sys/types.h

in order to get the mode of a file, we need to get the information of Inode struct

fortunately, there is a api stat() or fstat()

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

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

       int fd;

       struct stat info;                  // in order to get the status of a file
       fd = open(argv[1],O_REWR);
       fstat(fd, &info);                   //fstat(int fileDescriptor, struct stat* info)
       printf(fd, (unsigned long)info.st_mode);
        return 0;
}

st_mode is one structure in struct stat info. it has a mode of a file(permission)
so if we use this we can copy a file whose mode is exactly same as the file we want to copy from