1 files changed, 53 insertions, 9 deletions

diff --git a/Documentation/connector/ucon.c b/Documentation/connector/ucon.c
index d738cde2a8d..a8e4d5885ad 100644
--- a/Documentation/connector/ucon.c
+++ b/Documentation/connector/ucon.c
@@ -30,18 +30,24 @@
 
 #include <arpa/inet.h>
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
 #include <time.h>
+#include <getopt.h>
 
 #include <linux/connector.h>
 
 #define DEBUG
 #define NETLINK_CONNECTOR 	11
 
+/* Hopefully your userspace connector.h matches this kernel */
+#define CN_TEST_IDX		CN_NETLINK_USERS + 3
+#define CN_TEST_VAL		0x456
+
 #ifdef DEBUG
 #define ulog(f, a...) fprintf(stdout, f, ##a)
 #else
@@ -83,6 +89,25 @@ static int netlink_send(int s, struct cn_msg *msg)
 	return err;
 }
 
+static void usage(void)
+{
+	printf(
+		"Usage: ucon [options] [output file]\n"
+		"\n"
+		"\t-h\tthis help screen\n"
+		"\t-s\tsend buffers to the test module\n"
+		"\n"
+		"The default behavior of ucon is to subscribe to the test module\n"
+		"and wait for state messages.  Any ones received are dumped to the\n"
+		"specified output file (or stdout).  The test module is assumed to\n"
+		"have an id of {%u.%u}\n"
+		"\n"
+		"If you get no output, then verify the cn_test module id matches\n"
+		"the expected id above.\n"
+		, CN_TEST_IDX, CN_TEST_VAL
+	);
+}
+
 int main(int argc, char *argv[])
 {
 	int s;
@@ -94,17 +119,34 @@ int main(int argc, char *argv[])
 	FILE *out;
 	time_t tm;
 	struct pollfd pfd;
+	bool send_msgs = false;
 
-	if (argc < 2)
-		out = stdout;
-	else {
-		out = fopen(argv[1], "a+");
+	while ((s = getopt(argc, argv, "hs")) != -1) {
+		switch (s) {
+		case 's':
+			send_msgs = true;
+			break;
+
+		case 'h':
+			usage();
+			return 0;
+
+		default:
+			/* getopt() outputs an error for us */
+			usage();
+			return 1;
+		}
+	}
+
+	if (argc != optind) {
+		out = fopen(argv[optind], "a+");
 		if (!out) {
 			ulog("Unable to open %s for writing: %s\n",
 				argv[1], strerror(errno));
 			out = stdout;
 		}
-	}
+	} else
+		out = stdout;
 
 	memset(buf, 0, sizeof(buf));
 
@@ -115,9 +157,11 @@ int main(int argc, char *argv[])
 	}
 
 	l_local.nl_family = AF_NETLINK;
-	l_local.nl_groups = 0x123; /* bitmask of requested groups */
+	l_local.nl_groups = -1; /* bitmask of requested groups */
 	l_local.nl_pid = 0;
 
+	ulog("subscribing to %u.%u\n", CN_TEST_IDX, CN_TEST_VAL);
+
 	if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) {
 		perror("bind");
 		close(s);
@@ -130,15 +174,15 @@ int main(int argc, char *argv[])
 		setsockopt(s, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &on, sizeof(on));
 	}
 #endif
-	if (0) {
+	if (send_msgs) {
 		int i, j;
 
 		memset(buf, 0, sizeof(buf));
 
 		data = (struct cn_msg *)buf;
 
-		data->id.idx = 0x123;
-		data->id.val = 0x456;
+		data->id.idx = CN_TEST_IDX;
+		data->id.val = CN_TEST_VAL;
 		data->seq = seq++;
 		data->ack = 0;
 		data->len = 0;