long sys_getcwd(char* buf, size_t size)
{
	struct buffer_head* bh;
	struct m_inode* n_inode, * f_inode;
	struct dir_entry* dir;
	char* tmp, * b;
	int k, i;
	tmp = (char*)malloc(256);
	b = (char*)malloc(256);
	n_inode = current->pwd;
	if (n_inode == current->root)strcpy(tmp, "/");
	bh = bread(n_inode->i_dev, n_inode->i_zone[0]);
	while (n_inode != current->root)
	{
		dir = (struct dir_entry*)(bh->b_data + sizeof(struct dir_entry));
		f_inode = iget(n_inode->i_dev, dir->inode);
		brelse(bh);
		bh = bread(f_inode->i_dev, f_inode->i_zone[0]);
		k = 0;
		while (k < f_inode->i_size)
		{
			dir = (struct dir_entry*)(bh->b_data + k);
			if (dir->inode == n_inode->i_num)break;
			k += sizeof(struct dir_entry);
		}
		strcpy(b, "/");
		strcat(b, dir->name);
		strcat(b, tmp);
		strcpy(tmp, b);
		n_inode = f_inode;
	}
	brelse(bh);
	if (strlen(tmp) > size)return NULL;
	for (i = 0; i < 256; i++)
		put_fs_byte(tmp[i], buf + i);
	return (long)buf;
}