Unix file descriptor

Today I found very interesting behavior of file descriptors in Linux. Look at this code:

#include <dirent.h>     /* Defines DT_* constants */
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <errno.h>


#define handle_error(msg) \
do { trace(msg); exit(0); } while (0)
#define trace printf

int createFile(const char* name) {
    int r;
    r = ::open( name, 0 );
    if (r < 0)
    {
        trace("create file : %s\n", name);
        r = ::open( name, O_CREAT, 0666 );
        if (r < 0)
            trace("error r < 0 %d\n",errno);
    }
    return r;
}

int createDir(const char* name) {
    int r = ::mkdir( name, 0777 );
    if (r != 0) {
        trace("error r!=0\n");
    }
    r = open(name, 0);
    if (r < 0) {
        trace("error create dir r <0\n");
    }
    return r;
}

struct linux_dirent {
    long           d_ino;
    off_t          d_off;
    unsigned short d_reclen;
    char           d_name[];
};

#include <sys/types.h>
#include <dirent.h>
void test123(int fd) {
    int nread;
    char buf[1024];
    unsigned char buffer[1024];
    struct linux_dirent *d;
    int bpos,r;
    char d_type;


    if (fd == -1)
        handle_error("open");

    for ( ; ; ) {
        nread = syscall(SYS_getdents, fd, buf, 1024);
        if (nread == -1)
            handle_error("getdents");

        if (nread == 0)
            break;

        trace("--------------- nread=%d ---------------\n", nread);
        trace("i-node#  file type  d_reclen  d_off   d_name\n");
        for (bpos = 0; bpos < nread;) {
            d = (struct linux_dirent *) (buf + bpos);
            trace("%8ld  ", d->d_ino);
            d_type = *(buf + bpos + d->d_reclen - 1);
            trace("%4d %10lld  %s\n", d->d_reclen,
                  (long long) d->d_off, d->d_name);
            bpos += d->d_reclen;
        }
    }
}


int main(int argc, const char * argv[]) {



    int dir = createDir("test");

    int file = createFile("test/file.gg");

    test123(dir);
    close(dir);
    close(file);


    return 0;
}

      

        
        
        
      

    

in this code, I create a folder, store its file descriptor, create a file in that folder and after I want to print all files in that directory via file descriptors. However, I am getting this output:

create file : test/file.gg
--------------- nread=32 ---------------
i-node#  file type  d_reclen  d_off   d_name
   48879    16          1  .
   48880    16          2  ..

      

        
        
        
      

    

There is no file.gg file in this folder. So my question is, how is this and how to work properly with file descriptors? As I understand it, the file descriptor is just an index on the local process table with all files and directories open. But it looks like this folder descriptor is caching some files in this folder. How do I work with descriptors in my case?