Add a function to check for legal exclusions

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

diff --git a/src/bin/lttng/commands/enable_events.c b/src/bin/lttng/commands/enable_events.c
index 2dff63b92fb4969423f6b9e0a2f84c5f44d6a89f..231b7b38ee7750e8fd3d256a07b0c242f5ea59df 100644 (file)
--- a/src/bin/lttng/commands/enable_events.c
+++ b/src/bin/lttng/commands/enable_events.c
@@ -43,6 +43,7 @@ static char *opt_function;
 static char *opt_function_entry_symbol;
 static char *opt_channel_name;
 static char *opt_filter;
+static char *opt_exclude;
 #if 0
 /* Not implemented yet */
 static char *opt_cmd_name;
@@ -61,6 +62,7 @@ enum {
        OPT_LOGLEVEL_ONLY,
        OPT_LIST_OPTIONS,
        OPT_FILTER,
+       OPT_EXCLUDE,
 };
 
 static struct lttng_handle *handle;
@@ -89,6 +91,7 @@ static struct poptOption long_options[] = {
        {"loglevel-only",  0,     POPT_ARG_STRING, 0, OPT_LOGLEVEL_ONLY, 0, 0},
        {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
        {"filter",         'f', POPT_ARG_STRING, &opt_filter, OPT_FILTER, 0, 0},
+       {"exclude",        'x', POPT_ARG_STRING, &opt_exclude, OPT_EXCLUDE, 0, 0},
        {0, 0, 0, 0, 0, 0, 0}
 };
 
@@ -192,6 +195,12 @@ static void usage(FILE *ofp)
        fprintf(ofp, "                           '$ctx.procname == \"demo*\"'\n");
        fprintf(ofp, "                           '$ctx.vpid >= 4433 && $ctx.vpid < 4455'\n");
        fprintf(ofp, "                           '$ctx.vtid == 1234'\n");
+       fprintf(ofp, "  -x, --exclude LIST\n");
+       fprintf(ofp, "                           Add exclusions to UST tracepoints:\n");
+       fprintf(ofp, "                           Events that match any of the items\n");
+       fprintf(ofp, "                           in the comma-separated LIST are not\n");
+       fprintf(ofp, "                           enabled, even if they match a wildcard\n");
+       fprintf(ofp, "                           definition of the event.\n");
        fprintf(ofp, "\n");
 }
 
@@ -327,6 +336,94 @@ const char *print_raw_channel_name(const char *name)
        return name ? : "<default>";
 }
 
+/*
+ * Compare list of exclusions against an event name.
+ * Return a list of legal exclusion names.
+ * Produce an error or a warning about others (depending on the situation)
+ */
+static
+int check_exclusion_subsets(const char *event_name,
+               const char *exclusions,
+               int *exclusion_count_ptr,
+               char ***exclusion_list_ptr)
+{
+       const char *excluder_ptr;
+       const char *event_ptr;
+       const char *next_excluder;
+       int excluder_length;
+       int exclusion_count = 0;
+       char **exclusion_list = NULL;
+       int ret = CMD_SUCCESS;
+
+       if (event_name[strlen(event_name) - 1] != '*') {
+               ERR("Event %s: Excluders can only be used with wildcarded events", event_name);
+               goto error;
+       }
+
+       next_excluder = exclusions;
+       while (*next_excluder != 0) {
+               event_ptr = event_name;
+               excluder_ptr = next_excluder;
+               excluder_length = strcspn(next_excluder, ",");
+
+               /* Scan both the excluder and the event letter by letter */
+               while (1) {
+                       char e, x;
+
+                       e = *event_ptr;
+                       x = *excluder_ptr;
+
+                       if (x == '*') {
+                               /* Event is a subset of the excluder */
+                               ERR("Event %s: %.*s excludes all events from %s",
+                                               event_name,
+                                               excluder_length,
+                                               next_excluder,
+                                               event_name);
+                               goto error;
+                       }
+                       if (e == '*') {
+                               /* Excluder is a proper subset of event */
+                               exclusion_count++;
+                               exclusion_list = realloc(exclusion_list, sizeof(char **) * exclusion_count);
+                               exclusion_list[exclusion_count - 1] = strndup(next_excluder, excluder_length);
+
+                               break;
+                       }
+                       if (x != e) {
+                               /* Excluder and event sets have no common elements */
+                               WARN("Event %s: %.*s does not exclude any events from %s",
+                                               event_name,
+                                               excluder_length,
+                                               next_excluder,
+                                               event_name);
+                               break;
+                       }
+                       excluder_ptr++;
+                       event_ptr++;
+               }
+               /* next excluder */
+               next_excluder += excluder_length;
+               if (*next_excluder == ',') {
+                       next_excluder++;
+               }
+       }
+       goto end;
+error:
+       while (exclusion_count--) {
+               free(exclusion_list[exclusion_count]);
+       }
+       if (exclusion_list != NULL) {
+               free(exclusion_list);
+       }
+       exclusion_list = NULL;
+       exclusion_count = 0;
+       ret = CMD_ERROR;
+end:
+       *exclusion_count_ptr = exclusion_count;
+       *exclusion_list_ptr = exclusion_list;
+       return ret;
+}
 /*
  * Enabling event using the lttng API.
  */
@@ -714,6 +811,8 @@ int cmd_enable_events(int argc, const char **argv)
                        goto end;
                case OPT_FILTER:
                        break;
+               case OPT_EXCLUDE:
+                       break;
                default:
                        usage(stderr);
                        ret = CMD_UNDEFINED;