#!/bin/bash
#
# Script to "commit" aufs tmpfs changes back to the underlying persistent filesystem.
#

SCRIPT="`realpath $0`"
ROOT=/.rw
AUFS=$ROOT/.tmpfs
arg1="$1"

MIRRORDIR=/usr/bin/mirrordir
if [ ! -x $MIRRORDIR ]; then
        echo "$MIRRORDIR: not found; aborting." >&2
        exit 1
fi

COMMIT=""
if [ "$1" = "--commit" ]; then
        COMMIT="$1"
        shift
fi

function doit(){
        echo "$*"
        [ "$COMMIT" = "--commit" ] && $*
}

if [ "$1" = "" ]; then
        cd $AUFS || exit 1
        find . -type f -name .wh.\* | xargs -n1 $SCRIPT $COMMIT WHITEOUT
        doit sync

        cd $AUFS || exit 1
        find . | xargs -n1 $SCRIPT $COMMIT COPY
        doit sync

        [ "$COMMIT" = "--commit" ] || (echo ;echo "$SCRIPT: Dry run complete. Use --commit to do it for real"; echo)
        exit 0
fi

if [ "$1" = "WHITEOUT" ]; then
        cd $AUFS || exit 1
        dir="${2%%/.wh.*}"
        fn="${2##*/.wh.}"
        if [ "$dir" = "." ]; then
                [ "$fn" = ".rw" -o "$fn" = ".aufs" -o "$fn" = ".tmpfs" ] && exit 0
        fi
        if [ "$fn" = ".wh..opq" ]; then
                if [ -d "$ROOT/$dir" ]; then
                        if [ -d "$dir" ]; then
                                doit $MIRRORDIR -v --exclude-regexp '.*/[.]wh[.].*' "$dir" "$ROOT/$dir"
                        else
                                doit rm -rf "$ROOT/$dir"
                        fi
                fi
                exit 0
        fi
        if [ "$dir/.wh.$fn" = "$2" ]; then
                [ -e "$ROOT/$dir/$fn" ] && doit rm -rf "$ROOT/$dir/$fn"
        fi
        exit 0
fi

if [ "$1" = "COPY" ]; then
        cd $AUFS || exit 1
        if [ -d "$2" ]; then
                [ "$2" = "./.wh..wh.plink" ] && exit 0
                cd $AUFS || exit 1
                dir="${2%%/.wh.*}"
                if [ ! -e "$ROOT/$dir" ]; then
                        doit mkdir -p "$ROOT/$dir"
                        doit $MIRRORDIR -v --exclude-regexp '.*/[.]wh[.].*' "$dir" "$ROOT/$dir"
                fi
                exit 0
        fi
        [ "${2:0:6}"  = "./.wh."     ] && exit 0
        [ "${2:0:6}"  = "./tmp/"     ] && exit 0
        [ "${2:0:10}" = "./var/tmp/" ] && exit 0
        dir="${2%%/*}"
        fn="${2##*/}"
        [ "${fn:0:4}" = ".wh." ] && exit 0
        [ ! -e "$ROOT/$dir" ] && doit mkdir -p "$ROOT/$dir"
        if [ -f "$2" -a -f "$ROOT/$2" ]; then
                if diff -q "$2" "$ROOT/$2" >/dev/null ; then
                        [ "$2" -nt "$ROOT/$2" ] && touch -m -r "$2" "$ROOT/$2"
                        exit 0
                fi
        fi
        doit cp -dp "$2" "$ROOT/$2"
        exit 0
fi

echo "$SCRIPT: huh?  $*" >&2