linux-live/livekitlib

#!/bin/sh

# Functions library :: for Linux Live Kit scripts
# Author: Tomas M. <http://www.linux-live.org>
#

# =================================================================
# debug and output functions
# =================================================================

# global variable
DEBUG_IS_ENABLED="$(cat /proc/cmdline 2>/dev/null | grep debug)"

debug_log()
{
   if [ "$DEBUG_IS_ENABLED" ]; then
      echo "- debug: $*" >&2
      log "- debug: $*"
   fi
}

# header
# $1 = text to show
#
header()
{
   echo """$@"""
}


# echogreen will echo $@ in green color
# $1 = text
#
echogreen()
{
   echo -ne """$@"""
}

# log - store given text in /var/log/livedbg
log()
{
   echo "$@" 2>/dev/null >>/var/log/livedbg
}

# show information about the debug shell
show_debug_banner()
{
   echo
   echo "====="
   echo ": Debugging started. Here is the root shell for you."
   echo ": Type your desired commands or hit Ctrl+D to continue booting."
   echo
}

# debug_shell
# executed when debug boot parameter is present
#
debug_shell()
{
   if [ "$DEBUG_IS_ENABLED" ]; then
      show_debug_banner
      sh < /dev/console
      echo
   fi
}

fatal()
{
   echolog
   header "Fatal error occured - $1"
   echolog "Something went wrong and we can't continue. This should never happen."
   echolog "Please reboot your computer with Ctrl+Alt+Delete ..."
   echolog
   sh < /dev/console
}


# test if the script is started by root user. If not, exit
#
allow_only_root()
{
  if [ "0$UID" -ne 0 ]; then
     echo "Only root can run $(basename $0)"; exit 1
  fi
}

# Create bundle
# call mksquashfs with apropriate arguments
# $1 = directory which will be compressed to squashfs bundle
# $2 = output file
# $3..$9 = optional arguments like -keep-as-directory or -b 123456789
#
create_bundle()
{
   debug_log "create_module" "$*"
   rm -f "$2" # overwrite, never append to existing file
   mksquashfs "$1" "$2" -comp xz -b 512K $3 $4 $5 $6 $7 $8 $9>/dev/null
}


# mount virtual filesystems like proc etc
#
init_proc()
{
   debug_log "vfs_mount_init"
   mount -n -t proc proc /proc
   echo "0" >/proc/sys/kernel/printk
   mount -n -t sysfs sysfs /sys
   mount -n -o remount,rw rootfs /
   ln -sf /proc/mounts /etc/mtab
}

# make sure some devices are there
init_devs()
{
   echo /sbin/mdev > /proc/sys/kernel/hotplug
   mdev -s
   modprobe zram 2>/dev/null
   modprobe loop 2>/dev/null
   modprobe squashfs 2>/dev/null
}

# Activate zram (auto-compression of RAM)
# Compressed RAM consumes 1/2 or even 1/4 of original size
# Setup static size of 500MB
#
init_zram()
{
   debug_log "init_zram"
   echo "Setting dynamic RAM compression using ZRAM"
   echo 536870912 > /sys/block/zram0/disksize # 512MB
   mkswap /dev/zram0
   swapon /dev/zram0 -p 32767
   echo 100 > /proc/sys/vm/swappiness
}

# load the AUFS kernel module if needed
#
init_aufs()
{
   debug_log "init_aufs"
   # TODO maybe check here if aufs support is working at all
   # and procude useful error message if user has no aufs
   modprobe aufs 2>/dev/null
}

# Setup empty union
# $1 = memory directory (tmpfs will be mounted there)
# $2 = union directory where to mount the union
#
init_union()
{
   debug_log "init_union"
   mkdir -p "$1"
   mkdir -p "$2"
   mount -t aufs -o xino="$1/.xino",br="$1" none "$2"
}

# Make sure to mount FAT12/16/32 using vfat
# in order to support long filenames
# $1 = device
#
device_bestfs()
{
   debug_log "device_bestfs"
   local PEEK

   PEEK="$(dd if="$1" bs=1k count=1 2>/dev/null | strings)"
   if [ "$(echo "$PEEK" | egrep -i "FAT[13][26]")" != "" ]; then
      echo "-t vfat"
   # TODO: this will work only with fuse
   #   else if [ "$(echo "$PEEK" | egrep -i 'NTFS')" != "" ]; then
   #      echo "-t ntfs-3g"
   fi
}

# Find LIVEKIT data by mounting all devices
# If found, retain mounted disk
# $1 = data directory to mount
#
find_data()
{
   debug_log "find_data"

   local DEVICE FS MNT

   mkdir -p "$1"
   blkid | sort | cut -d: -f 1 | while read DEVICE; do
      FS="$(device_bestfs "$DEVICE")"
      mount -r "$DEVICE" "$1" $FS
      if [ -d "$1/$LIVEKITNAME" ]; then
         echo "$1/$LIVEKITNAME"
         return
      fi
      umount "$1" 2>/dev/null
   done
}

# Mount squashfs filesystem bundles
# and add them to union
# $1 = directory where to search for bundles
# $2 = directory where to mount bundles
# $3 = directory where union is mounted
#
union_append_bundles()
{
   ls -1 "$1" | grep '.sb$' | sort | while read BUNDLE; do
      mkdir -p "$2/$BUNDLE"
      mount -o loop -t squashfs "$1/$BUNDLE" "$2/$BUNDLE"
      mount -o remount,add:1:"$2/$BUNDLE" none "$3"
   done
}

# Create empty fstab properly
# $1 = root directory
#
fstab_create()
{
   local FSTAB
   FSTAB="$1/etc/fstab"
   echo aufs / aufs defaults 0 0 > $FSTAB
   echo proc /proc proc defaults 0 0 >> $FSTAB
   echo sysfs /sys sysfs defaults 0 0 >> $FSTAB
   echo devpts /dev/pts devpts gid=5,mode=620 0 0 >> $FSTAB
   echo tmpfs /dev/shm tmpfs defaults 0 0 >> $FSTAB
}


# Change root and execute init
# $1 = where to change root
#
change_root()
{
   cd "$1"

   # make sure important devices are in union
   if [ ! -e dev/console ]; then mknod dev/console c 5 1; fi
   if [ ! -e dev/null ]; then mknod dev/null c 1 3; fi

   # find chroot and init
   if [ -x bin/chroot ]; then  CHROOT=bin/chroot; fi
   if [ -x sbin/chroot ]; then  CHROOT=sbin/chroot; fi
   if [ -x usr/bin/chroot ]; then  CHROOT=usr/bin/chroot; fi
   if [ -x usr/sbin/chroot ]; then CHROOT=usr/sbin/chroot; fi
   if [ "$CHROOT" = "" ]; then fatal "Can't find executable chroot command"; fi

   if [ -x bin/init ]; then INIT=bin/init; fi
   if [ -x sbin/init ]; then INIT=sbin/init; fi
   if [ "$INIT" = "" ]; then fatal "Can't find executable init command"; fi

   mkdir -p mnt/memory
   mount -n -o remount,ro aufs .
   pivot_root . mnt/memory
   exec $CHROOT . $INIT <dev/console >dev/console 2>&1
#   exec switch_root -c /dev/console . $INIT
}