perf evswitch: Introduce init() method to set the on/off evsels from the command line

Another step in having all the boilerplate in just one place to then use
in the other tools.

Cc: Adrian Hunter <[e-mail]>
Cc: Florian Weimer <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: William Cohen <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-script.c

···
 						  script.range_num);
 	}
 
-	if (script.evswitch.on_name) {
-		script.evswitch.on = perf_evlist__find_evsel_by_str(session->evlist, script.evswitch.on_name);
-		if (script.evswitch.on == NULL) {
-			fprintf(stderr, "switch-on event not found (%s)\n", script.evswitch.on_name);
-			err = -ENOENT;
-			goto out_delete;
-		}
-		script.evswitch.discarding = true;
-	}
-
-	if (script.evswitch.off_name) {
-		script.evswitch.off = perf_evlist__find_evsel_by_str(session->evlist, script.evswitch.off_name);
-		if (script.evswitch.off == NULL) {
-			fprintf(stderr, "switch-off event not found (%s)\n", script.evswitch.off_name);
-			err = -ENOENT;
-			goto out_delete;
-		}
-	}
+	err = evswitch__init(&script.evswitch, session->evlist, stderr);
+	if (err)
+		goto out_delete;
 
 	err = __cmd_script(&script);
 

tools/perf/util/evswitch.c

···
 // Copyright (C) 2019, Red Hat Inc, Arnaldo Carvalho de Melo <[e-mail]>
 
 #include "evswitch.h"
+#include "evlist.h"
 
 bool evswitch__discard(struct evswitch *evswitch, struct evsel *evsel)
 {
···
 	}
 
 	return false;
+}
+
+int evswitch__init(struct evswitch *evswitch, struct evlist *evlist, FILE *fp)
+{
+	if (evswitch->on_name) {
+		evswitch->on = perf_evlist__find_evsel_by_str(evlist, evswitch->on_name);
+		if (evswitch->on == NULL) {
+			fprintf(fp, "switch-on event not found (%s)\n", evswitch->on_name);
+			return -ENOENT;
+		}
+		evswitch->discarding = true;
+	}
+
+	if (evswitch->off_name) {
+		evswitch->off = perf_evlist__find_evsel_by_str(evlist, evswitch->off_name);
+		if (evswitch->off == NULL) {
+			fprintf(fp, "switch-off event not found (%s)\n", evswitch->off_name);
+			return -ENOENT;
+		}
+	}
+
+	return 0;
 }

tools/perf/util/evswitch.h

···
 #define __PERF_EVSWITCH_H 1
 
 #include <stdbool.h>
+#include <stdio.h>
 
 struct evsel;
+struct evlist;
 
 struct evswitch {
 	struct evsel *on, *off;
···
 	bool	     discarding;
 	bool	     show_on_off_events;
 };
+
+int evswitch__init(struct evswitch *evswitch, struct evlist *evlist, FILE *fp);
 
 bool evswitch__discard(struct evswitch *evswitch, struct evsel *evsel);