log2ram/log2ram

#!/usr/bin/env sh

. /etc/log2ram.conf

if [ -z "$PATH_DISK" ]; then
    PATH_DISK='/var/log'
fi

LOG_NAME='log2ram.log'
NO_RSYNC=${USE_RSYNC#true}

isSafe () {
    [ -d "$HDD_LOG" ] || echo "ERROR: $HDD_LOG/ doesn't exist! Can't sync."
    [ -d "$HDD_LOG" ] || exit 1
}

remountOriginal() {
    OPTION="$1"
    mount -o remount,"$OPTION" "$HDD_LOG"
}

syncToDisk () {
    isSafe

    if [ -z "${NO_RSYNC}" -a -x "$(command -v rsync)" ]; then
        rsync -aXv --inplace --no-whole-file --delete-after "$RAM_LOG"/ "$HDD_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    else
        cp -rfup "$RAM_LOG"/ -T "$HDD_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    fi
}

syncFromDisk () {
    isSafe

    TP_SIZE=$SIZE
    if [ "$ZL2R" = true ]; then
        TP_SIZE=$LOG_DISK_SIZE
    fi

    if [ -n "$(du -sh -t "$TP_SIZE" "$HDD_LOG"/ | cut -f1)" ]; then
        echo "ERROR: RAM disk for \"$HDD_LOG/\" too small. Can't sync."
        umount -l "$RAM_LOG"/
        umount -l "$HDD_LOG"/
        if [ "$MAIL" = true ]; then
            echo "LOG2RAM : No place on RAM for \"$HDD_LOG/\" anymore, fallback on the disk" | mail -s 'Log2Ram Error' root;
        fi
        exit 1
    fi

    if [ -z "${NO_RSYNC}" -a -x "$(command -v rsync)" ]; then
        rsync -aXv --inplace --no-whole-file --delete-after "$HDD_LOG"/ "$RAM_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    else
        cp -rfup "$HDD_LOG"/ -T "$RAM_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    fi

}

wait_for () {
    while ! findmnt "$1" > /dev/null; do
      sleep 0.1
    done
    
    while [ ! -f "$1/log2ram.test" ]; do
        touch "$1/log2ram.test"
        sleep 0.1
    done
    rm "$1/log2ram.test"
}

createZramLogDrive () {
	# Check Zram Class created
	if [ ! -d "/sys/class/zram-control" ]; then
		modprobe zram
		RAM_DEV='0'
	else
		RAM_DEV=$(cat /sys/class/zram-control/hot_add)
	fi
	echo "$COMP_ALG" > "/sys/block/zram${RAM_DEV}/comp_algorithm"
	echo "$LOG_DISK_SIZE" > "/sys/block/zram${RAM_DEV}/disksize"
	echo "$SIZE" > "/sys/block/zram${RAM_DEV}/mem_limit"
	mke2fs -t ext4 "/dev/zram${RAM_DEV}"
}

make_log_dir () {
    [ -d "$HDD_LOG" ] || mkdir "$HDD_LOG"
}

case "$1" in
    start)
        IFS=';'
        for i in $PATH_DISK; do
            # Skip the path if the folder doesn't exist
            [ ! -d "$i" ] && continue
            
            PATH_FIRST_PART="${i%/*}"
            PATH_LAST_PART="${i##/*/}"
            RAM_LOG="$i"
            HDD_LOG="${PATH_FIRST_PART}/hdd.${PATH_LAST_PART}"
            LOG2RAM_LOG="${RAM_LOG}/${LOG_NAME}"

            make_log_dir

            mount --bind "$RAM_LOG"/ "$HDD_LOG"/
            mount --make-private "$HDD_LOG"/
            wait_for "$HDD_LOG"

            if [ "$ZL2R" = true ]; then
                createZramLogDrive
                mount -t ext4 -o nosuid,noexec,noatime,nodev,user=log2ram "/dev/zram${RAM_DEV}" "$RAM_LOG"/
            else
                mount -t tmpfs -o "nosuid,noexec,noatime,nodev,mode=0755,size=${SIZE}" log2ram "$RAM_LOG"/
            fi
            wait_for "$RAM_LOG"
            syncFromDisk
        done
        exit 0
        ;;

    stop)
        IFS=';'
        for i in $PATH_DISK; do
            PATH_FIRST_PART="${i%/*}"
            PATH_LAST_PART="${i##/*/}"
            RAM_LOG="$i"
            HDD_LOG="${PATH_FIRST_PART}/hdd.${PATH_LAST_PART}"
            LOG2RAM_LOG="${RAM_LOG}/${LOG_NAME}"

            syncToDisk
            #ZRAM_LOG=$(awk '$2 == "/var/log" {print $1}' /proc/mounts)
            #ZRAM_LOG=$(echo ${ZRAM_LOG} | grep -o -E '[0-9]+')
            umount -l "$RAM_LOG"/
            umount -l "$HDD_LOG"/
            # Unsure as even with Root permision denied
            #echo ${ZRAM_LOG} > /sys/class/zram-control/hot_remove
        done
        exit 0
        ;;

    write)
        IFS=';'
        for i in $PATH_DISK; do
            PATH_FIRST_PART="${i%/*}"
            PATH_LAST_PART="${i##/*/}"
            RAM_LOG="$i"
            HDD_LOG="${PATH_FIRST_PART}/hdd.${PATH_LAST_PART}"
            LOG2RAM_LOG="${RAM_LOG}/${LOG_NAME}"

            syncToDisk
        done
        exit 0
        ;;

    *)
        echo 'Usage: log2ram {start|stop|write}' >&2
        exit 1
        ;;
esac