Print ignored events/syscalls with -i (#359)

When run with -i, print out all ignored syscalls/event names and exit.

userspace/falco/falco.cpp

@@ -22,6 +22,8 @@ along with falco.  If not, see <http://www.gnu.org/licenses/>.
 #include <fstream>
 #include <set>
 #include <list>
+#include <vector>
+#include <algorithm>
 #include <string>
 #include <signal.h>
 #include <fcntl.h>
@@ -32,6 +34,7 @@ along with falco.  If not, see <http://www.gnu.org/licenses/>.
 #include <sinsp.h>
 
 #include "logger.h"
+#include "utils.h"
 
 #include "configuration.h"
 #include "falco_engine.h"
@@ -241,6 +244,47 @@ uint64_t do_inspect(falco_engine *engine,
 	return num_evts;
 }
 
+static void print_all_ignored_events(sinsp *inspector)
+{
+	sinsp_evttables* einfo = inspector->get_event_info_tables();
+	const struct ppm_event_info* etable = einfo->m_event_info;
+	const struct ppm_syscall_desc* stable = einfo->m_syscall_info_table;
+
+	std::set<string> ignored_event_names;
+	for(uint32_t j = 0; j < PPM_EVENT_MAX; j++)
+	{
+		if(!sinsp::falco_consider_evtnum(j))
+		{
+			std::string name = etable[j].name;
+			// Ignore event names NA*
+			if(name.find("NA") != 0)
+			{
+				ignored_event_names.insert(name);
+			}
+		}
+	}
+
+	for(uint32_t j = 0; j < PPM_SC_MAX; j++)
+	{
+		if(!sinsp::falco_consider_syscallid(j))
+		{
+			std::string name = stable[j].name;
+			// Ignore event names NA*
+			if(name.find("NA") != 0)
+			{
+				ignored_event_names.insert(name);
+			}
+		}
+	}
+
+	printf("Ignored Event(s):");
+	for(auto it : ignored_event_names)
+	{
+		printf(" %s", it.c_str());
+	}
+	printf("\n");
+}
+
 //
 // ARGUMENT PARSING AND PROGRAM SETUP
 //
@@ -270,6 +314,7 @@ int falco_init(int argc, char **argv)
 	string output_format = "";
 	bool replace_container_info = false;
 	int duration_to_tot = 0;
+	bool print_ignored_events = false;
 
 	// Used for writing trace files
 	int duration_seconds = 0;
@@ -299,6 +344,7 @@ int falco_init(int argc, char **argv)
 		{"version", no_argument, 0, 0 },
 		{"validate", required_argument, 0, 'V' },
 		{"writefile", required_argument, 0, 'w' },
+		{"ignored-events", no_argument, 0, 'i'},
 
 		{0, 0, 0, 0}
 	};
@@ -315,7 +361,7 @@ int falco_init(int argc, char **argv)
 		// Parse the args
 		//
 		while((op = getopt_long(argc, argv,
-                                        "hc:AdD:e:k:K:Ll:m:M:o:P:p:r:s:T:t:UvV:w:",
+                                        "hc:AdD:e:ik:K:Ll:m:M:o:P:p:r:s:T:t:UvV:w:",
                                         long_options, &long_index)) != -1)
 		{
 			switch(op)
@@ -341,6 +387,9 @@ int falco_init(int argc, char **argv)
 				k8s_api = new string();
 				mesos_api = new string();
 				break;
+			case 'i':
+				print_ignored_events = true;
+				break;
 			case 'k':
 				k8s_api = new string(optarg);
 				break;
@@ -431,12 +480,20 @@ int falco_init(int argc, char **argv)
 			return EXIT_SUCCESS;
 		}
 
-
 		inspector = new sinsp();
+
+		if(print_ignored_events)
+		{
+			print_all_ignored_events(inspector);
+			delete(inspector);
+			return EXIT_SUCCESS;
+		}
+
 		engine = new falco_engine();
 		engine->set_inspector(inspector);
 		engine->set_extra(output_format, replace_container_info);
 
+
 		outputs = new falco_outputs();
 		outputs->set_inspector(inspector);