disrpm / undeb, a small script to extract/unzip/unpack/unarchive *.rpm or *.deb packages

disrpm

#!/bin/bash

# disrpm / undeb
# small (bourne) shell script to extract/unzip/unpack/unarchive *.rpm or *.deb packages.
# uses sh, sed, hexdump|od, gzip|bzip2, dd, cpio.
# released under the Gnu General Public License (GPL)
# (c) bjdouma@xs4all.nl
######################
VER="v1.5, october 2004"
ME="${0##*/}"

# change HEADER_SIZE here or issue e.g.
# $> HEADER_SIZE=512000 disrpm -v foo.rpm
[ -z $HEADER_SIZE ] && HEADER_SIZE=256000
######################

usage()
{
	echo -e "disrpm $VER (bjdouma@xs4all.nl)

usage:	 $ME -v|-x foo.rpm
	 $ME -v|-x foo.deb

options: -v|-l  view (list) contents of foo.
	 -x     extract foo.
"
	exit 1
}

error_exit()
{
	echo $1 >&2
	exit 1
}

gzip_sieve()
{
	# gzip-magic: 0x1F,0x8B
	sed -ne '/1[fF]/{;N;/8[bB]$/{;s/1[fF]//g;s/^0*//g;P;};}'
}

bzip2_sieve()
{
	# bzip2-magic: 0x42,0x5A,0x68
	sed -ne '/42/{;N;/5[aA]$/{;N;/68$/{s/42//g;s/5[aA]//g;s/^0*//g;P;};};}'
}

probe()
{
	dd if=$FILE ibs=$O skip=1 2>/dev/null \
	| $2 -dc - 2>/dev/null \
	| cpio "$1" 2>/dev/null
}

######################

XDUMP=`type -P hexdump` || XDUMP=`type -P od` || error_exit "oops, can't find hexdump or od -- bailing out"
XDUMP="${XDUMP##*/}"

OPT=$1
[ -z $OPT ] && usage

PASS1="probe -tv"
{ [ "$OPT" = "-l" -o "$OPT" = "-v" ] && PASS2=":" ; } || { [ "$OPT" = "-x" ] && PASS2="probe -mid" ; } || usage

FILE=$2
[ x"$FILE"x == xx ] && usage
[ -e "$FILE" ] || error_exit "$FILE: No such file or directory"
 
for AR in gzip bzip2
do
	e=1

	[ "$XDUMP" = "od" ] && AR_OFFSETS=`$XDUMP -A d -N $HEADER_SIZE -v -t x1 -w1 $FILE | ${AR}_sieve`
	[ "$XDUMP" = "hexdump" ] && AR_OFFSETS=`$XDUMP -n $HEADER_SIZE -v -e '"%_ad " 1/1 "%02x" "\n"' $FILE | ${AR}_sieve`

	for O in $AR_OFFSETS
	do
		echo "--> at offset $O:" >&2
		$PASS1 $AR 2>/dev/null && $PASS2 $AR && e=0 \
		|| echo "... hmm, probably false drop" >&2
	done

	[ $e -eq 0 ] && break
done

[ $e -eq 1 ] && echo "$ME: failed to find anything -- maybe HEADER_SIZE is too small (currently $HEADER_SIZE, see line 14)" >&2

exit $e

This little gem of a script seems to be nearly lost on the internet. I've seen it on iBiblio and referenced in various discussions like this Puppy Linux forum, but not in any code repository. It supposedly works better than rpm2cpio, but I haven't used it in 10+ years. I doubt it works on RPM v5 since that fork uses xar rather than cpio.

I claim neither ownership nor authorship; disrpm was written by and is copyright Bauke Jan Douma. It is posted here for convenience, as permitted by the GNU GPL. I assume, given the date given in the script, that this is GPL version 2.