Re: vlock command

[Petr Pisar <ppisar@redhat.com>]

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On Thu, Nov 15, 2012 at 08:52:53AM +0100, Karel Zak wrote:
> On Thu, Nov 15, 2012 at 10:44:47AM +0400, Alexey Gladkov wrote:
> > 15.11.2012 03:31, Dmitry V. Levin wrote:
> > > On Wed, Nov 14, 2012 at 01:26:10PM +0100, Karel Zak wrote:
> > >
> > >>  Alexey, just today I added --erase option to Fedora version. Maybe
> > >>  you can apply the patch below to your repository too. Author of the
> > >>  patch is Petr Pisar <ppisar@redhat.com>.
> > > 
> > > The first vlock RFE for ages!  Alexey, please apply.
> > 
> > Dmitry, I mistakenly did not add you in the Cc. I wrote Karel that
> > similar functionality you have already implemented.
> > Here is my answer:
> > 
> > > On closer look I found out that the my version of vlock already erases
> > > display if we are on the virtual console:
> > > 
> > > http://git.altlinux.org/people/legion/packages/kbd.git?p=kbd.git;a=blob;f=src/vlock/screen.c;h=720d880080f9030553a32d625756b5e30c6d4266;hb=768b8c314e1d3c465d895b206da4aa4543914d1d#l37
> > > 
> > > http://git.altlinux.org/people/legion/packages/kbd.git?p=kbd.git;a=blob;f=src/vlock/vt.c;h=50746de238f5acc231d2ffef8a5604dfbef3cfad;hb=768b8c314e1d3c465d895b206da4aa4543914d1d#l194
> > > 
> > > As I understand you want a similar functionality. Is this enough for
> > > you,
It's similar but insufficient. The difference between your clear_str[]
= "\33[H\33[J" and my string is my way clears scroll-back buffer of Linux
virtual terminal too. This prevents from reading history using Shift-PgUp
while the terminal is locked. Read current console_codes(4) page, especially
search for word "buffer".

So what I ask is to prepend "\33[3J" to your clear_str[]. This even users with
older kernel not implementing this code get console cleared.

> or you want to be able to clear the display regardless of conditions?

If I understand the code correctly, you clear screen only if it's a virtual
terminal. I have no idea how usefull is vlock on other terminals (I use
"screen" there), so I do not request any change in this matter.

-- Petr

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