Fix: do not return error on LTTNG_ERR_SNAPSHOT_NODATA

[lttng-tools.git] / src / bin / lttng / commands / snapshot.c

diff --git a/src/bin/lttng/commands/snapshot.c b/src/bin/lttng/commands/snapshot.c
index 1d7843954ecc60e6ad94ea62b8004338eb372325..298bc6ef36cee6a1bac7cb362464c0dd22f9915c 100644 (file)
--- a/src/bin/lttng/commands/snapshot.c
+++ b/src/bin/lttng/commands/snapshot.c
@@ -78,41 +78,6 @@ static struct cmd_struct actions[] = {
        { NULL, NULL }  /* Array closure */
 };
 
-/*
- * usage
- */
-static void usage(FILE *ofp)
-{
-       fprintf(ofp, "usage: lttng snapshot [OPTION] ACTION\n");
-       fprintf(ofp, "\n");
-       fprintf(ofp, "Actions:\n");
-       fprintf(ofp, "   add-output [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>\n");
-       fprintf(ofp, "      Setup and add an snapshot output for a session.\n");
-       fprintf(ofp, "\n");
-       fprintf(ofp, "   del-output ID | NAME [-s <NAME>]\n");
-       fprintf(ofp, "      Delete an output for a session using the ID.\n");
-       fprintf(ofp, "\n");
-       fprintf(ofp, "   list-output [-s <NAME>]\n");
-       fprintf(ofp, "      List the output of a session.\n");
-       fprintf(ofp, "\n");
-       fprintf(ofp, "   record [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]\n");
-       fprintf(ofp, "      Snapshot a session's buffer(s) for all domains. If an URL is\n");
-       fprintf(ofp, "      specified, it is used instead of a previously added output.\n");
-       fprintf(ofp, "      Specifying only a name or/a size will override the current output value.\n");
-       fprintf(ofp, "      For instance, you can record a snapshot with a custom maximum size\n");
-       fprintf(ofp, "      or with a different name.\n");
-       fprintf(ofp, "\n");
-       fprintf(ofp, "Options:\n");
-       fprintf(ofp, "  -h, --help           Show this help\n");
-       fprintf(ofp, "      --list-options   Simple listing of options\n");
-       fprintf(ofp, "  -s, --session NAME   Apply to session name\n");
-       fprintf(ofp, "  -n, --name NAME      Name of the output or snapshot\n");
-       fprintf(ofp, "  -m, --max-size SIZE  Maximum bytes size of the snapshot {+k,+M,+G}\n");
-       fprintf(ofp, "  -C, --ctrl-url URL   Set control path URL. (Must use -D also)\n");
-       fprintf(ofp, "  -D, --data-url URL   Set data path URL. (Must use -C also)\n");
-       fprintf(ofp, "\n");
-}
-
 /*
  * Count and return the number of arguments in argv.
  */
@@ -455,7 +420,6 @@ static int cmd_add_output(int argc, const char **argv)
        int ret;
 
        if (argc < 2 && (!opt_data_url || !opt_ctrl_url)) {
-               usage(stderr);
                ret = CMD_ERROR;
                goto end;
        }
@@ -477,7 +441,6 @@ static int cmd_del_output(int argc, const char **argv)
        long id;
 
        if (argc < 2) {
-               usage(stderr);
                ret = CMD_ERROR;
                goto end;
        }
@@ -615,7 +578,6 @@ static int handle_command(const char **argv)
 
        if (argv == NULL || (!opt_ctrl_url && opt_data_url) ||
                        (opt_ctrl_url && !opt_data_url)) {
-               usage(stderr);
                command_ret = CMD_ERROR;
                goto end;
        }
@@ -739,7 +701,6 @@ int cmd_snapshot(int argc, const char **argv)
                        break;
                }
                default:
-                       usage(stderr);
                        ret = CMD_UNDEFINED;
                        goto end;
                }
@@ -764,6 +725,15 @@ int cmd_snapshot(int argc, const char **argv)
                        break;
                case LTTNG_ERR_SNAPSHOT_NODATA:
                        WARN("%s", lttng_strerror(command_ret));
+
+                       /*  A warning is fine since the user has no control on
+                        *  whether or not applications (or the kernel) have
+                        *  produced any event between the start of the tracing
+                        *  session and the recording of the snapshot. MI wise
+                        *  the command is not a success since nothing was
+                        *  recorded.
+                        */
+                       command_ret = 0;
                        break;
                default:
                        ERR("%s", lttng_strerror(command_ret));