#include "boot.h"#include "squeeze.h" /* * 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. */ #define	EXECHDRLEN	(8*4) typedef struct Squeeze Squeeze;struct Squeeze {	int	n;	ulong	tab[7*256];}; #define	GET4(p)	(((((((p)[0]<<8)|(p)[1])<<8)|(p)[2])<<8)|(p)[3]) /* * for speed of unsqueezing from Flash, certain checks are * not done inside the loop (as they would be in the unsqueeze program zqs), * but instead the checksum is expected to catch corrupted files. * in fact the Squeeze array bounds can't be exceeded in practice * because the tables are always full for a squeezed kernel. */enum {	QFLAG = 1,	/* invert powerpc-specific code transformation */	CHECK = 0,	/* check precise bounds in Squeeze array (otherwise checksum detects error) */}; static	ulong	chksum;static	int	rdtab(Block*, Squeeze*, int);static	ulong*	unsqueeze(ulong*, uchar*, uchar*, Squeeze*, Squeeze*, ulong);static	uchar*	unsqzseg(uchar*, Block*, long, long, char*);static	Alarm*	unsqzal; intissqueezed(uchar *b){	return GET4(b) == SQMAGIC? GET4(b+SQHDRLEN): 0;} static voidunsqzdot(Alarm*){	unsqzal = alarm(500, unsqzdot, nil);	print(".");} longunsqueezef(Block *b, ulong *entryp){	uchar *loada, *wp;	ulong toptxt, topdat, oldsum;	long asis, nst, nsd;	Sqhdr *sqh;	Exec *ex; 	if(BLEN(b) < SQHDRLEN+EXECHDRLEN)		return -1;	sqh = (Sqhdr*)b->rp;	if(GET4(sqh->magic) != SQMAGIC)		return -1;	chksum = 0;	toptxt = GET4(sqh->toptxt);	topdat = GET4(sqh->topdat);	oldsum = GET4(sqh->sum);	asis = GET4(sqh->asis);	nst = GET4(sqh->text);	nsd = GET4(sqh->data);	b->rp += SQHDRLEN;	ex = (Exec*)b->rp;	if(GET4(ex->magic) != Q_MAGIC){		print("zqs: not powerPC executable\n");		return -1;	}	*entryp = GET4(ex->entry);	b->rp += EXECHDRLEN;	loada = KADDR(PADDR(*entryp));	wp = unsqzseg(loada, b, nst, toptxt, "text");	if(wp == nil){		print("zqs: format error\n");		return -1;	}	if(nsd){		wp = (uchar*)PGROUND((ulong)wp);		wp = unsqzseg(wp, b, nsd, topdat, "data");		if(wp == nil){			print("zqs: format error\n");			return -1;		}	}	if(asis){		memmove(wp, b->rp, asis);		wp += asis;		b->rp += asis;	}	if(chksum != oldsum){		print("\nsqueezed kernel: checksum error: %8.8lux need %8.8lux\n", chksum, oldsum);		return -1;	}	return wp-loada;} static uchar *unsqzseg(uchar *wp, Block *b, long ns, long top, char *what){	static Squeeze sq3, sq4; 	print("unpack %s %8.8lux %lud:", what, wp, ns);	if(ns == 0)		return wp;	if(rdtab(b, &sq3, 0) < 0)		return nil;	if(rdtab(b, &sq4, 8) < 0)		return nil;	if(BLEN(b) < ns){		print(" **size error\n");		return nil;	}	unsqzal = alarm(500, unsqzdot, nil);	wp = (uchar*)unsqueeze((ulong*)wp, b->rp, b->rp+ns, &sq3, &sq4, top);	cancel(unsqzal);	unsqzal = nil;	print("\n");	if(wp == nil){		print("zqs: corrupt squeezed data stream\n");		return nil;	}	b->rp += ns;	return wp;} static ulong*unsqueeze(ulong *wp, uchar *rp, uchar *ep, Squeeze *sq3, Squeeze *sq4, ulong top){	ulong nx, csum;	int code, n; 	if(QFLAG){		QREMAP(top);	/* adjust top just once, outside the loop */	}	csum = chksum;	while(rp < ep){		/* no function calls within this loop for speed */		code = *rp;		rp++;		n = 0;		nx = code>>4;		do{			if(nx == 0){				nx = top;			}else{				if(nx==1){					nx = (((((rp[3]<<8)|rp[2])<<8)|rp[1])<<8)|rp[0];					rp += 4;				}else if(nx <= 8){	/* 2 to 8 */					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 */					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);				}			}			*wp = nx;			wp++;			csum += nx;			nx = code & 0xF;		}while(++n == 1);	}	chksum = csum;	return wp;} static intrdtab(Block *b, Squeeze *sq, int shift){	uchar *p, *ep;	ulong v, w;	int i; 	if(BLEN(b) < 2)		return -1;	i = (b->rp[0]<<8) | b->rp[1];	if(1)		print(" T%d", i);	b->rp += 2;	if((i -= 2) > 0){		if(BLEN(b) < i)			return -1;	}	sq->n = 0;	p = b->rp;	ep = b->rp+i;	b->rp += 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)			print("%d %8.8lux %8.8lux\n", sq->n, v, w);		sq->tab[sq->n++] = v<<shift;	}	return 0;}