unlzw.c

   1 /* unlzw.c -- decompress files in LZW format.
   2  * The code in this file is directly derived from the public domain 'compress'
   3  * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
   4  * Ken Turkowski, Dave Mack and Peter Jannesen.
   5  *
   6  * This is a temporary version which will be rewritten in some future version
   7  * to accommodate in-memory decompression.
   8  */
   9
  10 #ifdef RCSID
  11 static char rcsid[] = "$Id: unlzw.c,v 0.15 1993/06/10 13:28:35 jloup Exp $";
  12 #endif
  13
  14 #include <sys/types.h>
  15
  16 #include "tailor.h"
  17
  18 #ifdef HAVE_UNISTD_H
  19 #  include <unistd.h>
  20 #endif
  21 #ifndef NO_FCNTL_H
  22 #  include <fcntl.h>
  23 #endif
  24
  25 #include "gzip.h"
  26 #include "lzw.h"
  27
  28 typedef unsigned char   char_type;
  29 typedef          long   code_int;
  30 typedef unsigned long   count_int;
  31 typedef unsigned short  count_short;
  32 typedef unsigned long   cmp_code_int;
  33
  34 #define MAXCODE(n)      (1L << (n))
  35
  36 #ifndef REGISTERS
  37 #       define  REGISTERS       2
  38 #endif
  39 #define REG1
  40 #define REG2
  41 #define REG3
  42 #define REG4
  43 #define REG5
  44 #define REG6
  45 #define REG7
  46 #define REG8
  47 #define REG9
  48 #define REG10
  49 #define REG11
  50 #define REG12
  51 #define REG13
  52 #define REG14
  53 #define REG15
  54 #define REG16
  55 #if REGISTERS >= 1
  56 #       undef   REG1
  57 #       define  REG1    register
  58 #endif
  59 #if REGISTERS >= 2
  60 #       undef   REG2
  61 #       define  REG2    register
  62 #endif
  63 #if REGISTERS >= 3
  64 #       undef   REG3
  65 #       define  REG3    register
  66 #endif
  67 #if REGISTERS >= 4
  68 #       undef   REG4
  69 #       define  REG4    register
  70 #endif
  71 #if REGISTERS >= 5
  72 #       undef   REG5
  73 #       define  REG5    register
  74 #endif
  75 #if REGISTERS >= 6
  76 #       undef   REG6
  77 #       define  REG6    register
  78 #endif
  79 #if REGISTERS >= 7
  80 #       undef   REG7
  81 #       define  REG7    register
  82 #endif
  83 #if REGISTERS >= 8
  84 #       undef   REG8
  85 #       define  REG8    register
  86 #endif
  87 #if REGISTERS >= 9
  88 #       undef   REG9
  89 #       define  REG9    register
  90 #endif
  91 #if REGISTERS >= 10
  92 #       undef   REG10
  93 #       define  REG10   register
  94 #endif
  95 #if REGISTERS >= 11
  96 #       undef   REG11
  97 #       define  REG11   register
  98 #endif
  99 #if REGISTERS >= 12
 100 #       undef   REG12
 101 #       define  REG12   register
 102 #endif
 103 #if REGISTERS >= 13
 104 #       undef   REG13
 105 #       define  REG13   register
 106 #endif
 107 #if REGISTERS >= 14
 108 #       undef   REG14
 109 #       define  REG14   register
 110 #endif
 111 #if REGISTERS >= 15
 112 #       undef   REG15
 113 #       define  REG15   register
 114 #endif
 115 #if REGISTERS >= 16
 116 #       undef   REG16
 117 #       define  REG16   register
 118 #endif
 119
 120 #ifndef BYTEORDER
 121 #       define  BYTEORDER       0000
 122 #endif
 123
 124 #ifndef NOALLIGN
 125 #       define  NOALLIGN        0
 126 #endif
 127
 128
 129 union   bytes {
 130     long  word;
 131     struct {
 132 #if BYTEORDER == 4321
 133         char_type       b1;
 134         char_type       b2;
 135         char_type       b3;
 136         char_type       b4;
 137 #else
 138 #if BYTEORDER == 1234
 139         char_type       b4;
 140         char_type       b3;
 141         char_type       b2;
 142         char_type       b1;
 143 #else
 144 #       undef   BYTEORDER
 145         int  dummy;
 146 #endif
 147 #endif
 148     } bytes;
 149 };
 150
 151 #if BYTEORDER == 4321 && NOALLIGN == 1
 152 #  define input(b,o,c,n,m){ \
 153      (c) = (*(long *)(&(b)[(o)>>3])>>((o)&0x7))&(m); \
 154      (o) += (n); \
 155    }
 156 #else
 157 #  define input(b,o,c,n,m){ \
 158      REG1 char_type *p = &(b)[(o)>>3]; \
 159      (c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
 160      ((long)(p[2])<<16))>>((o)&0x7))&(m); \
 161      (o) += (n); \
 162    }
 163 #endif
 164
 165 #ifndef MAXSEG_64K
 166    /* DECLARE(ush, tab_prefix, (1<<BITS)); -- prefix code */
 167 #  define tab_prefixof(i) tab_prefix[i]
 168 #  define clear_tab_prefixof()  memzero(tab_prefix, 256);
 169 #else
 170    /* DECLARE(ush, tab_prefix0, (1<<(BITS-1)); -- prefix for even codes */
 171    /* DECLARE(ush, tab_prefix1, (1<<(BITS-1)); -- prefix for odd  codes */
 172    ush *tab_prefix[2];
 173 #  define tab_prefixof(i) tab_prefix[(i)&1][(i)>>1]
 174 #  define clear_tab_prefixof()  \
 175       memzero(tab_prefix0, 128), \
 176       memzero(tab_prefix1, 128);
 177 #endif
 178 #define de_stack        ((char_type *)(&d_buf[DIST_BUFSIZE-1]))
 179 #define tab_suffixof(i) tab_suffix[i]
 180
 181 int block_mode = BLOCK_MODE; /* block compress mode -C compatible with 2.0 */
 182
 183 /* ============================================================================
 184  * Decompress in to out.  This routine adapts to the codes in the
 185  * file building the "string" table on-the-fly; requiring no table to
 186  * be stored in the compressed file.
 187  * IN assertions: the buffer inbuf contains already the beginning of
 188  *   the compressed data, from offsets iptr to insize-1 included.
 189  *   The magic header has already been checked and skipped.
 190  *   bytes_in and bytes_out have been initialized.
 191  */
 192 int unlzw(in, out)
 193     int in, out;    /* input and output file descriptors */
 194 {
 195     REG2   char_type  *stackp;
 196     REG3   code_int   code;
 197     REG4   int        finchar;
 198     REG5   code_int   oldcode;
 199     REG6   code_int   incode;
 200     REG7   long       inbits;
 201     REG8   long       posbits;
 202     REG9   int        outpos;
 203 /*  REG10  int        insize; (global) */
 204     REG11  unsigned   bitmask;
 205     REG12  code_int   free_ent;
 206     REG13  code_int   maxcode;
 207     REG14  code_int   maxmaxcode;
 208     REG15  int        n_bits;
 209     REG16  int        rsize;
 210
 211     maxbits = get_byte();
 212     block_mode = maxbits & BLOCK_MODE;
 213     if ((maxbits & LZW_RESERVED) != 0) {
 214         WARN((stderr, "\n%s: %s: warning, unknown flags 0x%x\n",
 215               progname, ifname, maxbits & LZW_RESERVED));
 216     }
 217     maxbits &= BIT_MASK;
 218     maxmaxcode = MAXCODE(maxbits);
 219
 220     if (maxbits > BITS) {
 221         fprintf(stderr,
 222                 "\n%s: %s: compressed with %d bits, can only handle %d bits\n",
 223                 progname, ifname, maxbits, BITS);
 224         exit_code = ERROR;
 225         return ERROR;
 226     }
 227     rsize = insize;
 228     maxcode = MAXCODE(n_bits = INIT_BITS)-1;
 229     bitmask = (1<<n_bits)-1;
 230     oldcode = -1;
 231     finchar = 0;
 232     outpos = 0;
 233     posbits = inptr<<3;
 234
 235     free_ent = ((block_mode) ? FIRST : 256);
 236
 237     clear_tab_prefixof(); /* Initialize the first 256 entries in the table. */
 238
 239     for (code = 255 ; code >= 0 ; --code) {
 240         tab_suffixof(code) = (char_type)code;
 241     }
 242     do {
 243         REG1 int i;
 244         int  e;
 245         int  o;
 246
 247     resetbuf:
 248         e = insize-(o = (posbits>>3));
 249
 250         for (i = 0 ; i < e ; ++i) {
 251             inbuf[i] = inbuf[i+o];
 252         }
 253         insize = e;
 254         posbits = 0;
 255
 256         if (insize < INBUF_EXTRA) {
 257             if ((rsize = read(in, (char*)inbuf+insize, INBUFSIZ)) == EOF) {
 258                 read_error();
 259             }
 260             insize += rsize;
 261             bytes_in += (ulg)rsize;
 262         }
 263         inbits = ((rsize != 0) ? ((long)insize - insize%n_bits)<<3 :
 264                   ((long)insize<<3)-(n_bits-1));
 265
 266         while (inbits > posbits) {
 267             if (free_ent > maxcode) {
 268                 posbits = ((posbits-1) +
 269                            ((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
 270                 ++n_bits;
 271                 if (n_bits == maxbits) {
 272                     maxcode = maxmaxcode;
 273                 } else {
 274                     maxcode = MAXCODE(n_bits)-1;
 275                 }
 276                 bitmask = (1<<n_bits)-1;
 277                 goto resetbuf;
 278             }
 279             input(inbuf,posbits,code,n_bits,bitmask);
 280             Tracev((stderr, "%d ", code));
 281
 282             if (oldcode == -1) {
 283                 if (code >= 256) error("corrupt input.");
 284                 outbuf[outpos++] = (char_type)(finchar = (int)(oldcode=code));
 285                 continue;
 286             }
 287             if (code == CLEAR && block_mode) {
 288                 clear_tab_prefixof();
 289                 free_ent = FIRST - 1;
 290                 posbits = ((posbits-1) +
 291                            ((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
 292                 maxcode = MAXCODE(n_bits = INIT_BITS)-1;
 293                 bitmask = (1<<n_bits)-1;
 294                 goto resetbuf;
 295             }
 296             incode = code;
 297             stackp = de_stack;
 298
 299             if (code >= free_ent) { /* Special case for KwKwK string. */
 300                 if (code > free_ent) {
 301 #ifdef DEBUG
 302                     char_type *p;
 303
 304                     posbits -= n_bits;
 305                     p = &inbuf[posbits>>3];
 306                     fprintf(stderr,
 307                             "code:%ld free_ent:%ld n_bits:%d insize:%u\n",
 308                             code, free_ent, n_bits, insize);
 309                     fprintf(stderr,
 310                             "posbits:%ld inbuf:%02X %02X %02X %02X %02X\n",
 311                             posbits, p[-1],p[0],p[1],p[2],p[3]);
 312 #endif
 313
 314 #ifdef NOT_NEEDED
 315                     if (!test && outpos > 0) {
 316                         write_buf(out, (char*)outbuf, outpos);
 317                         bytes_out += (ulg)outpos;
 318                     }
 319 #endif
 320                     error(to_stdout ? "corrupt input." :
 321                           "corrupt input. Use zcat to recover some data.");
 322                 }
 323                 *--stackp = (char_type)finchar;
 324                 code = oldcode;
 325             }
 326
 327             while ((cmp_code_int)code >= (cmp_code_int)256) {
 328                 /* Generate output characters in reverse order */
 329                 *--stackp = tab_suffixof(code);
 330                 code = tab_prefixof(code);
 331             }
 332             *--stackp = (char_type)(finchar = tab_suffixof(code));
 333
 334             /* And put them out in forward order */
 335             {
 336                 REG1 int        i;
 337
 338                 if (outpos+(i = (de_stack-stackp)) >= outbuflen) {
 339                     do {
 340                         if (i > outbuflen-outpos) i = outbuflen-outpos;
 341
 342                         if (i > 0) {
 343                             memcpy(outbuf+outpos, stackp, i);
 344                             outpos += i;
 345                         }
 346                         if (outpos >= outbuflen) {
 347 #ifdef NOT_NEEDED
 348                           if (!test) {
 349                             write_buf(out, (char*)outbuf, outpos);
 350                             bytes_out += (ulg)outpos;
 351                           }
 352 #endif
 353                           fprintf(stderr, "Error: Chamber overflow!\n");
 354                           outpos = 0;
 355                         }
 356                         stackp+= i;
 357                     } while ((i = (de_stack-stackp)) > 0);
 358                 } else {
 359                     memcpy(outbuf+outpos, stackp, i);
 360                     outpos += i;
 361                 }
 362             }
 363
 364             if ((code = free_ent) < maxmaxcode) { /* Generate the new entry. */
 365
 366                 tab_prefixof(code) = (unsigned short)oldcode;
 367                 tab_suffixof(code) = (char_type)finchar;
 368                 free_ent = code+1;
 369             }
 370             oldcode = incode;   /* Remember previous code.      */
 371         }
 372     } while (rsize != 0);
 373
 374     if (!test && outpos > 0) {
 375         write_buf(out, (char*)outbuf, outpos);
 376         bytes_out += (ulg)outpos;
 377     }
 378     return OK;
 379 }