donot touch my files if you are not root!

inotify.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/inotify.h>
#include <signal.h>

#define R_NOERR    0
#define R_ERROR -1

int fd = 0;
char *dir = "/home/wugq";
char *topdir = NULL;

void signal_handler(int signum)
{
    printf("Ctrl + C  Exit\n");
    if (0 != fd)
    {
        if (close(fd) < 0)
        {
            printf("close(fd) Error\n");
        }
    }
    exit(0);
}

void handle_event(struct inotify_event *event);

int main(int argc, char **argv)
{
    fd_set rfds;
    char buf[1024];
    struct inotify_event * event;
    int index, cnt;

    topdir = dir;
    
    if (signal(SIGINT, signal_handler) == SIG_IGN)
    {
        printf("SIGINT Error\n");
        signal(SIGINT, SIG_IGN);
    }
    
    daemon(0, 0);

    fd = inotify_init();
    if (fd < 0)
    {
        perror("inotify_init() Error\n");
        return -1;
    }

    if (inotify_add_watch(fd, topdir, IN_ISDIR|IN_ATTRIB) < 0)
    {
        printf("Watch %s Error\n", topdir);
        return -1;
    }

    while (1)
    {
        FD_ZERO(&rfds);
        FD_SET(fd, &rfds);
        
        if (select(FD_SETSIZE, &rfds, NULL, NULL, NULL) > 0)
        {
            if (FD_ISSET(fd, &rfds))
            {
                cnt = read(fd, buf, 1024);
                index = 0;
                while (cnt > index)
                {
                    event = (struct inotify_event *)&buf[index];
                    index = index + event->len + 16;
                    handle_event(event);
                }
                fflush(NULL);
            }
        }
    }
    
    return 0;
}

void handle_event(struct inotify_event *event)
{
    //printf("Event : %s/%x\n", event->name, event->mask);
    struct stat buf;
    
    if (event->mask & IN_ATTRIB)
    {
        stat(topdir, &buf);
        //printf("stat : %x \n", buf.st_mode);
        if (buf.st_mode & (S_IROTH|S_IWOTH|S_IXOTH|S_IXGRP|S_IWGRP|S_IRGRP))
        {
            //printf("Match!\n");
            chmod(topdir, S_IRUSR | S_IWUSR | S_IXUSR);
        }
    }
}