Re: [PATCH] linux ttyname and ttyname_r: do not return wrong results

["Dmitry V. Levin" <ldv@altlinux.org>]

On Tue, Nov 08, 2016 at 05:56:38PM +0100, Christian Brauner wrote:
> If a link (say /proc/self/fd/0) pointing to a device, say /dev/pts/2, in a
> parent mount namespace is passed to ttyname, and a /dev/pts/2 exists (in a
> different devpts) in the current namespace, then it returns /dev/pts/2. But
> /dev/pts/2 is NOT the current tty, it is a different file and device.
> 
> Detect this case and return ENODEV. Userspace can choose to take this as a hint
> that the fd points to a tty device but to act on the fd rather than the link.
> 
> Signed-off-by: Serge Hallyn <serge@hallyn.com>
> Signed-off-by: Christian Brauner <christian.brauner@canonical.com>
> ---
> Changelog: 2016-11-08
> 	- remove obsolete comment in ttyname_r.c
> 	- move is_pty() to common header file and mark as static inline
> ---
>  sysdeps/unix/sysv/linux/ttyname.c   | 17 +++++++++++++----
>  sysdeps/unix/sysv/linux/ttyname.h   | 35 +++++++++++++++++++++++++++++++++++
>  sysdeps/unix/sysv/linux/ttyname_r.c | 18 ++++++++++++++----
>  3 files changed, 62 insertions(+), 8 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/ttyname.h
> 
> diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c
> index 7a001b4..dabed22 100644
> --- a/sysdeps/unix/sysv/linux/ttyname.c
> +++ b/sysdeps/unix/sysv/linux/ttyname.c
> @@ -25,9 +25,12 @@
>  #include <unistd.h>
>  #include <string.h>
>  #include <stdlib.h>
> +#include <sys/sysmacros.h>

This is probably a leftover from previous editions and could be safely removed.

[...]
> diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c
> index d15bc74..542114b 100644
> --- a/sysdeps/unix/sysv/linux/ttyname_r.c
> +++ b/sysdeps/unix/sysv/linux/ttyname_r.c
> @@ -25,9 +25,12 @@
>  #include <unistd.h>
>  #include <string.h>
>  #include <stdlib.h>
> +#include <sys/sysmacros.h>

Likewise.

Besides that, it looks good.


-- 
ldv