host: Allow matching of device to USB path, not just address

USB addresses change every time the device re-enumerates, while the path
reflects the physical topology of USB connections and stays persistent
unless the usb cabling is changed.  Let's allow the user to specify the
path instead of the address to uniquely identify a given slot.

host/simtrace2-remsim.c

@@ -522,6 +522,7 @@ static const struct option opts[] = {
 	{ "usb-interface", 1, 0, 'I' },
 	{ "usb-altsetting", 1, 0, 'S' },
 	{ "usb-address", 1, 0, 'A' },
+	{ "usb-path", 1, 0, 'H' },
 	{ NULL, 0, 0, 0 }
 };
 
@@ -601,6 +602,7 @@ int main(int argc, char **argv)
 	int if_num = 0, vendor_id = -1, product_id = -1;
 	int config_id = -1, altsetting = 0, addr = -1;
 	char *remote_udp_host = NULL;
+	char *path = NULL;
 	struct osim_reader_hdl *reader;
 	struct osim_card_hdl *card;
 
@@ -609,7 +611,7 @@ int main(int argc, char **argv)
 	while (1) {
 		int option_index = 0;
 
-		c = getopt_long(argc, argv, "r:p:hi:V:P:C:I:S:A:ak", opts, &option_index);
+		c = getopt_long(argc, argv, "r:p:hi:V:P:C:I:S:A:H:ak", opts, &option_index);
 		if (c == -1)
 			break;
 		switch (c) {
@@ -650,6 +652,9 @@ int main(int argc, char **argv)
 		case 'A':
 			addr = atoi(optarg);
 			break;
+		case 'H':
+			path = optarg;
+			break;
 		}
 	}
 
@@ -714,6 +719,8 @@ int main(int argc, char **argv)
 			ifm->interface = if_num;
 			ifm->altsetting = altsetting;
 			ifm->addr = addr;
+			if (path)
+				osmo_strlcpy(ifm->path, path, sizeof(ifm->path));
 			transp->usb_devh = usb_open_claim_interface(NULL, ifm);
 			if (!transp->usb_devh) {
 				fprintf(stderr, "can't open USB device\n");