From fed086b1d7efc52cae01de32aaeb2dd00d1836c3 Mon Sep 17 00:00:00 2001
From: Robert O'Callahan <robert@ocallahan.org>
Date: Tue, 12 Jan 2010 10:45:20 +1300
Subject: [PATCH] Bug 526394. Part 34: Create
 nsContentUtils::AddScriptBlockerAndPreventAddingRunners. r=sicking

---
 content/base/public/nsContentUtils.h |  8 ++++++++
 content/base/src/nsContentUtils.cpp  | 19 ++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/content/base/public/nsContentUtils.h b/content/base/public/nsContentUtils.h
index 740facda054f..3c0e8906c7e4 100644
--- a/content/base/public/nsContentUtils.h
+++ b/content/base/public/nsContentUtils.h
@@ -1366,6 +1366,13 @@ public:
    */
   static void AddScriptBlocker();
 
+  /**
+   * Increases the count of blockers preventing scripts from running.
+   * Also, while this script blocker is active, script runners must not be
+   * added --- we'll assert if one is, and ignore it.
+   */
+  static void AddScriptBlockerAndPreventAddingRunners();
+
   /**
    * Decreases the count of blockers preventing scripts from running.
    * NOTE: You might want to use nsAutoScriptBlocker rather than calling
@@ -1590,6 +1597,7 @@ private:
   static PRUint32 sRemovableScriptBlockerCount;
   static nsCOMArray<nsIRunnable>* sBlockedScriptRunners;
   static PRUint32 sRunnersCountAtFirstBlocker;
+  static PRUint32 sScriptBlockerCountWhereRunnersPrevented;
 
   static nsIInterfaceRequestor* sSameOriginChecker;
 };
diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index 9a7694109030..fd3e3fda1839 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -223,6 +223,7 @@ PRUint32 nsContentUtils::sScriptBlockerCount = 0;
 PRUint32 nsContentUtils::sRemovableScriptBlockerCount = 0;
 nsCOMArray<nsIRunnable>* nsContentUtils::sBlockedScriptRunners = nsnull;
 PRUint32 nsContentUtils::sRunnersCountAtFirstBlocker = 0;
+PRUint32 nsContentUtils::sScriptBlockerCountWhereRunnersPrevented = 0;
 nsIInterfaceRequestor* nsContentUtils::sSameOriginChecker = nsnull;
 
 nsIJSRuntimeService *nsAutoGCRoot::sJSRuntimeService;
@@ -4493,12 +4494,25 @@ nsContentUtils::AddScriptBlocker()
   ++sScriptBlockerCount;
 }
 
+/* static */
+void
+nsContentUtils::AddScriptBlockerAndPreventAddingRunners()
+{
+  AddScriptBlocker();
+  if (sScriptBlockerCountWhereRunnersPrevented == 0) {
+    sScriptBlockerCountWhereRunnersPrevented = sScriptBlockerCount;
+  }
+}
+
 /* static */
 void
 nsContentUtils::RemoveScriptBlocker()
 {
   NS_ASSERTION(sScriptBlockerCount != 0, "Negative script blockers");
   --sScriptBlockerCount;
+  if (sScriptBlockerCount < sScriptBlockerCountWhereRunnersPrevented) {
+    sScriptBlockerCountWhereRunnersPrevented = 0;
+  }
   if (sScriptBlockerCount) {
     return;
   }
@@ -4522,7 +4536,6 @@ nsContentUtils::RemoveScriptBlocker()
   }
 }
 
-
 /* static */
 PRBool
 nsContentUtils::AddScriptRunner(nsIRunnable* aRunnable)
@@ -4532,6 +4545,10 @@ nsContentUtils::AddScriptRunner(nsIRunnable* aRunnable)
   }
 
   if (sScriptBlockerCount) {
+    if (sScriptBlockerCountWhereRunnersPrevented > 0) {
+      NS_ERROR("Adding a script runner when that is prevented!");
+      return PR_FALSE;
+    }
     return sBlockedScriptRunners->AppendObject(aRunnable);
   }