Bug 861920 - Avoid apps to write in its local storage while device free storage is low. r=honzab

dom/src/storage/DOMStorageCache.cpp

@@ -194,6 +194,11 @@ DOMStorageCache::ProcessUsageDelta(const DOMStorage* aStorage, int64_t aDelta)
 bool
 DOMStorageCache::ProcessUsageDelta(uint32_t aGetDataSetIndex, const int64_t aDelta)
 {
+  // Check if we are in a low disk space situation
+  if (aDelta > 0 && mManager && mManager->IsLowDiskSpace()) {
+    return false;
+  }
+
   // Check limit per this origin
   Data& data = mData[aGetDataSetIndex];
   uint64_t newOriginUsage = data.mOriginQuotaUsage + aDelta;

dom/src/storage/DOMStorageIPC.cpp

@@ -9,6 +9,7 @@
 
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/unused.h"
+#include "nsIDiskSpaceWatcher.h"
 
 namespace mozilla {
 namespace dom {
@@ -294,10 +295,10 @@ DOMStorageDBParent::ReleaseIPDLReference()
 
 namespace { // anon
 
-class SendScopesHavingDataRunnable : public nsRunnable
+class SendInitialChildDataRunnable : public nsRunnable
 {
 public:
-  SendScopesHavingDataRunnable(DOMStorageDBParent* aParent)
+  SendInitialChildDataRunnable(DOMStorageDBParent* aParent)
     : mParent(aParent)
   {}
 
@@ -315,6 +316,17 @@ private:
       mozilla::unused << mParent->SendScopesHavingData(scopes);
     }
 
+    // We need to check if the device is in a low disk space situation, so
+    // we can forbid in that case any write in localStorage.
+    nsCOMPtr<nsIDiskSpaceWatcher> diskSpaceWatcher =
+      do_GetService("@mozilla.org/toolkit/disk-space-watcher;1");
+    bool lowDiskSpace = false;
+    diskSpaceWatcher->GetIsDiskFull(&lowDiskSpace);
+    if (lowDiskSpace) {
+      mozilla::unused << mParent->SendObserve(
+        nsDependentCString("low-disk-space"), EmptyCString());
+    }
+
     return NS_OK;
   }
 
@@ -336,8 +348,8 @@ DOMStorageDBParent::DOMStorageDBParent()
 
   // Cannot send directly from here since the channel
   // is not completely built at this moment.
-  nsRefPtr<SendScopesHavingDataRunnable> r =
-    new SendScopesHavingDataRunnable(this);
+  nsRefPtr<SendInitialChildDataRunnable> r =
+    new SendInitialChildDataRunnable(this);
   NS_DispatchToCurrentThread(r);
 }
 

dom/src/storage/DOMStorageManager.cpp

@@ -109,6 +109,7 @@ NS_IMPL_ISUPPORTS1(DOMStorageManager,
 
 DOMStorageManager::DOMStorageManager(nsPIDOMStorage::StorageType aType)
   : mType(aType)
+  , mLowDiskSpace(false)
 {
   mCaches.Init(10);
   DOMStorageObserver* observer = DOMStorageObserver::Self();
@@ -566,6 +567,22 @@ DOMStorageManager::Observe(const char* aTopic, const nsACString& aScopePrefix)
     return NS_OK;
   }
 
+  if (!strcmp(aTopic, "low-disk-space")) {
+    if (mType == LocalStorage) {
+      mLowDiskSpace = true;
+    }
+
+    return NS_OK;
+  }
+
+  if (!strcmp(aTopic, "no-low-disk-space")) {
+    if (mType == LocalStorage) {
+      mLowDiskSpace = false;
+    }
+
+    return NS_OK;
+  }
+
 #ifdef DOM_STORAGE_TESTS
   if (!strcmp(aTopic, "test-reload")) {
     if (mType != LocalStorage) {

dom/src/storage/DOMStorageManager.h

@@ -87,6 +87,12 @@ private:
   nsTHashtable<DOMStorageCacheHashKey> mCaches;
   const nsPIDOMStorage::StorageType mType;
 
+  // If mLowDiskSpace is true it indicates a low device storage situation and
+  // so no localStorage writes are allowed. sessionStorage writes are still
+  // allowed.
+  bool mLowDiskSpace;
+  bool IsLowDiskSpace() const { return mLowDiskSpace; };
+
   static PLDHashOperator ClearCacheEnumerator(DOMStorageCacheHashKey* aCache,
                                               void* aClosure);
 

dom/src/storage/DOMStorageObserver.cpp

@@ -68,6 +68,11 @@ DOMStorageObserver::Init()
   obs->AddObserver(sSelf, "profile-before-change", true);
   obs->AddObserver(sSelf, "xpcom-shutdown", true);
 
+  // Observe low device storage notifications. Only in the parent.
+  if (XRE_GetProcessType() == GeckoProcessType_Default) {
+    obs->AddObserver(sSelf, "disk-space-watcher", true);
+  }
+
 #ifdef DOM_STORAGE_TESTS
   // Testing
   obs->AddObserver(sSelf, "domstorage-test-flush-force", true);
@@ -300,6 +305,16 @@ DOMStorageObserver::Observe(nsISupports* aSubject,
     return NS_OK;
   }
 
+  if (!strcmp(aTopic, "disk-space-watcher")) {
+    if (NS_LITERAL_STRING("full").Equals(aData)) {
+      Notify("low-disk-space");
+    } else if (NS_LITERAL_STRING("free").Equals(aData)) {
+      Notify("no-low-disk-space");
+    }
+
+    return NS_OK;
+  }
+
 #ifdef DOM_STORAGE_TESTS
   if (!strcmp(aTopic, "domstorage-test-flush-force")) {
     DOMStorageDBBridge* db = DOMStorageCache::GetDatabase();