Re: [LTP] [PATCH] ioctl01: change the errno to ENOTTY when passed an invalid command

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> To: "LTP" <ltp-list@lists.sourceforge.net>
> Cc: "sanil kumar" <sanil.kumar@huawei.com>, "Mike Frysinger" <vapier@gentoo.org>, "shyju pv" <shyju.pv@huawei.com>,
> "max maxiansheng" <max.maxiansheng@huawei.com>
> Sent: Thursday, 1 November, 2012 5:00:19 AM
> Subject: [LTP] [PATCH] ioctl01: change the errno to ENOTTY when passed an	invalid command
> 
> As linus said at the below commit,
> commit 07d106d0a33d6063d2061305903deb02489eba20
> Author: Linus Torvalds <torvalds@linux-foundation.org>
> Date:   Thu Jan 5 15:40:12 2012 -0800
> 
>     vfs: fix up ENOIOCTLCMD error handling
> 
>     We're doing some odd things there, which already messes up
>     various users
>     (see the net/socket.c code that this removes), and it was going
>     to add
>     yet more crud to the block layer because of the incorrect error
>     code
>     translation.
> 
>     ENOIOCTLCMD is not an error return that should be returned to
>     user mode
>     from the "ioctl()" system call, but it should *not* be translated
>     as
>     EINVAL ("Invalid argument").  It should be translated as ENOTTY
>     ("Inappropriate ioctl for device").
> 
>     That EINVAL confusion has apparently so permeated some code that
>     the
>     block layer actually checks for it, which is sad.  We continue to
>     do so
>     for now, but add a big comment about how wrong that is, and we
>     should
>     remove it entirely eventually.  In the meantime, this tries to
>     keep the
>     changes localized to just the EINVAL -> ENOTTY fix, and removing
>     code
>     that makes it harder to do the right thing.
> 
>     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> 
> Return ENOTTY is right. And with the tty driver change with below
> commit,
> commit bbb63c514a3464342967237a51a21ea8f61ab951
> Author: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> Date:   Mon Aug 27 15:23:12 2012 +0800
> 
>     drivers:tty:fix up ENOIOCTLCMD error handling
> 
>     At commit 07d106d0, Linus pointed out that ENOIOCTLCMD should be
>     translated as ENOTTY to user mode.
>     For example:
>         fd = open("/dev/tty", O_RDWR);
>         ioctl(fd, -1, &argp);
> 
>     then the errno should be ENOTTY but not EINVAL.
> 
>     Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
>     Acked-by: Alan Cox <alan@linux.intel.com>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> The tty driver will return the right ENOTTY in upstream kernel when
> passed a invalid ioctl command, so we fixed the LTP test case to
> suit this return value change.
> ---
>  testcases/kernel/syscalls/ioctl/ioctl01.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/testcases/kernel/syscalls/ioctl/ioctl01.c
> b/testcases/kernel/syscalls/ioctl/ioctl01.c
> index 8b044e7..ef64896 100644
> --- a/testcases/kernel/syscalls/ioctl/ioctl01.c
> +++ b/testcases/kernel/syscalls/ioctl/ioctl01.c
> @@ -87,7 +87,7 @@ struct test_case_t {
>  	&fd, TCGETA, (struct termio *)-1, EFAULT},
>  	    /* command is invalid */
>  	{
> -	&fd, INVAL_IOCTL, &termio, EINVAL},
> +	&fd, INVAL_IOCTL, &termio, ENOTTY},

Won't this break on older kernels? Can we test for kernel version with tst_kvercmp()?

Regards,
Jan

>  	    /* file descriptor is for a regular file */
>  	{
>  	&fd1, TCGETA, &termio, ENOTTY},
> --
> 1.8.0
> 
> 
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