--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/fifo.py	Wed Mar 26 02:30:34 2008 +0200
@@ -0,0 +1,100 @@
+# read a stream from a fifo
+
+from twisted.internet import reactor, interfaces
+from twisted.python import log
+from zope.interface import implements
+
+import os, fcntl, errno
+
+class EOF (Exception) : pass
+
+BUF_SIZE = 2048
+
+class Fifo (object) :
+    implements(interfaces.IReadDescriptor)
+
+    def __init__ (self, path) :
+        self.path = path
+        self._open()
+
+    def _open (self) :
+        self.fd = os.open(self.path, os.O_RDONLY | os.O_NONBLOCK)
+
+        reactor.addReader(self)
+        
+        log.msg("opened fifo %s as %d" % (self.path, self.fd))
+
+    def _close (self) :
+        if self.fd :
+            reactor.removeReader(self)
+            os.close(self.fd)
+
+            log.msg("closed fifo %d at %s" % (self.fd, self.path))
+            
+            self.fd = None
+    close = _close
+
+    def reopen (self) :
+        """
+            Close and re-open the fifo. This is useful for handling EOF
+        """
+        self._close()
+        self._open()
+
+    def _read (self, length) :
+
+        log.msg("(read %d bytes from %d:%s)" % (length, self.fd, self.path))
+        try :
+            data = os.read(self.fd, length)
+
+        except OSError, e :
+            if e.errno == errno.EAGAIN :
+                log.msg("\tEAGAIN")
+                return None
+            else :
+                log.msg("\tERROR: %s" % e)
+                raise
+
+        if not data :
+            log.msg("\tEOF")
+            raise EOF()
+        
+        log.msg("\tDATA: %d: %r" % (len(data), data))
+        return data
+    
+    def fileno (self) :
+        return self.fd
+
+    def doRead (self) :
+        while True :
+            log.msg("fifo doRead loop")
+
+            try :
+                data = self._read(BUF_SIZE)
+            except EOF :
+                self.handleEOF()
+                return
+
+            if data :
+                self.dataReceived(data)
+            else :
+                break
+        
+    def dataReceived (self, data) :
+        pass
+    
+    def handleEOF (self) :
+        pass
+    
+    def connectionLost (self, reason) :
+        self.close()
+    
+    def logPrefix (self) :
+        return "FIFO:%d:%s" % (self.fd, self.path)
+
+    def __del__ (self) :
+        """
+            !!! this is important
+        """
+        self.close()
+