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#include <lib9.h>
#include <a.out.h>
#include "squeeze.h"
/*
* forsyth@vitanuova.com
*/
/*
* for details of `unsqueeze' see:
*
* %A Mark Taunton
* %T Compressed Executables: An Exercise in Thinking Small
* %P 385-404
* %I USENIX
* %B USENIX Conference Proceedings
* %D Summer 1991
* %C Nashville, TN
*
* several of the unimplemented improvements described in the paper
* have been implemented here
*
* there is a further transformation on the powerpc (QFLAG!=0) to shuffle bits
* in certain instructions so as to push the fixed bits to the top of the word.
*/
typedef struct Squeeze Squeeze;
struct Squeeze {
int n;
ulong tab[7*256];
};
enum {
CHECK = 1 /* check precise bounds in Squeeze array */
};
#define GET4(p) (((((((p)[0]<<8)|(p)[1])<<8)|(p)[2])<<8)|(p)[3])
static uchar out[3*1024*1024];
static uchar bigb[1024*1024];
static ulong top;
static int qflag = 1;
static int islittle = 0;
static ulong chksum, oldsum;
static int rdtab(int, Squeeze*, int);
static long unsqueezefd(int, void*);
static uchar* unsqueeze(uchar*, uchar*, uchar*, Squeeze*, Squeeze*, ulong);
static uchar* unsqzseg(int, uchar*, long, ulong);
void
main(int argc, char **argv)
{
int fd;
long n;
if(argc < 2)
exits("args");
fd = open(argv[1], OREAD);
if(fd < 0)
exits("open");
n = unsqueezefd(fd, out);
if(n < 0){
fprint(2, "zqs: can't unsqueeze\n");
exits("err");
}
if(write(1, out, n) != n){
fprint(2, "zqs: write error: %r\n");
exits("err");
}
fprint(2, "%ld bytes, %8.8lux csum\n", n, chksum);
exits(0);
}
static long
unsqueezefd(int fd, void *v)
{
uchar *wp, *out;
ulong toptxt, topdat;
long asis, nst, nsd;
Sqhdr sqh;
Exec ex;
out = (uchar*)v;
if(read(fd, &sqh, SQHDRLEN) != SQHDRLEN)
return -1;
if(GET4(sqh.magic) != SQMAGIC)
return -1;
if(read(fd, &ex, sizeof(Exec)) != sizeof(Exec))
return -1;
toptxt = GET4(sqh.toptxt);
topdat = GET4(sqh.topdat);
oldsum = GET4(sqh.sum);
asis = GET4(sqh.asis);
if(asis < 0)
asis = 0;
nst = GET4(sqh.text);
nsd = GET4(sqh.data);
switch(GET4((uchar*)&ex.magic)){
case Q_MAGIC:
if(qflag)
fprint(2, "PowerPC mode\n");
islittle = 0;
break;
case E_MAGIC:
case 0xA0E1: /* arm AIF */
islittle = 1;
qflag = 0;
break;
default:
fprint(2, "Unknown magic: %8.8ux\n", GET4((uchar*)&ex.magic));
qflag = 0;
break;
}
memmove(out, &ex, sizeof(ex));
wp = unsqzseg(fd, out + sizeof(ex), nst, toptxt);
if(wp == nil)
return -1;
wp = unsqzseg(fd, wp, nsd, topdat);
if(wp == nil)
return -1;
if(asis){
if(read(fd, wp, asis) != asis)
return -1;
wp += asis;
}
return wp-out;
}
static uchar*
unsqzseg(int fd, uchar *wp, long ns, ulong top)
{
Squeeze sq3, sq4;
if(ns == 0)
return wp;
if(rdtab(fd, &sq3, 0) < 0)
return nil;
if(rdtab(fd, &sq4, 8) < 0)
return nil;
fprint(2, "tables: %d %d\n", sq3.n, sq4.n);
if(read(fd, bigb, ns) != ns)
return nil;
return unsqueeze(wp, bigb, bigb+ns, &sq3, &sq4, top);
}
static uchar*
unsqueeze(uchar *wp, uchar *rp, uchar *ep, Squeeze *sq3, Squeeze *sq4, ulong top)
{
ulong nx;
int code, n;
if(qflag){
QREMAP(top); /* adjust top just once, outside the loop */
}
while(rp < ep){
code = *rp++;
n = 0;
nx = code>>4;
do{
if(nx == 0){
nx = top;
}else{
if(nx==1){
if(rp+3 >= ep)
return nil;
nx = (((((rp[3]<<8)|rp[2])<<8)|rp[1])<<8)|rp[0];
rp += 4;
}else if(nx <= 8){ /* 2 to 8 */
if(rp+1 >= ep)
return nil;
nx = ((nx-2)<<8) | rp[0];
if(CHECK && nx >= sq4->n)
return nil; /* corrupted file */
nx = sq4->tab[nx] | rp[1];
rp += 2;
}else{ /* 9 to 15 */
if(rp >= ep)
return nil; /* corrupted file */
nx = ((nx-9)<<8) | rp[0];
if(CHECK && nx >= sq3->n)
return nil; /* corrupted file */
nx = sq3->tab[nx];
rp++;
}
if(rp > ep)
return nil; /* corrupted file */
if(qflag){
QREMAP(nx);
}
}
if(islittle){
wp[0] = nx;
wp[1] = nx>>8;
wp[2] = nx>>16;
wp[3] = nx>>24;
}else{
wp[0] = nx>>24;
wp[1] = nx>>16;
wp[2] = nx>>8;
wp[3] = nx;
}
wp += 4;
chksum += nx;
nx = code & 0xF;
}while(++n == 1);
}
return wp;
}
static int
rdtab(int fd, Squeeze *sq, int shift)
{
uchar b[7*256*5], *p, *ep;
ulong v, w;
int i;
if(read(fd, b, 2) != 2)
return -1;
i = (b[0]<<8) | b[1];
if(1)
fprint(2, "table: %d\n", i);
if((i -= 2) > 0){
if(read(fd, b, i) != i)
return -1;
}
sq->n = 0;
p = b;
ep = b+i;
v = 0;
while(p < ep){
w = 0;
do{
if(p >= ep)
return -1;
w = (w<<7) | (*p & 0x7F);
}while(*p++ & 0x80);
v += w;
if(0)
fprint(2, "%d %8.8lux %8.8lux\n", sq->n, v, w);
sq->tab[sq->n++] = v << shift;
}
return 0;
}
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