GPS presence testing

testGpsPort.c

const char* GPS_PORT_NAME = "/dev/ttyS2";

int testResult = 0;
int fd;

SF_PACKET_ERROR_CODE_t err = SF_FAILED_EXEC;

fd = open(GPS_PORT_NAME, O_RDONLY | O_NOCTTY | O_SYNC);
if (fd > 0)
{
    tcflush(fd,TCIOFLUSH); // Flush the previously buffered data
    if( set_interface_attribs(fd, B9600, 0) == 0 )
    {
        err = SF_SUCCESS;
        set_blocking(fd, 0);
    
        char buf [256];
        memset(buf,256,0);
    
        sleep(1); // Wait for at least 1 PPS
        int n = read (fd, buf, sizeof buf);
    
        if( n > 0 )
        {
            // Find a $GP string coming from the gps
            char * pch = strstr(buf ,"$GP");
            if( pch != NULL ){
                testResult = 1;
            }
        }
    
    }
    else
    {
        err = SF_ERROR_SETTING_GPSCOM_ATTR;
    }

    close(fd);
}
else
{
    err = SF_ERROR_OPENING_GPSCOM;
}