 0;
         child->GetDocshellID(&dID);
         if (dID == docshellID) {
           pChild = child;
           break;
         }
       }
     }
     // Finally recursively call this method.
     // This will either load a new page to shell or some subshell or
     // do nothing.
     CompareFrames(pChild, nChild, dsChild, aLoadType, aIsFrameFound);
   }
   return result;
 }
 nsresult
 nsSHistory::InitiateLoad(nsISHEntry * aFrameEntry, nsIDocShell * aFrameDS, long aLoadType)
 {
   NS_ENSURE_STATE(aFrameDS && aFrameEntry);
   nsCOMPtr<nsIDocShellLoadInfo> loadInfo;
   /* Set the loadType in the SHEntry too to  what was passed on.
    * This will be passed on to child subframes later in nsDocShell,
    * so that proper loadType is maintained through out a frameset
    */
   aFrameEntry->SetLoadType(aLoadType);
   aFrameDS->CreateLoadInfo (getter_AddRefs(loadInfo));
   loadInfo->SetLoadType(aLoadType);
   loadInfo->SetSHEntry(aFrameEntry);
   nsCOMPtr<nsIURI> nextURI;
   aFrameEntry->GetURI(getter_AddRefs(nextURI));
   // Time   to initiate a document load
   return aFrameDS->LoadURI(nextURI, loadInfo, nsIWebNavigation::LOAD_FLAGS_NONE, false);
 }
 NS_IMETHODIMP
 nsSHistory::SetRootDocShell(nsIDocShell * aDocShell)
 {
   mRootDocShell = aDocShell;
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GetRootDocShell(nsIDocShell ** aDocShell)
 {
   NS_ENSURE_ARG_POINTER(aDocShell);
   *aDocShell = mRootDocShell;
   //Not refcounted. May this method should not be available for public
   // NS_IF_ADDREF(*aDocShell);
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHistory::GetSHistoryEnumerator(nsISimpleEnumerator** aEnumerator)
 {
   nsresult status = NS_OK;
   NS_ENSURE_ARG_POINTER(aEnumerator);
   nsSHEnumerator * iterator = new nsSHEnumerator(this);
   if (iterator && NS_FAILED(status = CallQueryInterface(iterator, aEnumerator)))
     delete iterator;
   return status;
 }
 //*****************************************************************************
 //***    nsSHEnumerator: Object Management
 //*****************************************************************************
 nsSHEnumerator::nsSHEnumerator(nsSHistory * aSHistory):mIndex(-1)
 {
   mSHistory = aSHistory;
 }
 nsSHEnumerator::~nsSHEnumerator()
 {
   mSHistory = nullptr;
 }
 NS_IMPL_ISUPPORTS(nsSHEnumerator, nsISimpleEnumerator)
 NS_IMETHODIMP
 nsSHEnumerator::HasMoreElements(bool * aReturn)
 {
   int32_t cnt;
   *aReturn = false;
   mSHistory->GetCount(&cnt);
   if (mIndex >= -1 && mIndex < (cnt-1) ) {
     *aReturn = true;
   }
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSHEnumerator::GetNext(nsISupports **aItem)
 {
   NS_ENSURE_ARG_POINTER(aItem);
   int32_t cnt= 0;
   nsresult  result = NS_ERROR_FAILURE;
   mSHistory->GetCount(&cnt);
   if (mIndex < (cnt-1)) {
     mIndex++;
     nsCOMPtr<nsISHEntry> hEntry;
     result = mSHistory->GetEntryAtIndex(mIndex, false, getter_AddRefs(hEntry));
     if (hEntry)
       result = CallQueryInterface(hEntry, aItem);
   }
   return result;
 }

The Tor Browser / annotate

docshell/shistory/src/nsSHistory.cpp@97036ab72558 (annotated)

docshell/shistory/src/nsSHistory.cpp