// https://syzkaller.appspot.com/bug?id=136c70e33470358b114e91d488a9e8156ab03793
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <string.h>
#include <errno.h>

#define NUM_THREADS 16
#define MAX_FILES 256

char pci_files[MAX_FILES][256];
int num_pci_files = 0;

char acpi_files[MAX_FILES][256];
int num_acpi_files = 0;

void *pci_worker(void *arg)
{
    int thread_id = (int)(long)arg;
    for (int loop = 0; loop < 100; loop++) {
        for (int i = 0; i < num_pci_files; i++) {
            int fd = open(pci_files[i], O_WRONLY);
            if (fd < 0) {
                printf("[-] Thread %d failed to open %s: %s\n", thread_id, pci_files[i], strerror(errno));
                exit(1);
            }
            ssize_t res = write(fd, "auto\n", 5);
            if (res < 0) {
                printf("[-] Thread %d failed to write 'auto' to %s: %s\n", thread_id, pci_files[i], strerror(errno));
                exit(1);
            }
            close(fd);
            
            fd = open(pci_files[i], O_WRONLY);
            if (fd < 0) {
                printf("[-] Thread %d failed to open %s: %s\n", thread_id, pci_files[i], strerror(errno));
                exit(1);
            }
            res = write(fd, "on\n", 3);
            if (res < 0) {
                printf("[-] Thread %d failed to write 'on' to %s: %s\n", thread_id, pci_files[i], strerror(errno));
                exit(1);
            }
            close(fd);
        }
    }
    printf("[+] Thread %d finished PCI loop successfully.\n", thread_id);
    return NULL;
}

void *acpi_worker(void *arg)
{
    int thread_id = (int)(long)arg;
    char buf[32];
    for (int loop = 0; loop < 100; loop++) {
        for (int i = 0; i < num_acpi_files; i++) {
            int fd = open(acpi_files[i], O_RDONLY);
            if (fd < 0) {
                printf("[-] Thread %d failed to open %s: %s\n", thread_id, acpi_files[i], strerror(errno));
                exit(1);
            }
            ssize_t res = read(fd, buf, sizeof(buf));
            if (res < 0) {
                printf("[-] Thread %d failed to read %s: %s\n", thread_id, acpi_files[i], strerror(errno));
                exit(1);
            }
            close(fd);
        }
    }
    printf("[+] Thread %d finished ACPI loop successfully.\n", thread_id);
    return NULL;
}

int main(void)
{
    setvbuf(stdout, NULL, _IONBF, 0);
    
    DIR *dir = opendir("/sys/bus/pci/devices");
    if (!dir) {
        printf("[-] Failed to opendir /sys/bus/pci/devices: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] opendir /sys/bus/pci/devices successful.\n");

    struct dirent *ent;
    while ((ent = readdir(dir)) != NULL) {
        if (ent->d_name[0] == '.') 
            continue;
        
        char path[256];
        snprintf(path, sizeof(path), "/sys/bus/pci/devices/%s/power/control", ent->d_name);
        
        if (access(path, W_OK) == 0) {
            strncpy(pci_files[num_pci_files++], path, sizeof(pci_files[0]) - 1);
            if (num_pci_files >= MAX_FILES) {
                break;
            }
        }
    }
    closedir(dir);
    printf("[+] Found %d PCI power control files.\n", num_pci_files);

    dir = opendir("/sys/bus/acpi/devices");
    if (!dir) {
        printf("[-] Failed to opendir /sys/bus/acpi/devices: %s\n", strerror(errno));
        exit(1);
    }
    printf("[+] opendir /sys/bus/acpi/devices successful.\n");

    while ((ent = readdir(dir)) != NULL) {
        if (ent->d_name[0] == '.') 
            continue;
        
        char path[256];
        snprintf(path, sizeof(path), "/sys/bus/acpi/devices/%s/status", ent->d_name);
        
        if (access(path, R_OK) == 0) {
            strncpy(acpi_files[num_acpi_files++], path, sizeof(acpi_files[0]) - 1);
            if (num_acpi_files >= MAX_FILES) {
                break;
            }
        }
    }
    closedir(dir);
    printf("[+] Found %d ACPI status files.\n", num_acpi_files);

    if (num_pci_files == 0 && num_acpi_files == 0) {
        printf("[-] No suitable PCI or ACPI files found.\n");
        exit(1);
    }

    pthread_t threads[NUM_THREADS];
    for (int i = 0; i < NUM_THREADS; i++) {
        void *(*worker)(void *) = NULL;
        if (i % 2 == 0 && num_acpi_files > 0) {
            worker = acpi_worker;
        } else if (num_pci_files > 0) {
            worker = pci_worker;
        } else if (num_acpi_files > 0) {
            worker = acpi_worker;
        }
        
        if (worker) {
            int res = pthread_create(&threads[i], NULL, worker, (void *)(long)i);
            if (res != 0) {
                printf("[-] Failed to create thread %d: %s\n", i, strerror(res));
                exit(1);
            }
        }
    }
    printf("[+] Created %d threads.\n", NUM_THREADS);

    for (int i = 0; i < NUM_THREADS; i++) {
        int res = pthread_join(threads[i], NULL);
        if (res != 0) {
            printf("[-] Failed to join thread %d: %s\n", i, strerror(res));
            exit(1);
        }
    }

    printf("[+] All threads finished.\n");
    sleep(2);
    printf("[+] Exit successful.\n");
    return 0;
}