2 files changed, 48 insertions, 17 deletions

diff --git a/OpenSim/Framework/Console/LocalConsole.cs b/OpenSim/Framework/Console/LocalConsole.cs
index be936b6..a3036d0 100644
--- a/OpenSim/Framework/Console/LocalConsole.cs
+++ b/OpenSim/Framework/Console/LocalConsole.cs
@@ -38,7 +38,7 @@ namespace OpenSim.Framework.Console
 {
     /// <summary>
     /// A console that uses cursor control and color
-    /// </summary>
+    /// </summary>    
     public class LocalConsole : CommandConsole
     {
 //        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
@@ -100,24 +100,40 @@ namespace OpenSim.Framework.Console
         private int SetCursorTop(int top)
         {
             // From at least mono 2.4.2.3, window resizing can give mono an invalid row and column values.  If we try
-            // to set a cursor row position with a currently invalid column, mono will throw an exception.
-            // Therefore, we need to make sure that the column position is valid first.
+            // to set a cursor row position with a currently invalid column, mono will throw an exception.  
+            // Therefore, we need to make sure that the column position is valid first.              
             int left = System.Console.CursorLeft;
 
             if (left < 0)
+            {
                 System.Console.CursorLeft = 0;
-            else if (left >= System.Console.BufferWidth)
-                System.Console.CursorLeft = System.Console.BufferWidth - 1;
+            }
+            else 
+            {
+                int bw = System.Console.BufferWidth;
+                
+                // On Mono 2.4.2.3 (and possibly above), the buffer value is sometimes erroneously zero (Mantis 4657)
+                if (bw > 0 && left >= bw)
+                    System.Console.CursorLeft = bw - 1;
+            }
             
             if (top < 0)
+            {
                 top = 0;
-            if (top >= System.Console.BufferHeight)
-                top = System.Console.BufferHeight - 1;
+            }
+            else                
+            {
+                int bh = System.Console.BufferHeight;
+                
+                // On Mono 2.4.2.3 (and possibly above), the buffer value is sometimes erroneously zero (Mantis 4657)
+                if (bh > 0 && top >= bh)
+                    top = bh - 1;
+            }
 
             System.Console.CursorTop = top;
 
             return top;
-        }
+        }        
 
         /// <summary>
         /// Set the cursor column.
@@ -129,23 +145,38 @@ namespace OpenSim.Framework.Console
         /// </param>
         /// <returns>
         /// The new cursor column.
-        /// </returns>
+        /// </returns>        
         private int SetCursorLeft(int left)
         {
             // From at least mono 2.4.2.3, window resizing can give mono an invalid row and column values.  If we try
-            // to set a cursor column position with a currently invalid row, mono will throw an exception.
-            // Therefore, we need to make sure that the row position is valid first.
+            // to set a cursor column position with a currently invalid row, mono will throw an exception.  
+            // Therefore, we need to make sure that the row position is valid first.               
             int top = System.Console.CursorTop;
 
             if (top < 0)
+            {
                 System.Console.CursorTop = 0;
-            else if (top >= System.Console.BufferHeight)
-                System.Console.CursorTop = System.Console.BufferHeight - 1;
+            }
+            else 
+            {
+                int bh = System.Console.BufferHeight;
+                // On Mono 2.4.2.3 (and possibly above), the buffer value is sometimes erroneously zero (Mantis 4657)
+                if (bh > 0 && top >= bh)
+                    System.Console.CursorTop = bh - 1;
+            }
             
             if (left < 0)
+            {
                 left = 0;
-            if (left >= System.Console.BufferWidth)
-                left = System.Console.BufferWidth - 1;
+            }
+            else
+            {
+                int bw = System.Console.BufferWidth;
+
+                // On Mono 2.4.2.3 (and possibly above), the buffer value is sometimes erroneously zero (Mantis 4657)
+                if (bw > 0 && left >= bw)
+                    left = bw - 1;
+            }
 
             System.Console.CursorLeft = left;
 
@@ -183,7 +214,7 @@ namespace OpenSim.Framework.Console
                     System.Console.Write("{0}", prompt);
 
                 SetCursorTop(new_y);
-                SetCursorLeft(new_x);
+                SetCursorLeft(new_x);                
             }
         }
 
diff --git a/OpenSim/Framework/Util.cs b/OpenSim/Framework/Util.cs
index 48435cb..ec33b5e 100644
--- a/OpenSim/Framework/Util.cs
+++ b/OpenSim/Framework/Util.cs
@@ -1441,4 +1441,4 @@ namespace OpenSim.Framework
             return (diff >= 0) ? diff : (diff + EnvironmentTickCountMask + 1);
         }
     }
-}
+}
\ No newline at end of file