/*  listen-select.c     Patrick Brison, E-mail: pbn@rtbf.be    I tweaked the receive-select example to use "listen-only"     mode which is better to spy on the bus. The modification is trivial     (just an ioctl), but I attached the source in case you're interested.*/#include <stdio.h>#include <stdlib.h>#include <sys/ioctl.h>#include <sys/types.h>#include <sys/stat.h>#include <sys/time.h>#include <fcntl.h>#include <unistd.h>#include <can4linux.h>#define STDDEV "can0"int main(int argc,char **argv){int can_fd;			/* CAN file descriptor */int got;canmsg_t rx;char device[40];	/* string to hold the CAN device Name */fd_set rfds;		/* file descriptors for select() */    printf("usage: %s <dev>]\n", argv[0]);    printf("   e.g.:\n");    printf("   %s /dev/can0\n", argv[0]);    printf("   wait for CAN messages using select()\n");    if(argc == 2) {	sprintf(device, "/dev/%s", argv[1]);    }    else {	sprintf(device, "/dev/%s", STDDEV);    }    printf("using CAN device %s\n", device);        if(( can_fd = open(device, O_RDWR )) < 0 ) {	fprintf(stderr,"Error opening CAN device %s\n", device);        exit(1);    }    printf("got can_fd  %d\n", can_fd);    printf("Setting listen only mode...");    Config_par_t  cfg;    volatile Command_par_t cmd;    cmd.cmd = CMD_STOP;    ioctl(can_fd, CAN_IOCTL_COMMAND, &cmd);    cfg.target = CONF_LISTEN_ONLY_MODE;     cfg.val1    = 1;    ioctl(can_fd, CAN_IOCTL_CONFIG, &cfg);    cmd.cmd = CMD_START;    ioctl(can_fd, CAN_IOCTL_COMMAND, &cmd);    printf(" done...\n");    while(1) {        FD_ZERO(&rfds);        FD_SET(can_fd, &rfds);		/* watch on fd for CAN */        FD_SET(0, &rfds);		/* watch on fd for stdin */	if( select(FD_SETSIZE, &rfds, NULL, NULL,     NULL  ) > 0 )	if( FD_ISSET(can_fd, &rfds) ) {	    got = read(can_fd, &rx, 1);	    if( got > 0) {	    int i;		printf("Received at "		"%12lu.%06lu ",			rx.timestamp.tv_sec,			rx.timestamp.tv_usec);		 printf(": %c%c 0x%08lx : %d bytes:",				       rx.flags & MSG_EXT ? 'x' : 's',				       rx.flags & MSG_RTR ? 'R' : 'D',				       rx.id,   rx.length);		    if(rx.length > 0) {			printf("\t");			if(rx.flags & MSG_RTR) {			    /* dont show date for RTR frames */			    printf("(RTR no data)");			} else {			    for(i = 0; i < rx.length; i++) {				printf("%02x ", rx.data[i]);			    }			}		    }		    printf("\n");		fflush(stdout);	    } else {		printf("Received with ret=%d\n", got);		fflush(stdout);	    }	}	if( FD_ISSET(0, &rfds) ) {	int c, i;	    /* it was the stdio terminal fd */	    i = read(0 , &c, 1);	    printf(" key = %x\n", c);	} /* stdio fd */    }    close(can_fd);    return 0;}