From 4501f646c7171394005727af423c12096a356bfc Mon Sep 17 00:00:00 2001
From: Gian-Carlo Pascutto <gpascutto@mozilla.com>
Date: Sat, 30 Jul 2011 09:24:22 +0200
Subject: [PATCH] Bug 667075 - Use nsIRandomGenerator instead of querying
 SQLite. r=dcamp

---
 .../nsUrlClassifierDBService.cpp              | 39 +++++--------------
 1 file changed, 10 insertions(+), 29 deletions(-)

diff --git a/toolkit/components/url-classifier/nsUrlClassifierDBService.cpp b/toolkit/components/url-classifier/nsUrlClassifierDBService.cpp
index 8d1d7bb362bc..771c07d643e3 100644
--- a/toolkit/components/url-classifier/nsUrlClassifierDBService.cpp
+++ b/toolkit/components/url-classifier/nsUrlClassifierDBService.cpp
@@ -62,6 +62,7 @@
 #include "nsIProxyObjectManager.h"
 #include "nsToolkitCompsCID.h"
 #include "nsIUrlClassifierUtils.h"
+#include "nsIRandomGenerator.h"
 #include "nsUrlClassifierDBService.h"
 #include "nsUrlClassifierUtils.h"
 #include "nsURILoader.h"
@@ -480,10 +481,6 @@ public:
                             PRBool before,
                             nsTArray<nsUrlClassifierEntry> &entries);
 
-  // Ask the db for a random number.  This is temporary, and should be
-  // replaced with nsIRandomGenerator when 419739 is fixed.
-  nsresult RandomNumber(PRInt64 *randomNum);
-
 protected:
   nsresult ReadEntries(mozIStorageStatement *statement,
                        nsTArray<nsUrlClassifierEntry>& entries);
@@ -501,8 +498,6 @@ protected:
   nsCOMPtr<mozIStorageStatement> mPartialEntriesAfterStatement;
   nsCOMPtr<mozIStorageStatement> mLastPartialEntriesStatement;
   nsCOMPtr<mozIStorageStatement> mPartialEntriesBeforeStatement;
-
-  nsCOMPtr<mozIStorageStatement> mRandomStatement;
 };
 
 nsresult
@@ -559,11 +554,6 @@ nsUrlClassifierStore::Init(nsUrlClassifierDBServiceWorker *worker,
      getter_AddRefs(mPartialEntriesBeforeStatement));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = mConnection->CreateStatement
-    (NS_LITERAL_CSTRING("SELECT abs(random())"),
-     getter_AddRefs(mRandomStatement));
-  NS_ENSURE_SUCCESS(rv, rv);
-
   return NS_OK;
 }
 
@@ -581,7 +571,6 @@ nsUrlClassifierStore::Close()
   mPartialEntriesAfterStatement = nsnull;
   mPartialEntriesBeforeStatement = nsnull;
   mLastPartialEntriesStatement = nsnull;
-  mRandomStatement = nsnull;
 
   mConnection = nsnull;
 }
@@ -764,21 +753,6 @@ nsUrlClassifierStore::ReadNoiseEntries(PRInt64 rowID,
   return ReadEntries(wraparoundStatement, entries);
 }
 
-nsresult
-nsUrlClassifierStore::RandomNumber(PRInt64 *randomNum)
-{
-  mozStorageStatementScoper randScoper(mRandomStatement);
-  PRBool exists;
-  nsresult rv = mRandomStatement->ExecuteStep(&exists);
-  NS_ENSURE_SUCCESS(rv, rv);
-  if (!exists)
-    return NS_ERROR_NOT_AVAILABLE;
-
-  *randomNum = mRandomStatement->AsInt64(0);
-
-  return NS_OK;
-}
-
 // -------------------------------------------------------------------------
 // nsUrlClassifierAddStore class implementation
 
@@ -1752,9 +1726,16 @@ nsUrlClassifierDBServiceWorker::AddNoise(PRInt64 nearID,
     return NS_OK;
   }
 
-  PRInt64 randomNum;
-  nsresult rv = mMainStore.RandomNumber(&randomNum);
+  nsCOMPtr<nsIRandomGenerator> rg =
+    do_GetService("@mozilla.org/security/random-generator;1");
+  NS_ENSURE_STATE(rg);
+
+  PRInt32 randomNum;
+  PRUint8 *temp;
+  nsresult rv = rg->GenerateRandomBytes(sizeof(randomNum), &temp);
   NS_ENSURE_SUCCESS(rv, rv);
+  memcpy(&randomNum, temp, sizeof(randomNum));
+  NS_Free(temp);
 
   PRInt32 numBefore = randomNum % count;