add VCSA watchdog prototype

play zone/epollScreen.py

@@ -0,0 +1,41 @@
+#!/bin/python
+
+import select
+import time
+
+vcsa = {}
+for i in range(1,7):
+    vcsa[str(i)] = open('/dev/vcs'+str(i),'rb')
+    vcsa[str(i)].read()
+
+tty = open('/sys/devices/virtual/tty/tty0/active','r')
+
+oldTty = str(tty.read()[3:-1])
+watchdog = select.poll()
+watchdog.register(tty, select.EPOLLPRI)
+watchdog.register(vcsa[ oldTty ], select.EPOLLPRI)
+
+while True:
+    changed = watchdog.poll()
+    print('-----------------------------')
+    print(changed,tty.fileno())
+    for fileno, event in changed:
+        if tty.fileno() == fileno: 
+            currTty = tty.seek(0)
+            #b = open('/sys/devices/virtual/tty/tty0/active','r')  
+            currTty = str(tty.read()[3:-1])
+            print('|'+currTty+'|'+oldTty+'|')
+            if currTty != oldTty:
+                watchdog.register(vcsa[ currTty ].fileno(), select.EPOLLPRI)   
+                watchdog.unregister(vcsa[ oldTty ].fileno())  
+                oldTty = currTty
+                print('new screen ' + currTty)
+        else:
+            print('update '+ currTty + ' ' + str(fileno))
+            vcsa[currTty].seek(0)
+            b = vcsa[currTty].read()
+            #print(b)
+    time.sleep(0.5)
+
+
+