[gpsd-users] gps_open() return -1

[Guilherme Vale]

Hi

i am trying to test my program with fakegps but when i call open_gps() this function return -1.  I dont understand why. I hope you can help me.

I run the fakegps + cgps in the terminal without problems.

code:

#include <stdio.h>
#include <stdlib.h>
#include <gps.h>
#include <errno.h>

void debugDump(struct gps_data_t* gpsdata){
    fprintf(stderr,"Longitude: %lf\nLatitude: %lf\nAltitude: %lf\nAccuracy: %lf\n\n",
                gpsdata->fix.latitude, gpsdata->fix.longitude, gpsdata->fix.altitude,
                (gpsdata->fix.epx>gpsdata->fix.epy)?gpsdata->fix.epx:gpsdata->fix.epy);
}

int main(){
    int result = 0;
    static struct gps_data_t *gpsdata;

    char* server = "localhost";
    char* port = "2947";
    char *err_str = NULL;

    printf ("%s %s \n", server, port);
    result = gps_open(server, port, gpsdata);
    printf("open returned %d %s\n",result,gps_errstr(errno));

    if (gpsdata == NULL) {
        printf("Could not connect to gpsd!\n");
        return 1;
    }

    //register for updates
    gps_stream(gpsdata, WATCH_ENABLE, NULL);

    printf("Waiting for gps lock.\n");

    //when status is >0, you have data.
    while(gpsdata->status==0){
        //block for up to .5 seconds
        if (gps_waiting(gpsdata, 500)){
            //dunno when this would happen but its an error
            if(gps_read(gpsdata)==-1){
                printf("GPSd Error\n");
                gps_stream(gpsdata, WATCH_DISABLE, NULL);
                gps_close(gpsdata);
                return(-1);
                break;
            }
            else{
                //status>0 means you have data
                if(gpsdata->status>0){
                    //sometimes if your GPS doesnt have a fix, it sends you data anyways
                    //the values for the fix are NaN. this is a clever way to check for NaN.
                    if(gpsdata->fix.longitude!=gpsdata->fix.longitude || gpsdata->fix.altitude!=gpsdata->fix.altitude){
                        printf("Could not get a GPS fix.\n");
                        gps_stream(gpsdata, WATCH_DISABLE, NULL);
                        gps_close(gpsdata);
                        return(-1);
                    }
                    //otherwise you have a legitimate fix!
                    else
                        debugDump(gpsdata);
                        printf("hm\n");
                }
                //if you don't have any data yet, keep waiting for it.
                else
                    printf(".");
            }
        }
        //apparently gps_stream disables itself after a few seconds.. in this case, gps_waiting returns false.
        //we want to re-register for updates and keep looping! we dont have a fix yet.
        else
            gps_stream(gpsdata, WATCH_ENABLE | WATCH_JSON, NULL);
 
        //just a sleep for good measure.
        sleep(1);
    }
    //cleanup
    gps_stream(gpsdata, WATCH_DISABLE, NULL);
    gps_close(gpsdata);
}


best regards

glsv