On Thu, Dec 01, 2016 at 10:03:23PM +0100, Manuel Schölling wrote:

Hi Andrey,

On Di, 2016-11-29 at 10:01 +0000, Andrey Utkin wrote:

quoted

On Mon, Nov 28, 2016 at 10:28:19PM +0100, Manuel Schölling wrote:
Regarding logout scrollback clearing not working for me. ncurses-6.0-rc1
which I tested it with is the latest available in Gentoo portage, please
confirm whether I need any newer version, or should I tune something
else. I'd appreciate if you also tested your patch with gentoo setup.

I finally setup gentoo

Wow, what a big undertaking.

running agetty (util-linux-2.26.2) and patching
the file term-utils/agetty.c with

static void termio_clear(int fd)
{
	/*
	 * Do not write a full reset (ESC c) because this destroys
	 * the unicode mode again if the terminal was in unicode
	 * mode.  Also it clears the CONSOLE_MAGIC features which
	 * are required for some languages/console-fonts.
	 * Just put the cursor to the home position (ESC [ H),
	 * erase everything below the cursor (ESC [ J), and set the
	 * scrolling region to the full window (ESC [ r)
	 */
-	write_all(fd, "\033[r\033[H\033[J", 9);
+	write_all(fd, "\033[3J\033[r\033[H\033[J", 13);
}

solves the issue with the scrollback buffer after log out.
Let me know if you agree that this is the right way to go and I will
send a patch to the maintainer of util-linux.

I believe you that this works and you must know better than me whether
this solution is correct. Besides that, I'd suggest updating that large
block comment before the updated write_all() call to describe the new
action you're doing. Please CC me in your discussion with util-linux
maintainers.

Also I'd suggest coming back in a while, to set this feature enabled by
default. I wonder how many years to wait gracefully until "stable"
distros update util-linux to ensure secure scrollback wiping. 3? 5?

Thanks again for spending all this time to test the patch!

Thank you very much for your time and effort in bringing this useful
feature!

I give all sorts of my approval on this patchset:
Reviewed-by: Andrey Utkin <redacted>
Tested-by: Andrey Utkin <redacted>