Use blocking socket in `rs-canopen-dump` to avoid "Resource temporarily unavailable" error (or handle it)

[follower]

When using rs-canopen-dump I frequently encountered these errors and the tool would exit:

read: can raw socket read: Resource temporarily unavailable

This is because a non-blocking socket is opened when using can_socket_open():

libcanopen/bin/rs-canopen-dump.c

Lines 49 to 50 in 6e4758b

	/* Create the socket */
	if ((sock = can_socket_open(argv[1])) < 0)

An alternate approach is to use can_socket_open_timeout() with a timeout of 0 instead:

diff --git a/bin/rs-canopen-dump.c b/bin/rs-canopen-dump.c
index 7b68661..7439799 100644
--- a/bin/rs-canopen-dump.c
+++ b/bin/rs-canopen-dump.c
@@ -47,7 +47,7 @@ main(int argc, char **argv)
     }
 
     /* Create the socket */
-    if ((sock = can_socket_open(argv[1])) < 0)
+    if ((sock = can_socket_open_timeout(argv[1], 0)) < 0)
     {
         fprintf(stderr, "Error: Failed to create socket.\n");
         return -1;

This is consistent with how rs-canopen-monitor operates:

libcanopen/bin/rs-canopen-monitor.c

Lines 174 to 190 in 6e4758b

	/* Create the socket */
	if ((sock = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0)
	{
	fprintf(stderr, "Error: Failed to create socket.\n");
	return -1;
	}
	/* Locate the interface you wish to use */
	strcpy(ifr.ifr_name, argv[1]);
	ioctl(sock, SIOCGIFINDEX, &ifr); /* ifr.ifr_ifindex gets filled
	* with that device's index */
	// XXX add check
	/* Select that CAN interface, and bind the socket to it. */
	addr.can_family = AF_CAN;
	addr.can_ifindex = ifr.ifr_ifindex;
	bind(sock, (struct sockaddr*)&addr, sizeof(addr)); // XXX Add check

Thanks for your work on libcanopen.