From bbbf5d7503c22286e02a9e65c7d0d12d870f0215 Mon Sep 17 00:00:00 2001
From: Jesse McConnell <jesse.mcconnell@gmail.com>
Date: Thu, 29 Oct 2009 18:16:10 +0000
Subject: [PATCH] bugzilla 293506 - resolve double locking mechanism and
 address violation in getPermissions that jmx tickles.

git-svn-id: svn+ssh://dev.eclipse.org/svnroot/rt/org.eclipse.jetty/jetty/trunk@1017 7e9141cc-0065-0410-87d8-b60c137991c4
---
 .../org/eclipse/jetty/policy/JettyPolicy.java | 90 ++++++-------------
 1 file changed, 27 insertions(+), 63 deletions(-)

diff --git a/jetty-policy/src/main/java/org/eclipse/jetty/policy/JettyPolicy.java b/jetty-policy/src/main/java/org/eclipse/jetty/policy/JettyPolicy.java
index 65e89a7c793..27512291a1c 100644
--- a/jetty-policy/src/main/java/org/eclipse/jetty/policy/JettyPolicy.java
+++ b/jetty-policy/src/main/java/org/eclipse/jetty/policy/JettyPolicy.java
@@ -94,29 +94,19 @@ public class JettyPolicy extends Policy
     public PermissionCollection getPermissions(ProtectionDomain domain)
     {
 
-        if (!_initialized)
+        synchronized (_initialized)
         {
-            synchronized (_initialized)
+            if (!_initialized)
             {
-                // make sure we haven't been initialized since obtaining lock
-                if (!_initialized)
-                {
-                    refresh();
-                }
+                refresh();
             }
         }
 
-        if (_cache.containsKey(domain))
-        {
-            return _cache.get(domain);
-        }
-
         synchronized (_cache)
         {
-            // check if it was added in since we obtained lock
             if (_cache.containsKey(domain))
             {
-                return _cache.get(domain);
+                return copyOf(_cache.get(domain));
             }
 
             PermissionCollection perms = new Permissions();
@@ -158,36 +148,26 @@ public class JettyPolicy extends Policy
 
             _cache.put(domain,perms);
 
-            return perms;
+            return copyOf(perms);
         }
     }
 
     @Override
     public PermissionCollection getPermissions(CodeSource codesource)
     {
-        if (!_initialized)
+        synchronized (_initialized)
         {
-            synchronized (_initialized)
+            if (!_initialized)
             {
-                // make sure we haven't been initialized since obtaining lock
-                if (!_initialized)
-                {
-                    refresh();
-                }
+                refresh();
             }
         }
 
-        if (_cache.containsKey(codesource))
-        {
-            return _cache.get(codesource);
-        }
-
         synchronized (_cache)
         {
-            // check if it was added in since we obtained lock
             if (_cache.containsKey(codesource))
             {
-                return _cache.get(codesource);
+                return copyOf(_cache.get(codesource));
             }
 
             PermissionCollection perms = new Permissions();
@@ -225,45 +205,16 @@ public class JettyPolicy extends Policy
 
             _cache.put(codesource,perms);
 
-            return perms;
+            return copyOf(perms);
         }
     }
 
     @Override
-    public boolean implies(ProtectionDomain domain, Permission permission) {
-        PermissionCollection pc;
-
-        if (!_initialized)
-        {
-            synchronized (_initialized)
-            {
-                // make sure we haven't been initialized since obtaining lock
-                if (!_initialized)
-                {
-                    refresh();
-                }
-            }
-        }
-
-        synchronized (_cache) {
-            pc = _cache.get(domain);
-        }
-
-        if (pc != null) {
-            return pc.implies(permission);
-        } 
+    public boolean implies(ProtectionDomain domain, Permission permission)
+    {
+        PermissionCollection pc = getPermissions(domain);
         
-        pc = getPermissions(domain);
-        if (pc == null) {
-            return false;
-        }
-
-        synchronized (_cache) {
-            // cache it 
-            _cache.put(domain, pc);
-        }
-        
-        return pc.implies(permission);
+        return (pc == null ? false : pc.implies(permission));
     }
     
 
@@ -398,4 +349,17 @@ public class JettyPolicy extends Policy
         }
         write.flush();
     }
+    
+    public PermissionCollection copyOf(final PermissionCollection in)
+    {
+        PermissionCollection out  = new Permissions();
+        synchronized (in)
+        {
+            for (Enumeration el = in.elements() ; el.hasMoreElements() ;)
+            {
+                out.add((Permission)el.nextElement());
+            }
+        }
+        return out;
+    }
 }