Re: [PATCH v3] linux ttyname and ttyname_r: do not return wrong results

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

On Thu, Nov 24, 2016 at 02:32:36AM +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@ubuntu.com>
> ---
> Changelog: 2016-11-08
> 	- remove obsolete comment in ttyname_r.c
> 	- move is_pty() to common header file and mark as static inline
> Changelog: 2016-11-22
> 	- remove unneeded sys/symacros.h header
> Changelog: 2016-11-24
> 	- add Changelog entry
> ---
>  ChangeLog                           |  8 ++++++++
>  sysdeps/unix/sysv/linux/ttyname.c   | 16 ++++++++++++----
>  sysdeps/unix/sysv/linux/ttyname.h   | 35 +++++++++++++++++++++++++++++++++++
>  sysdeps/unix/sysv/linux/ttyname_r.c | 17 +++++++++++++----
>  4 files changed, 68 insertions(+), 8 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/ttyname.h
> 
> diff --git a/ChangeLog b/ChangeLog
> index b6fc831..c236992 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,11 @@
> +2016-11-23  Christian Brauner  <christian.brauner@ubuntu.com>
> +
> +	* sysdeps/unix/sysv/linux/ttyname.c: do not return wrong results when
> +	detecting tty devices residing in a different namespace
> +	* sysdeps/unix/sysv/linux/ttyname_r.c: do not return wrong results when
> +	detecting tty devices residing in a different namespace
> +	* sysdeps/unix/sysv/linux/ttyname.h: New file

This doesn't quite follow the style guidelines.  A properly formatted
ChangeLog for this change would look like this:

2016-11-24  Christian Brauner  <christian.brauner@ubuntu.com>

	* sysdeps/unix/sysv/linux/ttyname.h: New file.
	* sysdeps/unix/sysv/linux/ttyname.c: Include "ttyname.h".
	(ttyname) [!_STATBUF_ST_RDEV]: Make code unconditional.
	Call is_pty when the link does not exist or does not match, fail
	with ENODEV when it returns true.
	* sysdeps/unix/sysv/linux/ttyname_r.c: Include "ttyname.h".
	(__ttyname_r) [!_STATBUF_ST_RDEV]: Make code unconditional.
	Call is_pty when the link does not exist or does not match, fail
	with ENODEV when it returns true.


-- 
ldv

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