#!/bin/bash
# squash_portage
#
# Author: Magnus Rosenbaum <squash_portage@cmr.cx>
# Project Homepage: http://cmr.cx/squash_portage/
#
# Requirements:
# - sys-fs/squashfs-tools
# - squashfs kernel patch from http://squashfs.sourceforge.net/
#
# Installation:
#
# - Put this script to for example /usr/local/sbin and make sure it is
#   executable only by root.
#
# - If your "distfiles" and "packages" directories still reside in /usr/portage,
#   move them for example to /var/portage:
#
#        # mkdir /var/portage
#        # mv /usr/portage/packages /usr/portage/distfiles /var/portage
#
#   Then you have to add the following to /etc/make.conf:
#
#        PKGDIR="/var/portage/packages"
#        DISTDIR="/var/portage/distfiles"
#
# - Add the following line to your /etc/fstab:
#
#        /usr/portage.squashfs  /usr/portage  squashfs  loop,ro  0 0
#
# - Start the inital squashing:
#
#        # squash_portage squash
#
# - Use portage as usual. The only difference is, that you have to use
#   "squash_portage sync" instead of "emerge --sync" or "eix-sync" now.
#


# Configuration (only needed for use on multiple machines)
SYNC_HOST=detritus
REMOTE_PORTAGE=/automnt/vol1/usr/portage
REMOTE_FILE=/automnt/vol1/usr/portage.squashfs


function help {
	cat <<EOT
Usage: squash_portage command [options]
Save disk space by moving portage into a squashfs file system

Commands:
  squash       Move the portage directory tree into a squashfs file system
  unsquash     Extract portage from squashfs and recreate the standard portage
               directory tree 
  sync         Replacement for emerge --sync or eix-sync
  portagesync  Sync from a portage directory tree on another machine
  filesync     Sync from a already generated squashfs file on another machine

EOT
}


function squash {
	mksquashfs portage portage.squashfs_tmp -always-use-fragments -all-root
	mv portage.squashfs_tmp portage.squashfs
	mv portage portage_squashfs_old
	mkdir portage
	mount portage
	rm -r portage_squashfs_old
}


function unsquash {
	unsquashfs -d portage_squashfs_tmp portage.squashfs 
	umount portage
	rmdir portage
	mv portage_squashfs_tmp portage
	rm portage.squashfs
}


function switch_squashfs {
	umount portage
	mv portage.squashfs_tmp portage.squashfs
	mount portage
	if which eix-sync
	then
		eix-sync -m
	else
		emerge --metadata
	fi
}


cd /usr

case "$1" in
        squash)
		if [ -e portage/distfiles -o -e portage/packages ]
		then
			cat <<-EOT
The directories /usr/portage/distfiles and /usr/portage/packages still exist in
the portage tree. They have to be moved somewhere else, for example to
/var/portage/distfiles and /var/portage/packages. The new locations also have
to be set in /etc/make.conf:
  DISTDIR=/var/portage/distfiles
  PKGDIR=/var/portage/packages
EOT
			exit 1
		fi
		set -e -x
                squash
		;;
	unsquash)
		set -e -x
		unsquash
		;;
	sync)
		set -e -x
		unsquash
		if which eix-sync
		then
			eix-sync
		else
			emerge --sync
		fi
		squash
		;;
	portagesync)
		if [ ! -d $REMOTE_PORTAGE ]
		then
			echo "The remote portage tree does not exists or is not accessible!"
			exit 1
		fi
		set -e -x
		mksquashfs $REMOTE_PORTAGE portage.squashfs_tmp -always-use-fragments -all-root
		switch_squashfs
		;;
	filesync)
		if [ ! -r $REMOTE_FILE ]
		then
			echo "The remote file does not exists or is not readable!"
			exit 1
		fi
		if cmp -s $REMOTE_FILE portage.squashfs
		then
			echo "The files are already synced."
			exit 0
		fi
		if [ $REMOTE_FILE -ot portage.squashfs ]
		then
			echo "The remote file is older than the local one."
			exit 0
		fi
		set -e -x
		cp $REMOTE_FILE portage.squashfs_tmp
		switch_squashfs
		;;
	--help)
		help
		;;
	"")	
		help
		exit 1
		;;
	*)
		echo "Unrecognized command '$1'"
		help
		exit 1
		;;
esac