1 files changed, 53 insertions, 9 deletions

diff --git a/Documentation/connector/ucon.c b/Documentation/connector/ucon.c
index c5092ad0ce4b..4848db8c71ff 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;