Exit from gps_sock_mainloop() if connection to gpsd is lost

The current mainloop function does not evaluate the return value of
gps_read(). If the socket is closed (because gpsd is stopped) the
mainloop will consume 99% CPU constantly doing a recv() from the socket
which returns zero. gps_read already returns -1 if this condition is
encountered.

This patch checks the return value of gps_read() and if it is -1 the
mainloop is exited. This is also what happens in gps_shm_mainloop().

1 files changed, 6 insertions, 2 deletions

diff --git a/libgps_sock.c b/libgps_sock.c
index 2a846a13..e84a1eb2 100644
--- a/libgps_sock.c
+++ b/libgps_sock.c
@@ -572,8 +572,12 @@ int gps_sock_mainloop(struct gps_data_t *gpsdata, int timeout,
 	if (!gps_waiting(gpsdata, timeout)) {
 	    return -1;
 	} else {
-	    (void)gps_read(gpsdata);
-	    (*hook)(gpsdata);
+	    int status = gps_read(gpsdata);
+
+	    if (status == -1)
+		return -1;
+	    if (status > 0)
+		(*hook)(gpsdata);
 	}
     }
     //return 0;