#!/bin/bash
# ----------------------------------------------------------------------
# (boglin:)based almost entirely on code by mrubel from:
# (boglin:)The only really important thing I added is a pretend option.
# mikes handy rotating-filesystem-snapshot utility
# http://www.mikerubel.org/computers/rsync_snapshots/
# thanks to anme for the link, additions are commented.
# ----------------------------------------------------------------------
# this needs to be a lot more general, but the basic idea is it makes
# rotating backup-snapshots of / to $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.n
# whenever 
called
# ----------------------------------------------------------------------

# -------------(boglin:) general settings ------------------------------

#The 'name' of this rotating backup, becomes subdirectory under $SNAPSHOT_RW
BU_NAME="Gentoo-1.4/rsync"
#The number of copies to keep
BU_DEPTH=3
#The type of backup, ie: if run fron cron.daily; set to daily
BU_TYPE="daily"
#The excludes I choose (why not make them default?)
L_EXCLUDES="/dev /mnt /tmp /usr/portage/distfiles /var/tmp /proc /home /usr/scr/linux-* tmp/"

# ------------- file locations -----------------------------------------
# (boglin:)mrubel reccommends that all users have read-only access to the
# back up filesystem through a local nfs share, can also be accomplished
# with smb, but you shouldn't let anything write to the back up fs at all, 
# except when this script is run. :)
MOUNT_DEVICE=/dev/hde1
SNAPSHOT_RW=/mnt/BU

# ------------- the script itself --------------------------------------

L_P=""
Rotate()
{
        # make sure we're running as root
        if (( `id -u` != 0 )); then { echo "Sorry, must be root.
Exiting...";
exit; 
} fi

        # attempt to remount the RW mount point as RW; else abort
        mount -o remount,rw $MOUNT_DEVICE $SNAPSHOT_RW ;
        if (( $? )); then
        {
        echo "snapshot: could not remount $SNAPSHOT_RW readwrite";
        exit;
        }
        fi;

        # step 1: delete the oldest snapshot, if it exists:
        if [ -d $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.$BU_DEPTH ] ; then
        rm -rf $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.$BU_DEPTH ;
        fi ;

        #(boglin:) rotating snapshots of /$BU_NAME (fixme: this should be more general)
        # fix: (BG) Use 'seq' for a C-like loop.
        for i in `seq $BU_DEPTH -1 2`;
        do

                # step 2: shift the middle snapshots(s) back by one, if they exist
                if [ -d $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.$(($i - 1)) ] ; then
                mv $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.$(($i - 1)) $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.$i ;\
                fi;

        done

        # step 3: make a hard-link-only (except for dirs) copy of the latest snapshot,
        # if that exists
        if [ -d $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0 ] ; then
        cp -al $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0 $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.1 ;\
        fi;

        # step 4: rsync from the system into the latest snapshot (notice
        # that
        # rsync behaves like cp --remove-destination by default, so the destination
        # is unlinked first.  If it were not so, this would copy over the
        # other
        # snapshot(s) too!
        if [ ! -d $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0 ] ; then
                if [ -f $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0 ] ; then 
                        rm $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0;\ 
                fi;
        mkdir $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0;\
        fi;
        L_P=""
} #end Rotate

Doit()
{
        #(boglin:) Build $EXCLUDES
        EXCLUDES=""
        for arg in $L_EXCLUDES;
        do
                EXCLUDES="$EXCLUDES--exclude=$arg "
        done
        pushd / > /dev/null
        rsync $L_P-va --delete-excluded $EXCLUDES .  $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0/ ;
        popd > /dev/null

        # step 5: update the mtime of $BU_TYPE.0 to reflect the snapshot
        # time
        touch $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0 ;
        }

        Cleanup()
        {
        # now remount the RW snapshot mountpoint as readonly
        mount -o remount,ro $MOUNT_DEVICE $SNAPSHOT_RW ;
        if (( $? )); then
        {
        echo "snapshot: could not remount $SNAPSHOT_RW readonly";
        exit;
        } fi;
}

Usage() # Prints some help
{
  echo
  echo "############## make_snapshot help #####################"
  echo
  echo "This script will clone your gentoo root partition to $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.#'s "
  echo "Edit this script to configure levels and locations. Usage:"
  echo "make_snapshot [-ph]"
  echo "        -h: show this message."
  echo "        -p: pretend mode (passes -n to rsync)"
}

#Entry
case "$#" in
0)
  echo "Begining backup of / to $SNAPSHOT_RW/$BU_NAME/$BU_TYPE.0"
  echo "If you haven't edited this script to you liking I suggest you ^C and do so now."
  Rotate
  Doit
  Cleanup
  echo "Finished backup of /"
  exit 0
  ;;
1)
  case "$1" in
  -p)
    L_P="-n "
    Doit
    exit 0
    ;;
  -h)
    Usage
    exit 0
    ;;
  *)
    echo
    echo "Unknown parameter..."
    echo
    Usage
    exit 1
    ;;
  esac
  ;;
esac
;;