#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>

#define BLOCK 4096
#define MAX_PATH 256

static char buff[BLOCK];
static char path[MAX_PATH];
static bool cp_dir(DIR*);
static struct stat stbuf;

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

   if(argc != 3)
   {
      fprintf(stderr,"invalid arg num!\n");
      exit(EXIT_FAILURE);
   }

   DIR *dp  = opendir(argv[1]);

   if(dp == NULL)
   {
       fprintf(stderr," 1:\t%s\n",strerror(errno));
       exit(EXIT_FAILURE);
   }

   strcpy(path,argv[2]);

   if(stat(argv[1],&stbuf) < 0)
   {
      fprintf(stderr,"2:\t%s \n",strerror(errno));
      exit(EXIT_FAILURE);
   }

   if(mkdir(path,stbuf.st_mode) < 0)
   {
      fprintf(stderr,"3:\t%s\n",strerror(errno));
      exit(EXIT_FAILURE);
   }

   return cp_dir(dp);
}

static struct dirent *dirp;
static bool cp_dir(DIR *dp)
{
    int sfd = dirfd(dp);
    int dfd;
    fchdir(sfd);
    int n = strlen(path);
    path[n++] = '/';
    path[n] = 0;

    while((dirp = readdir(dp)) != NULL)
    {
       if(strcmp(dirp->d_name,".") == 0 || strcmp(dirp->d_name,"..") == 0)
           continue;
       
       if(stat(dirp->d_name,&stbuf) < 0)
       {
             fprintf(stderr,"4:\t%s\n",strerror(errno));
             return false;
       }

       strcpy(path+n,dirp->d_name);
       
       if(S_ISDIR(stbuf.st_mode))
       {
           DIR *sdp =  opendir(dirp->d_name);

           if(mkdir(path,stbuf.st_mode) < 0)
           {
               fprintf(stderr,"5:\t%s\n",strerror(errno));
               return false;
           }

           cp_dir(sdp);
           
           closedir(sdp);
       }
       else
       {
           int cfd = open(dirp->d_name,O_RDONLY);
           int tfd = open(path,O_CREAT|O_EXCL|O_WRONLY,stbuf.st_mode);
           
           int n;

           while((n = read(cfd,buff,BLOCK)) > 0)
           {
                if(write(tfd,buff,n) < n)
                {
                    fprintf(stderr,"6:\t%s\n",strerror(errno));
                    break;
                }

           }

           close(cfd);
           close(tfd);
                 
       }
             
    }

    chdir("..");   
    path[n-1] = 0;
}

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