// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"

char _license[] SEC("license") = "GPL";

struct {
        __uint(type, BPF_MAP_TYPE_RINGBUF);
} ringbuf SEC(".maps");

/* inputs */
int pid = 0;

/* outputs */
long passed = 0;
long discarded = 0;

SEC("fentry/" SYS_PREFIX "sys_getpgid")
int test_ringbuf_write(void *ctx)
{
        int *foo, cur_pid = bpf_get_current_pid_tgid() >> 32;
        void *sample1, *sample2;

        if (cur_pid != pid)
                return 0;

        sample1 = bpf_ringbuf_reserve(&ringbuf, 0x30000, 0);
        if (!sample1)
                return 0;
        /* first one can pass */
        sample2 = bpf_ringbuf_reserve(&ringbuf, 0x30000, 0);
        if (!sample2) {
                bpf_ringbuf_discard(sample1, 0);
                __sync_fetch_and_add(&discarded, 1);
                return 0;
        }
        /* second one must not */
        __sync_fetch_and_add(&passed, 1);
        foo = sample2 + 4084;
        *foo = 256;
        bpf_ringbuf_discard(sample1, 0);
        bpf_ringbuf_discard(sample2, 0);
        return 0;
}