/mandos/trunk

#!/bin/bash

# 

# Initramfs unpacker - unpacks initramfs images into /tmp

# 

# Copyright © 2013-2019 Teddy Hogeborn

# Copyright © 2013-2019 Björn Påhlsson

# 

# This file is part of Mandos.

#

# Mandos is free software: you can redistribute it and/or modify it

# under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

#     Mandos is distributed in the hope that it will be useful,

#     but WITHOUT ANY WARRANTY; without even the implied warranty of

#     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

#     GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with Mandos.  If not, see

# <http://www.gnu.org/licenses/>.

# 

# Contact the authors at <mandos@recompile.se>.

cpio="cpio --extract --make-directories --unconditional --preserve-modification-time"

if [ -z "$*" ]; then

    set -- /boot/initrd.img-*

fi

for imgfile in "$@"; do

    if ! [ -f "$imgfile" ]; then

	echo "Error: Not an existing file: $imgfile" >&2

	continue

    fi

    imgdir="${TMPDIR:-/tmp}/${imgfile##*/}"

    if [ -d "$imgdir" ]; then

	rm --recursive -- "$imgdir"

    fi

    mkdir --parents "$imgdir"

    # Does this image contain microcode?

    if $cpio --quiet --list --file="$imgfile" >/dev/null 2>&1; then

	# Number of bytes to skip to get to the compressed archive

	skip=$(($(LANG=C $cpio --io-size=1 --list --file="$imgfile" 2>&1 \

		      | sed --quiet \

			    --expression='s/^\([0-9]\+\) blocks$/\1/p')+8))

	if [ -x /usr/lib/dracut/skipcpio ]; then

	    catimg="/usr/lib/dracut/skipcpio $imgfile"

	else

	    catimg="dd if=$imgfile bs=$skip skip=1 status=noxfer"

	fi

    else

	echo "No microcode detected"

	catimg="cat -- $imgfile"

    fi

    while :; do

	# Determine the compression method

	if { $catimg 2>/dev/null | zcat --test >/dev/null 2>&1;

	     [ ${PIPESTATUS[-1]} -eq 0 ]; }; then

	    decomp="zcat"

	elif { $catimg 2>/dev/null | bzip2 --test >/dev/null 2>&1;

	       [ ${PIPESTATUS[-1]} -eq 0 ]; }; then

	    decomp="bzip2 --stdout --decompress"

	elif { $catimg 2>/dev/null | lzop --test >/dev/null 2>&1;

	       [ ${PIPESTATUS[-1]} -eq 0 ]; }; then

	    decomp="lzop --stdout --decompress"

	elif { $catimg 2>/dev/null | zstd --test >/dev/null 2>&1;

	       [ ${PIPESTATUS[-1]} -eq 0 ]; }; then

	    decomp="zstdcat --stdout --decompress"

	else

	    skip=$((${skip}+1))

	    echo "Could not determine compression of ${imgfile}; trying to skip ${skip} bytes" >&2

	    catimg="dd if=$imgfile bs=$skip skip=1 status=noxfer"

	    continue

	fi

	break

    done

    case "$catimg" in

	*skipcpio*) echo "Microcode detected, skipping";;

	*) echo "Microcode detected, skipping ${skip} bytes";;

    esac

    $catimg 2>/dev/null | $decomp | ( cd -- "$imgdir" && $cpio --quiet )

    if [ ${PIPESTATUS[-1]} -eq 0 ]; then

	echo "$imgfile unpacked into $imgdir"

    fi

done