cansend: send multiple frames in one invocation

It is sometimes convenient to be able to send multiple frames with a
single cansend invocation, otherwise the time between frames can get
very large.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

README.md

@@ -11,7 +11,7 @@ subsystem (aka SocketCAN):
 
 * candump : display, filter and log CAN data to files
 * canplayer : replay CAN logfiles
-* cansend : send a single frame
+* cansend : send single frames
 * cangen : generate (random) CAN traffic
 * cansniffer : display CAN data content differences (just 11bit CAN IDs)
 

cansend.c

@@ -60,14 +60,15 @@ int main(int argc, char **argv)
 	int s; /* can raw socket */ 
 	int required_mtu;
 	int mtu;
-	int enable_canfd = 1;
+	int enable_canfd = 0;
+	int framecnt;
 	struct sockaddr_can addr;
 	struct canfd_frame frame;
 	struct ifreq ifr;
 
 	/* check command line options */
-	if (argc != 3) {
-		fprintf(stderr, "Usage: %s <device> <can_frame>.\n", argv[0]);
+	if (argc < 3) {
+		fprintf(stderr, "Usage: %s <device> <can_frame>...\n", argv[0]);
 		return 1;
 	}
 
@@ -100,8 +101,9 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	for (framecnt = 2; framecnt < argc; framecnt++) {
 		/* parse CAN frame */
-	required_mtu = parse_canframe(argv[2], &frame);
+		required_mtu = parse_canframe(argv[framecnt], &frame);
 		if (!required_mtu){
 			fprintf(stderr, "\nWrong CAN-frame format! Try:\n\n");
 			fprintf(stderr, "    <can_id>#{R|data}          for CAN 2.0 frames\n");
@@ -119,6 +121,7 @@ int main(int argc, char **argv)
 
 		if (required_mtu > CAN_MTU) {
 
+			if (enable_canfd == 0) {
 				/* check if the frame fits into the CAN netdevice */
 				if (ioctl(s, SIOCGIFMTU, &ifr) < 0) {
 					perror("SIOCGIFMTU");
@@ -132,11 +135,13 @@ int main(int argc, char **argv)
 				}
 
 				/* interface is ok - try to switch the socket into CAN FD mode */
+				enable_canfd = 1;
 				if (setsockopt(s, SOL_CAN_RAW, CAN_RAW_FD_FRAMES,
 					&enable_canfd, sizeof(enable_canfd))){
 					printf("error when enabling CAN FD support\n");
 					return 1;
 				}
+			}
 
 			/* ensure discrete CAN FD length values 0..8, 12, 16, 20, 24, 32, 64 */
 			frame.len = can_dlc2len(can_len2dlc(frame.len));
@@ -147,6 +152,7 @@ int main(int argc, char **argv)
 			perror("write");
 			return 1;
 		}
+	}
 
 	close(s);