televideo_screensaver

Screen saver with password lock for old school televideo terminals (tested on Televideo 910)

Forked from https://github.com/mezantrop/sclocka

should run on *BSD, macOS and Linux (tested on macOS only)

Differences from Sclocka

• no animation whatsoever - screen will just be blanked
• removed window resize support (not needed on real hardware terminals)
• screen size harcoded to 80x24 (as supported on Televideo terminals)
• supports Televideo escape sequences
• correctly handles cursor show and hide function for these terminals
• invokes a login shell when launched
• will un-blank and redraw screen when new data arrives (when -B b, which is default)
• when redrawing screen, it will redraw it correctly, without lines already out of view, no scrolling
• redraw of the screen is much faster (well, hw baud rate will make it seem slow still, LOL)
• hitting space bar when terminal is locked will redraw screen for the set time then back to blank
• hitting any other key when terminal is locked will ask for password

Build and install

Build Requirements

• CLANG or GCC
• make
• PAM development libraries

FreeBSD

# make install clean

Note, the default login PAM service on FreeBSD doesn't check a user's password for the same login. To allow tvi_screensaver perform password authentication via PAM, install unix-selfauth-helper:

# pkg install unix-selfauth-helper

Create and configure a special PAM service e.g. /etc/pam.d/tvi_screensaver:

auth            sufficient      pam_exec.so             return_prog_exit_status expose_authtok /usr/local/libexec/unix-selfauth-helper
auth            include         system
account         include         system

Start tvi_screensaver with -P tvi_screensaver option:

$ tvi_screensaver -P tvi_screensaver

NetBSD

# make install clean

See notes about PAM helper from FreeBSD section

OpenBSD

No PAM supported

# make without_pam install clean

macOS

# make install clean

Note, you may be prompted to install command line developer tools

Debian flavor Linux

Make sure you have everything to compile sources:

$ sudo apt-get install build-essential
$ sudo apt-get install libpam0g-dev

$ sudo make install clean

Red Hat based Linux

Make sure you have everything to compile sources:

$ sudo dnf groupinstall "Development Tools"
$ sudo dnf install pam-devel

$ sudo make install clean

Run

# tvi_screensaver

Wait for a screensaver to appear

Options

tvi_screensaver can be invoked with several options:

$ tvi_screensaver -h

Usage:
        tvi_screensaver [-b n|f|b|c] [-c] [-i n] [-p] [-P service] [-h]

[-b f]          Screen restore: (n)one, (f)ormfeed, (b)uffer, (c)apabilities
[-c]            Do not clear the window
[-i X]          Wait X minutes before blanking the screen
[-p]            Disable PAM password check (terminal is not locked just blanked)
[-P login]      Use custom PAM service

[-h]            This message