Bug#416310: [Patch] fix fault in grub_serial_console

[Alex Owen]

This bug lies in the grub-installer script in the function grub_serial_console.
Attached is the file grub_serial_console.txt is a replacement
grub_serial_console function which parses the kernel command line
"console=" argument in a more robust and (I hope) readable manner.

A test script test.sh is also attached which can be used to excercise
the grub_serial_console  function in the file grub_serial_console.txt.

I know this is very late in the release cycle but I would like to see
this rewrite of
grub_serial_console enter d-i for Etch.

Regards
Alex Owen

[For Lenny: While rewriting grub_serial_console I thought I would tidy
up the function get_serial_console. Attached is the file
get_serial_console.txt which contains a drop-in replacement for the
function get_serial_console. This should _not_ be targeted at Etch]

grub_serial_console() {
        #$1=output of get_serial_console
        local serconsole=${1##console=}
        local device=${serconsole%%,*}
        local unit=${device##ttyS}
        local options=${serconsole##*,}
        #Handle case when no options given
        [ "$options" == "$device" ] && local options=""
        local speed=$(echo $options | sed -e's%^\([0-9]\+\).*%\1%')
        local parity_word_flow=${options##${speed}}
        local word_flow=${parity_word_flow#?}
        local parity=${parity_word_flow%%${word_flow}}
        local flow=${word_flow#?}
        local word=${word_flow%%${flow}}
        case "$parity" in
                "n") local parity="--parity=no" ;;
                "e") local parity="--parity=even" ;;
                "o") local parity="--parity=odd" ;;
                *)   local parity="" ;;
        esac
        [ $word ] && local word="--word=$word"
        [ $speed ] || local speed=9600 #Match Kernel Default
        echo serial --unit=$unit --speed=$speed $word $parity --stop=1
        echo terminal serial
        }

test.sh
Description: Bourne shell script

#For Lenny
get_serial_console() {
        for x in $(cat /proc/cmdline); do
                case $x in
console=*)
                local defconsole="${x#*=}" ;;
                esac
        done
        if echo "${defconsole}" | grep -q ttyS; then
                echo "console=$defconsole"
        fi
}