ref: 12e226ac6798412271020d42645f69138715c519
dir: /utils/sqz/zqs.c/
#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; }