add windows virtio serial handler

w32serial.py

+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Serial port support for Windows.
+
+Requires PySerial and pywin32.
+"""
+
+# system imports
+
+import win32file
+import win32event
+import win32con
+
+# twisted imports
+from twisted.internet import abstract
+
+# sibling imports
+import logging
+logger = logging.getLogger()
+
+
+class SerialPort(abstract.FileDescriptor):
+
+    """A serial device, acting as a transport, that uses a win32 event."""
+
+    connected = 1
+
+    def __init__(self, protocol, deviceNameOrPortNumber, reactor):
+        #self._serialFactory = VirtioSerial
+        #self._serial = self._serialFactory(port=deviceNameOrPortNumber)
+        self.hComPort = win32file.CreateFile(deviceNameOrPortNumber,
+                                             win32con.GENERIC_READ | win32con.GENERIC_WRITE,
+                                             0,  # exclusive access
+                                             None,  # no security
+                                             win32con.OPEN_EXISTING,
+                                             win32con.FILE_ATTRIBUTE_NORMAL | win32con.FILE_FLAG_OVERLAPPED,
+                                             0)
+        self.reactor = reactor
+        self.protocol = protocol
+        self.outQueue = []
+        self.closed = 0
+        self.closedNotifies = 0
+        self.writeInProgress = 0
+
+        self.protocol = protocol
+        self._overlappedRead = win32file.OVERLAPPED()
+        self._overlappedRead.hEvent = win32event.CreateEvent(None, 1, 0, None)
+        self._overlappedWrite = win32file.OVERLAPPED()
+        self._overlappedWrite.hEvent = win32event.CreateEvent(None, 0, 0, None)
+
+        self.reactor.addEvent(
+            self._overlappedRead.hEvent,
+            self,
+            'serialReadEvent')
+        self.reactor.addEvent(
+            self._overlappedWrite.hEvent,
+            self,
+            'serialWriteEvent')
+
+        self.protocol.makeConnection(self)
+        self._finishPortSetup()
+
+    def _finishPortSetup(self):
+        """
+        Finish setting up the serial port.
+
+        This is a separate method to facilitate testing.
+        """
+        rc, self.read_buf = win32file.ReadFile(self.hComPort,
+                                               win32file.AllocateReadBuffer(1),
+                                               self._overlappedRead)
+
+    def serialReadEvent(self):
+        # get that character we set up
+        try:
+            n = win32file.GetOverlappedResult(
+                self.hComPort,
+                self._overlappedRead,
+                0)
+        except:
+            n = 0
+        if n:
+            first = str(self.read_buf[:n])
+            # now we should get everything that is already in the buffer
+            win32event.ResetEvent(self._overlappedRead.hEvent)
+            rc, buf = win32file.ReadFile(self.hComPort,
+                                         win32file.AllocateReadBuffer(n),
+                                         self._overlappedRead)
+            n = win32file.GetOverlappedResult(
+                self.hComPort,
+                self._overlappedRead,
+                1)
+            # handle all the received data:
+            self.protocol.dataReceived(first + str(buf[:n]))
+
+        # set up next one
+        win32event.ResetEvent(self._overlappedRead.hEvent)
+        # rc, self.read_buf = win32file.ReadFile(self.hComPort,
+        #                                       win32file.AllocateReadBuffer(1),
+        #                                       self._overlappedRead)
+
+    def write(self, data):
+        if data:
+            if self.writeInProgress:
+                self.outQueue.append(data)
+                logger.debug("added to queue")
+            else:
+                self.writeInProgress = 1
+                win32file.WriteFile(self.hComPort, data, self._overlappedWrite)
+                logger.debug("Writed to file")
+
+    def serialWriteEvent(self):
+        try:
+            dataToWrite = self.outQueue.pop(0)
+        except IndexError:
+            self.writeInProgress = 0
+            return
+        else:
+            win32file.WriteFile(
+                self.hComPort,
+                dataToWrite,
+                self._overlappedWrite)
+
+    def connectionLost(self, reason):
+        """
+        Called when the serial port disconnects.
+
+        Will call C{connectionLost} on the protocol that is handling the
+        serial data.
+        """
+        self.reactor.removeEvent(self._overlappedRead.hEvent)
+        self.reactor.removeEvent(self._overlappedWrite.hEvent)
+        abstract.FileDescriptor.connectionLost(self, reason)
+        win32file.CloseHandle(self.hComPort)
+        self.protocol.connectionLost(reason)