Bug 309459: Crash when using cacheService.visitEntries. Patch by Adam Guthrie <ispiked@gmail.com>, r+sr=darin.

netwerk/protocol/about/src/nsAboutCache.cpp

@@ -152,6 +152,10 @@ nsAboutCache::VisitDevice(const char *deviceID,
 
     if (mDeviceID.IsEmpty() || mDeviceID.Equals(deviceID)) {
 
+        // We need mStream for this
+        if (!mStream)
+          return NS_ERROR_FAILURE;
+	
         // Write out the Cache Name
         deviceInfo->GetDescription(getter_Copies(str));
 
@@ -206,6 +210,10 @@ nsAboutCache::VisitEntry(const char *deviceID,
                          nsICacheEntryInfo *entryInfo,
                          PRBool *visitNext)
 {
+    // We need mStream for this
+    if (!mStream)
+      return NS_ERROR_FAILURE;
+
     nsresult        rv;
     PRUint32        bytesWritten;
     nsCAutoString   key;