int copy_file(const char *from, const char *to, int flags, mode_t mode);
int copy_tree(const char *from, const char *to, bool merge);
int copy_bytes(int fdf, int fdt, off_t max_bytes);
int copy_file(const char *from, const char *to, int flags, mode_t mode);
int copy_tree(const char *from, const char *to, bool merge);
int copy_bytes(int fdf, int fdt, off_t max_bytes);