set_overscan.sh

#!/bin/bash
#########################################################################
# set_overscan.sh v0.11
# Modify overscan on the fly.                                            
# By Russell "ukscone" Davis using code from Broadcom, Dom Cobley & Alex Bradbury
# 2013-03-10, 2014-07-23, 2015-05-01, 2017-08-01
#   
# There is very little, ok no error/sanity checking. I've left that as an exercise
# for the reader :D This is a very simplistic script but it works and i'm sure someone
# will take it and make it all flashy and cool looking.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions, and the following disclaimer,
#    without modification.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. The names of the above-listed copyright holders may not be used
#    to endorse or promote products derived from this software without
#    specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

CONFIG=/boot/config.txt

#########################################################################
# Function                                                              #
#########################################################################
get_kc ()
{
    od -t o1 | awk '{ for (i=2; i<=NF; i++)
                        printf("%s%s", i==2 ? "" : " ", $i)
                        exit }'
}

set_config_var() {
  lua - "$1" "$2" "$3" <<EOF > "$3.bak"
local key=assert(arg[1])
local value=assert(arg[2])
local fn=assert(arg[3])
local file=assert(io.open(fn))
local made_change=false
for line in file:lines() do
  if line:match("^#?%s*"..key.."=.*$") then
    line=key.."="..value
    made_change=true
  end
  print(line)
end

if not made_change then
  print(key.."="..value)
end
EOF
mv "$3.bak" "$3"
}

#########################################################################
# Check we are root or using sudo otherwise why bother?                 #
#########################################################################
# Make sure only root can run our script
if [[ $EUID -ne 0 ]]; then
        echo "This script must be run by root or using sudo" 1>&2
        exit 1
fi

#########################################################################
# Is overscan enabled? If not the fix it & reboot                       #
#########################################################################
if [ "$(vcgencmd get_config disable_overscan | awk -F '=' '{print $2}')" -eq "1" ]; then
        set_config_var disable_overscan 0 $CONFIG
        whiptail --msgbox  "disable_overscan=0 added to config.txt, overscan will be enabled on next reboot. reboot & then rerun this script." 10 45
        exit 1
fi

#########################################################################
# Variables & Constants & create some files                             #
#########################################################################
# Grab terminal capabilities
tty_cuu1=$(tput cuu1 2>&1 | get_kc)            # up arrow
tty_kcuu1=$(tput kcuu1 2>&1 | get_kc)
tty_cud1=$(tput cud1 2>&1 | get_kc)            # down arrow
tty_kcud1=$(tput kcud1 2>&1 | get_kc)
tty_cub1=$(tput cub1 2>&1 | get_kc)            # left arrow
tty_kcub1=$(tput kcud1 2>&1 | get_kc)
tty_cuf1=$(tput cuf1 2>&1 | get_kc)            # right arrow
tty_kcuf1=$(tput kcud1 2>&1 | get_kc)
# Some terminals (e.g. PuTTY) send the wrong code for certain arrow keys
if [ "$tty_cuu1" = "033 133 101" -o "$tty_kcuu1" = "033 133 101" ]; then
    tty_cudx="033 133 102"
    tty_cufx="033 133 103"
    tty_cubx="033 133 104"
fi

# Check for mailbox & if not existing create it.
created_mailbox=0
if [ ! -c /dev/vcio ]; then
       mknod /dev/vcio c 100 0
       created_mailbox=1
fi

# Get current overscan values from GPU
TEMP=$(./overscan)
GPU_OVERSCAN_TOP=$(echo "$TEMP" | awk -F ' ' '{print $1}')
GPU_OVERSCAN_BOTTOM=$(echo "$TEMP" | awk -F ' ' '{print $2}')
GPU_OVERSCAN_LEFT=$(echo "$TEMP" | awk -F ' ' '{print $3}')
GPU_OVERSCAN_RIGHT=$(echo "$TEMP" | awk -F ' ' '{print $4}')

# How big is the screen?
TEMP=$(fbset | grep 'mode "' | awk -F ' ' '{print $2}' | tr \" \ )
FXRES=$(echo "$TEMP" |awk -F 'x' '{print $1}')
FYRES=$(echo "$TEMP" |awk -F 'x' '{print $2}')
BYTES=$(expr $FXRES \* $FYRES \* 4)

TXRES=$(stty size | awk -F ' ' '{print $2}')
TYRES=$(stty size | awk -F ' ' '{print $1}')

XMIDPOINT=$((TXRES/2))
YMIDPOINT=$((TYRES/2))

# Create some random data & zero'ed data
head -c $BYTES < /dev/urandom > rand
head -c $BYTES </dev/zero > cleared

########################################################################
# Main()
########################################################################
tty_save=$(stty -g)

stty cs8 -icanon -echo min 3 time 1
stty intr '' susp ''

trap 'stty $tty_save; tput cnorm ; exit'  INT HUP TERM

# Going to modify top-left overscan
whiptail --title "Instructions" --msgbox "We are going to fill the screen with a checker pattern. Once the screen is full of dots use the arrow keys to increase or decrease the top-left corner's overscan and WSAD to move the lower-right corner & press the q key when finished." 12 50

clear

# We don't need no cursor messing up my pretty screen
tput civis

# Make a checker pattern
RESOLUTION=$(fbset | grep geometry | sed -E 's/.* ([0-9]+) ([0-9]+) .*/\1 \2/')
XRES=$(echo $RESOLUTION | cut -f 1 -d ' ')
YRES=$(echo $RESOLUTION | cut -f 2 -d ' ')
(
  Y=0
  while [ $Y -lt 16 ]; do
    X=0
    while [ $X -lt $XRES ]; do
      printf '\xFF\xFF\xFF\xFF\x00\x00\x00\x00'
      let X=X+2
    done
    X=0
    while [ $X -lt $XRES ]; do
      printf '\x00\x00\x00\x00\xFF\xFF\xFF\xFF'
      let X=X+2
    done
    let Y=Y+2
  done
) > /tmp/16scans

(
  Y=0
  while [ $Y -lt $YRES ]; do
    cat /tmp/16scans
    let Y=Y+16
  done
) > /dev/fb0

rm /tmp/16scans

#cat rand >/dev/fb0

# Set overscan top-left corner
LOOP=1
while [ $LOOP -eq 1 ]; do
	
	TEXT=" TOP=$GPU_OVERSCAN_TOP, LEFT=$GPU_OVERSCAN_LEFT, BOTTOM=$GPU_OVERSCAN_BOTTOM, RIGHT=$GPU_OVERSCAN_RIGHT   "
        LEN=$((${#TEXT}/2))
        XPOS=$((XMIDPOINT-LEN))
        echo -ne "\033[${YMIDPOINT};${XPOS}f$TEXT"
	
	keypress=$(dd bs=3 count=1 2> /dev/null | get_kc)
	case "$keypress" in
        	"$tty_cuu1"|"$tty_kcuu1") ((GPU_OVERSCAN_TOP--));;
        	"$tty_cud1"|"$tty_kcud1"|"$tty_cudx") ((GPU_OVERSCAN_TOP++));;
        	"$tty_cub1"|"$tty_kcub1"|"$tty_cubx") ((GPU_OVERSCAN_LEFT--));;
        	"$tty_cuf1"|"$tty_kcuf1"|"$tty_cufx") ((GPU_OVERSCAN_LEFT++));;

		"054") ((GPU_OVERSCAN_BOTTOM++));;
		"157") ((GPU_OVERSCAN_BOTTOM--));;
		"141") ((GPU_OVERSCAN_RIGHT++));;
		"145") ((GPU_OVERSCAN_RIGHT--));;

		"161") LOOP=0;; 
    	esac

	./overscan $GPU_OVERSCAN_TOP $GPU_OVERSCAN_BOTTOM $GPU_OVERSCAN_LEFT $GPU_OVERSCAN_RIGHT > /dev/null
done

# Finished so update $CONFIG
set_config_var disable_overscan 1 $CONFIG
set_config_var overscan_top $GPU_OVERSCAN_TOP $CONFIG
set_config_var overscan_bottom $GPU_OVERSCAN_BOTTOM $CONFIG
set_config_var overscan_left $GPU_OVERSCAN_LEFT $CONFIG
set_config_var overscan_right $GPU_OVERSCAN_RIGHT $CONFIG

# Clean up 
if [ $created_mailbox -eq 1 ]; then
	rm -f /dev/vcio
fi
rm rand
rm cleared

# Restore stty to old value
stty $tty_save
clear
tput cnorm