Update gps_client.py return -1 if no socket

gps_client.py

@@ -11,55 +11,54 @@ run this way: python3 example1.py.txt
 import gps               # the gpsd interface module
 import time
 
-session = gps.gps(mode=gps.WATCH_ENABLE)
-
-start = time.perf_counter()
-
-mode = -1
-
-lat = 0
-
-lon = 0
-
+mode = -1    
+lat = 0    
+lon = 0    
 alt = 0
 
 try:
-    while (session.read() == 0) and ((time.perf_counter() - start) < 2) and (mode < 2):
-#        print(gps.MODE_SET)
- #       print(session.valid)
-        if (session.valid):
-            # not useful, probably not a TPV message
-#            continue
-
-#        print('Mode: %s(%d) Time: ' %
-#              (("Invalid", "NO_FIX", "2D", "3D")[session.fix.mode],
-#               session.fix.mode), end="")
-        # print time, if we have it
-            print("%d " % session.fix.mode, end="")
-            if (session.fix.mode > mode):
-                mode = session.fix.mode
-    #        if gps.TIME_SET & session.valid:
-    #            print(session.fix.time, end="")
-    #        else:
-    #            print('n/a', end="")
-        
-            if gps.isfinite(session.fix.latitude): 
-                lat = session.fix.latitude
-            if gps.isfinite(session.fix.longitude):         
-                lon = session.fix.longitude 
-            if gps.isfinite(session.fix.altitude):        
-                alt = session.fix.altitude     
-            print("%.6f %.6f %.6f" %
-                      (session.fix.latitude, session.fix.longitude, session.fix.altitude))
-           
-#            else:
-#                print(" 0 0 0")
-
-except KeyboardInterrupt:
-    # got a ^C.  Say bye, bye
-    print('')
-
-# Got ^C, or fell out of the loop.  Cleanup, and leave.
-session.close()
+    
+    session = gps.gps(mode=gps.WATCH_ENABLE)
+    
+    start = time.perf_counter()
+    
+    try:
+        while (session.read() == 0) and ((time.perf_counter() - start) < 2) and (mode < 2):
+    #        print(gps.MODE_SET)
+     #       print(session.valid)
+            if (session.valid):
+                # not useful, probably not a TPV message
+    #            continue
+    
+    #        print('Mode: %s(%d) Time: ' %
+    #              (("Invalid", "NO_FIX", "2D", "3D")[session.fix.mode],
+    #               session.fix.mode), end="")
+            # print time, if we have it
+                print("%d " % session.fix.mode, end="")
+                if (session.fix.mode > mode):
+                    mode = session.fix.mode
+        #        if gps.TIME_SET & session.valid:
+        #            print(session.fix.time, end="")
+        #        else:
+        #            print('n/a', end="")
+            
+                if gps.isfinite(session.fix.latitude): 
+                    lat = session.fix.latitude
+                if gps.isfinite(session.fix.longitude):         
+                    lon = session.fix.longitude 
+                if gps.isfinite(session.fix.altitude):        
+                    alt = session.fix.altitude     
+                print("%.6f %.6f %.6f" %
+                          (session.fix.latitude, session.fix.longitude, session.fix.altitude))
+               
+    #            else:
+    #                print(" 0 0 0")
+    
+    except KeyboardInterrupt:
+        # got a ^C.  Say bye, bye
+        print('')
+    
+    # Got ^C, or fell out of the loop.  Cleanup, and leave.
+    session.close()
 print("%d %.6f %.6f %.1f" % (mode, lat, lon, alt))
 exit(0)