helper_lib.sh

#!/bin/sh

# Returns the absolute path of a given string
abspath () { case "$1" in /*)printf "%s\n" "$1";; *)printf "%s\n" "$PWD/$1";; esac; }

# Compares versions of software of the format X.Y.Z
do_version_check() {
    [ "$1" = "$2" ] && return 10

    ver1front=$(printf "%s" "$1" | cut -d "." -f -1)
    ver1back=$(printf "%s" "$1" | cut -d "." -f 2-)
    ver2front=$(printf "%s" "$2" | cut -d "." -f -1)
    ver2back=$(printf "%s" "$2" | cut -d "." -f 2-)

    if [ "$ver1front" != "$1" ] || [ "$ver2front" != "$2" ]; then
        [ "$ver1front" -gt "$ver2front" ] && return 11
        [ "$ver1front" -lt "$ver2front" ] && return 9

        [ "$ver1front" = "$1" ] || [ -z "$ver1back" ] && ver1back=0
        [ "$ver2front" = "$2" ] || [ -z "$ver2back" ] && ver2back=0
        do_version_check "$ver1back" "$ver2back"
        return $?
    else
        [ "$1" -gt "$2" ] && return 11 || return 9
    fi
}

# Compares two strings and returns 0 if the second is a substring of the first
contains() {
    string="$1"
    substring="$2"
    if [ "${string#*$substring}" != "$string" ]
    then
        return 0    # $substring is in $string
    else
        return 1    # $substring is not in $string
    fi
}

# Extracts all commandline args from the oldest running processes named like the first parameter
get_command_line_args() {
    PROC="$1"

    for PID in $(pgrep -x -o "$PROC")
    do
        tr "\0" " " < /proc/"$PID"/cmdline
    done
}

# Extract the cumulative command line arguments for the docker daemon
#
# If specified multiple times, all matches are returned.
# Accounts for long and short variants, call with short option.
# Does not account for option defaults or implicit options.
get_docker_cumulative_command_line_args() {
    OPTION="$1"

    get_command_line_args docker |
    # normalize known long options to their short versions
    sed \
        -e 's/\-\-debug/-D/g' \
        -e 's/\-\-host/-H/g' \
        -e 's/\-\-log-level/-l/g' \
        -e 's/\-\-version/-v/g' \
        |
    # normalize parameters separated by space(s) to -O=VALUE
    sed \
        -e 's/\-\([DHlv]\)[= ]\([^- ][^ ]\)/-\1=\2/g' \
        |
    # get the last interesting option
    tr ' ' "\n" |
    grep "^${OPTION}" |
    # normalize quoting of values
    sed \
        -e 's/"//g' \
        -e "s/'//g"
}

# Extract the effective command line arguments for the docker daemon
#
# Accounts for multiple specifications, takes the last option.
# Accounts for long and short variants, call with short option
# Does not account for option default or implicit options.
get_docker_effective_command_line_args() {
    OPTION="$1"
    get_docker_cumulative_command_line_args $OPTION | tail -n1
}

get_etc_path(){
    # running in Docker container: mount /etc directory to /host/etc
    if [ -d /host/etc ]; then
        echo "/host/etc"
    else
        echo "/etc"
    fi
}

get_systemd_service_file(){
    SERVICE="$1"

    if [ -f "$(get_etc_path)/systemd/system/$SERVICE" ]; then
      echo "$(get_etc_path)/systemd/system/$SERVICE"
    elif systemctl show -p FragmentPath "$SERVICE" 2> /dev/null 1>&2; then
      systemctl show -p FragmentPath "$SERVICE" | sed 's/.*=//'
    else
      echo "/usr/lib/systemd/system/$SERVICE"
    fi
}