make-rootfs

#!/bin/sh
#
# mkrootfs -- Create an EVE rootfs
#
# Input is a tarball containing the rootfs partition.
# Output is a raw partition on stdout
#
# The following env variables change the behaviour of this script
#     DEBUG - makes this script verbose

set -e
[ -n "$DEBUG" ] && set -x

IMGFILE=/rootfs.img
[ -f "$IMGFILE" ] || EXPORT_CMD="cat $IMGFILE"

# we want everything except the final result to stderr
( exec 1>&2;

  mkdir -p /tmp/rootfs
  cd /tmp/rootfs

  [ -t 0 ] || bsdtar xzf -

  # This _filesystem_ UUID will be later reused as the _partition_
  # UUID when creating the final image. This will allow us to have
  # a static grub configuration.
  ROOTFS_UUID=$(cat /proc/sys/kernel/random/uuid)
  ROOTFS_BLOCKSZ=4096
  ROOTFS_PART_HEADROOM_BLOCKS=16000

  ROOTFS_FILE_SIZE_KB=$(du -sk . | awk '{print $1}')
  ROOTFS_PART_BLOCKS=$(( $ROOTFS_FILE_SIZE_KB / 4 + $ROOTFS_PART_HEADROOM_BLOCKS ))
  # Increase fs size on 800MB. We need extra room for updating packages while
  # building live image. See 'LIVE_UPDATE=1 live' in the Makefile.
  ROOTFS_PART_EXTRA_SPACE=$((800<<20))
  ROOTFS_PART_SIZE=$(((ROOTFS_PART_BLOCKS * ROOTFS_BLOCKSZ) + ROOTFS_PART_EXTRA_SPACE))
  ROOTFS_PART_SIZE_KB=$(((ROOTFS_PART_SIZE + 1023) / 1024))

  dd if=/dev/zero of=$IMGFILE bs=1024 seek="$ROOTFS_PART_SIZE_KB" count=0
  mkfs.ext4 -b 4096 -L eve_rootfs -U "$ROOTFS_UUID" -v "$IMGFILE"
  mkdir -p /mnt
  mount -o loop $IMGFILE /mnt
  cp -R /tmp/rootfs/* /mnt
  umount /mnt

)

$EXPORT_CMD