Switch only if vt number from stdin different than current vt, for Op…

…enRoberta#72

roberta/lab.py

@@ -33,8 +33,7 @@
 # TRUE: use a new token per reconnect
 # FALSE: try keep using the token for as long as possible
 #        (needs robertalab > 1.4 or develop branch)
-#TOKEN_PER_SESSION = True
-TOKEN_PER_SESSION = False
+TOKEN_PER_SESSION = True
 
 
 # helpers
@@ -154,16 +153,18 @@ def status(self, status):
 class GfxMode(object):
 
     def __init__(self):
+        # get target vt from stdin, if vt number given by stdin is different than active vt number, we will have to switch then switch back
         self.tty_name = os.ttyname(sys.stdin.fileno())
         # get digit from string
         self.tty_num = int(list(filter(str.isdigit, self.tty_name))[0])
         try:
+            # ugly hack to get current vt number, I didn't find any dbus properties to get it properly
             stream = os.popen('fgconsole')
             self.previous_tty_num = int(stream.readline())
-            logger.info('current vt number is: %d', self.previous_tty_num)
+            logger.info('current virtual terminal number is: %d', self.previous_tty_num)
         except:
-            logger.exception('cannot read current vt number from fgconsole command, setting 3 by default')
-            self.previous_tty_num = 3            
+            self.previous_tty_num = self.tty_num
+            logger.exception('cannot read current virtual terminal number from fgconsole command, setting to %d', self.previous_tty_num)
         self.previous_tty_name = '/dev/tty' + str(self.previous_tty_num)
         try:
             bus = dbus.SystemBus()
@@ -173,28 +174,32 @@ def __init__(self):
             logger.exception('cannot open dbus interface for org.freedesktop.login1.Seat')
 
     def __enter__(self):
-        logger.info('running on tty: %s', self.tty_name)
         # really useful ? Can block if permission is not set correctly on /dev/ttyx
         with open(self.tty_name, 'r') as tty:
             # KDSETMODE = 0x4B3A, GRAPHICS = 0x01
             ioctl(tty, 0x4B3A, 0x01)
-        try:
-            self.seat_methods.SwitchTo(self.tty_num)
-        except:
-            logger.exception('cannot switch to: %s', self.tty_name)
+        # change vt if not already done by caller
+        if self.tty_name != self.previous_tty_num:
+            logger.info('switching to tty: %s', self.tty_name)
+            try:
+                self.seat_methods.SwitchTo(self.tty_num)
+            except:
+                logger.exception('cannot switch to: %s', self.tty_name)
 
     def __exit__(self, type, value, traceback):
-        logger.info('switching back to tty: %s', self.previous_tty_name)
         # really useful ? Can block if permission is not set correctly on /dev/ttyx
         with open(self.tty_name, 'w') as tty:
             # KDSETMODE = 0x4B3A, TEXT = 0x00
             ioctl(tty, 0x4B3A, 0x00)
             # send Ctrl-L to tty to clear
             tty.write('\033c')
-        try:
-            self.seat_methods.SwitchTo(self.previous_tty_num)
-        except:
-            logger.exception('cannot switch back to: %s', self.previous_tty_name)
+        # change vt if not managed by caller
+        if self.tty_name != self.previous_tty_num:
+            logger.info('switching back to tty: %s', self.previous_tty_name)
+            try:
+                self.seat_methods.SwitchTo(self.previous_tty_num)
+            except:
+                logger.exception('cannot switch back to: %s', self.previous_tty_name)
 
 
 class AbortHandler(threading.Thread):