#include <dirent.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main()
{
    struct stat stat_buf;   
    struct dirent *file_info;
    ino_t itself_ino;        /* holds current directory inode */
    ino_t parent_ino;        /* holds parent directory inode */
    char Current[PATH_MAX];  /* directory name */
    char Path[PATH_MAX];     /* holds the full path */
    char Slash[PATH_MAX];    /* add / before the directory name */
    DIR *dir;

    while (1)
    {   
        dir = opendir(".");
        if(dir == NULL) {
            fprintf(stderr, "cannot get current directory.\n");
            exit(-1);
        }
        /* read the information about the current directory */
        file_info = readdir(dir);

        lstat(file_info->d_name, &stat_buf);
        itself_ino = stat_buf.st_ino;
        closedir(dir);

        chdir("..");    /* go to parent directory */

        dir = opendir(".");

        // printf("DEBUG1*:\tci=%d,\tpi=%d,\tnm=%s,\tsl=%s\n\n", itself_ino, parent_ino, file_info->d_name, Slash);

        while (file_info = readdir(dir)) {
          lstat(file_info->d_name, &stat_buf);
          parent_ino = stat_buf.st_ino;

              // printf("DEBUG2**:\tci=%d,\tpi=%d,\tnm=%s,\tsl=%s\n", itself_ino, parent_ino, file_info->d_name, Slash);
          if (itself_ino == parent_ino && itself_ino != 2) {
 
              strcpy(Slash, "/");
              strcpy(Current, file_info->d_name);
              strcat(Slash, Current);  /* add "/" as the first */
              strcat(Slash, Path);     /* charcter of the directory */
  
              /* check the length of the pathname */
              if(strlen(Slash)  >= PATH_MAX) {
                  fprintf(stderr, "Error! Path too long!\n");
                  exit(0);
              }           
              /* save the full pathname */       
              strcpy(Path, Slash);
              // printf("\nDEBUG3***:\tci=%d,\tpi=%d,\tnm=%s,\tsl=%s\n\n", itself_ino, parent_ino, file_info->d_name, Slash);
              break;
          }
        }
        closedir(dir);
        if (itself_ino == 2) { break; }
    }

    /* print the full path of the current working directory */
    if (strlen(Path) == 0) {
      printf("/\n");
    } else {
      printf("%s\n", Path);
    }
    return 0;
}