Merge branch 'master' into careminster

Conflicts:
	OpenSim/Framework/Watchdog.cs
	OpenSim/Region/CoreModules/Avatar/Attachments/AttachmentsModule.cs
	OpenSim/Region/Framework/Scenes/Scene.cs
	OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
	OpenSim/Region/Framework/Scenes/ScenePresence.cs

10 files changed, 346 insertions, 96 deletions

diff --git a/OpenSim/Region/Framework/Interfaces/IEntityInventory.cs b/OpenSim/Region/Framework/Interfaces/IEntityInventory.cs
index 4f0e100..4274cbe 100644
--- a/OpenSim/Region/Framework/Interfaces/IEntityInventory.cs
+++ b/OpenSim/Region/Framework/Interfaces/IEntityInventory.cs
@@ -92,7 +92,7 @@ namespace OpenSim.Region.Framework.Interfaces
         void ResumeScripts();
 
         /// <summary>
-        /// Stop all the scripts in this entity.
+        /// Stop and remove all the scripts in this entity from the scene.
         /// </summary>
         /// <param name="sceneObjectBeingDeleted">
         /// Should be true if these scripts are being removed because the scene
@@ -101,6 +101,11 @@ namespace OpenSim.Region.Framework.Interfaces
         void RemoveScriptInstances(bool sceneObjectBeingDeleted);
 
         /// <summary>
+        /// Stop all the scripts in this entity.
+        /// </summary>
+        void StopScriptInstances();
+
+        /// <summary>
         /// Start a script which is in this entity's inventory.
         /// </summary>
         /// <param name="item"></param>
@@ -131,7 +136,7 @@ namespace OpenSim.Region.Framework.Interfaces
         ArrayList CreateScriptInstanceEr(UUID itemId, int startParam, bool postOnRez, string engine, int stateSource);
 
         /// <summary>
-        /// Stop a script which is in this prim's inventory.
+        /// Stop and remove a script which is in this prim's inventory from the scene.
         /// </summary>
         /// <param name="itemId"></param>
         /// <param name="sceneObjectBeingDeleted">
@@ -141,6 +146,12 @@ namespace OpenSim.Region.Framework.Interfaces
         void RemoveScriptInstance(UUID itemId, bool sceneObjectBeingDeleted);
 
         /// <summary>
+        /// Stop a script which is in this prim's inventory.
+        /// </summary>
+        /// <param name="itemId"></param>
+        void StopScriptInstance(UUID itemId);
+
+        /// <summary>
         /// Add an item to this entity's inventory.  If an item with the same name already exists, then an alternative
         /// name is chosen.
         /// </summary>
diff --git a/OpenSim/Region/Framework/Interfaces/INPCModule.cs b/OpenSim/Region/Framework/Interfaces/INPCModule.cs
index 860483d..d582149 100644
--- a/OpenSim/Region/Framework/Interfaces/INPCModule.cs
+++ b/OpenSim/Region/Framework/Interfaces/INPCModule.cs
@@ -184,6 +184,14 @@ namespace OpenSim.Region.Framework.Interfaces
         bool Stand(UUID agentID, Scene scene);
 
         /// <summary>
+        /// Get the NPC to touch an object.
+        /// </summary>
+        /// <param name="agentID"></param>
+        /// <param name="partID"></param>
+        /// <returns>true if the touch is actually attempted, false if not</returns>
+        bool Touch(UUID agentID, UUID partID);
+
+        /// <summary>
         /// Delete an NPC.
         /// </summary>
         /// <param name="agentID">The UUID of the NPC</param>
diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index a63ed13..eae8b8e 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -2281,13 +2281,30 @@ namespace OpenSim.Region.Framework.Scenes
         /// <summary>
         /// Synchronously delete the given object from the scene.
         /// </summary>
+        /// <remarks>
+        /// Scripts are also removed.
+        /// </remarks>
         /// <param name="group">Object Id</param>
         /// <param name="silent">Suppress broadcasting changes to other clients.</param>
         public void DeleteSceneObject(SceneObjectGroup group, bool silent)
+        {
+            DeleteSceneObject(group, silent, true);
+        }
+
+        /// <summary>
+        /// Synchronously delete the given object from the scene.
+        /// </summary>
+        /// <param name="group">Object Id</param>
+        /// <param name="silent">Suppress broadcasting changes to other clients.</param>
+        /// <param name="removeScripts">If true, then scripts are removed.  If false, then they are only stopped.</para>
+        public void DeleteSceneObject(SceneObjectGroup group, bool silent, bool removeScripts)
         {            
 //            m_log.DebugFormat("[SCENE]: Deleting scene object {0} {1}", group.Name, group.UUID);
 
-            group.RemoveScriptInstances(true);
+            if (removeScripts)
+                group.RemoveScriptInstances(true);
+            else
+                group.StopScriptInstances();
 
             SceneObjectPart[] partList = group.Parts;
 
@@ -2595,7 +2612,16 @@ namespace OpenSim.Region.Framework.Scenes
             }
             catch (Exception e)
             {
-                m_log.WarnFormat("[SCENE]: Problem casting object, exception {0}{1}", e.Message, e.StackTrace);
+                m_log.WarnFormat("[INTERREGION]: Problem casting object, exception {0}{1}", e.Message, e.StackTrace);
+                return false;
+            }
+
+            // If the user is banned, we won't let any of their objects
+            // enter. Period.
+            //
+            if (RegionInfo.EstateSettings.IsBanned(newObject.OwnerID, 36))
+            {
+                m_log.InfoFormat("[INTERREGION]: Denied prim crossing for banned avatar {0}", newObject.OwnerID);
                 return false;
             }
 
@@ -2606,14 +2632,28 @@ namespace OpenSim.Region.Framework.Scenes
 
             if (!AddSceneObject(newObject))
             {
-                m_log.DebugFormat("[SCENE]: Problem adding scene object {0} in {1} ", sog.UUID, RegionInfo.RegionName);
+                m_log.DebugFormat(
+                    "[INTERREGION]: Problem adding scene object {0} in {1} ", newObject.UUID, RegionInfo.RegionName);
                 return false;
             }
 
-            // For attachments, we need to wait until the agent is root
-            // before we restart the scripts, or else some functions won't work.
             if (!newObject.IsAttachment)
             {
+                // FIXME: It would be better to never add the scene object at all rather than add it and then delete
+                // it
+                if (!Permissions.CanObjectEntry(newObject.UUID, true, newObject.AbsolutePosition))
+                {
+                    // Deny non attachments based on parcel settings
+                    //
+                    m_log.Info("[INTERREGION]: Denied prim crossing because of parcel settings");
+
+                    DeleteSceneObject(newObject, false);
+
+                    return false;
+                }
+
+                // For attachments, we need to wait until the agent is root
+                // before we restart the scripts, or else some functions won't work.
                 newObject.RootPart.ParentGroup.CreateScriptInstances(0, false, DefaultScriptEngine, GetStateSource(newObject));
                 newObject.ResumeScripts();
             }
@@ -2650,8 +2690,6 @@ namespace OpenSim.Region.Framework.Scenes
                 return false;
             }
 
-            sceneObject.SetScene(this);
-
             // Force allocation of new LocalId
             //
             SceneObjectPart[] parts = sceneObject.Parts;
@@ -2707,18 +2745,6 @@ namespace OpenSim.Region.Framework.Scenes
                     return false;
                 }
                 AddRestoredSceneObject(sceneObject, true, false);
-
-                if (!Permissions.CanObjectEntry(sceneObject.UUID,
-                        true, sceneObject.AbsolutePosition))
-                {
-                    // Deny non attachments based on parcel settings
-                    //
-                    m_log.Info("[INTERREGION]: Denied prim crossing because of parcel settings");
-
-                    DeleteSceneObject(sceneObject, false);
-
-                    return false;
-                }
             }
 
             return true;
@@ -4654,6 +4680,17 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
+        /// Get all the scene object groups.
+        /// </summary>
+        /// <returns>
+        /// The scene object groups.  If the scene is empty then an empty list is returned.
+        /// </returns>
+        public List<SceneObjectGroup> GetSceneObjectGroups()
+        {
+            return m_sceneGraph.GetSceneObjectGroups();
+        }
+
+        /// <summary>
         /// Get a group via its UUID
         /// </summary>
         /// <param name="fullID"></param>
diff --git a/OpenSim/Region/Framework/Scenes/SceneGraph.cs b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
index 3390aba..b23d2e5 100644
--- a/OpenSim/Region/Framework/Scenes/SceneGraph.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
@@ -401,9 +401,9 @@ namespace OpenSim.Region.Framework.Scenes
 
             if (Entities.ContainsKey(sceneObject.UUID))
             {
-//                m_log.DebugFormat(
-//                    "[SCENEGRAPH]: Scene graph for {0} already contains object {1} in AddSceneObject()",
-//                    m_parentScene.RegionInfo.RegionName, sceneObject.UUID);
+                m_log.DebugFormat(
+                    "[SCENEGRAPH]: Scene graph for {0} already contains object {1} in AddSceneObject()",
+                    m_parentScene.RegionInfo.RegionName, sceneObject.UUID);
 
                 return false;
             }
@@ -1038,6 +1038,18 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
+        /// Get all the scene object groups.
+        /// </summary>
+        /// <returns>
+        /// The scene object groups.  If the scene is empty then an empty list is returned.
+        /// </returns>
+        protected internal List<SceneObjectGroup> GetSceneObjectGroups()
+        {
+            lock (SceneObjectGroupsByFullID)
+                return new List<SceneObjectGroup>(SceneObjectGroupsByFullID.Values);
+        }
+
+        /// <summary>
         /// Get a group in the scene
         /// </summary>
         /// <param name="fullID">UUID of the group</param>
@@ -1180,11 +1192,7 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="action"></param>
         protected internal void ForEachSOG(Action<SceneObjectGroup> action)
         {
-            List<SceneObjectGroup> objlist;
-            lock (SceneObjectGroupsByFullID)
-                objlist = new List<SceneObjectGroup>(SceneObjectGroupsByFullID.Values);
-
-            foreach (SceneObjectGroup obj in objlist)
+            foreach (SceneObjectGroup obj in GetSceneObjectGroups())
             {
                 try
                 {
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.Inventory.cs b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.Inventory.cs
index 1038111..26524fb 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.Inventory.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.Inventory.cs
@@ -79,7 +79,7 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
-        /// Stop the scripts contained in all the prims in this group
+        /// Stop and remove the scripts contained in all the prims in this group
         /// </summary>
         public void RemoveScriptInstances(bool sceneObjectBeingDeleted)
         {
@@ -89,6 +89,14 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
+        /// Stop the scripts contained in all the prims in this group
+        /// </summary>
+        public void StopScriptInstances()
+        {
+            Array.ForEach<SceneObjectPart>(m_parts.GetArray(), p => p.Inventory.StopScriptInstances());
+        }
+
+        /// <summary>
         /// Add an inventory item from a user's inventory to a prim in this scene object.
         /// </summary>
         /// <param name="agentID">The agent adding the item.</param>
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
index f68a5b3..cc7d0fb 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
@@ -1674,16 +1674,6 @@ namespace OpenSim.Region.Framework.Scenes
         {
             return Utils.FloatToUInt16(m_scene.TimeDilation, 0.0f, 1.0f);
         }
-
-        /// <summary>
-        /// Added as a way for the storage provider to reset the scene,
-        /// most likely a better way to do this sort of thing but for now...
-        /// </summary>
-        /// <param name="scene"></param>
-        public void SetScene(Scene scene)
-        {
-            m_scene = scene;
-        }
         
         /// <summary>
         /// Set a part to act as the root part for this scene object
@@ -4324,6 +4314,20 @@ namespace OpenSim.Region.Framework.Scenes
             return count;
         }
 
+        /// <summary>
+        /// Gets the number of sitting avatars.
+        /// </summary>
+        /// <remarks>This applies to all sitting avatars whether there is a sit target set or not.</remarks>
+        /// <returns></returns>
+        public int GetSittingAvatarsCount()
+        {
+             int count = 0;
+
+             Array.ForEach<SceneObjectPart>(m_parts.GetArray(), p => count += p.GetSittingAvatarsCount());
+
+             return count;
+        }
+
         public override string ToString()
         {
             return String.Format("{0} {1} ({2})", Name, UUID, AbsolutePosition);
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs b/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
index 7b1f5d2..1f1caca 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
@@ -147,6 +147,21 @@ namespace OpenSim.Region.Framework.Scenes
             get { return ParentGroup.RootPart == this; } 
         }
 
+        /// <summary>
+        /// Is an explicit sit target set for this part?
+        /// </summary>
+        public bool IsSitTargetSet
+        {
+            get
+            {
+                return
+                    !(SitTargetPosition == Vector3.Zero
+                      && (SitTargetOrientation == Quaternion.Identity // Valid Zero Rotation quaternion
+                       || SitTargetOrientation.X == 0f && SitTargetOrientation.Y == 0f && SitTargetOrientation.Z == 1f && SitTargetOrientation.W == 0f // W-Z Mapping was invalid at one point
+                       || SitTargetOrientation.X == 0f && SitTargetOrientation.Y == 0f && SitTargetOrientation.Z == 0f && SitTargetOrientation.W == 0f)); // Invalid Quaternion
+            }
+        }
+
         #region Fields
 
         public bool AllowedDrop;
@@ -426,7 +441,6 @@ namespace OpenSim.Region.Framework.Scenes
         private uint _category;
         private Int32 _creationDate;
         private uint _parentID = 0;
-        private UUID m_sitTargetAvatar = UUID.Zero;
         private uint _baseMask = (uint)PermissionMask.All;
         private uint _ownerMask = (uint)PermissionMask.All;
         private uint _groupMask = (uint)PermissionMask.None;
@@ -1312,13 +1326,20 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
-        /// ID of the avatar that is sat on us.  If there is no such avatar then is UUID.Zero
+        /// ID of the avatar that is sat on us if we have a sit target.  If there is no such avatar then is UUID.Zero
         /// </summary>
-        public UUID SitTargetAvatar
-        {
-            get { return m_sitTargetAvatar; }
-            set { m_sitTargetAvatar = value; }
-        }
+        public UUID SitTargetAvatar { get; set; }
+
+        /// <summary>
+        /// IDs of all avatars start on this object part.
+        /// </summary>
+        /// <remarks>
+        /// We need to track this so that we can stop sat upon prims from being attached.
+        /// </remarks>
+        /// <value>
+        /// null if there are no sitting avatars.  This is to save us create a hashset for every prim in a scene.
+        /// </value>
+        private HashSet<UUID> m_sittingAvatars;
 
         public virtual UUID RegionID
         {
@@ -5128,5 +5149,99 @@ namespace OpenSim.Region.Framework.Scenes
                 Inventory.UpdateInventoryItem(item, false, false);
             }
         }
+
+        /// <summary>
+        /// Record an avatar sitting on this part.
+        /// </summary>
+        /// <remarks>This is called for all the sitting avatars whether there is a sit target set or not.</remarks>
+        /// <returns>
+        /// true if the avatar was not already recorded, false otherwise.
+        /// </returns>
+        /// <param name='avatarId'></param>
+        protected internal bool AddSittingAvatar(UUID avatarId)
+        {
+            if (IsSitTargetSet && SitTargetAvatar == UUID.Zero)
+                SitTargetAvatar = avatarId;
+
+            HashSet<UUID> sittingAvatars = m_sittingAvatars;
+
+            if (sittingAvatars == null)
+                sittingAvatars = new HashSet<UUID>();
+
+            lock (sittingAvatars)
+            {
+                m_sittingAvatars = sittingAvatars;
+                return m_sittingAvatars.Add(avatarId);
+            }
+        }
+
+        /// <summary>
+        /// Remove an avatar recorded as sitting on this part.
+        /// </summary>
+        /// <remarks>This applies to all sitting avatars whether there is a sit target set or not.</remarks>
+        /// <returns>
+        /// true if the avatar was present and removed, false if it was not present.
+        /// </returns>
+        /// <param name='avatarId'></param>
+        protected internal bool RemoveSittingAvatar(UUID avatarId)
+        {
+            if (SitTargetAvatar == avatarId)
+                SitTargetAvatar = UUID.Zero;
+
+            HashSet<UUID> sittingAvatars = m_sittingAvatars;
+
+            // This can occur under a race condition where another thread
+            if (sittingAvatars == null)
+                return false;
+
+            lock (sittingAvatars)
+            {
+                if (sittingAvatars.Remove(avatarId))
+                {
+                    if (sittingAvatars.Count == 0)
+                        m_sittingAvatars = null;
+
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Get a copy of the list of sitting avatars.
+        /// </summary>
+        /// <remarks>This applies to all sitting avatars whether there is a sit target set or not.</remarks>
+        /// <returns>A hashset of the sitting avatars.  Returns null if there are no sitting avatars.</returns>
+        public HashSet<UUID> GetSittingAvatars()
+        {
+            HashSet<UUID> sittingAvatars = m_sittingAvatars;
+
+            if (sittingAvatars == null)
+            {
+                return null;
+            }
+            else
+            {
+                lock (sittingAvatars)
+                    return new HashSet<UUID>(sittingAvatars);
+            }
+        }
+
+        /// <summary>
+        /// Gets the number of sitting avatars.
+        /// </summary>
+        /// <remarks>This applies to all sitting avatars whether there is a sit target set or not.</remarks>
+        /// <returns></returns>
+        public int GetSittingAvatarsCount()
+        {
+            HashSet<UUID> sittingAvatars = m_sittingAvatars;
+
+            if (sittingAvatars == null)
+                return 0;
+
+            lock (sittingAvatars)
+                return sittingAvatars.Count;
+        }
     }
 }
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectPartInventory.cs b/OpenSim/Region/Framework/Scenes/SceneObjectPartInventory.cs
index 1dff088..e5e29d0 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectPartInventory.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectPartInventory.cs
@@ -292,7 +292,7 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
-        /// Stop all the scripts in this prim.
+        /// Stop and remove all the scripts in this prim.
         /// </summary>
         /// <param name="sceneObjectBeingDeleted">
         /// Should be true if these scripts are being removed because the scene
@@ -309,6 +309,14 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
+        /// Stop all the scripts in this prim.
+        /// </summary>
+        public void StopScriptInstances()
+        {
+            GetInventoryItems(InventoryType.LSL).ForEach(i => StopScriptInstance(i));
+        }
+
+        /// <summary>
         /// Start a script which is in this prim's inventory.
         /// </summary>
         /// <param name="item"></param>
@@ -596,7 +604,7 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
-        /// Stop a script which is in this prim's inventory.
+        /// Stop and remove a script which is in this prim's inventory.
         /// </summary>
         /// <param name="itemId"></param>
         /// <param name="sceneObjectBeingDeleted">
@@ -615,7 +623,7 @@ namespace OpenSim.Region.Framework.Scenes
             }
             else
             {
-                m_log.ErrorFormat(
+                m_log.WarnFormat(
                     "[PRIM INVENTORY]: " +
                     "Couldn't stop script with ID {0} since it couldn't be found for prim {1}, {2} at {3} in {4}",
                     itemId, m_part.Name, m_part.UUID, 
@@ -624,6 +632,51 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
+        /// Stop a script which is in this prim's inventory.
+        /// </summary>
+        /// <param name="itemId"></param>
+        /// <param name="sceneObjectBeingDeleted">
+        /// Should be true if this script is being removed because the scene
+        /// object is being deleted.  This will prevent spurious updates to the client.
+        /// </param>
+        public void StopScriptInstance(UUID itemId)
+        {
+            TaskInventoryItem scriptItem;
+
+            lock (m_items)
+                m_items.TryGetValue(itemId, out scriptItem);
+
+            if (scriptItem != null)
+            {
+                StopScriptInstance(scriptItem);
+            }
+            else
+            {
+                m_log.WarnFormat(
+                    "[PRIM INVENTORY]: " +
+                    "Couldn't stop script with ID {0} since it couldn't be found for prim {1}, {2} at {3} in {4}",
+                    itemId, m_part.Name, m_part.UUID, 
+                    m_part.AbsolutePosition, m_part.ParentGroup.Scene.RegionInfo.RegionName);
+            }
+        }
+
+        /// <summary>
+        /// Stop a script which is in this prim's inventory.
+        /// </summary>
+        /// <param name="itemId"></param>
+        /// <param name="sceneObjectBeingDeleted">
+        /// Should be true if this script is being removed because the scene
+        /// object is being deleted.  This will prevent spurious updates to the client.
+        /// </param>
+        public void StopScriptInstance(TaskInventoryItem item)
+        {
+            m_part.ParentGroup.Scene.EventManager.TriggerStopScript(m_part.LocalId, item.ItemID);
+
+            // At the moment, even stopped scripts are counted as active, which is probably wrong.
+//            m_part.ParentGroup.AddActiveScriptCount(-1);
+        }
+
+        /// <summary>
         /// Check if the inventory holds an item with a given name.
         /// </summary>
         /// <param name="name"></param>
diff --git a/OpenSim/Region/Framework/Scenes/ScenePresence.cs b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
index f0ceff6..e27d309 100644
--- a/OpenSim/Region/Framework/Scenes/ScenePresence.cs
+++ b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
@@ -594,6 +594,12 @@ namespace OpenSim.Region.Framework.Scenes
         private UUID m_parentUUID = UUID.Zero;
 
         /// <summary>
+        /// Are we sitting on an object?
+        /// </summary>
+        /// <remarks>A more readable way of testing presence sit status than ParentID == 0</remarks>
+        public bool IsSatOnObject { get { return ParentID != 0; } }
+
+        /// <summary>
         /// If the avatar is sitting, the prim that it's sitting on.  If not sitting then null.
         /// </summary>
         /// <remarks>
@@ -1940,10 +1946,6 @@ namespace OpenSim.Region.Framework.Scenes
                     }
                 }
 
-                // Reset sit target.
-                if (part.SitTargetAvatar == UUID)
-                    part.SitTargetAvatar = UUID.Zero;
-
                 part.ParentGroup.DeleteAvatar(UUID);
 //                ParentPosition = part.GetWorldPosition();
                 ControllingClient.SendClearFollowCamProperties(part.ParentUUID);
@@ -1961,6 +1963,8 @@ namespace OpenSim.Region.Framework.Scenes
                 SendAvatarDataToAllAgents();
                 m_requestedSitTargetID = 0;
 
+                part.RemoveSittingAvatar(UUID);
+
                 if (part != null)
                     part.ParentGroup.TriggerScriptChangedEvent(Changed.LINK);
             }
@@ -1994,15 +1998,7 @@ namespace OpenSim.Region.Framework.Scenes
             //look for prims with explicit sit targets that are available
             foreach (SceneObjectPart part in partArray)
             {
-                // Is a sit target available?
-                Vector3 avSitOffset = part.SitTargetPosition;
-                Quaternion avSitOrientation = part.SitTargetOrientation;
-                UUID avOnTargetAlready = part.SitTargetAvatar;
-
-                bool SitTargetUnOccupied = avOnTargetAlready == UUID.Zero;
-                bool SitTargetisSet = avSitOffset != Vector3.Zero || avSitOrientation != Quaternion.Identity;
-
-                if (SitTargetisSet && SitTargetUnOccupied)
+                if (part.IsSitTargetSet && part.SitTargetAvatar == UUID.Zero)
                 {
                     //switch the target to this prim
                     return part;
@@ -2013,10 +2009,8 @@ namespace OpenSim.Region.Framework.Scenes
             return targetPart;
         }
 
-        private void SendSitResponse(UUID targetID, Vector3 offset, Quaternion pSitOrientation)
+        private void SendSitResponse(UUID targetID, Vector3 offset, Quaternion sitOrientation)
         {
-            Vector3 pos = new Vector3();
-            Quaternion sitOrientation = pSitOrientation;
             Vector3 cameraEyeOffset = Vector3.Zero;
             Vector3 cameraAtOffset = Vector3.Zero;
             bool forceMouselook = false;
@@ -2028,42 +2022,21 @@ namespace OpenSim.Region.Framework.Scenes
             // TODO: determine position to sit at based on scene geometry; don't trust offset from client
             // see http://wiki.secondlife.com/wiki/User:Andrew_Linden/Office_Hours/2007_11_06 for details on how LL does it
 
-            // Is a sit target available?
-            Vector3 avSitOffSet = part.SitTargetPosition;
-            Quaternion avSitOrientation = part.SitTargetOrientation;
-            UUID avOnTargetAlready = part.SitTargetAvatar;
-
-            bool SitTargetUnOccupied = (!(avOnTargetAlready != UUID.Zero));
-            bool SitTargetisSet =
-                (!(avSitOffSet == Vector3.Zero &&
-                   (
-                       avSitOrientation == Quaternion.Identity // Valid Zero Rotation quaternion
-                       || avSitOrientation.X == 0f && avSitOrientation.Y == 0f && avSitOrientation.Z == 1f && avSitOrientation.W == 0f // W-Z Mapping was invalid at one point
-                       || avSitOrientation.X == 0f && avSitOrientation.Y == 0f && avSitOrientation.Z == 0f && avSitOrientation.W == 0f // Invalid Quaternion
-                   )
-                   ));
-
-//                m_log.DebugFormat("[SCENE PRESENCE]: {0} {1}", SitTargetisSet, SitTargetUnOccupied);
-
             if (PhysicsActor != null)
                 m_sitAvatarHeight = PhysicsActor.Size.Z * 0.5f;
 
             bool canSit = false;
-            pos = part.AbsolutePosition + offset;
+            Vector3 pos = part.AbsolutePosition + offset;
 
-            if (SitTargetisSet)
+            if (part.IsSitTargetSet && part.SitTargetAvatar == UUID.Zero)
             {
-                if (SitTargetUnOccupied)
-                {
 //                    m_log.DebugFormat(
 //                        "[SCENE PRESENCE]: Sitting {0} on {1} {2} because sit target is set and unoccupied",
 //                        Name, part.Name, part.LocalId);
 
-                    part.SitTargetAvatar = UUID;
-                    offset = new Vector3(avSitOffSet.X, avSitOffSet.Y, avSitOffSet.Z);
-                    sitOrientation = avSitOrientation;
-                    canSit = true;
-                }
+                offset = part.SitTargetPosition;
+                sitOrientation = part.SitTargetOrientation;
+                canSit = true;
             }
             else
             {
@@ -2076,6 +2049,12 @@ namespace OpenSim.Region.Framework.Scenes
                     AbsolutePosition = pos + new Vector3(0.0f, 0.0f, m_sitAvatarHeight);
                     canSit = true;
                 }
+//                else
+//                {
+//                    m_log.DebugFormat(
+//                        "[SCENE PRESENCE]: Ignoring sit request of {0} on {1} {2} because sit target is unset and outside 10m",
+//                        Name, part.Name, part.LocalId);
+//                }
             }
 
             if (canSit)
@@ -2086,6 +2065,8 @@ namespace OpenSim.Region.Framework.Scenes
                     RemoveFromPhysicalScene();
                 }
 
+                part.AddSittingAvatar(UUID);
+
                 cameraAtOffset = part.GetCameraAtOffset();
                 cameraEyeOffset = part.GetCameraEyeOffset();
                 forceMouselook = part.GetForceMouselook();
@@ -2362,6 +2343,15 @@ namespace OpenSim.Region.Framework.Scenes
 
             if (part != null)
             {
+                if (part.ParentGroup.IsAttachment)
+                {
+                    m_log.WarnFormat(
+                        "[SCENE PRESENCE]: Avatar {0} tried to sit on part {1} from object {2} in {3} but this is an attachment for avatar id {4}",
+                        Name, part.Name, part.ParentGroup.Name, Scene.Name, part.ParentGroup.AttachedAvatar);
+
+                    return;
+                }
+
                 if (part.SitTargetAvatar == UUID)
                 {
                     Vector3 sitTargetPos = part.SitTargetPosition;
diff --git a/OpenSim/Region/Framework/Scenes/Tests/ScenePresenceSitTests.cs b/OpenSim/Region/Framework/Scenes/Tests/ScenePresenceSitTests.cs
index ed39be1..493ab70 100644
--- a/OpenSim/Region/Framework/Scenes/Tests/ScenePresenceSitTests.cs
+++ b/OpenSim/Region/Framework/Scenes/Tests/ScenePresenceSitTests.cs
@@ -26,6 +26,7 @@
  */
 
 using System;
+using System.Collections.Generic;
 using System.Reflection;
 using Nini.Config;
 using NUnit.Framework;
@@ -69,6 +70,8 @@ namespace OpenSim.Region.Framework.Scenes.Tests
             m_sp.HandleAgentRequestSit(m_sp.ControllingClient, m_sp.UUID, part.UUID, Vector3.Zero);
 
             Assert.That(part.SitTargetAvatar, Is.EqualTo(UUID.Zero));
+            Assert.That(part.GetSittingAvatarsCount(), Is.EqualTo(0));
+            Assert.That(part.GetSittingAvatars(), Is.Null);
             Assert.That(m_sp.ParentID, Is.EqualTo(0));
         }
 
@@ -86,7 +89,13 @@ namespace OpenSim.Region.Framework.Scenes.Tests
 
             m_sp.HandleAgentRequestSit(m_sp.ControllingClient, m_sp.UUID, part.UUID, Vector3.Zero);
 
+            Assert.That(m_sp.PhysicsActor, Is.Null);
+
             Assert.That(part.SitTargetAvatar, Is.EqualTo(UUID.Zero));
+            Assert.That(part.GetSittingAvatarsCount(), Is.EqualTo(1));
+            HashSet<UUID> sittingAvatars = part.GetSittingAvatars();
+            Assert.That(sittingAvatars.Count, Is.EqualTo(1));
+            Assert.That(sittingAvatars.Contains(m_sp.UUID));
             Assert.That(m_sp.ParentID, Is.EqualTo(part.LocalId));
         }
 
@@ -104,10 +113,6 @@ namespace OpenSim.Region.Framework.Scenes.Tests
 
             m_sp.HandleAgentRequestSit(m_sp.ControllingClient, m_sp.UUID, part.UUID, Vector3.Zero);
 
-            Assert.That(part.SitTargetAvatar, Is.EqualTo(UUID.Zero));
-            Assert.That(m_sp.ParentID, Is.EqualTo(part.LocalId));
-            Assert.That(m_sp.PhysicsActor, Is.Null);
-
             // FIXME: This is different for live avatars - z position is adjusted.  This is half the height of the
             // default avatar.
             // Curiously, Vector3.ToString() will not display the last two places of the float.  For example,
@@ -119,6 +124,8 @@ namespace OpenSim.Region.Framework.Scenes.Tests
             m_sp.StandUp();
 
             Assert.That(part.SitTargetAvatar, Is.EqualTo(UUID.Zero));
+            Assert.That(part.GetSittingAvatarsCount(), Is.EqualTo(0));
+            Assert.That(part.GetSittingAvatars(), Is.Null);
             Assert.That(m_sp.ParentID, Is.EqualTo(0));
             Assert.That(m_sp.PhysicsActor, Is.Not.Null);
         }
@@ -145,11 +152,20 @@ namespace OpenSim.Region.Framework.Scenes.Tests
                 Is.EqualTo(part.AbsolutePosition + part.SitTargetPosition + ScenePresence.SIT_TARGET_ADJUSTMENT));
             Assert.That(m_sp.PhysicsActor, Is.Null);
 
+            Assert.That(part.GetSittingAvatarsCount(), Is.EqualTo(1));
+            HashSet<UUID> sittingAvatars = part.GetSittingAvatars();
+            Assert.That(sittingAvatars.Count, Is.EqualTo(1));
+            Assert.That(sittingAvatars.Contains(m_sp.UUID));
+
             m_sp.StandUp();
 
             Assert.That(part.SitTargetAvatar, Is.EqualTo(UUID.Zero));
             Assert.That(m_sp.ParentID, Is.EqualTo(0));
             Assert.That(m_sp.PhysicsActor, Is.Not.Null);
+
+            Assert.That(part.SitTargetAvatar, Is.EqualTo(UUID.Zero));
+            Assert.That(part.GetSittingAvatarsCount(), Is.EqualTo(0));
+            Assert.That(part.GetSittingAvatars(), Is.Null);
         }
 
         [Test]