fd2open_file
f = fd2open_file(fd);
f = fd2open_file(fd);
f = fd2open_file(fd);
f = fd2open_file(fd);
f = fd2open_file(-1);
f = fd2open_file(fd);
f = fd2open_file(fd);
extern struct open_file *fd2open_file(int);
f = fd2open_file(fd);