SerialPortStream: Don't close the port on ERROR_HANDLE_EOF

It is observed that WinError.ERROR_HANDLE_EOF can occur in normal circumstances and should not result in the serial port stream closing down. Issue: #142 Issue: DOTNET-975
jcurl · Mar 4, 2024 · 956636d · 956636d
1 parent 81aff4d
commit 956636d
Showing 1 changed file with 72 additions and 42 deletions.
diff --git a/code/Native/Windows/CommOverlappedIo.cs b/code/Native/Windows/CommOverlappedIo.cs
@@ -1,4 +1,4 @@
-// Copyright © Jason Curl 2012-2023
+// Copyright © Jason Curl 2012-2024
 // Sources at https://github.com/jcurl/SerialPortStream
 // Licensed under the Microsoft Public License (Ms-PL)
 
@@ -457,20 +457,7 @@ private void OverlappedIoThreadMainLoop()
                     } else if (whandles[ev] == m_ReadEvent) {
                         result = Kernel32.GetOverlappedResult(m_ComPortHandle, ref readOverlapped, out bytes, true);
                         if (!result) {
-                            int win32Error = Marshal.GetLastWin32Error();
-                            int hr = Marshal.GetHRForLastWin32Error();
-                            // Should never get ERROR_IO_PENDING, as this method is only called when the event is triggered.
-                            if (win32Error != WinError.ERROR_OPERATION_ABORTED || bytes > 0) {
-                                if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Error))
-                                    m_Log.TraceEvent(System.Diagnostics.TraceEventType.Error,
-                                        "{0}: SerialThread: Overlapped ReadFile() error {1} bytes {2}", m_Name, win32Error, bytes);
-                                Marshal.ThrowExceptionForHR(hr);
-                            } else {
-                                // ERROR_OPERATION_ABORTED may be caused by CancelIo or PurgeComm
-                                if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
-                                    m_Log.TraceEvent(System.Diagnostics.TraceEventType.Verbose,
-                                        "{0}: SerialThread: Overlapped ReadFile() error {1} bytes {2}", m_Name, win32Error, bytes);
-                            }
+                            ProcessReadEventError(bytes);
                         } else {
                             ProcessReadEvent(bytes);
                         }
@@ -481,19 +468,7 @@ private void OverlappedIoThreadMainLoop()
                     } else if (whandles[ev] == m_WriteEvent) {
                         result = Kernel32.GetOverlappedResult(m_ComPortHandle, ref writeOverlapped, out bytes, true);
                         if (!result) {
-                            int win32Error = Marshal.GetLastWin32Error();
-                            int hr = Marshal.GetHRForLastWin32Error();
-                            // Should never get ERROR_IO_PENDING, as this method is only called when the event is triggered.
-                            if (win32Error != WinError.ERROR_OPERATION_ABORTED || bytes > 0) {
-                                if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Error))
-                                    m_Log.TraceEvent(System.Diagnostics.TraceEventType.Error,
-                                        "{0}: SerialThread: Overlapped WriteFile() error {1} bytes {2}", m_Name, win32Error, bytes);
-                                Marshal.ThrowExceptionForHR(hr);
-                            } else {
-                                // ERROR_OPERATION_ABORTED may be caused by CancelIo or PurgeComm
-                                if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
-                                    m_Log.TraceEvent(System.Diagnostics.TraceEventType.Verbose, "{0}: SerialThread: Overlapped WriteFile() error {1} bytes {2}", m_Name, win32Error, bytes);
-                            }
+                            ProcessWriteEventError(bytes);
                         } else {
                             ProcessWriteEvent(bytes);
                         }
@@ -508,20 +483,7 @@ private void OverlappedIoThreadMainLoop()
                             m_PurgePending = true;
                             result = Kernel32.PurgeComm(m_ComPortHandle,
                                 Kernel32.PurgeFlags.PURGE_TXABORT | Kernel32.PurgeFlags.PURGE_TXCLEAR);
-                            if (!result) {
-                                int win32Error = Marshal.GetLastWin32Error();
-                                int hr = Marshal.GetHRForLastWin32Error();
-                                if (win32Error != WinError.ERROR_OPERATION_ABORTED) {
-                                    if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Error))
-                                        m_Log.TraceEvent(System.Diagnostics.TraceEventType.Error,
-                                        "{0}: SerialThread: PurgeComm() error {1}", m_Name, win32Error);
-                                    Marshal.ThrowExceptionForHR(hr);
-                                } else {
-                                    if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
-                                        m_Log.TraceEvent(System.Diagnostics.TraceEventType.Verbose,
-                                            "{0}: SerialThread: PurgeComm() error {1}", m_Name, win32Error);
-                                }
-                            }
+                            if (!result) ProcessPurgeCommError();
                         } else {
                             lock (m_Buffer.WriteLock) {
                                 if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
@@ -737,6 +699,33 @@ private void ProcessReadEvent(uint bytes)
             }
         }
 
+        private void ProcessReadEventError(uint bytes)
+        {
+            int win32Error = Marshal.GetLastWin32Error();
+            int hr = Marshal.GetHRForLastWin32Error();
+
+            // Should never get ERROR_IO_PENDING, as this method is only called when the event is triggered.
+            if (bytes == 0) {
+                switch (win32Error) {
+                case WinError.ERROR_OPERATION_ABORTED:
+                    // ERROR_OPERATION_ABORTED may be caused by CancelIo or PurgeComm
+                    if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
+                        m_Log.TraceEvent(System.Diagnostics.TraceEventType.Verbose,
+                            "{0}: SerialThread: Overlapped ReadFile() error {1} bytes {2}", m_Name, win32Error, bytes);
+                    return;
+                case WinError.ERROR_HANDLE_EOF:
+                    if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Information))
+                        m_Log.TraceEvent(System.Diagnostics.TraceEventType.Information,
+                            "{0}: SerialThread: Overlapped ReadFile() error {1} bytes {2}", m_Name, win32Error, bytes);
+                    return;
+                }
+            }
+            if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Error))
+                m_Log.TraceEvent(System.Diagnostics.TraceEventType.Error,
+                    "{0}: SerialThread: Overlapped ReadFile() error {1} bytes {2}", m_Name, win32Error, bytes);
+            Marshal.ThrowExceptionForHR(hr);
+        }
+
         /// <summary>
         /// Check if we should WriteFile() and update buffers if serial data is immediately cached by driver.
         /// </summary>
@@ -826,6 +815,47 @@ private void ProcessWriteEvent(uint bytes)
             }
         }
 
+        private void ProcessWriteEventError(uint bytes)
+        {
+            int win32Error = Marshal.GetLastWin32Error();
+            int hr = Marshal.GetHRForLastWin32Error();
+
+            if (bytes == 0) {
+                switch (win32Error) {
+                case WinError.ERROR_OPERATION_ABORTED:
+                    // ERROR_OPERATION_ABORTED may be caused by CancelIo or PurgeComm
+                    if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
+                        m_Log.TraceEvent(System.Diagnostics.TraceEventType.Verbose,
+                            "{0}: SerialThread: Overlapped WriteFile() error {1} bytes {2}", m_Name, win32Error, bytes);
+                    return;
+                }
+            }
+            if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Error))
+                m_Log.TraceEvent(System.Diagnostics.TraceEventType.Error,
+                    "{0}: SerialThread: Overlapped WriteFile() error {1} bytes {2}", m_Name, win32Error, bytes);
+            Marshal.ThrowExceptionForHR(hr);
+        }
+
+        private void ProcessPurgeCommError()
+        {
+            int win32Error = Marshal.GetLastWin32Error();
+            int hr = Marshal.GetHRForLastWin32Error();
+
+            switch (win32Error) {
+            case WinError.ERROR_OPERATION_ABORTED:
+                if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Verbose))
+                    m_Log.TraceEvent(System.Diagnostics.TraceEventType.Verbose,
+                        "{0}: SerialThread: PurgeComm() error {1}", m_Name, win32Error);
+                return;
+            default:
+                if (m_Log.ShouldTrace(System.Diagnostics.TraceEventType.Error))
+                    m_Log.TraceEvent(System.Diagnostics.TraceEventType.Error,
+                    "{0}: SerialThread: PurgeComm() error {1}", m_Name, win32Error);
+                Marshal.ThrowExceptionForHR(hr);
+                break;
+            }
+        }
+
         #region Event Handling
         public event EventHandler<CommEventArgs> CommEvent;