growimg

#!/bin/sh
#
# Chris Cappuccio <chris@nmedia.net>
#
# This is an example of how to create a new image, transfer the contents
# of an old image to it, and keep the user from screwing it up too bad, by
# performing some basic sanity checks.
#
# -t target-disk causes this script to write directly to a disk instead of
# a new VND image.  This may be useful if you want to write a small image
# to a large flash without overwriting the unused space (which can be rather
# slow).  This is as fast as running flashrd, without requiring
# the source files from flashrd.
#

uname=`uname -s`

[ -z "$distloc" ] && distloc=/

###
#
# disktab dance

if [[ ! -w /etc ]]; then
 echo "Can't do it, depends on disktab being replaceable!"
 exit 1
fi

random=`dd if=/dev/urandom bs=512 count=1 2>/dev/null | sha512`
tabname=`printf "%.8s" $random`

vncfgroot() {
 c 0 vnconfig $rootdevice $1
}

vnuncfgroot() {
 c 0 vnconfig -u $rootdevice
}

sourcesectors2mbytes() {
 echo $(((($1 / 1024) * sourcebytessec) / 1024))
}

###
#
# fall back

4() {
 umount -f /dev/"$device"a
}
3() {
 [ -z "$alt" ] && vnconfig -u $device
}
2() {
 umount -f /dev/"$rootdevice"a
}
1() {
 vnuncfgroot
}
0() {
 rmdir $OldDir $NewDir
 rm -f $NewImg $NewLabel
 [[ -f /etc/disktab.${tabname} ]] && mv /etc/disktab.${tabname} /etc/disktab
 exit 1
}

. ./flashrd.sub

if [ "$uname" != "OpenBSD" -a "$uname" != "Bitrig" ]; then
 echo Sorry, cowboy.  This script only runs on OpenBSD and similar systems.
 exit 1
fi

[ `id -u` != 0 ] && echo root required && exit 1

syntax()
{
  echo "disk target mode:"
  echo "  growimg <-t target-disk> <source-image-filename>"
  echo
  echo "image target mode:"
  echo "  growimg <-l sectors> <source-image-filename>"
}

islezero()
{
  if [ "$1" -le "0" ]; then
   syntax
   echo -n expected a value larger than 0, got \"$1\"
   if [ "$2" != "" ]; then
    echo " for $2"
   else
    echo
   fi
   exit 1
  fi
}

if [ "$1" == "-t" ]; then
 # target device specified, use its geometry
 device="$2"
 alt=/dev/"$2"c
 if [ ! -b $alt ]; then
  echo "${device}(${alt}) is an invalid disk device, not found or not block device"
  exit 1
 fi

 image=$3
else
 if [ "$1" != "-l" ]; then
  syntax
  exit 1
 fi

 islezero $2 sectors
 totalsize=$2

 if [ "$3" == "-b" ]; then
  islezero $4 bytessec
  bytessec=$4
  image=$5
 else
  image=$3
 fi
 if [ ! -f "$image" ]; then
  syntax
  exit 1
 fi
fi

if [ ! -f $image ]; then
  echo "Error: ${image} not found"
  exit 1
fi

if [ -z "$device" ]; then
 getavailvnd 2
 rootdevice=${vndevices[0]}
 device=${vndevices[1]}
else
 [ -z "$rootdevice" ] && getavailvnd 1 && rootdevice=${vndevices[0]}
fi

if [ -z "$bytessec" ]; then
 # destination bytes/sector
 bytessec=512
fi

sourcebytessec=512

if [ -z "$alt" ]; then
 cylinders=$((totalsize / 64))
 trackscylinder=1
 sectorstrack=64
else
 # Here we use disklabel as a way to grab these values. OpenBSD 4.8+
 # always reports actual detected values (not what was stored on disk)

 tmplabel=`c 0 mktemp -t growimg.XXXXXX`
 c 0 disklabel $device > $tmplabel

 totalsize=`awk -F": " ' /^total sectors:/ {print $2} ' $tmplabel`
 bytessec=`awk -F": " ' /^bytes\/sector:/ {print $2} ' $tmplabel`
 sectorstrack=`awk -F": " ' /^sectors\/track:/ {print $2} ' $tmplabel`
 trackscylinder=`awk -F": " ' /^tracks\/cylinder:/ {print $2} ' $tmplabel`
 cylinders=`awk -F": " ' /^cylinders:/ {print $2} ' $tmplabel`

 c 0 rm $tmplabel
fi

# The source image must be 4GB or less, or this will break.
imgbytes=`ls -l $image | awk ' { print $5 } '`
imgsize=$((imgbytes / sourcebytessec))

if [ $((imgsize * sourcebytessec)) != "$imgbytes" ]; then
 cat <<-__FluxCapacitor
	Size of image $image is not divisible by $sourcebytessec bytes/sector
	without a remainder. Is this a disk image?
	__FluxCapacitor
 exit 1
fi

dstimgmb=`sectors2mbytes $totalsize`
srcimgmb=`sourcesectors2mbytes $imgsize`

echo Image: $image
echo Image size: $(((imgbytes / 1024) / 1024))MB
echo Requested size: ${dstimgmb}MB
echo Size increase: $((dstimgmb - srcimgmb))MB
echo

if [ $bytessec -gt 512 ]; then
 factor=$((bytessec / 512))
 if [ $((factor * 512)) != $bytessec ]; then
  echo Block size $bytessec not divisible by 512. Are you sure?
  exit
 fi
else
 unset factor
fi

if [ -z "$alt" ]; then
 freespace=`df . | tail -1 | awk ' { print $4 } '`

 if [ $bytessec -gt 512 ]; then
  # df reports in 512 byte sectors, so scale freespace for comparison
  # to media with different bytes/sec
  freespace=$((freespace / factor))
 fi

 # The new image will not take more disk space than the old one, in fact
 # it may take less (sparse file).
 if [ "$imgsize" -gt "$freespace" ]; then
  echo imgsize: $imgsize sectors
  echo freespace: $freespace sectors
  echo
  echo there is not enough free disk space for the new image!
  exit 1
 fi
fi

vncfgroot $image

if [ -z "$alt" ]; then
 [ -z "$NewImg" ] && NewImg=$(c 0 mktemp -t growimg.XXXXXX)
fi
[ -z "$NewLabel" ] && NewLabel=$(c 0 mktemp -t growimg.disklabel.XXXXXX)
[ -z "$OldDir" ] && OldDir=$(c 0 mktemp -t -d growimg.XXXXXX)
[ -z "$NewDir" ] && NewDir=$(c 0 mktemp -t -d growimg.XXXXXX)

c 1 mount -o rdonly /dev/"$rootdevice"a $OldDir

offset=$((4*1024*1024/${bytessec}))
asize=$((totalsize - offset))

echo "vnd-${tabname}:\\" > $NewLabel
echo "	:dt=SCSI:ty=${tabname}:se#${bytessec}:nt#${trackscylinder}:ns#${sectorstrack}:nc#${cylinders}:su#${totalsize}:\\" >> $NewLabel
echo "	:pa#${asize}:oa#${offset}:fa#$((bytessec * 2)):ba#$((bytessec * 16)):ta=4.2BSD:\\" >> $NewLabel
echo "	:pc#${totalsize}:oc#0:" >> $NewLabel

# DISKTAB MODIFIED
c 2 mv /etc/disktab /etc/disktab.${tabname}
c 2 cp $NewLabel /etc/disktab

if [ -z "$alt" ]; then
 echo Creating new image...
 c 2 dd if=/dev/zero bs=512 count=512 of=$NewImg >/dev/null

 c 2 vnconfig -t vnd-${tabname} $device $NewImg
 
 c 3 fdisk -l $totalsize -f /usr/mdec/mbr -yi $device
else
 c 3 fdisk -f /usr/mdec/mbr -yi $device
fi

echo
echo Writing flashrd disklabel...
c 3 disklabel -w $device vnd-${tabname}

# DISKTAB ORIGINAL
c 3 mv /etc/disktab.${tabname} /etc/disktab

echo
echo Creating new filesystem...
c 3 newfs -S $bytessec -q /dev/r"$device"a

c 3 mount -o async /dev/"$device"a $NewDir

used=`c 4 df $OldDir | tail -1 | awk ' { print $3 } '`
usedmb=`sourcesectors2mbytes $used`

free=`c 4 df $NewDir | tail -1 | awk ' { print $4 } '`
freemb=`sourcesectors2mbytes $free`

if [ "$freemb" -le "$usedmb" ]; then
 echo
 echo "Image files use ${usedmb}MB, but only ${freemb}MB available. Game over."
 4; 3; 2; 1; 0;
fi

echo
echo Copying installation...
c 4 tar cf - -C $OldDir . | c 4 tar xpf - -C $NewDir

echo
echo Installing boot blocks...
c 4 installboot -r $NewDir $device $distloc/usr/mdec/biosboot $distloc/usr/mdec/boot

echo
echo Generate initial random seeds...
c 4 "mkdir -p $NewDir/etc"
c 4 "dd if=/dev/random of=$NewDir/etc/random.seed bs=512 count=1 status=none"
c 4 chmod 600 $NewDir/etc/random.seed
c 4 "dd if=/dev/random of=$NewDir/etc/host.random bs=65536 count=1 status=none"
c 4 chmod 600 $NewDir/etc/host.random

echo
echo Checking filesystem...
c 4 fsck -f /dev/"$device"a

umountwait 4 /dev/"$device"a
umountwait 3 /dev/"$rootdevice"a

if [ -z "$alt" ]; then
 c 1 vnconfig -u $device
fi
c 0 vnuncfgroot

echo
echo Grow completed.
if [ -z "$alt" ]; then
 echo New `sectors2mbytes $totalsize`MB image is located at $NewImg
 if [ $bytessec -gt 512 ]; then
  echo
  echo disktab for mounting:
  cat $NewLabel
 fi
else
 echo "New image written to ${device}(${alt})"
fi
echo

rmdir $NewDir $OldDir
rm $NewLabel

exit 0