all repos — slstatus @ 80fc20d1d69b14f36ad9bb64d8af38481cbf1ff5

my build of slstatus (tools.suckless.org/slstatus/)

components/kernel_release.c

/* See LICENSE file for copyright and license details. */
#include <errno.h>
#include <sys/utsname.h>
#include <stdio.h>
#include <string.h>

#include "../util.h"

const char *
kernel_release(void)
{
	struct utsname udata;

	if (uname(&udata) < 0) {
		warn("uname:");
		return NULL;
	}

	return bprintf("%s", udata.release);
}