#! /bin/bash

# This script takes an unpacked s390x Live iso image in the form KIWI-NG currently creates.
#
# It modifies the tree to match s390x expectations.
#
# Usage:
#
# fix_bootconfig.s390x DST_DIR
#
# iso layout before:
# .
# ├── LiveOS
# │   └── squashfs.img
# └── boot
#     └── s390x
#         └── loader
#             ├── initrd
#             ├── isolinux.cfg
#             ├── isolinux.msg
#             └── linux
#
#
# iso layout adjusted:
# .
# ├── LiveOS
# │   └── squashfs.img
# ├── boot
# │   └── s390x
# │       └── loader
# │           ├── cd.ikr
# │           ├── initrd
# │           ├── initrd.off
# │           ├── initrd.siz
# │           ├── linux
# │           ├── parmfile
# │           ├── parmfile.hmc
# │           ├── sles.exec
# │           └── suse.ins
# ├── suse.ins
# └── susehmc.ins
#

set -e

dst="$1"

if [ ! -d "$dst" ] ; then
  echo "fix_bootconfig.s390x: image dir \"$dst\" not found"
  exit 1
fi

# ----------------

# Note:
#
# KIWI-NG creates an iso with isolinux boot files in boot/s390x/loader.
#
# These files are not needed except for kernel and initrd (and kernel params from isolinux.cfg).
#
# This script removes the isolinux config and adds s390x related config
# files. It also moves kernel and initrd to the usual location (in boot/s390x).
#

boot_dir=$dst/boot/s390x/loader
grub_dir=$dst/boot/grub2

# Create parmfile.
#
# These parameters are taken from a sampel isolinux.cfg; the required parameters will
# possibly change according to the KIWI config.
#
parmfile_content=
echo "$parmfile_content" >$boot_dir/parmfile

# Note on parmfile:
#
# Possibly s390 expects parmfile to have a maximal line length of 80 chars - but you can have several lines.
#
# In contrast the parmfile blob embedded in cd.ikr should have no line breaks but can be longer than 80 chars.
#

# Create suse.ins & cd.ikr.
#
# cd.ikr is an image file combining kernel and initrd; suse.ins describes its layout.
#
# cd.ikr is used as boot image in El-torito style cd booting.
#

# Offsets used for cd.ikr.
initrd_ofs_ofs=0x0001040c
initrd_siz_ofs=0x00010414
initrd_ofs=0x01000000
parmfile_ofs=0x00010480

# Create initrd.off (note: 32 bit, stored in big endian).
printf "%08x" $((initrd_ofs)) | xxd -r -p - $boot_dir/initrd.off

# Create initrd.siz (note: 32 bit, stored in big endian).
read initrd_size x < <(du -b $boot_dir/initrd)
printf "%08x" $((initrd_size)) | xxd -r -p - $boot_dir/initrd.siz

# Create suse.ins.
cat >$boot_dir/suse.ins <<XXX
* SUSE Linux for IBM z Systems Installation System
linux 0x00000000
initrd.off $initrd_ofs_ofs
initrd.siz $initrd_siz_ofs
initrd $initrd_ofs
parmfile $parmfile_ofs
XXX

# A suse.ins copy at media root dir - note the different paths.
cat >$dst/suse.ins <<XXX
* SUSE Linux for IBM z Systems Installation System
boot/s390x/loader/linux 0x00000000
boot/s390x/loader/initrd.off $initrd_ofs_ofs
boot/s390x/loader/initrd.siz $initrd_siz_ofs
boot/s390x/loader/initrd $initrd_ofs
boot/s390x/loader/parmfile $parmfile_ofs
XXX

# Another suse.ins copy at media root dir - note the different paths and the hmc stuff.
cat >$dst/susehmc.ins <<XXX
* SUSE Linux for IBM z Systems Installation System via HMC
boot/s390x/loader/linux 0x00000000
boot/s390x/loader/initrd.off $initrd_ofs_ofs
boot/s390x/loader/initrd.siz $initrd_siz_ofs
boot/s390x/loader/initrd $initrd_ofs
boot/s390x/loader/parmfile.hmc $parmfile_ofs
XXX
echo "$parmfile_content console=ttyS1" >$boot_dir/parmfile.hmc

# Some rexx script to ipl something...
cat >$boot_dir/sles.exec <<XXX
/* REXX LOAD EXEC FOR SUSE LINUX S/390 VM GUESTS       */                       
/* LOADS SUSE LINUX S/390 FILES INTO READER            */                       
SAY ''                                                                          
SAY 'LOADING SLES FILES INTO READER...'                                         
'CP CLOSE RDR'                                                                  
'PURGE RDR ALL'                                                                 
'SPOOL PUNCH * RDR'                                                             
'PUNCH SLES LINUX A (NOH'                                                       
'PUNCH SLES PARMFILE A (NOH'                                                    
'PUNCH SLES INITRD A (NOH'                                                      
'IPL 00C'                                                                       
XXX

# Strip CDLABEL from the kiwi-generated grub configuration
# We are specifying the correct one in /etc/cmdline.d (see config.sh)
# and having it here might be confusing to repackers such as
# mksusecd (bsc#1245453)
sed -i -E 's|root=live:CDLABEL=[^ ]+||g' $grub_dir/grub.cfg

# Note:
#
# SUSE installer media also have boot/s390x/zpxe.rexx - a rexx script
# that comes directly from the s390-tools package.
#

# Create cd.ikr with all the file blobs mentioned in suse.ins.
dd status=none if=$boot_dir/linux of=$boot_dir/cd.ikr
dd status=none conv=notrunc obs=1 seek=$((initrd_ofs_ofs)) if=$boot_dir/initrd.off of=$boot_dir/cd.ikr
dd status=none conv=notrunc obs=1 seek=$((initrd_siz_ofs)) if=$boot_dir/initrd.siz of=$boot_dir/cd.ikr
dd status=none conv=notrunc obs=4096 seek=$((initrd_ofs/4096)) if=$boot_dir/initrd of=$boot_dir/cd.ikr
# clear kernel cmdline area; it's actually 4 kiB, but 1 block should be more than enough
dd status=none conv=notrunc bs=1 count=512 seek=$((parmfile_ofs)) if=/dev/zero of=$boot_dir/cd.ikr
echo -n "$parmfile_content" | dd status=none conv=notrunc obs=1 seek=$((parmfile_ofs)) of=$boot_dir/cd.ikr

# S390 Magic?
echo 80010000 | xxd -r -p -seek 4 - $boot_dir/cd.ikr

# Pad cd.ikr to full 4k blocks.
dd status=none conv=notrunc oflag=append bs=1 count=$((-initrd_size & 0xfff)) if=/dev/zero of=$boot_dir/cd.ikr

# Add zipl map file for later use
dd status=none if=/dev/zero of=$boot_dir/zipl.map bs=4k count=4