src/trace_event.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <fcntl.h>
#include <linux/kernel.h>

#include "event-parse.h"
#include "trace_event.h"

#define PATH_MAX		4096

char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";

/*
 * global trace_event object used by trace_event__tp_format
 *
 * TODO There's no cleanup call for this. Add some sort of
 * __exit function support and call trace_event__cleanup
 * there.
 */
static struct trace_event tevent;

int trace_event__init(struct trace_event *t)
{
	struct pevent *pevent = pevent_alloc();

	if (pevent) {
		/*t->plugin_list = traceevent_load_plugins(pevent);*/
		t->pevent  = pevent;
	}

	return pevent ? 0 : -1;
}

void trace_event__cleanup(struct trace_event *t)
{
	/*traceevent_unload_plugins(t->plugin_list, t->pevent);*/
	pevent_free(t->pevent);
}

static struct event_format*
tp_format(const char *sys, const char *name)
{
	struct pevent *pevent = tevent.pevent;
	struct event_format *event = NULL;
	char path[PATH_MAX];
	size_t size;
	char *data;

	scnprintf(path, PATH_MAX, "%s/%s/%s/format",
		  tracing_events_path, sys, name);

	if (filename__read_str(path, &data, &size))
		return NULL;

	pevent_parse_format(pevent, &event, data, size, sys);

	free(data);
	return event;
}

struct event_format*
trace_event__tp_format(const char *sys, const char *name)
{
	static bool initialized;

	if (!initialized) {
		int be = traceevent_host_bigendian();
		struct pevent *pevent;

		if (trace_event__init(&tevent))
			return NULL;

		pevent = tevent.pevent;
		pevent_set_flag(pevent, PEVENT_NSEC_OUTPUT);
		pevent_set_file_bigendian(pevent, be);
		pevent_set_host_bigendian(pevent, be);
		initialized = true;
	}

	return tp_format(sys, name);
}

void event_format__print(struct event_format *event,
			 int cpu, void *data, int size)
{
	struct pevent_record record;
	struct trace_seq s;

	memset(&record, 0, sizeof(record));
	record.cpu = cpu;
	record.size = size;
	record.data = data;

	fprintf(data_file, "%s:%s: ", event->system, event->name);
	trace_seq_init(&s);
	pevent_event_info(&s, event, &record);
	trace_seq_do_printf(&s);
	trace_seq_destroy(&s);
	fprintf(data_file, "\n");
}