alsa multiseat script

#!/bin/bash

# Copyright 2014 Dagg Stompler <daggs@gmx.com>
#
# This script manages sound card selection for non PulseAudio based systems.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

PREFIX="ms_alsa_"
INSTANCE="$(basename $0)"
SERVED=0
CONF_FILE_PATH="/etc/conf.d/multiseat_alsa_sound.conf"
LINKS_PATH="/usr/local/bin"
GROUP="users"
INT_REGEX='^[0-9]+$'
LABELS_DB_PATH="/usr/share/misc"

# entry 0 must be install.
declare -a CONNECTORS=("${LINKS_PATH}/install" "${LINKS_PATH}/uninstall" "/etc/profile.d/update_asoundrc" "${LINKS_PATH}/list_seats")
declare -a ASOUNDRC_ADDONS=("defaults.pcm.card" "defaults.ctl.card" "defaults.pcm.device" "defaults.ctl.device")
declare cards_info=()
declare assignments=()

populate_cards()
{
    OLDIFS=${IFS}
    IFS=$'\n'
    i=0

    for card in $(egrep -lR "^id: " /proc/asound/card* | egrep "pcm[0-9]{1,}p" | egrep -v "sub[0-9]{1,}"); do
        local line=""
        local folder="$(realpath $(dirname ${card})/..)"
        local card_path_id="$(basename ${folder})"
        local vendor=""
        local device=""
        local type_usb=0

        if [ -f "${folder}/usbid" ]; then
            vendor=$(cat ${folder}/usbid | cut -f1 -d:)
            device=$(cat ${folder}/usbid | cut -f2 -d:)
            type_usb=1
        else
            vendor=$(cat /sys/class/sound/${card_path_id}/device/vendor | sed 's/0x//g')
            device=$(cat /sys/class/sound/${card_path_id}/device/device | sed 's/0x//g')
        fi
        line+="${vendor};${device}"
        line+=";$(grep "^name: " ${card} | sed 's/^name: //g');${type_usb}"
        cards_info[${i}]=${line}
        i=$((i+1))
    done
    IFS=${OLDIFS}
}

get_card_label()
{
    local vid="$1"
    local did="$2"
    local type_usb="$3"
    local db_file=${LABELS_DB_PATH}

    if [ ${type_usb} -eq 1 ]; then
        db_file+="/usb.ids"
    else
        db_file+="/pci.ids"
    fi
    local sline=$(egrep -n "^[0-9a-f]{4} " ${db_file} | grep -A1 ${vid} | head -1 | cut -f 1 -d ':')
    local eline=$(egrep -n "^[0-9a-f]{4} " ${db_file} | grep -A1 ${vid} | tail -1 | cut -f 1 -d ':')
    local label="$(sed -n "${sline},${eline}p" ${db_file} | grep ${did} | head -1 | cut -d' ' -f2- | sed 's/^\s*//g')"

    echo "${label}"
}

install_files()
{
    echo "installing..."
    rm ${CONF_FILE_PATH} -rf
    for i in $(seq 0 $((${#assignments[@]}-1))); do
        echo "${assignments[${i}]}" >> ${CONF_FILE_PATH}
    done

    local link_path="$(realpath $0)"
    local target_path
    for option in "${CONNECTORS[@]}"; do
        target_path="$(dirname ${option})/${PREFIX}$(basename ${option})"
        if [ ! -h "${target_path}" ]; then
            echo "creating link ${target_path}..."
            ln -s ${link_path} ${target_path}
        fi
    done
    chown root:${GROUP} $0 ${CONF_FILE_PATH}
    chmod 754 $0 ${CONF_FILE_PATH}
    IFS=$'\n'
    for entry in $(getent passwd); do
        username="$(echo ${entry} | cut -d: -f1)"
        if [ $(groups ${username} | grep -c users) -eq 1 ]; then
            local home="$(getent passwd ${username} | cut -d: -f6)"
            rm -rf ${home}/.asoundrc
            for option in "${ASOUNDRC_ADDONS[@]}"; do
                echo "${option} 0" >> ${home}/.asoundrc
            done
        fi
    done
    unset IFS
}

get_seat_id()
{
    local seat=$(echo ${DISPLAY} | sed 's/^://g')

    if ! [[ ${seat} =~ ${INT_REGEX} ]]; then
        echo "invalid seat id"
        exit 1
    fi
    echo ${seat}
}
#
get_data_from_entry()
{
    local entry="$*"
    local vid=$(echo ${entry} | cut -f 1 -d ';')
    local did=$(echo ${entry} | cut -f 2 -d ';')
    local hdr=$(echo ${entry} | cut -f 3 -d ';')
    local is_type_usb=$(echo ${entry} | cut -f 4 -d ';')
    local line=""

    for card in $(egrep -lR "^id: " /proc/asound/card* | egrep "pcm[0-9]{1,}p" | egrep -v "sub[0-9]{1,}"); do
        local folder="$(realpath $(dirname ${card})/..)"
        local card_path_id="$(basename ${folder})"
        local vendor=""
        local device=""
        local header=""
        local type_usb=0

        if [ -f "${folder}/usbid" ]; then
            vendor=$(cat ${folder}/usbid | cut -f1 -d:)
            device=$(cat ${folder}/usbid | cut -f2 -d:)
            type_usb=1
        else
            vendor=$(cat /sys/class/sound/${card_path_id}/device/vendor | sed 's/0x//g')
            device=$(cat /sys/class/sound/${card_path_id}/device/device | sed 's/0x//g')
        fi
        header="$(grep "^name: " ${card} | sed 's/^name: //g')"
        if [ "${vid}" == "${vendor}" -a "${did}" == "${device}" -a  "${hdr}" == "${header}" -a ${is_type_usb} -eq ${type_usb} ]; then
            line="${card}"
            break
        fi
    done
    echo "${line}"
 }

get_card_id()
{
    local path_to_file=$(get_data_from_entry $*)

    if [ -z "${path_to_file}" ]; then
        echo ""
    else
        echo "$(egrep "^card: " ${path_to_file} | cut -f 2 -d ':' | sed 's/ //g')"
    fi
}

get_dev_id()
{
    local path_to_file=$(get_data_from_entry $*)

    if [ -z "${path_to_file}" ]; then
        echo ""
    else
        echo "$(egrep "^device: " ${path_to_file} | cut -f 2 -d ':' | sed 's/ //g')"
    fi
}

list_seats()
{
    IFS=$'\n'
    echo "Seats sound config:"
    for entry in $(cat ${CONF_FILE_PATH}); do
        local key=$(echo ${entry} | cut -f1 -d=)
        local value=$(echo ${entry} | cut -f2 -d=)
        local vid=$(echo ${value} | cut -f 1 -d ';')
        local did=$(echo ${value} | cut -f 2 -d ';')
        local type_usb=$(echo ${value} | cut -f 4 -d ';')
        local label="$(get_card_label ${vid} ${did} ${type_usb})"
        echo -n "    - $(echo ${key} | sed 's/t/t /g')) Vendor ID ${vid}, Device ID ${did}: ${label}, type: "
        if [ ${type_usb} -eq 1 ]; then
            echo "usb."
        else
            echo "pci."
        fi
    done
    unset IFS
}

install()
{
    if [ "$(whoami)" != "root" ]; then
        echo "this program must be run as root"
        exit 1
    fi
    local i=0
    populate_cards

    avail_enteries=("${cards_info[@]}")
    local selection=""
    local seat_id=0
    local avail_card

    while [ 1 ]; do
        echo "Available cards:"
        avail_card=0
        while [ ${#avail_enteries[@]} -gt ${avail_card} ]; do
            local vid=$(echo ${avail_enteries[${avail_card}]} | cut -f 1 -d ';')
            local did=$(echo ${avail_enteries[${avail_card}]} | cut -f 2 -d ';')
            local type_usb=$(echo ${avail_enteries[${avail_card}]} | cut -f 4 -d ';')
            local label="$(get_card_label ${vid} ${did} ${type_usb})"
            echo "  $((avail_card+1)). ${vid}:${did}, Label: ${label}, type $(echo ${avail_enteries[${avail_card}]} | cut -f 3 -d ';')"
            avail_card=$((${avail_card} + 1))
        done

        echo -n "please select card for seat ${seat_id}, I to install or q to quit: "
        read selection
        if [ "${selection}" = "I" -o "${selection}" = "q" ]; then
            break
        fi
        if ! [[ ${selection} =~ ${INT_REGEX} ]]; then
            echo "invalid seletion, please select again."
            continue
        elif [ ${selection} -lt 1 -o ${selection} -gt ${#avail_enteries[@]} ]; then
            echo "invalid seletion, please select again."
            continue
        fi
        local pos=$((${selection} - 1))
        assignments=("${assignments[@]}" "Seat${seat_id}=$(echo ${avail_enteries[${pos}]})")
        seat_id=$((seat_id + 1))
        local last_entry_idx=${#avail_enteries[@]}
        last_entry_idx=$((last_entry_idx-1))
        avail_enteries[${pos}]=${avail_enteries[${last_entry_idx}]}
        unset avail_enteries[${last_entry_idx}]
    done
    if [ "${selection}" = "I" ]; then
        install_files
    fi
 }

uninstall()
{
    for option in "${CONNECTORS[@]}"; do
        target_path="$(dirname ${option})/${PREFIX}$(basename ${option})"
        if [ -h "${target_path}" ]; then
            rm -f ${target_path}
        fi
    done
}

update_asoundrc()
{
    if [ "$(whoami)" != "root" -a -f ~/.asoundrc -a $(who | grep "${USER}" | grep -cv "pts") -eq 1 ]; then
        local entry=$(grep "^Seat$(get_seat_id)=" ${CONF_FILE_PATH} | cut -f 2 -d '=')
        sed -i "s/\.card [0-9]*/\.card $(get_card_id ${entry})/g" ~/.asoundrc
        sed -i "s/\.device [0-9]*/\.device $(get_dev_id ${entry} )/g" ~/.asoundrc
    fi
}

for option in "${CONNECTORS[@]}"; do
    cmd="${PREFIX}$(basename ${option})"
    if [ "$(basename ${INSTANCE})" = "${cmd}" ]; then
        $(basename ${option}) $*
        SERVED=1
    fi
done

if [ ${SERVED} -eq 0 ]; then
    entry=${CONNECTORS[0]}
    if [ ! -h "$(dirname ${entry})/${PREFIX}$(basename ${entry})" ]; then
        $(basename ${entry}) $*
    else
        echo -n "possible commands: "
        line=""
        for option in "${CONNECTORS[@]}"; do
            line="${line} ${PREFIX}$(basename ${option}), "
        done
        echo "$(echo ${line} | sed 's/,$/./g')"
    fi
fi