On Sat, 27 May 2006 07:54:38 -0600 Eric W. Biederman wrote:
> "Randy.Dunlap" <[email protected]> writes:
>
> >> > "Randy.Dunlap" <[email protected]> writes:
> >> >
> >> > > This patch is against 2.6.17-rc5, for review/comments, please.
> >> > > It won't apply to -mm since Andrew has merged the uts-namespace patches.
> >> > > I'll see about merging it with those patches next.
> >> > > ---
> >
> > Per Eric's comments:
> >
> > 1. use existing sys_gethostname() and sys_sethostname().
> >
> > 2. add sys_uname_long() to read struct long_utsname;
> >
> > 3. removed EXPORT_SYMBOL()s
>
> I have to confess I am still uneasy with sys_uname_long.
>
> The problem is that we have several revisions of this system
> call almost always simply to accommodate long string lengths,
> and the new interface doesn't seem any less susceptible to
> handling longer strings than the old one.
so you want an interface that is self-describing and extensible?
There are lots of syscalls that require struct pointers
from userspace... that users can get wrong.
Ulrich, do you have any comments/suggestions about this from
the userspace/lib perspective?
> Could we do something like:
> long sys_unamev(int count, char __user **name, size_t name_len)
> {
> char *table[] = {
> system_utsname.sysname,
> system_utsname.nodename,
> system_utsname.release,
> system_utsname.version,
> system_utsname.machine,
> system_utsname.domainname,
> };
> char __user *data;
> long error;
> long len;
> int i;
>
> down_read(&uts_sem);
>
> error = -EINVAL;
> if (count > 6)
> goto out;
>
> len = sizeof(char __user *) * count;
> for (i = 0; i < count; i++) {
> len += strlen(table[i]) + 1;
> }
>
> error = -ERANGE;
> if (len > name_len)
> goto out;
>
> error = -EFAULT;
> if (!name)
> goto out;
> if (!access_ok(VERIFY_WRITE, name, name_len))
> goto out;
>
> error = 0;
> data = (char __user *)&name[count];
> for (i = 0; i < count; i++) {
> size_t len = strlen(table[i]) + 1;
> error |= __put_user(data, name[i]);
> error |= __copy_to_user(data, table[i], len);
> data += len;
> }
> out:
> up_read(&uts_sem);
> return error;
> }
>
> And then in user space we can do.
> struct utsname {
> char *sysname;
> char *nodename;
> char *release;
> char *version;
> char *machine;
> char *domainname;
> char buf[4096 - (sizeof(char *)*6)];
> };
>
> int uname(struct utsname *buf)
> {
> return sys_unamev(6, buf, sizeof(*buf));
> }
---
~Randy
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
