fedora-fromiso

#!/bin/sh
#
# fedora-fromiso - Patch the ramdisk of Fedora to allow booting from
#                  ISO image
#
# Copyright (C) 2012 Mansour <[email protected]>
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
# 
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

# Example:
#
# Let's say Fedora ISO file is located at ~/fedora.iso
# Then the following will generate a patched ramdisk which we will use
# later to boot from ISO (run as root or sudo):
# 
# $ ./fedora-fromiso ~/fedora.iso ~/initrd-fromiso
#
# Let's also assume the following layout of your final boot media:
#
# /
# /fedora.iso
# /initrd-fromiso (generated by this script earlier)
#
# Then the following grub2 menu entry will boot DSL from the ISO file:
#
# menuentry "Fedora Live" {
#   loopback loop /fedora.iso
#   linux (loop)/EFI/boot/vmlinuz0 root=live:/fedora.iso rootfstype=auto ro liveimg quiet rhgb rd.luks=0 rd.md=0
#   initrd /initrd-fromiso
# }

# Parse command line arguments

ISOPATH="$1"
OUTPATH="$2"
if [ -z "$ISOPATH" ]; then
  echo "Usage $0: <iso-path> [<out>]"
  exit 1
fi

# Mount ISO and extract initrd

ISOMNT=$(mktemp -d /tmp/tmpXXXXXX)
if mount -t iso9660 -o ro,loop "$ISOPATH" "$ISOMNT"
then

TMPHOLD=$(mktemp -d /tmp/tmpXXXXXX)
gzip -d < "$ISOMNT"/EFI/boot/initrd0.img > "$TMPHOLD"/initrd
umount "$ISOMNT"

INITDIR=$(mktemp -d /tmp/tmpXXXXXX)
(cd $INITDIR; cpio -id < "$TMPHOLD"/initrd)

# Patch relevant files to handle live:/*.iso boot parameter

patch -d "$INITDIR" -p1 <<"EOF"
diff -Naur a/init b/init
--- a/init	2012-03-20 16:30:32.028407329 +1100
+++ b/init	2012-03-20 06:44:45.471723446 +1100
@@ -439,6 +439,11 @@
     mount --bind /run/initramfs "$NEWRUN"
 fi
 
+# move isodevice mount to new spot
+
+mkdir -p "$NEWROOT/isodevice"
+mount --move /isodevice "$NEWROOT/isodevice"
+
 wait_for_loginit
 
 # remove helper symlink
diff -Naur a/lib/dracut/hooks/pre-udev/30dmsquash-liveiso-genrules.sh b/lib/dracut/hooks/pre-udev/30dmsquash-liveiso-genrules.sh
--- a/lib/dracut/hooks/pre-udev/30dmsquash-liveiso-genrules.sh	2012-03-20 16:30:32.072406888 +1100
+++ b/lib/dracut/hooks/pre-udev/30dmsquash-liveiso-genrules.sh	2012-03-20 02:00:36.163756463 +1100
@@ -3,7 +3,7 @@
 # ex: ts=8 sw=4 sts=4 et filetype=sh
 if [ "${root%%:*}" = "liveiso" ]; then
     {
-        printf 'KERNEL=="loop0", RUN+="/sbin/initqueue --settled --onetime --unique /sbin/dmsquash-live-root `/sbin/losetup -f --show %s`"\n' \
+        printf 'KERNEL=="loop0", RUN+="/sbin/initqueue --settled --onetime --unique /sbin/dmsquash-live-root `/sbin/liveiso-find %s`"\n' \
             ${root#liveiso:}
     } >> /etc/udev/rules.d/99-liveiso-mount.rules
     echo '[ -e /dev/root ]' > $hookdir/initqueue/finished/dmsquash.sh
diff -Naur a/sbin/liveiso-find b/sbin/liveiso-find
--- a/sbin/liveiso-find	1970-01-01 10:00:00.000000000 +1000
+++ b/sbin/liveiso-find	2012-03-20 06:35:30.634222494 +1100
@@ -0,0 +1,24 @@
+#!/bin/sh
+# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
+# ex: ts=8 sw=4 sts=4 et filetype=sh
+
+[ -z "$1" ] && exit 1
+isopath="$1"
+
+# try all the block devices under /dev and attempt to mount them
+
+mkdir -p /isodevice
+ls -l /dev/ | grep '^b' | grep -o '[a-z0-9-]\+$' | grep -v loop | while read device; do
+  device_fs=`blkid -s TYPE -o value "/dev/$device"`
+  [ -z "$device_fs" ] && continue
+  if mount -t "$device_fs" -o ro "/dev/$device" /isodevice; then
+    if [ -f "/isodevice$isopath" ]; then
+      losetup /dev/loop5 "/isodevice$isopath"
+      echo /dev/loop5
+      exit 0
+    else
+      umount /isodevice
+    fi
+  fi
+done
+rmdir /isodevice
EOF

chmod +x "$INITDIR/sbin/liveiso-find"

test -z "$OUTPATH" && OUTPATH="initrd-fromiso"
(
  cd "$INITDIR";
  echo './init
./sbin/liveiso-find
./lib/dracut/hooks/pre-udev/30dmsquash-liveiso-genrules.sh' |
    cpio -o -H newc -A -F "$TMPHOLD"/initrd
)
gzip -9 < "$TMPHOLD"/initrd > "$OUTPATH"

rm -Rf "$INITDIR"
rm "$TMPHOLD"/initrd
rmdir "$TMPHOLD"
fi
rmdir "$ISOMNT"