[syslinux] syslinux 3.72 fails where 3.71 didn't

[Ramón Casares]

I have written a bash script (see below) to generate bootable SD-USB
images using syslinux as booter. The script works OK with versions
3.63 and 3.71, but I get a null pointer error executing
  /tmp/$SYSLINUX/linux/syslinux -sf -o 16384 SD.img
in 3.72.

If you execute
  $ sudo sh SDformat.sh sys
then you can test the image easily with qemu
  $ qemu -hda SD.img

++++++ SDformat.sh ++++++++++++++++++++
#!/bin/bash

# SDformat.sh fs
#    makes a bootable disk file image
#    formated with one big fs partition
#    fs = iso | sys | ext | zip
#       iso is iso9660 (CD)
#       sys is vfat (Windows)
#       ext is ext2 (Linux)
#       zip is vfat as zip
# The file will be called SD.iso, or SD.img

if test $(whoami) != 'root'
then
 echo 'Only the root can run this script!'
 exit 1
fi

#SLV="3.72" ## Doesn't work
#SLV="3.63" ## Works
SLV="3.71"
SYSLINUX="syslinux-$SLV"
MTV="2.10"
MEMTEST="memtest86+-$MTV"

RDIR=$(cd $(dirname $0) && pwd)
cd ${RDIR}
if test ! -d downloads ; then mkdir downloads ; fi

echo "$SYSLINUX"
cd ${RDIR}/downloads
if test ! -f $SYSLINUX.tar.bz2
then
 echo "   Getting Syslinux"
 wget http://www.kernel.org/pub/linux/utils/boot/syslinux/$SYSLINUX.tar.bz2
fi
cd /tmp
if test ! -d $SYSLINUX
then
 echo "   Extracting Syslinux"
 tar xjf ${RDIR}/downloads/$SYSLINUX.tar.bz2
 chown -R root:root $SYSLINUX # 1026:1026
fi

echo "$MEMTEST"
cd ${RDIR}/downloads
if test ! -f "$MEMTEST.bin.gz"
then
 echo "   Getting Memtest"
 wget http://www.memtest.org/download/$MTV/$MEMTEST.bin.gz
fi
if test ! -f /tmp/memtest
then
 echo "   Extracting Memtest"
 gzip -cd "$MEMTEST.bin.gz" > /tmp/memtest
fi

echo "Writing configuration file"

##BEGIN CONFIG##

#BEGIN HEADER#
#Don't move this part. You can change the timeout and menu title, however.
cat > /tmp/syslinux.cfg << "EOF"
DEFAULT menu.c32
TIMEOUT 0
PROMPT 0
menu title Welcome to GNU/Linux!
EOF
#END HEADER#

#BEGIN HD BOOT OPTION#
#If this bugs you, get rid of it.
cat >> /tmp/syslinux.cfg << "EOF"
label local
menu label Boot from ^hard drive
localboot 0x80
EOF
#END HD BOOT OPTION#

# HERE YOU CAN ADD YOUR OWN ENTRIES

#BEGIN MEMTEST ENTRY#
cat >> /tmp/syslinux.cfg << "EOF"
label memtest
menu label ^Memtest86+ v2.10
kernel /boot/memtest
EOF
#END MEMTEST ENTRY#

#BEGIN REBOOT ENTRY#
cat >> /tmp/syslinux.cfg << "EOF"
menu separator
label reboot
menu label ^reboot
com32 reboot.c32
EOF
#END REBOOT ENTRY#

##END CONFIG##

if test $1 == "iso"
then
 echo "Creating ISO image"
 cd /tmp
 if test -d CDroot ; then rm -r CDroot/* ; else mkdir CDroot ; fi
 mkdir -p CDroot/boot/isolinux
 cp $SYSLINUX/core/isolinux.bin CDroot/boot/isolinux/ ## 3.72
 #cp $SYSLINUX/isolinux.bin CDroot/boot/isolinux/ ## 3.63
 cp $SYSLINUX/com32/modules/reboot.c32 CDroot/boot/isolinux/
 cp $SYSLINUX/com32/menu/menu.c32 CDroot/boot/isolinux/
 cp memtest CDroot/boot/
 cp syslinux.cfg CDroot/boot/isolinux/isolinux.cfg
 genisoimage -r -J -l -V "ISOboot" -input-charset iso8859-1 \
    -b boot/isolinux/isolinux.bin -c boot/isolinux/boot.cat \
    -no-emul-boot -boot-load-size 4 -boot-info-table \
    -o ${RDIR}/SD.iso CDroot
 echo "ISO image generated: ${RDIR}/SD.iso"
 exit
fi

FSCode="c" ; if test $1 == "ext" ; then FSCode="83" ; fi
PART="1"   ; if test $1 == "zip" ; then PART="4"    ; fi

echo "Creating HD image"
cat > /tmp/fdisk.cmd << EOF
o
n
p
$PART


t
$FSCode
a
$PART
p
w
EOF

cd ${RDIR}
if test -f SD.img ; then rm SD.img ; fi
dd if=/dev/zero of=SD.img bs=512 count=251904
losetup /dev/loop/0 SD.img
fdisk -b 512 -H 8 -S 32 -C 984 /dev/loop/0 < /tmp/fdisk.cmd
dd if=/tmp/$SYSLINUX/mbr/mbr.bin of=/dev/loop/0
kpartx -av /dev/loop/0

if test $1 == "ext" ; then
 mkfs.ext2 -L Linuxboot /dev/mapper/0p1
 mount /dev/mapper/0p1 /mnt/loop/
 mkdir -p /mnt/loop/boot/extlinux/
 cd /mnt/loop
 cp /tmp/$SYSLINUX/com32/menu/menu.c32 /mnt/loop/boot/extlinux/
 cp /tmp/$SYSLINUX/com32/modules/reboot.c32 /mnt/loop/boot/extlinux/
 cp /tmp/memtest /mnt/loop/boot/
 cp /tmp/syslinux.cfg /mnt/loop/boot/extlinux/extlinux.conf
 /tmp/$SYSLINUX/extlinux/extlinux -i boot/extlinux/
 cd ${RDIR}
 umount /mnt/loop
 kpartx -d /dev/loop/0
 losetup -d /dev/loop/0
else
 mkfs.msdos -v -n DOSboot /dev/mapper/0p$PART
 mount /dev/mapper/0p$PART /mnt/loop/
 mkdir -p /mnt/loop/boot/syslinux/
 cp /tmp/$SYSLINUX/com32/menu/menu.c32 /mnt/loop/boot/syslinux/
 cp /tmp/$SYSLINUX/com32/modules/reboot.c32 /mnt/loop/boot/syslinux/
 cp /tmp/memtest /mnt/loop/boot/
 cp /tmp/syslinux.cfg /mnt/loop/boot/syslinux/
 umount /mnt/loop
 kpartx -d /dev/loop/0
 losetup -d /dev/loop/0
 /tmp/$SYSLINUX/linux/syslinux -sf -o 16384 SD.img ## 3.72
 #/tmp/$SYSLINUX/unix/syslinux -sf -o 16384 SD.img ## 3.63
fi

echo "SD image generated: ${RDIR}/SD.img"
exit
++++++ SDformat.sh ++++++++++++++++++++