Change to safer native PenHelper call

Author: govert

Source/ExcelDna.IntelliSense.Host/ExcelDna.IntelliSense.Host.csproj

@@ -13,6 +13,8 @@
 	  <ExcelDna32BitAddInSuffix>32</ExcelDna32BitAddInSuffix>
 	  <ExcelDna64BitAddInSuffix>64</ExcelDna64BitAddInSuffix>
 	  <ExcelDnaPackXllSuffix></ExcelDnaPackXllSuffix>
+    <ExcelDnaPack32BitXllName>ExcelDna.IntelliSense</ExcelDnaPack32BitXllName>
+    <ExcelDnaPack64BitXllName>ExcelDna.IntelliSense64</ExcelDnaPack64BitXllName>
   </PropertyGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">

Source/ExcelDna.IntelliSense/IntelliSenseServer.cs

@@ -30,7 +30,7 @@ namespace ExcelDna.IntelliSense
     // REMEMBER: COM events are not necessarily safe macro contexts.
     public static class IntelliSenseServer
     {
-        const string ServerVersion = "1.7.1";  // TODO: Define and manage this somewhere else
+        const string ServerVersion = "1.7.2";  // TODO: Define and manage this somewhere else
 
         // NOTE: Do not change these constants in custom versions. 
         //       They are part of the co-operative safety mechanism allowing different add-ins providing IntelliSense to work together safely.
@@ -157,7 +157,7 @@ static void CurrentDomain_ProcessExit(object sender, EventArgs e)
             if (_isActive)
             {
                 // Parachute in asap a call to prevent further XLPenHelper calls
-                XlCall.ShutdownStarted();
+                XlCallHelper.ShutdownStarted();
 
                 // Don't try to clean up clean up on process exit - all our resources are in-process anyway
                 // Leads to an error with the main thread SynchronizationContext, which might be shut down already.

Source/ExcelDna.IntelliSense/UIMonitor/FormulaEditWatcher.cs

@@ -329,7 +329,7 @@ void UpdateEditState(bool moveOnly = false)
 
         void UpdateEditStateImpl(bool moveOnly = false)
         {
-            Logger.WindowWatcher.Verbose($"> FormulaEdit UpdateEditState - Thread {Thread.CurrentThread.ManagedThreadId}");
+            // Logger.WindowWatcher.Verbose($"> FormulaEdit UpdateEditState - Thread {Thread.CurrentThread.ManagedThreadId}");
             Logger.WindowWatcher.Verbose($"FormulaEdit UpdateEditState - Focus: {_formulaEditFocus} Window: {(_formulaEditFocus == FormulaEditFocus.FormulaBar ? _hwndFormulaBar : _hwndInCellEdit)}");
 
             IntPtr hwnd = IntPtr.Zero;
@@ -365,7 +365,7 @@ void UpdateEditStateImpl(bool moveOnly = false)
                     IsEditingFormula = true;
                 }
 
-                var newPrefix = XlCall.GetFormulaEditPrefix();  // What thread do we have to use here ...?
+                var newPrefix = XlCallHelper.GetFormulaEditPrefix();    // This call must be on the main thread
                 if (CurrentPrefix != newPrefix)
                 {
                     CurrentPrefix = newPrefix;

Source/ExcelDna.IntelliSense/UIMonitor/XlCall.cs renamed to Source/ExcelDna.IntelliSense/UIMonitor/XlCallHelper.cs

@@ -1,35 +1,13 @@
-using System;
+using ExcelDna.Integration;
+using System;
 using System.Diagnostics;
 using System.Runtime.ExceptionServices;
 using System.Runtime.InteropServices;
 
 namespace ExcelDna.IntelliSense
 {
-    class XlCall
+    class XlCallHelper
     {
-        [DllImport("XLCALL32.DLL")]
-        static extern int LPenHelper(int wCode, ref FmlaInfo fmlaInfo); // 'long' return value means 'int' in C (so why different?)
-
-        const int xlSpecial = 0x4000;
-        const int xlGetFmlaInfo = (14 | xlSpecial);
-
-        // Edit Modes
-        const int xlModeReady = 0;	// not in edit mode
-        const int xlModeEnter = 1;	// enter mode
-        const int xlModeEdit  = 2;	// edit mode
-        const int xlModePoint = 4;	// point mode
-
-        [StructLayout(LayoutKind.Sequential)]
-        struct FmlaInfo
-        {
-            public int wPointMode;    // current edit mode.  0 => rest of struct undefined
-            public int cch;           // count of characters in formula
-            public IntPtr lpch;       // pointer to formula characters.  READ ONLY!!!
-            public int ichFirst;      // char offset to start of selection
-            public int ichLast;       // char offset to end of selection (may be > cch)
-            public int ichCaret;      // char offset to blinking caret
-        }
-
         // This give a global mechanism to indicate shutdown as early as possible
         // Maybe helps with debugging...
         static bool _shutdownStarted = false;
@@ -38,21 +16,17 @@ public static void ShutdownStarted()
             _shutdownStarted = true;
         }
 
+        // This call must be made on the main thread
         // Returns null if not in edit mode
-        // TODO: What do we know about the threading constraints on this call?
-
-        // NOTE: I've only seen this crash during shutdown
-        //       We enable handling of the AccessViolation as best we can
-        [HandleProcessCorruptedStateExceptions]
         public static string GetFormulaEditPrefix()
         {
             if (_shutdownStarted)
                 return null;
 
             try
             {
-                var fmlaInfo = new FmlaInfo();
-                var result = LPenHelper(xlGetFmlaInfo, ref fmlaInfo);
+                var fmlaInfo = new XlCall.FmlaInfo();
+                var result = XlCall.PenHelper(XlCall.xlGetFmlaInfo, ref fmlaInfo);
                 if (result != 0)
                 {
                     Logger.WindowWatcher.Warn($"LPenHelper Failed. Result: {result}");
@@ -62,7 +36,7 @@ public static string GetFormulaEditPrefix()
                     // throw new InvalidOperationException("LPenHelper Failed. Result: " + result);
                     return null;
                 }
-                if (fmlaInfo.wPointMode == xlModeReady)
+                if (fmlaInfo.wPointMode == XlCall.xlModeReady)
                 {
                     Logger.WindowWatcher.Verbose($"LPenHelper PointMode Ready");
                     return null;
@@ -76,11 +50,6 @@ public static string GetFormulaEditPrefix()
                 var prefixLen = Math.Min(Math.Max(fmlaInfo.ichCaret, fmlaInfo.ichLast), fmlaInfo.cch);  // I've never seen ichLast > cch !?
                 return Marshal.PtrToStringUni(fmlaInfo.lpch, prefixLen);
             }
-            catch (AccessViolationException)
-            {
-                Logger.WindowWatcher.Warn("LPenHelper - Access Violation!");
-                return null;
-            }
             catch (Exception ex)
             {
                 // Some unexpected error - for now we log as an error and re-throw