bpf_util.h

/*
 * from https://raw.githubusercontent.com/netoptimizer/prototype-kernel/989411001a1237d6b5d2f764fa205c9352026c8c/kernel/samples/bpf/bpf_util.h
 */
#ifndef __BPF_UTIL__
#define __BPF_UTIL__

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

static inline unsigned int bpf_num_possible_cpus(void)
{
	static const char *fcpu = "/sys/devices/system/cpu/possible";
	unsigned int start, end, possible_cpus = 0;
	char buff[128];
	FILE *fp;
	int n;

	fp = fopen(fcpu, "r");
	if (!fp) {
		printf("Failed to open %s: '%s'!\n", fcpu, strerror(errno));
		exit(1);
	}

	while (fgets(buff, sizeof(buff), fp)) {
		n = sscanf(buff, "%u-%u", &start, &end);
		if (n == 0) {
			printf("Failed to retrieve # possible CPUs!\n");
			exit(1);
		} else if (n == 1) {
			end = start;
		}
		possible_cpus = start == 0 ? end + 1 : 0;
		break;
	}
	fclose(fp);

	return possible_cpus;
}

#endif /* __BPF_UTIL__ */