зеркало из https://github.com/mozilla/pjs.git
Bug 579236: Fix shutdown crash and lesser bugs with remote pref observers. r=dwitte
This commit is contained in:
Chris Jones
Родитель
8332fbce83
Коммит
95f3c5429a
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@ -45,7 +45,14 @@
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#include "mozilla/ipc/XPCShellEnvironment.h"
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#include "mozilla/jsipc/PContextWrapperChild.h"
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#include "nsIObserverService.h"
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#include "nsTObserverArray.h"
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#include "nsIObserver.h"
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#include "nsIPrefService.h"
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#include "nsIPrefBranch.h"
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#include "nsServiceManagerUtils.h"
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#include "nsXULAppAPI.h"
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#include "nsWeakReference.h"
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#include "base/message_loop.h"
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#include "base/task.h"
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@ -59,9 +66,115 @@ using namespace mozilla::net;
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namespace mozilla {
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namespace dom {
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class PrefObserver
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{
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public:
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/**
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* Pass |aHoldWeak=true| to force this to hold a weak ref to
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* |aObserver|. Otherwise, this holds a strong ref.
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*
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* XXX/cjones: what do domain and prefRoot mean?
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*/
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PrefObserver(nsIObserver *aObserver, bool aHoldWeak,
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const nsCString& aPrefRoot, const nsCString& aDomain)
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: mPrefRoot(aPrefRoot)
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, mDomain(aDomain)
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{
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if (aHoldWeak) {
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nsCOMPtr<nsISupportsWeakReference> supportsWeakRef =
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do_QueryInterface(aObserver);
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if (supportsWeakRef)
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mWeakObserver = do_GetWeakReference(aObserver);
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} else {
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mObserver = aObserver;
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}
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}
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~PrefObserver() {}
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/**
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* Return true if this observer can no longer receive
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* notifications.
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*/
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bool IsDead() const
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{
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nsCOMPtr<nsIObserver> observer = GetObserver();
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return !!observer;
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}
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/**
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* Return true iff a request to remove observers matching
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* <aObserver, aDomain, aPrefRoot> entails removal of this.
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*/
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bool ShouldRemoveFrom(nsIObserver* aObserver,
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const nsCString& aPrefRoot,
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const nsCString& aDomain) const
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{
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nsCOMPtr<nsIObserver> observer = GetObserver();
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return (observer == aObserver &&
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mDomain == aDomain && mPrefRoot == aPrefRoot);
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}
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/**
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* Return true iff this should be notified of changes to |aPref|.
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*/
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bool Observes(const nsCString& aPref) const
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{
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nsCAutoString myPref(mPrefRoot);
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myPref += mDomain;
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return StringBeginsWith(aPref, myPref);
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}
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/**
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* Notify this of a pref change that's relevant to our interests
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* (see Observes() above). Return false iff this no longer cares
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* to observe any more pref changes.
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*/
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bool Notify() const
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{
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nsCOMPtr<nsIObserver> observer = GetObserver();
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if (!observer) {
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return false;
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}
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nsCOMPtr<nsIPrefBranch> prefBranch;
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nsCOMPtr<nsIPrefService> prefService =
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do_GetService(NS_PREFSERVICE_CONTRACTID);
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if (prefService) {
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prefService->GetBranch(mPrefRoot.get(),
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getter_AddRefs(prefBranch));
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observer->Observe(prefBranch, "nsPref:changed",
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NS_ConvertASCIItoUTF16(mDomain).get());
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}
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return true;
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}
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private:
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already_AddRefed<nsIObserver> GetObserver() const
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{
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nsCOMPtr<nsIObserver> observer =
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mObserver ? mObserver : do_QueryReferent(mWeakObserver);
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return observer.forget();
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}
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// We only either hold a strong or a weak reference to the
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// observer, so only either mObserver or
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// GetReferent(mWeakObserver) is ever non-null.
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nsCOMPtr<nsIObserver> mObserver;
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nsWeakPtr mWeakObserver;
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nsCString mPrefRoot;
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nsCString mDomain;
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// disable these
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PrefObserver(const PrefObserver&);
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PrefObserver& operator=(const PrefObserver&);
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};
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ContentChild* ContentChild::sSingleton;
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ContentChild::ContentChild()
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: mDead(false)
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{
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}
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@ -159,60 +272,71 @@ ContentChild::ActorDestroy(ActorDestroyReason why)
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if (AbnormalShutdown == why)
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NS_WARNING("shutting down because of crash!");
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ClearPrefObservers();
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// We might be holding the last ref to some of the observers in
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// mPrefObserverArray. Some of them try to unregister themselves
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// in their dtors (sketchy). To side-step uaf problems and so
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// forth, we set this mDead flag. Then, if during a Clear() a
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// being-deleted observer tries to unregister itself, it hits the
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// |if (mDead)| special case below and we're safe.
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mDead = true;
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mPrefObservers.Clear();
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XRE_ShutdownChildProcess();
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}
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nsresult
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ContentChild::AddRemotePrefObserver(const nsCString &aDomain,
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const nsCString &aPrefRoot,
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nsIObserver *aObserver,
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ContentChild::AddRemotePrefObserver(const nsCString& aDomain,
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const nsCString& aPrefRoot,
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nsIObserver* aObserver,
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PRBool aHoldWeak)
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{
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nsPrefObserverStorage* newObserver =
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new nsPrefObserverStorage(aObserver, aDomain, aPrefRoot, aHoldWeak);
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mPrefObserverArray.AppendElement(newObserver);
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if (aObserver) {
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mPrefObservers.AppendElement(
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new PrefObserver(aObserver, aHoldWeak, aPrefRoot, aDomain));
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}
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return NS_OK;
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}
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nsresult
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ContentChild::RemoveRemotePrefObserver(const nsCString &aDomain,
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const nsCString &aPrefRoot,
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nsIObserver *aObserver)
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ContentChild::RemoveRemotePrefObserver(const nsCString& aDomain,
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const nsCString& aPrefRoot,
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nsIObserver* aObserver)
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{
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if (mPrefObserverArray.IsEmpty())
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if (mDead) {
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// Silently ignore, we're about to exit. See comment in
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// ActorDestroy().
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return NS_OK;
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}
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nsPrefObserverStorage *entry;
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for (PRUint32 i = 0; i < mPrefObserverArray.Length(); ++i) {
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entry = mPrefObserverArray[i];
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if (entry && entry->GetObserver() == aObserver &&
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entry->GetDomain().Equals(aDomain)) {
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// Remove this observer from our array
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mPrefObserverArray.RemoveElementAt(i);
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for (PRUint32 i = 0; i < mPrefObservers.Length();
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/*we mutate the array during the loop; ++i iff no mutation*/) {
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PrefObserver* observer = mPrefObservers[i];
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if (observer->IsDead()) {
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mPrefObservers.RemoveElementAt(i);
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continue;
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} else if (observer->ShouldRemoveFrom(aObserver, aPrefRoot, aDomain)) {
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mPrefObservers.RemoveElementAt(i);
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return NS_OK;
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}
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++i;
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}
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NS_WARNING("No preference Observer was matched !");
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NS_WARNING("RemoveRemotePrefObserver(): no observer was matched!");
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return NS_ERROR_UNEXPECTED;
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}
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bool
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ContentChild::RecvNotifyRemotePrefObserver(const nsCString& aDomain)
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ContentChild::RecvNotifyRemotePrefObserver(const nsCString& aPref)
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{
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nsPrefObserverStorage *entry;
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for (PRUint32 i = 0; i < mPrefObserverArray.Length(); ) {
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entry = mPrefObserverArray[i];
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nsCAutoString prefName(entry->GetPrefRoot() + entry->GetDomain());
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// aDomain here is returned from our global pref observer from parent
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// so it's really a full pref name (i.e. root + domain)
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if (StringBeginsWith(aDomain, prefName)) {
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if (!entry->NotifyObserver()) {
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// remove the observer from the list
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mPrefObserverArray.RemoveElementAt(i);
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continue;
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}
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for (PRUint32 i = 0; i < mPrefObservers.Length();
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/*we mutate the array during the loop; ++i iff no mutation*/) {
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PrefObserver* observer = mPrefObservers[i];
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if (observer->Observes(aPref) &&
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!observer->Notify()) {
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// |observer| had a weak ref that went away, so it no
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// longer cares about pref changes
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mPrefObservers.RemoveElementAt(i);
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continue;
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}
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++i;
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}
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@ -42,85 +42,24 @@
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#include "mozilla/dom/PContentChild.h"
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#include "nsIObserverService.h"
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#include "nsTObserverArray.h"
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#include "nsIObserver.h"
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#include "nsIPrefService.h"
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#include "nsIPrefBranch.h"
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#include "nsServiceManagerUtils.h"
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#include "nsTArray.h"
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#include "nsAutoPtr.h"
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#include "nsWeakReference.h"
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struct ChromePackage;
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class nsIObserver;
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struct ResourceMapping;
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struct OverrideMapping;
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namespace mozilla {
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namespace dom {
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class PrefObserver;
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class ContentChild : public PContentChild
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{
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public:
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ContentChild();
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virtual ~ContentChild();
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class nsPrefObserverStorage {
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public:
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nsPrefObserverStorage(nsIObserver *aObserver, nsCString aDomain,
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nsCString aPrefRoot, bool aHoldWeak) {
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mDomain = aDomain;
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mPrefRoot = aPrefRoot;
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mObserver = aObserver;
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if (aHoldWeak) {
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nsCOMPtr<nsISupportsWeakReference> weakRefFactory =
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do_QueryInterface(aObserver);
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if (weakRefFactory)
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mWeakRef = do_GetWeakReference(aObserver);
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} else {
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mWeakRef = nsnull;
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}
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}
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~nsPrefObserverStorage() {
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}
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bool NotifyObserver() {
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nsCOMPtr<nsIObserver> observer;
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if (mWeakRef) {
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observer = do_QueryReferent(mWeakRef);
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if (!observer) {
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// this weak referenced observer went away, tell
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// the caller so he can remove the observer from the list
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return false;
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}
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} else {
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observer = mObserver;
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}
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nsCOMPtr<nsIPrefBranch> prefBranch;
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nsCOMPtr<nsIPrefService> prefService =
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do_GetService(NS_PREFSERVICE_CONTRACTID);
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if (prefService) {
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prefService->GetBranch(mPrefRoot.get(),
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getter_AddRefs(prefBranch));
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observer->Observe(prefBranch, "nsPref:changed",
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NS_ConvertASCIItoUTF16(mDomain).get());
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}
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return true;
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}
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nsIObserver* GetObserver() { return mObserver; }
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const nsCString& GetDomain() { return mDomain; }
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const nsCString& GetPrefRoot() { return mPrefRoot; }
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private:
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nsCOMPtr<nsIObserver> mObserver;
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nsWeakPtr mWeakRef;
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nsCString mPrefRoot;
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nsCString mDomain;
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};
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bool Init(MessageLoop* aIOLoop,
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base::ProcessHandle aParentHandle,
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IPC::Channel* aChannel);
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@ -149,28 +88,28 @@ public:
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virtual bool RecvSetOffline(const PRBool& offline);
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nsresult AddRemotePrefObserver(const nsCString &aDomain,
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const nsCString &aPrefRoot,
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nsIObserver *aObserver, PRBool aHoldWeak);
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nsresult RemoveRemotePrefObserver(const nsCString &aDomain,
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const nsCString &aPrefRoot,
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nsIObserver *aObserver);
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inline void ClearPrefObservers() {
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mPrefObserverArray.Clear();
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}
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/**
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* Notify |aObserver| of changes to |aPrefRoot|.|aDomain|. If
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* |aHoldWeak|, only a weak reference to |aObserver| is held.
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*/
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nsresult AddRemotePrefObserver(const nsCString& aDomain,
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const nsCString& aPrefRoot,
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nsIObserver* aObserver, PRBool aHoldWeak);
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nsresult RemoveRemotePrefObserver(const nsCString& aDomain,
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const nsCString& aPrefRoot,
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nsIObserver* aObserver);
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virtual bool RecvNotifyRemotePrefObserver(
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const nsCString& aDomain);
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private:
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NS_OVERRIDE
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virtual void ActorDestroy(ActorDestroyReason why);
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static ContentChild* sSingleton;
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nsTArray<nsAutoPtr<PrefObserver> > mPrefObservers;
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bool mDead;
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nsTArray< nsAutoPtr<nsPrefObserverStorage> > mPrefObserverArray;
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static ContentChild* sSingleton;
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DISALLOW_EVIL_CONSTRUCTORS(ContentChild);
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};
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