src/zlib/inflate.c

   1 /* inflate.c -- zlib interface to inflate modules
   2  * Copyright (C) 1995-1998 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 #include "zutil.h"
   7 #include "infblock.h"
   8
   9 struct inflate_blocks_state {int dummy;}; /* for buggy compilers */
  10
  11 typedef enum {
  12       METHOD,   /* waiting for method byte */
  13       FLAG,     /* waiting for flag byte */
  14       DICT4,    /* four dictionary check bytes to go */
  15       DICT3,    /* three dictionary check bytes to go */
  16       DICT2,    /* two dictionary check bytes to go */
  17       DICT1,    /* one dictionary check byte to go */
  18       DICT0,    /* waiting for inflateSetDictionary */
  19       BLOCKS,   /* decompressing blocks */
  20       CHECK4,   /* four check bytes to go */
  21       CHECK3,   /* three check bytes to go */
  22       CHECK2,   /* two check bytes to go */
  23       CHECK1,   /* one check byte to go */
  24       DONE,     /* finished check, done */
  25       BAD}      /* got an error--stay here */
  26 inflate_mode;
  27
  28 /* inflate private state */
  29 struct internal_state {
  30
  31   /* mode */
  32   inflate_mode  mode;   /* current inflate mode */
  33
  34   /* mode dependent information */
  35   union {
  36     uInt method;        /* if FLAGS, method byte */
  37     struct {
  38       uLong was;                /* computed check value */
  39       uLong need;               /* stream check value */
  40     } check;            /* if CHECK, check values to compare */
  41     uInt marker;        /* if BAD, inflateSync's marker bytes count */
  42   } sub;        /* submode */
  43
  44   /* mode independent information */
  45   int  nowrap;          /* flag for no wrapper */
  46   uInt wbits;           /* log2(window size)  (8..15, defaults to 15) */
  47   inflate_blocks_statef
  48     *blocks;            /* current inflate_blocks state */
  49
  50 };
  51
  52
  53 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
  54 int ZEXPORT inflateReset(z_streamp z)
  55 #else
  56 int ZEXPORT inflateReset(z)
  57 z_streamp z;
  58 #endif
  59 {
  60   if (z == Z_NULL || z->state == Z_NULL)
  61     return Z_STREAM_ERROR;
  62   z->total_in = z->total_out = 0;
  63   z->msg = Z_NULL;
  64   z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
  65   inflate_blocks_reset(z->state->blocks, z, Z_NULL);
  66   Tracev((stderr, "inflate: reset\n"));
  67   return Z_OK;
  68 }
  69
  70
  71 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
  72 int ZEXPORT inflateEnd(z_streamp z)
  73 #else
  74 int ZEXPORT inflateEnd(z)
  75 z_streamp z;
  76 #endif
  77 {
  78   if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
  79     return Z_STREAM_ERROR;
  80   if (z->state->blocks != Z_NULL)
  81     inflate_blocks_free(z->state->blocks, z);
  82   ZFREE(z, z->state);
  83   z->state = Z_NULL;
  84   Tracev((stderr, "inflate: end\n"));
  85   return Z_OK;
  86 }
  87
  88 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
  89 int ZEXPORT inflateInit2_(z_streamp z, int w, const char* version, int stream_size)
  90 #else
  91 int ZEXPORT inflateInit2_(z, w, version, stream_size)
  92 z_streamp z;
  93 int w;
  94 const char *version;
  95 int stream_size;
  96 #endif
  97 {
  98   if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
  99       stream_size != sizeof(z_stream))
 100       return Z_VERSION_ERROR;
 101
 102   /* initialize state */
 103   if (z == Z_NULL)
 104     return Z_STREAM_ERROR;
 105   z->msg = Z_NULL;
 106   if (z->zalloc == Z_NULL)
 107   {
 108     z->zalloc = zcalloc;
 109     z->opaque = (voidpf)0;
 110   }
 111   if (z->zfree == Z_NULL) z->zfree = zcfree;
 112   if ((z->state = (struct internal_state FAR *)
 113        ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
 114     return Z_MEM_ERROR;
 115   z->state->blocks = Z_NULL;
 116
 117   /* handle undocumented nowrap option (no zlib header or check) */
 118   z->state->nowrap = 0;
 119   if (w < 0)
 120   {
 121     w = - w;
 122     z->state->nowrap = 1;
 123   }
 124
 125   /* set window size */
 126   if (w < 8 || w > 15)
 127   {
 128     inflateEnd(z);
 129     return Z_STREAM_ERROR;
 130   }
 131   z->state->wbits = (uInt)w;
 132
 133   /* create inflate_blocks state */
 134   if ((z->state->blocks =
 135       inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w))
 136       == Z_NULL)
 137   {
 138     inflateEnd(z);
 139     return Z_MEM_ERROR;
 140   }
 141   Tracev((stderr, "inflate: allocated\n"));
 142
 143   /* reset state */
 144   inflateReset(z);
 145   return Z_OK;
 146 }
 147
 148 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
 149 int ZEXPORT inflateInit_(z_streamp z, const char* version, int stream_size)
 150 #else
 151 int ZEXPORT inflateInit_(z, version, stream_size)
 152 z_streamp z;
 153 const char *version;
 154 int stream_size;
 155 #endif
 156 {
 157   return inflateInit2_(z, DEF_WBITS, version, stream_size);
 158 }
 159
 160 #define NEEDBYTE {if(z->avail_in==0)return r;r=f;}
 161 #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
 162
 163 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
 164 int ZEXPORT inflate(z_streamp z, int f)
 165 #else
 166 int ZEXPORT inflate(z, f)
 167 z_streamp z;
 168 int f;
 169 #endif
 170 {
 171   int r;
 172   uInt b;
 173
 174   if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
 175     return Z_STREAM_ERROR;
 176   f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
 177   r = Z_BUF_ERROR;
 178   while (1) switch (z->state->mode)
 179   {
 180     case METHOD:
 181       NEEDBYTE
 182       if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
 183       {
 184         z->state->mode = BAD;
 185         z->msg = (char*)"unknown compression method";
 186         z->state->sub.marker = 5;       /* can't try inflateSync */
 187         break;
 188       }
 189       if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
 190       {
 191         z->state->mode = BAD;
 192         z->msg = (char*)"invalid window size";
 193         z->state->sub.marker = 5;       /* can't try inflateSync */
 194         break;
 195       }
 196       z->state->mode = FLAG;
 197     case FLAG:
 198       NEEDBYTE
 199       b = NEXTBYTE;
 200       if (((z->state->sub.method << 8) + b) % 31)
 201       {
 202         z->state->mode = BAD;
 203         z->msg = (char*)"incorrect header check";
 204         z->state->sub.marker = 5;       /* can't try inflateSync */
 205         break;
 206       }
 207       Tracev((stderr, "inflate: zlib header ok\n"));
 208       if (!(b & PRESET_DICT))
 209       {
 210         z->state->mode = BLOCKS;
 211         break;
 212       }
 213       z->state->mode = DICT4;
 214     case DICT4:
 215       NEEDBYTE
 216       z->state->sub.check.need = (uLong)NEXTBYTE << 24;
 217       z->state->mode = DICT3;
 218     case DICT3:
 219       NEEDBYTE
 220       z->state->sub.check.need += (uLong)NEXTBYTE << 16;
 221       z->state->mode = DICT2;
 222     case DICT2:
 223       NEEDBYTE
 224       z->state->sub.check.need += (uLong)NEXTBYTE << 8;
 225       z->state->mode = DICT1;
 226     case DICT1:
 227       NEEDBYTE
 228       z->state->sub.check.need += (uLong)NEXTBYTE;
 229       z->adler = z->state->sub.check.need;
 230       z->state->mode = DICT0;
 231       return Z_NEED_DICT;
 232     case DICT0:
 233       z->state->mode = BAD;
 234       z->msg = (char*)"need dictionary";
 235       z->state->sub.marker = 0;       /* can try inflateSync */
 236       return Z_STREAM_ERROR;
 237     case BLOCKS:
 238       r = inflate_blocks(z->state->blocks, z, r);
 239       if (r == Z_DATA_ERROR)
 240       {
 241         z->state->mode = BAD;
 242         z->state->sub.marker = 0;       /* can try inflateSync */
 243         break;
 244       }
 245       if (r == Z_OK)
 246         r = f;
 247       if (r != Z_STREAM_END)
 248         return r;
 249       r = f;
 250       inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
 251       if (z->state->nowrap)
 252       {
 253         z->state->mode = DONE;
 254         break;
 255       }
 256       z->state->mode = CHECK4;
 257     case CHECK4:
 258       NEEDBYTE
 259       z->state->sub.check.need = (uLong)NEXTBYTE << 24;
 260       z->state->mode = CHECK3;
 261     case CHECK3:
 262       NEEDBYTE
 263       z->state->sub.check.need += (uLong)NEXTBYTE << 16;
 264       z->state->mode = CHECK2;
 265     case CHECK2:
 266       NEEDBYTE
 267       z->state->sub.check.need += (uLong)NEXTBYTE << 8;
 268       z->state->mode = CHECK1;
 269     case CHECK1:
 270       NEEDBYTE
 271       z->state->sub.check.need += (uLong)NEXTBYTE;
 272
 273       if (z->state->sub.check.was != z->state->sub.check.need)
 274       {
 275         z->state->mode = BAD;
 276         z->msg = (char*)"incorrect data check";
 277         z->state->sub.marker = 5;       /* can't try inflateSync */
 278         break;
 279       }
 280       Tracev((stderr, "inflate: zlib check ok\n"));
 281       z->state->mode = DONE;
 282     case DONE:
 283       return Z_STREAM_END;
 284     case BAD:
 285       return Z_DATA_ERROR;
 286     default:
 287       return Z_STREAM_ERROR;
 288   }
 289 #ifdef NEED_DUMMY_RETURN
 290   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
 291 #endif
 292 }
 293
 294 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
 295 int ZEXPORT inflateSetDictionary(z_streamp z, const Bytef* dictionary, uInt dictLength)
 296 #else
 297 int ZEXPORT inflateSetDictionary(z, dictionary, dictLength)
 298 z_streamp z;
 299 const Bytef *dictionary;
 300 uInt  dictLength;
 301 #endif
 302 {
 303   uInt length = dictLength;
 304
 305   if (z == Z_NULL || z->state == Z_NULL || z->state->mode != DICT0)
 306     return Z_STREAM_ERROR;
 307
 308   if (adler32(1L, dictionary, dictLength) != z->adler) return Z_DATA_ERROR;
 309   z->adler = 1L;
 310
 311   if (length >= ((uInt)1<<z->state->wbits))
 312   {
 313     length = (1<<z->state->wbits)-1;
 314     dictionary += dictLength - length;
 315   }
 316   inflate_set_dictionary(z->state->blocks, dictionary, length);
 317   z->state->mode = BLOCKS;
 318   return Z_OK;
 319 }
 320
 321 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
 322 int ZEXPORT inflateSync(z_streamp z)
 323 #else
 324 int ZEXPORT inflateSync(z)
 325 z_streamp z;
 326 #endif
 327 {
 328   uInt n;       /* number of bytes to look at */
 329   Bytef *p;     /* pointer to bytes */
 330   uInt m;       /* number of marker bytes found in a row */
 331   uLong r, w;   /* temporaries to save total_in and total_out */
 332
 333   /* set up */
 334   if (z == Z_NULL || z->state == Z_NULL)
 335     return Z_STREAM_ERROR;
 336   if (z->state->mode != BAD)
 337   {
 338     z->state->mode = BAD;
 339     z->state->sub.marker = 0;
 340   }
 341   if ((n = z->avail_in) == 0)
 342     return Z_BUF_ERROR;
 343   p = z->next_in;
 344   m = z->state->sub.marker;
 345
 346   /* search */
 347   while (n && m < 4)
 348   {
 349     static const Byte mark[4] = {0, 0, 0xff, 0xff};
 350     if (*p == mark[m])
 351       m++;
 352     else if (*p)
 353       m = 0;
 354     else
 355       m = 4 - m;
 356     p++, n--;
 357   }
 358
 359   /* restore */
 360   z->total_in += p - z->next_in;
 361   z->next_in = p;
 362   z->avail_in = n;
 363   z->state->sub.marker = m;
 364
 365   /* return no joy or set up to restart on a new block */
 366   if (m != 4)
 367     return Z_DATA_ERROR;
 368   r = z->total_in;  w = z->total_out;
 369   inflateReset(z);
 370   z->total_in = r;  z->total_out = w;
 371   z->state->mode = BLOCKS;
 372   return Z_OK;
 373 }
 374
 375 /* Returns true if inflate is currently at the end of a block generated
 376  * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
 377  * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
 378  * but removes the length bytes of the resulting empty stored block. When
 379  * decompressing, PPP checks that at the end of input packet, inflate is
 380  * waiting for these length bytes.
 381  */
 382 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
 383 int ZEXPORT inflateSyncPoint(z_streamp z)
 384 #else
 385 int ZEXPORT inflateSyncPoint(z)
 386 z_streamp z;
 387 #endif
 388 {
 389   if (z == Z_NULL || z->state == Z_NULL || z->state->blocks == Z_NULL)
 390     return Z_STREAM_ERROR;
 391   return inflate_blocks_sync_point(z->state->blocks);
 392 }