squash-portage.sh

#! /bin/sh

source /etc/portage/make.conf
SQUASHFS_DIR=/var/db/repos
dt=`date +%Y%m%d`
overlay_mounted=0;

die() {
	echo "Script failed: $@";
	umount /var/tmp/oldportage 2>/dev/null;
	umount /var/tmp/newportage 2>/dev/null;
	[ "$overlay_mounted" ] && umount $PORTDIR;
	exit 1;
}

which mksquashfs || die "mksquashfs command not found";

umount /var/tmp/oldportage 2>/dev/null
umount /var/tmp/newportage 2>/dev/null
mkdir -p /var/tmp/newportage /var/tmp/oldportage

mount -t tmpfs none /var/tmp/newportage || die "Can't mount tmpfs at /var/tmp/newportage";
mkdir /var/tmp/newportage/rw /var/tmp/newportage/work

if [ -e "$SQUASHFS_DIR/portage.sqsh" ]; then
	mount -o loop,ro "$SQUASHFS_DIR/portage.sqsh" /var/tmp/oldportage || die "Can't mount portage squashfile at /var/tmp/oldportage";
else
	echo "Warning: no $SQUASHFS_DIR/portage.sqsh, using current $PORTDIR as-is.";
	mount --bind $PORTDIR /var/tmp/oldportage || die "Can't bind-mount $PORTDIR to /var/tmp/oldportage";
fi

if grep unionfs /proc/filesystems >/dev/null; then
	mount -t unionfs -o dirs=/var/tmp/newportage/rw=rw:$PORTDIR=ro none $PORTDIR || die "Can't create overlay on $PORTDIR";
elif grep overlayfs /proc/filesystems >/dev/null; then
	mount -t overlayfs -o lowerdir=/var/tmp/oldportage,upperdir=/var/tmp/newportage/rw none $PORTDIR || die "Can't create overlay on $PORTDIR";
elif grep overlay /proc/filesystems >/dev/null; then
	mount -t overlay -o lowerdir=/var/tmp/oldportage,upperdir=/var/tmp/newportage/rw,workdir=/var/tmp/newportage/work none $PORTDIR || die "Can't create overlay on $PORTDIR";
else
	die "Require unionfs or overlayfs, and neither listed in /proc/filesystems";
fi
overlay_mounted=1;

emerge-webrsync || die "Emerge --sync failed";

if [ -f "$SQUASHFS_DIR/portage-${dt}.sqsh" ]; then
	echo "Warning: $SQUASHFS_DIR/portage-${dt}.sqsh already exists!";
	mv "$SQUASHFS_DIR/portage-${dt}.sqsh" "$SQUASHFS_DIR/portage-${dt}.sqsh.old" || die "Failed to move $SQUASHFS_DIR/portage-${dt}.sqsh";
	echo "Moved to $SQUASHFS_DIR/portage-${dt}.sqsh.old";
fi
mksquashfs $PORTDIR "$SQUASHFS_DIR/portage-${dt}.sqsh" || die "mksquashfs failed";
chmod 444 "$SQUASHFS_DIR/portage-${dt}.sqsh"
ln -sf "portage-${dt}.sqsh" "$SQUASHFS_DIR/portage.sqsh" || die "Can't create symlink for portage.sqsh";

umount $PORTDIR || die "Can't unmount $PORTDIR";
overlay_mounted=0;
umount /var/tmp/oldportage || die "Can't unmount /var/tmp/oldportage";
umount /var/tmp/newportage || die "Can't unmount /var/tmp/newportage";

umount $PORTDIR 2>/dev/null
mount "$SQUASHFS_DIR/portage.sqsh" $PORTDIR || die "Can't mount new portage.sqsh"