Re: no ioctls for serial ports? [was Re: LANANA: To Pending

Alexander Viro (viro@math.psu.edu)
Sun, 20 May 2001 08:45:47 -0400 (EDT)


On Sun, 20 May 2001 Andries.Brouwer@cwi.nl wrote:

> > Getting a list of all ioctls in the tree, along with types of their arguments
> > would be a great start. Anyone willing to help with that?
>
> % man 2 ioctl_list
>
> gives a very outdated list. Collecting the present list is trivial
> but time-consuming. If anyone does I would be happy if he also
> sent me an updated ioctl_list.2

Andries, I wouldn't call it trivial. Consider the following:
default:
if ((cmd & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT)) == JSIOCGNAME(0)) {
int len;
if (!dev->name) return 0;
len = strlen(dev->name) + 1;
if (len > _IOC_SIZE(cmd)) len = _IOC_SIZE(cmd);
if (copy_to_user((char *) arg, dev->name, len)) return -EFAULT;
return len;
}

Real-world example. From drivers/input/joydev.c::joydev_ioctl(). And it's far
from the worst ones - just one I'm currently looking at.

We have ~180 first-order ioctl() methods. Several (my guess would be 8--15)
subsystems of the second order and hell knows how many instances in each
of them. And I'm afraid that we have some third-order families. Each instance
of each family got some ioctls in it. I think that we have several thousands
of these beasts. And that's several thousands of undocumented system calls
hidden in bowels of sys_ioctl(). Undocumented == for most of them we have
no information of argument types, which arguments are in-, out- or in-out,
which contain pointers to other userland structures, etc.

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