// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2021 Sartura
 * Based on minimal.c by Facebook */

#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <sys/resource.h>
#include <bpf/libbpf.h>
#include "fentry.skel.h"

static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
{
	return vfprintf(stderr, format, args);
}

static void bump_memlock_rlimit(void)
{
	struct rlimit rlim_new = {
		.rlim_cur	= RLIM_INFINITY,
		.rlim_max	= RLIM_INFINITY,
	};

	if (setrlimit(RLIMIT_MEMLOCK, &rlim_new)) {
		fprintf(stderr, "Failed to increase RLIMIT_MEMLOCK limit!\n");
		exit(1);
	}
}

static volatile sig_atomic_t stop;

void sig_int(int signo)
{
	stop = 1;
}

int main(int argc, char **argv)
{
	struct fentry_bpf *skel;
	int err;

	/* Set up libbpf errors and debug info callback */
	libbpf_set_print(libbpf_print_fn);

	/* Bump RLIMIT_MEMLOCK to allow BPF sub-system to do anything */
	bump_memlock_rlimit();

	/* Open load and verify BPF application */
	skel = fentry_bpf__open_and_load();
	if (!skel) {
		fprintf(stderr, "Failed to open BPF skeleton\n");
		return 1;
	}

	/* Attach tracepoint handler */
	err = fentry_bpf__attach(skel);
	if (err) {
		fprintf(stderr, "Failed to attach BPF skeleton\n");
		goto cleanup;
	}

	if (signal(SIGINT, sig_int) == SIG_ERR) {
		fprintf(stderr, "can't set signal handler: %s\n", strerror(errno));
		goto cleanup;
	}

	printf("Successfully started! Please run `sudo cat /sys/kernel/debug/tracing/trace_pipe` "
	       "to see output of the BPF programs.\n");

	while (!stop) {
		fprintf(stderr, ".");
		sleep(1);
	}

cleanup:
	fentry_bpf__destroy(skel);
	return -err;
}