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From: jaw@ames.UUCP (James A. Woods)
Newsgroups: comp.sources.d
Subject: Towards minimalist self-decompressing 'shar'chives
Message-ID: <1666@ames.UUCP>
Date: Mon, 1-Jun-87 23:52:48 EDT
Article-I.D.: ames.1666
Posted: Mon Jun  1 23:52:48 1987
Date-Received: Wed, 3-Jun-87 04:44:07 EDT
Organization: NASA Ames Research Center, Moffett Field, CA
Lines: 82
Summary: further microsurgery on a twisted concept

#  "You've heard of Ali Baba -- forty thieves had he.
    Out for what we all want: lots of LSD."            -- V. Stanshall

     Re-directing a discussion from comp.sys.sources started by Karl Fox,
below we append the production version of a self-decompressing sharchive
maker.  It's yet another few hundred characters shorter (mainly from
combining 'atob' and 'zcat' into one program), but not enough to qualify
for 4th International Obfuscation Contest status!  The 1991-character script
still has a little fat in the way of "literary" allusion, preserved at
amazing cost for sheer perversity.  This one offers more robust tempfile
handling, swifter execution due to the single compilation, but more
importantly, capability to completely short-circuit the compile if the
requisite code is already installed on the target system.

     Raison-d'etre for this 'shar' remains its inherent nose-thumb at
what kind/version of decoding the other side might entertain.  You can
change things right out from under the recipient if desired, without need
for a "courier" to deliver the "key".  The basic idea probably goes back
to Claude Shannon.

     A contraindication for the shar would be for packaging USENET
postings, since the transport mechanism already does compression.
However, it should be just the ticket for a UNIX archive server.

-- James A. Woods (ames!jaw)

P.S. I dedicate the opaque-yet-functional brevity of what follows
to Donovan Fong, wherever he may be.

-------------- a bent 52-line compressing 'shar' machine ------------
echo '#!/bin/sh
# "Cleverly he dialed from within." -- D. Van Vliet, "Trout Mask Replica"
trap "rm -f zcat atob az$$*;exit" 0 1 2 3 15
echo decoding...
cat>az$$.c<<\_'
cat<<'TROUSER PRESS'
#include<stdio.h>
#define d define
#d R register
#d I if
#d E else
#d W while
#d C char
#d L long
#d U unsigned
#d B(n) (1<<(n))
#d K bcount
#d G getchar()
#d P putchar
#d X return
#d J 255
#d H(n) ((C*)h)[n]
#d V(a,b) (a&(B(b)-1))
#d Q 256
#d Y w=w*85+c-'!',
#d Z w=Q;W(w--)t[w]=0
#d x break;
#d F {fprintf(stderr,"shar botch: resend\n");X;}
L K,o,v,w,c,m,M=B(16),f;int i,q,b,n,k=16,e=128,j,O,S;U short t[69001];U L
h[69001];C D[J];FILE*T;d(c)R c;{I(c=='z'){I(K)F E{c=4;W(c--)y(0);}}E I(c>='!'
&&(c<'!'+85)){I(!K)w=c-'!',++K;E I(K<4)Y++K;E Y y(w>>24),y(w>>16),y(w>>8),y(w)
,w=K=0;}E F;}y(l)L l;{R c=(int)(l&J);o^=c;m+=c;m++;I(f&(1<<31))f*=2,f++;E f*=2
;f+=c;putc(c,T);}main(g,v)C**v;{R c;L i;L A,h,y,s,r;I(**v!='a')X(a());sprintf(
D,mktemp("azXXXXXX"));I(!(T=fopen(D,"w+")))F;unlink(D);W(1){I(!fgets(D,J,stdin
))F;I(!strcmp(D,"xbtoa Begin\n"))x}W((c=G)>=0){I(c=='\n')continue;E I(c=='x')x
E d(c);}I(scanf("btoa End N %ld %lx E %lx S %lx R %lx\n",&A,&h,&y,&s,&r)!=5)F;
I(A!=h||y!=o||s!=m||r!=f)F E{fseek(T,0L,0);i=A;W(i--)P(getc(T));}}L g(){R C*p=
D;I(j>0||O>=S||f>m){I(f>m)m= ++n==k?M:B(n)-1;I(j>0)m=B(n=9)-1,j=0;S=fread(D,1,
n,stdin);I(S<1)X-1;O=0;S=S*8-n+1;}q=O;b=n;p+=q>>3;q&=7;c=V(*p++>>q,8-q);q=8-q;
b-=q;I(b>7)c|=(*p++&J)<<q,q+=8,b-=8;c|=V(*p,b)<<q;O+=n;X c;}a(){I(G!=31||G!=
157)F;k=G;e=k&128;k&=31;M=B(k);I(k>16)F;z();}z(){L w;R C*s;m=B(n=9)-1;Z,H(w)=
(C)w;f=e?257:Q;i=o=g();I(o==-1)X;P((C)i);s=(C*)&H(B(16));W((w=g())>=0){I(w==Q
&&e){Z;j=1;f=Q;I((w=g())==-1)x}v=w;I(w>=f)*s++=i,w=o;W((U L)w>=(U L)Q)*s++=
H(w),w=t[w];*s++=i=H(w);do P(*--s);W(s>&H(B(16)));I((w=f)<M)t[w]=(U short)o,
H(w)=i,f=w+1;o=v;}}
TROUSER PRESS
echo '_
(echo T|compress|btoa|atob|zcat)2>/dev/null 1>&2||
(cc -o zcat az$$.c;ln zcat atob)
(atob|zcat|tar xvf -)<<\Feilgau'
tar cf - $*|compress|btoa
echo "Feilgau"