#!/bin/bash
#
# Copyright (c) 2020-2023 Wind River Systems, Inc.
#
# SPDX-License-Identifier: Apache-2.0
#

CRASHDUMPMGR_TAG=${CRASHDUMPMGR_TAG:-"crash-dump-manager"}

RETVAL=0

# Default values and constants
DEFAULT_MAX_SIZE=5368709120 # "5GiB"
DEFAULT_MAX_FILES=4
UNLIMITED="unlimited"
DEFAULT="default"
DEFAULT_MAX_USED="${UNLIMITED}"  # Assign UNLIMITED to DEFAULT_MAX_USED
DEFAULT_MIN_REMAINDER_PERCENT=10
MIN_REMAINDER_MINIMUM=1073741824  # 1GiB in bytes

# number format to/from human readable commands.
NUMFMT_TO_HR="/usr/bin/numfmt --to=iec"
NUMFMT_FROM_HR="/usr/bin/numfmt --from=auto"

#############################################################################
# Log message to syslog
#############################################################################

function log()
{
    logger -t "${CRASHDUMPMGR_TAG}" "$@"
}

#############################################################################
#
# Name   : manage_crash_dumps
#
# Purpose: Prevent crash dumps from filling up the root fs
#
# The kernel directs new crash dump bundles to
# /var/crash/<dated vmcore bundle>. Crash dump
# bundles are quite large and, if too many occur,
# can fill up its target filesystem.
#
# This function manages the crash dump bundles, creating tar archives for
# storage, handling maximum file count and storage limits, and preserving
# summaries of the crash dumps.
#
# The first bundle is tar'ed as vmcore_first.tar and preserved.
# Subsequent crash bundles are nicely tar'ed as vmcore_<date>.tar.
#
# Save the crash dump vmcore summary for all crash dumps.
#
# Assumptions: log rotation is used to compress these bundles in the background
#
# Parameters:
#   $1 = max_size ; maximum vmcore size to keep (human-readable size or "unlimited")
#   $2 = max_files ; maximum number of crash dump files to keep
#   $3 = max_used ; maximum used storage size (human-readable size or "unlimited")
#   $4 = min_available ; minimum available storage size (human-readable size)
#
############################################################################


function manage_crash_dumps()
{
    CRASH_DIR="/var/crash"
    CRASH_BUNDLE_DIR="/var/log/crash"
    OTHER_BUNDLE="${CRASH_BUNDLE_DIR}/vmcore"
    FIRST_BUNDLE="${CRASH_BUNDLE_DIR}/vmcore_first.tar"
    FIRST_BUNDLE_ROTATED="${CRASH_BUNDLE_DIR}/vmcore_first.tar.1.gz"
    CRASH_BUNDLE_SUMMARY="vmcore-dmesg.txt"
    CRASH_BUNDLE_SUMMARY_DEB="dmesg."

    if [ "${4}" = "" ] ; then
        # Get the size of the filesystem assigned to /var/log/crash in bytes
        fs_size=$(df -B1 ${CRASH_BUNDLE_DIR} | awk 'NR==2 {print $2}')
        # Calculate min_available as the percentage of the filesystem size
        min_available=$((${fs_size} * ${DEFAULT_MIN_REMAINDER_PERCENT} / 100))
    else
        min_available=${4}
    fi

    # Set a minimum value for min_available
    if [ ${min_available} -lt ${MIN_REMAINDER_MINIMUM} ]; then
        min_available=${MIN_REMAINDER_MINIMUM}
    fi

    max_size_hr=""
    max_used_hr=""
    if [ "${max_size}" != "${UNLIMITED}" ]; then
        max_size_hr="($(${NUMFMT_TO_HR} ${max_size}))"
    fi
    if [ "${max_used}" != "${UNLIMITED}" ]; then
        max_used_hr="($(${NUMFMT_TO_HR} ${max_used}))"
    fi
    min_available_hr=$(${NUMFMT_TO_HR} ${min_available})

    log "max crash dump files set to ${max_files}"
    log "max crash dump vmcore size is ${max_size} ${max_size_hr}"
    log "max used storage size is ${max_used} ${max_used_hr}"
    log "minimum available storage size is ${min_available} (${min_available_hr})"

    # tar command and nice levels
    TAR_CMD="tar -cf"
    NICE_CMD="/usr/bin/nice -n19"
    IONICE_CMD="/usr/bin/ionice -c2 -n7"

    log "managing ${CRASH_DIR}"

    # create dir if it does not exist
    if [ ! -d ${CRASH_BUNDLE_DIR} ] ; then
        mkdir ${CRASH_BUNDLE_DIR}
    fi
    for entry in $(ls -rt ${CRASH_DIR}/);
    do
        entry=${CRASH_DIR}/${entry}
        remove_entry=false
        max_files_saved=false
        if [ -d "${entry}" ] ; then
            time=${entry##*/}
            if [ -e "${entry}/${CRASH_BUNDLE_SUMMARY_DEB}${time}" ] ; then
                log "saving summary: ${CRASH_DIR}/$(basename ${time})_${CRASH_BUNDLE_SUMMARY_DEB}${time}"

                # save the crash dump dmesg.<date> for debian for all crash dumps
                cp -a ${entry}/${CRASH_BUNDLE_SUMMARY_DEB}${time} ${CRASH_DIR}/$(basename ${time})_${CRASH_BUNDLE_SUMMARY_DEB}${time}
            fi
            if [ -e "${entry}/${CRASH_BUNDLE_SUMMARY}" ] ; then
                log "saving summary: ${CRASH_DIR}/$(basename ${entry})_${CRASH_BUNDLE_SUMMARY}"

                # save the crash dump vmcore summary for all crash dumps
                cp -a ${entry}/${CRASH_BUNDLE_SUMMARY} ${CRASH_DIR}/$(basename ${entry})_${CRASH_BUNDLE_SUMMARY}
            fi
            if [ -e "${entry}/dump.${time}" ] || [ -e "${entry}/vmcore" ] ; then

                # get the size of this vmcore file ; raw and human readable
                if [ -e "${entry}/dump.${time}" ] ; then
                    vmcore_size=$(stat --format='%s' ${entry}/dump.${time})
                else
                    vmcore_size=$(stat --format='%s' ${entry}/vmcore)
                fi
                vmcore_size_hr=$(${NUMFMT_TO_HR} ${vmcore_size})

                # Manage max number of files
                files_in_crash_bundle_dir=$(ls -A ${CRASH_BUNDLE_DIR} | wc -l)
                num_files_to_remove=$((files_in_crash_bundle_dir-max_files+1))

                if [ "${num_files_to_remove}" -ge 1 ]; then
                    files_to_remove=$(ls -t ${CRASH_BUNDLE_DIR} | tail -$((num_files_to_remove+1)) | head -$((num_files_to_remove)))
                    files_to_remove_size=0
                    for file in ${files_to_remove}; do
                        files_to_remove_size+=$(stat --format='%s' ${file})
                    done
                    max_files_saved=true
                fi

                # get available ${CRASH_BUNDLE_DIR} fs space in bytes
                available=$(df -B1 ${CRASH_BUNDLE_DIR} | grep -v Available | awk '{ print $4 }')

                # get the current used space in the ${CRASH_BUNDLE_DIR} fs
                used_space=$(du -sb ${CRASH_BUNDLE_DIR} | awk '{print $1}')

                # if the ${CRASH_BUNDLE_DIR} contains the maximum number of files, the available and used_space
                # need to be updated to the value after deleting the oldest crash dump file.
                if [ "${max_files_saved}" = true ] ; then
                    available=$((available+files_to_remove_size))
                    used_space=$((used_space-files_to_remove_size))
                fi
                available_hr=$(${NUMFMT_TO_HR} ${available})
                log "new vmcore detected (size:${vmcore_size}:${vmcore_size_hr}) ;" \
                "${CRASH_BUNDLE_DIR} avail:${available}:${available_hr}"

                # Don't save this crash dump if it would leave the
                # ${CRASH_BUNDLE_DIR} filesystem with less than 1GiB.
                if [ ${available} -gt ${vmcore_size} ]; then
                    remaining=$((available-vmcore_size))
                else
                    remaining=0
                fi

                # Check if adding the file would exceed the maximum used space limit
                total_used_space=$((used_space + file_size))
                if [ "${max_used}" != "$UNLIMITED" ] && [ ${total_used_space} -gt ${max_used} ]; then

                     log "The last crash dump is not saved because it would exceed the maximum" \
                     "used space limit specified in the max_used parameter (${max_used} bytes)."
                    remove_entry=true

                # check for min required 'remaining' ${CRASH_BUNDLE_DIR} filesystem space
                elif [ ${remaining} -lt ${min_available} ] ; then
                    log "insufficient space in ${CRASH_BUNDLE_DIR} for ${vmcore_size_hr} ${entry};" \
                    "would leave only ${remaining} bytes"
                    remove_entry=true

                # create a new crash bundle if the vmcore file isn't oversized
                elif [ ${vmcore_size} -lt ${max_size} ] || [ "${max_size}" = "${UNLIMITED}" ] ; then

                    if [ ! -e "${FIRST_BUNDLE}" ] && [ ! -e "${FIRST_BUNDLE_ROTATED}" ]; then
                        log "creating first bundle from ${entry}"
                        ${IONICE_CMD} ${NICE_CMD} ${TAR_CMD} ${FIRST_BUNDLE} -C ${CRASH_DIR} $(basename ${entry})

                    else
                        if [ "${max_files_saved}" = true ] ; then
                            for file in ${files_to_remove}; do
                                # delete old vmcore file
                                log "removing old vmcore file: ${file}"
                                rm -rf "${CRASH_BUNDLE_DIR}/${file}"
                            done
                        fi
                        log "creating bundle from ${entry}"
                        ${IONICE_CMD} ${NICE_CMD} ${TAR_CMD} ${OTHER_BUNDLE}_${time}.tar -C ${CRASH_DIR} $(basename ${entry})
                    fi
                    remove_entry=true
                else
                    log "deleting oversize (${vmcore_size_hr}) vmcore file $(basename ${entry})"
                    remove_entry=true
                fi
            elif [[ "$entry" == *"_dmesg."* ]] || [[ "$entry" == *"_vmcore-dmesg.txt"* ]] ; then
                log "saved old $entry summary"
            elif [[ "$entry" != "$CRASH_DIR/*"  ]] ; then
                # removes vmcore files not named properly
                # i.e vmcore.incomplete
                remove_entry=true
            fi
        elif [[ "$entry" != *"_dmesg."* ]] && [[ "$entry" != *"_vmcore-dmesg.txt"* ]] ; then
            # removes files in /var/crash that are not crash dumps related
            remove_entry=true
        fi

        if [ "${remove_entry}" = true ] ; then
            log "removing ${entry}"
            rm -rf "${entry}"
        fi
    done
}

function print_help() {
    echo "Usage: $(basename "$0") [OPTIONS]"
    echo "Options:"
    echo "  --max-size <size>     Set maximum vmcore size (human-readable size or \"$UNLIMITED\")"
    echo "  --max-files <number>  Set maximum number of crash dump files"
    echo "  --max-used <size>     Set maximum used storage size (human-readable size or \"$UNLIMITED\")"
    echo "  --min-available <size> Set minimum available storage size (human-readable size)"
}

normalize_size_format() {
    echo "$1" | tr ',' '.'
}

# Initialize default values
max_size="${DEFAULT_MAX_SIZE}"
max_files="${DEFAULT_MAX_FILES}"
max_used="${DEFAULT_MAX_USED}"
min_available=""

# Initialize a flag to indicate if help has been shown
help_shown=false

# Parse the command line
while [[ $# -gt 0 ]]; do
    case "${1}" in
        -h|--help)
            print_help
            help_shown=true
            shift
            ;;

        --max-size)
            shift
            if [ "${1}" = "${UNLIMITED}" ]; then
                max_size=${UNLIMITED}
            else
                max_size=$(${NUMFMT_FROM_HR} "$(normalize_size_format "${1}")")
            fi
            shift
            ;;

        --max-files)
            shift
            max_files="${1}"
            shift
            ;;

        --max-used)
            shift
            if [ "${1}" = "${UNLIMITED}" ]; then
                max_used=${UNLIMITED}
            else
                max_used=$(${NUMFMT_FROM_HR} "$(normalize_size_format "${1}")")
            fi
            shift
            ;;

        --min-available)
            shift
            if [ "${1}" = "${DEFAULT}" ]; then
                min_available=""
            else
                min_available=$(${NUMFMT_FROM_HR} "$(normalize_size_format "${1}")")
            fi
            shift
            ;;

        *)
            if [ "${help_shown}" = false ]; then
                print_help
                help_shown=true
            else
                # Handle unknown options or arguments
                shift
            fi
            ;;
    esac
done

manage_crash_dumps ${max_size} ${max_files} ${max_used} ${min_available}

exit $RETVAL