zlib/inflate.c

   1 /* inflate.c -- zlib interface to inflate modules
   2  * Copyright (C) 1995-2002 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       zBAD}      /* 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 zBAD, 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 int ZEXPORT inflateReset(z)
  54 z_streamp z;
  55 {
  56   if (z == Z_NULL || z->state == Z_NULL)
  57     return Z_STREAM_ERROR;
  58   z->total_in = z->total_out = 0;
  59   z->msg = Z_NULL;
  60   z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
  61   inflate_blocks_reset(z->state->blocks, z, Z_NULL);
  62   Tracev((stderr, "inflate: reset\n"));
  63   return Z_OK;
  64 }
  65
  66
  67 int ZEXPORT inflateEnd(z)
  68 z_streamp z;
  69 {
  70   if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
  71     return Z_STREAM_ERROR;
  72   if (z->state->blocks != Z_NULL)
  73     inflate_blocks_free(z->state->blocks, z);
  74   ZFREE(z, z->state);
  75   z->state = Z_NULL;
  76   Tracev((stderr, "inflate: end\n"));
  77   return Z_OK;
  78 }
  79
  80
  81 int ZEXPORT inflateInit2_(z, w, version, stream_size)
  82 z_streamp z;
  83 int w;
  84 const char *version;
  85 int stream_size;
  86 {
  87   if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
  88       stream_size != sizeof(z_stream))
  89       return Z_VERSION_ERROR;
  90
  91   /* initialize state */
  92   if (z == Z_NULL)
  93     return Z_STREAM_ERROR;
  94   z->msg = Z_NULL;
  95   if (z->zalloc == Z_NULL)
  96   {
  97     z->zalloc = zcalloc;
  98     z->opaque = (voidpf)0;
  99   }
 100   if (z->zfree == Z_NULL) z->zfree = zcfree;
 101   if ((z->state = (struct internal_state FAR *)
 102        ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
 103     return Z_MEM_ERROR;
 104   z->state->blocks = Z_NULL;
 105
 106   /* handle undocumented nowrap option (no zlib header or check) */
 107   z->state->nowrap = 0;
 108   if (w < 0)
 109   {
 110     w = - w;
 111     z->state->nowrap = 1;
 112   }
 113
 114   /* set window size */
 115   if (w < 8 || w > 15)
 116   {
 117     inflateEnd(z);
 118     return Z_STREAM_ERROR;
 119   }
 120   z->state->wbits = (uInt)w;
 121
 122   /* create inflate_blocks state */
 123   if ((z->state->blocks =
 124       inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w))
 125       == Z_NULL)
 126   {
 127     inflateEnd(z);
 128     return Z_MEM_ERROR;
 129   }
 130   Tracev((stderr, "inflate: allocated\n"));
 131
 132   /* reset state */
 133   inflateReset(z);
 134   return Z_OK;
 135 }
 136
 137
 138 int ZEXPORT inflateInit_(z, version, stream_size)
 139 z_streamp z;
 140 const char *version;
 141 int stream_size;
 142 {
 143   return inflateInit2_(z, DEF_WBITS, version, stream_size);
 144 }
 145
 146
 147 #define NEEDBYTE {if(z->avail_in==0)return r;r=f;}
 148 #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
 149
 150 int ZEXPORT inflate(z, f)
 151 z_streamp z;
 152 int f;
 153 {
 154   int r;
 155   uInt b;
 156
 157   if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
 158     return Z_STREAM_ERROR;
 159   f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
 160   r = Z_BUF_ERROR;
 161   while (1) switch (z->state->mode)
 162   {
 163     case METHOD:
 164       NEEDBYTE
 165       if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
 166       {
 167         z->state->mode = zBAD;
 168         z->msg = (char*)"unknown compression method";
 169         z->state->sub.marker = 5;       /* can't try inflateSync */
 170         break;
 171       }
 172       if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
 173       {
 174         z->state->mode = zBAD;
 175         z->msg = (char*)"invalid window size";
 176         z->state->sub.marker = 5;       /* can't try inflateSync */
 177         break;
 178       }
 179       z->state->mode = FLAG;
 180     case FLAG:
 181       NEEDBYTE
 182       b = NEXTBYTE;
 183       if (((z->state->sub.method << 8) + b) % 31)
 184       {
 185         z->state->mode = zBAD;
 186         z->msg = (char*)"incorrect header check";
 187         z->state->sub.marker = 5;       /* can't try inflateSync */
 188         break;
 189       }
 190       Tracev((stderr, "inflate: zlib header ok\n"));
 191       if (!(b & PRESET_DICT))
 192       {
 193         z->state->mode = BLOCKS;
 194         break;
 195       }
 196       z->state->mode = DICT4;
 197     case DICT4:
 198       NEEDBYTE
 199       z->state->sub.check.need = (uLong)NEXTBYTE << 24;
 200       z->state->mode = DICT3;
 201     case DICT3:
 202       NEEDBYTE
 203       z->state->sub.check.need += (uLong)NEXTBYTE << 16;
 204       z->state->mode = DICT2;
 205     case DICT2:
 206       NEEDBYTE
 207       z->state->sub.check.need += (uLong)NEXTBYTE << 8;
 208       z->state->mode = DICT1;
 209     case DICT1:
 210       NEEDBYTE
 211       z->state->sub.check.need += (uLong)NEXTBYTE;
 212       z->adler = z->state->sub.check.need;
 213       z->state->mode = DICT0;
 214       return Z_NEED_DICT;
 215     case DICT0:
 216       z->state->mode = zBAD;
 217       z->msg = (char*)"need dictionary";
 218       z->state->sub.marker = 0;       /* can try inflateSync */
 219       return Z_STREAM_ERROR;
 220     case BLOCKS:
 221       r = inflate_blocks(z->state->blocks, z, r);
 222       if (r == Z_DATA_ERROR)
 223       {
 224         z->state->mode = zBAD;
 225         z->state->sub.marker = 0;       /* can try inflateSync */
 226         break;
 227       }
 228       if (r == Z_OK)
 229         r = f;
 230       if (r != Z_STREAM_END)
 231         return r;
 232       r = f;
 233       inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
 234       if (z->state->nowrap)
 235       {
 236         z->state->mode = DONE;
 237         break;
 238       }
 239       z->state->mode = CHECK4;
 240     case CHECK4:
 241       NEEDBYTE
 242       z->state->sub.check.need = (uLong)NEXTBYTE << 24;
 243       z->state->mode = CHECK3;
 244     case CHECK3:
 245       NEEDBYTE
 246       z->state->sub.check.need += (uLong)NEXTBYTE << 16;
 247       z->state->mode = CHECK2;
 248     case CHECK2:
 249       NEEDBYTE
 250       z->state->sub.check.need += (uLong)NEXTBYTE << 8;
 251       z->state->mode = CHECK1;
 252     case CHECK1:
 253       NEEDBYTE
 254       z->state->sub.check.need += (uLong)NEXTBYTE;
 255
 256       if (z->state->sub.check.was != z->state->sub.check.need)
 257       {
 258         z->state->mode = zBAD;
 259         z->msg = (char*)"incorrect data check";
 260         z->state->sub.marker = 5;       /* can't try inflateSync */
 261         break;
 262       }
 263       Tracev((stderr, "inflate: zlib check ok\n"));
 264       z->state->mode = DONE;
 265     case DONE:
 266       return Z_STREAM_END;
 267     case zBAD:
 268       return Z_DATA_ERROR;
 269     default:
 270       return Z_STREAM_ERROR;
 271   }
 272 #ifdef NEED_DUMMY_RETURN
 273   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
 274 #endif
 275 }
 276
 277
 278 int ZEXPORT inflateSetDictionary(z, dictionary, dictLength)
 279 z_streamp z;
 280 const Bytef *dictionary;
 281 uInt  dictLength;
 282 {
 283   uInt length = dictLength;
 284
 285   if (z == Z_NULL || z->state == Z_NULL || z->state->mode != DICT0)
 286     return Z_STREAM_ERROR;
 287
 288   if (adler32(1L, dictionary, dictLength) != z->adler) return Z_DATA_ERROR;
 289   z->adler = 1L;
 290
 291   if (length >= ((uInt)1<<z->state->wbits))
 292   {
 293     length = (1<<z->state->wbits)-1;
 294     dictionary += dictLength - length;
 295   }
 296   inflate_set_dictionary(z->state->blocks, dictionary, length);
 297   z->state->mode = BLOCKS;
 298   return Z_OK;
 299 }
 300
 301
 302 int ZEXPORT inflateSync(z)
 303 z_streamp z;
 304 {
 305   uInt n;       /* number of bytes to look at */
 306   Bytef *p;     /* pointer to bytes */
 307   uInt m;       /* number of marker bytes found in a row */
 308   uLong r, w;   /* temporaries to save total_in and total_out */
 309
 310   /* set up */
 311   if (z == Z_NULL || z->state == Z_NULL)
 312     return Z_STREAM_ERROR;
 313   if (z->state->mode != zBAD)
 314   {
 315     z->state->mode = zBAD;
 316     z->state->sub.marker = 0;
 317   }
 318   if ((n = z->avail_in) == 0)
 319     return Z_BUF_ERROR;
 320   p = z->next_in;
 321   m = z->state->sub.marker;
 322
 323   /* search */
 324   while (n && m < 4)
 325   {
 326     static const Byte mark[4] = {0, 0, 0xff, 0xff};
 327     if (*p == mark[m])
 328       m++;
 329     else if (*p)
 330       m = 0;
 331     else
 332       m = 4 - m;
 333     p++, n--;
 334   }
 335
 336   /* restore */
 337   z->total_in += p - z->next_in;
 338   z->next_in = p;
 339   z->avail_in = n;
 340   z->state->sub.marker = m;
 341
 342   /* return no joy or set up to restart on a new block */
 343   if (m != 4)
 344     return Z_DATA_ERROR;
 345   r = z->total_in;  w = z->total_out;
 346   inflateReset(z);
 347   z->total_in = r;  z->total_out = w;
 348   z->state->mode = BLOCKS;
 349   return Z_OK;
 350 }
 351
 352
 353 /* Returns true if inflate is currently at the end of a block generated
 354  * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
 355  * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
 356  * but removes the length bytes of the resulting empty stored block. When
 357  * decompressing, PPP checks that at the end of input packet, inflate is
 358  * waiting for these length bytes.
 359  */
 360 int ZEXPORT inflateSyncPoint(z)
 361 z_streamp z;
 362 {
 363   if (z == Z_NULL || z->state == Z_NULL || z->state->blocks == Z_NULL)
 364     return Z_STREAM_ERROR;
 365   return inflate_blocks_sync_point(z->state->blocks);
 366 }