#!/bin/bash

#

# This comes from the dracut-logger.sh

#

# The logger defined 4 logging levels:

#   - ddebug (4)

#     The DEBUG Level designates fine-grained informational events that are most

#     useful to debug an application.

#   - dinfo (3)

#     The INFO level designates informational messages that highlight the

#     progress of the application at coarse-grained level.

#   - dwarn (2)

#     The WARN level designates potentially harmful situations.

#   - derror (1)

#     The ERROR level designates error events that might still allow the

#     application to continue running.

#

# Logging is controlled by following global variables:

#   - @var kdump_stdloglvl - logging level to standard error (console output)

#   - @var kdump_sysloglvl - logging level to syslog (by logger command)

#   - @var kdump_kmsgloglvl - logging level to /dev/kmsg (only for boot-time)

#

# If any of the variables is not set, the function dlog_init() sets it to default:

#   - In the first kernel:

#     - @var kdump_stdloglvl = 3 (info)

#     - @var kdump_sysloglvl = 0 (no logging)

#     - @var kdump_kmsgloglvl = 0 (no logging)

#

#   -In the second kernel:

#    - @var kdump_stdloglvl = 0 (no logging)

#    - @var kdump_sysloglvl = 3 (info)

#    - @var kdump_kmsgloglvl = 0 (no logging)

#

# First of all you have to start with dlog_init() function which initializes

# required variables. Don't call any other logging function before that one!

#

# Define vairables for the log levels in this module.

kdump_stdloglvl=""

kdump_sysloglvl=""

kdump_kmsgloglvl=""

# The dracut-lib.sh is only available in the second kernel, and it won't

# be used in the first kernel because the dracut-lib.sh is invisible in

# the first kernel.

if [ -f /lib/dracut-lib.sh ]; then

    . /lib/dracut-lib.sh

fi

# @brief Get the log level from kernel command line.

# @retval 1 if something has gone wrong

# @retval 0 on success.

#

get_kdump_loglvl()

{

    (type -p getarg) && kdump_sysloglvl=$(getarg rd.kdumploglvl)

    [ -z "$kdump_sysloglvl" ] && return 1;

    (type -p isdigit) && isdigit $kdump_sysloglvl

    [ $? -ne 0 ] && return 1;

    return 0

}

# @brief Check the log level.

# @retval 1 if something has gone wrong

# @retval 0 on success.

#

check_loglvl()

{

    case "$1" in

        0|1|2|3|4)

            return 0

           ;;

        *)

            return 1

            ;;

        esac

}

# @brief Initializes Logger.

# @retval 1 if something has gone wrong

# @retval 0 on success.

#

dlog_init() {

    local ret=0; local errmsg

    if [ -s /proc/vmcore ];then

        get_kdump_loglvl

        if [ $? -ne 0 ];then

            logger -t "kdump[$$]" -p warn -- "Kdump is using the default log level(3)."

            kdump_sysloglvl=3

        fi

        kdump_stdloglvl=0

        kdump_kmsgloglvl=0

    else

        kdump_stdloglvl=$KDUMP_STDLOGLVL

        kdump_sysloglvl=$KDUMP_SYSLOGLVL

        kdump_kmsgloglvl=$KDUMP_KMSGLOGLVL

    fi

    [ -z "$kdump_stdloglvl" ] && kdump_stdloglvl=3

    [ -z "$kdump_sysloglvl" ] && kdump_sysloglvl=0

    [ -z "$kdump_kmsgloglvl" ] && kdump_kmsgloglvl=0

    for loglvl in "$kdump_stdloglvl" "$kdump_kmsgloglvl" "$kdump_sysloglvl"; do

        check_loglvl "$loglvl"

        if [ $? -ne 0 ]; then

            echo "Illegal log level: $kdump_stdloglvl $kdump_kmsgloglvl $kdump_sysloglvl"

            return 1

        fi

    done

    # Skip initialization if it's already done.

    [ -n "$kdump_maxloglvl" ] && return 0

    if [[ $UID -ne 0 ]]; then

        kdump_kmsgloglvl=0

        kdump_sysloglvl=0

    fi

    if [[ $kdump_sysloglvl -gt 0 ]]; then

        if [[ -d /run/systemd/journal ]] \

            && type -P systemd-cat &>/dev/null \

            && systemctl --quiet is-active systemd-journald.socket &>/dev/null; then

            readonly _systemdcatfile="/var/tmp/systemd-cat"

            mkfifo "$_systemdcatfile" &>/dev/null

            readonly _dlogfd=15

            systemd-cat -t 'kdump' --level-prefix=true <"$_systemdcatfile" &

            exec 15>"$_systemdcatfile"

        elif ! [ -S /dev/log -a -w /dev/log ] || ! command -v logger >/dev/null; then

            # We cannot log to syslog, so turn this facility off.

            kdump_kmsgloglvl=$kdump_sysloglvl

            kdump_sysloglvl=0

            ret=1

            errmsg="No '/dev/log' or 'logger' included for syslog logging"

        fi

    fi

    local lvl; local maxloglvl_l=0

    for lvl in $kdump_stdloglvl $kdump_sysloglvl $kdump_kmsgloglvl; do

        [[ $lvl -gt $maxloglvl_l ]] && maxloglvl_l=$lvl

    done

    readonly kdump_maxloglvl=$maxloglvl_l

    export kdump_maxloglvl

    if [[ $kdump_stdloglvl -lt 4 ]] && [[ $kdump_kmsgloglvl -lt 4 ]] && [[ $kdump_sysloglvl -lt 4 ]]; then

        unset ddebug

        ddebug() { :; };

    fi

    if [[ $kdump_stdloglvl -lt 3 ]] && [[ $kdump_kmsgloglvl -lt 3 ]] && [[ $kdump_sysloglvl -lt 3 ]]; then

        unset dinfo

        dinfo() { :; };

    fi

    if [[ $kdump_stdloglvl -lt 2 ]] && [[ $kdump_kmsgloglvl -lt 2 ]] && [[ $kdump_sysloglvl -lt 2 ]]; then

        unset dwarn

        dwarn() { :; };

        unset dwarning

        dwarning() { :; };

    fi

    if [[ $kdump_stdloglvl -lt 1 ]] && [[ $kdump_kmsgloglvl -lt 1 ]] && [[ $kdump_sysloglvl -lt 1 ]]; then

        unset derror

        derror() { :; };

    fi

    [ -n "$errmsg" ] && derror "$errmsg"

    return $ret

}

## @brief Converts numeric level to logger priority defined by POSIX.2.

#

# @param lvl Numeric logging level in range from 1 to 4.

# @retval 1 if @a lvl is out of range.

# @retval 0 if @a lvl is correct.

# @result Echoes logger priority.

_lvl2syspri() {

    case "$1" in

        1) echo error;;

        2) echo warning;;

        3) echo info;;

        4) echo debug;;

        *) return 1;;

    esac

}

## @brief Converts logger numeric level to syslog log level

#

# @param lvl Numeric logging level in range from 1 to 4.

# @retval 1 if @a lvl is out of range.

# @retval 0 if @a lvl is correct.

# @result Echoes kernel console numeric log level

#

# Conversion is done as follows:

#

# <tt>

#   none     -> LOG_EMERG (0)

#   none     -> LOG_ALERT (1)

#   none     -> LOG_CRIT (2)

#   ERROR(1) -> LOG_ERR (3)

#   WARN(2)  -> LOG_WARNING (4)

#   none     -> LOG_NOTICE (5)

#   INFO(3)  -> LOG_INFO (6)

#   DEBUG(4) -> LOG_DEBUG (7)

# </tt>

#

# @see /usr/include/sys/syslog.h

_dlvl2syslvl() {

    local lvl

    case "$1" in

        1) lvl=3;;

        2) lvl=4;;

        3) lvl=6;;

        4) lvl=7;;

        *) return 1;;

    esac

    # The number is constructed by multiplying the facility by 8 and then

    # adding the level.

    # About The Syslog Protocol, please refer to the RFC5424 for more details.

    echo $((24+$lvl))

}

## @brief Prints to stderr, to syslog and/or /dev/kmsg given message with

#  given level (priority).

#

# @param lvl Numeric logging level.

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

#

# @note This function is not supposed to be called manually. Please use

# dinfo(), ddebug(), or others instead which wrap this one.

#

# This is core logging function which logs given message to standard error

# and/or syslog (with POSIX shell command <tt>logger</tt>) and/or to /dev/kmsg.

# The format is following:

#

# <tt>X: some message</tt>

#

# where @c X is the first letter of logging level. See module description for

# details on that.

#

# Message to syslog is sent with tag @c kdump. Priorities are mapped as

# following:

#   - @c ERROR to @c error

#   - @c WARN to @c warning

#   - @c INFO to @c info

#   - @c DEBUG to @c debug

_do_dlog() {

    local lvl="$1"; shift

    local msg="$*"

    [[ $lvl -le $kdump_stdloglvl ]] && printf -- 'kdump: %s\n' "$msg" >&2

    if [[ $lvl -le $kdump_sysloglvl ]]; then

        if [[ "$_dlogfd" ]]; then

            printf -- "<%s>%s\n" "$(($(_dlvl2syslvl $lvl) & 7))" "$msg" >&$_dlogfd

        else

            logger -t "kdump[$$]" -p $(_lvl2syspri $lvl) -- "$msg"

        fi

    fi

    [[ $lvl -le $kdump_kmsgloglvl ]] && \

        echo "<$(_dlvl2syslvl $lvl)>kdump[$$] $msg" >/dev/kmsg

}

## @brief Internal helper function for _do_dlog()

#

# @param lvl Numeric logging level.

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

#

# @note This function is not supposed to be called manually. Please use

# dinfo(), ddebug(), or others instead which wrap this one.

#

# This function calls _do_dlog() either with parameter msg, or if

# none is given, it will read standard input and will use every line as

# a message.

#

# This enables:

# dwarn "This is a warning"

# echo "This is a warning" | dwarn

dlog() {

    [ -z "$kdump_maxloglvl" ] && return 0

    [[ $1 -le $kdump_maxloglvl ]] || return 0

    if [[ $# -gt 1 ]]; then

        _do_dlog "$@"

    else

        while read line || [ -n "$line" ]; do

            _do_dlog "$1" "$line"

        done

    fi

}

## @brief Logs message at DEBUG level (4)

#

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

ddebug() {

    set +x

    dlog 4 "$@"

    [ -n "$debug" ] && set -x || :

}

## @brief Logs message at INFO level (3)

#

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

dinfo() {

    set +x

    dlog 3 "$@"

    [ -n "$debug" ] && set -x || :

}

## @brief Logs message at WARN level (2)

#

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

dwarn() {

    set +x

    dlog 2 "$@"

    [ -n "$debug" ] && set -x || :

}

## @brief It's an alias to dwarn() function.

#

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

dwarning() {

    set +x

    dwarn "$@"

    [ -n "$debug" ] && set -x || :

}

## @brief Logs message at ERROR level (1)

#

# @param msg Message.

# @retval 0 It's always returned, even if logging failed.

derror() {

    set +x

    dlog 1 "$@"

    [ -n "$debug" ] && set -x || :

}