connector: get test code working by default

The connector test code currently does not work out of the box.  This is
because it uses a connector id that is above the registered limit.  So
rather than force people to stumble through undocumented code wondering
why it isn't working, have the test code use one of the "private" ids by
default.  While I'm in here, clean up the code (kernel and user app) so
that it's a bit more user friendly and verbose in significant things that
it does.  Terse test code wastes people time as they simply enumerate it
with all the same kind of debug messages to get a better feel of what code
is running at any time.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 53 insertions, 9 deletions

diff --git a/Documentation/connector/ucon.c b/Documentation/connector/ucon.c
index d738cde2a8d5..a8e4d5885ad4 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;