www.pudn.com > ZLib-check.rar > inflate.c

/* inflate.c -- zlib interface to inflate modules 
 * Copyright (C) 1995-2002 Mark Adler 
 * For conditions of distribution and use, see copyright notice in zlib.h  
 */ 
 
#include "zutil.h" 
#include "infblock.h" 
 
struct inflate_blocks_state {int dummy;}; /* for buggy compilers */ 
 
typedef enum { 
      METHOD,   /* waiting for method byte */ 
      FLAG,     /* waiting for flag byte */ 
      DICT4,    /* four dictionary check bytes to go */ 
      DICT3,    /* three dictionary check bytes to go */ 
      DICT2,    /* two dictionary check bytes to go */ 
      DICT1,    /* one dictionary check byte to go */ 
      DICT0,    /* waiting for inflateSetDictionary */ 
      BLOCKS,   /* decompressing blocks */ 
      CHECK4,   /* four check bytes to go */ 
      CHECK3,   /* three check bytes to go */ 
      CHECK2,   /* two check bytes to go */ 
      CHECK1,   /* one check byte to go */ 
      DONE,     /* finished check, done */ 
      BAD}      /* got an error--stay here */ 
inflate_mode; 
 
/* inflate private state */ 
struct internal_state { 
 
  /* mode */ 
  inflate_mode  mode;   /* current inflate mode */ 
 
  /* mode dependent information */ 
  union { 
    uInt method;        /* if FLAGS, method byte */ 
    struct { 
      uLong was;                /* computed check value */ 
      uLong need;               /* stream check value */ 
    } check;            /* if CHECK, check values to compare */ 
    uInt marker;        /* if BAD, inflateSync's marker bytes count */ 
  } sub;        /* submode */ 
 
  /* mode independent information */ 
  int  nowrap;          /* flag for no wrapper */ 
  uInt wbits;           /* log2(window size)  (8..15, defaults to 15) */ 
  inflate_blocks_statef  
    *blocks;            /* current inflate_blocks state */ 
 
}; 
 
 
int ZEXPORT inflateReset(z) 
z_streamp z; 
{ 
  if (z == Z_NULL || z->state == Z_NULL) 
    return Z_STREAM_ERROR; 
  z->total_in = z->total_out = 0; 
  z->msg = Z_NULL; 
  z->state->mode = z->state->nowrap ? BLOCKS : METHOD; 
  inflate_blocks_reset(z->state->blocks, z, Z_NULL); 
  Tracev((stderr, "inflate: reset\n")); 
  return Z_OK; 
} 
 
 
int ZEXPORT inflateEnd(z) 
z_streamp z; 
{ 
  if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL) 
    return Z_STREAM_ERROR; 
  if (z->state->blocks != Z_NULL) 
    inflate_blocks_free(z->state->blocks, z); 
  ZFREE(z, z->state); 
  z->state = Z_NULL; 
  Tracev((stderr, "inflate: end\n")); 
  return Z_OK; 
} 
 
 
int ZEXPORT inflateInit2_(z, w, version, stream_size) 
z_streamp z; 
int w; 
const char *version; 
int stream_size; 
{ 
  if (version == Z_NULL || version[0] != ZLIB_VERSION[0] || 
      stream_size != sizeof(z_stream)) 
      return Z_VERSION_ERROR; 
 
  /* initialize state */ 
  if (z == Z_NULL) 
    return Z_STREAM_ERROR; 
  z->msg = Z_NULL; 
  if (z->zalloc == Z_NULL) 
  { 
    z->zalloc = zcalloc; 
    z->opaque = (voidpf)0; 
  } 
  if (z->zfree == Z_NULL) z->zfree = zcfree; 
  if ((z->state = (struct internal_state FAR *) 
       ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL) 
    return Z_MEM_ERROR; 
  z->state->blocks = Z_NULL; 
 
  /* handle undocumented nowrap option (no zlib header or check) */ 
  z->state->nowrap = 0; 
  if (w < 0) 
  { 
    w = - w; 
    z->state->nowrap = 1; 
  } 
 
  /* set window size */ 
  if (w < 8 || w > 15) 
  { 
    inflateEnd(z); 
    return Z_STREAM_ERROR; 
  } 
  z->state->wbits = (uInt)w; 
 
  /* create inflate_blocks state */ 
  if ((z->state->blocks = 
      inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w)) 
      == Z_NULL) 
  { 
    inflateEnd(z); 
    return Z_MEM_ERROR; 
  } 
  Tracev((stderr, "inflate: allocated\n")); 
 
  /* reset state */ 
  inflateReset(z); 
  return Z_OK; 
} 
 
 
int ZEXPORT inflateInit_(z, version, stream_size) 
z_streamp z; 
const char *version; 
int stream_size; 
{ 
  return inflateInit2_(z, DEF_WBITS, version, stream_size); 
} 
 
 
#define NEEDBYTE {if(z->avail_in==0)return r;r=f;} 
#define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++) 
 
int ZEXPORT inflate(z, f) 
z_streamp z; 
int f; 
{ 
  int r; 
  uInt b; 
 
  if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL) 
    return Z_STREAM_ERROR; 
  f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK; 
  r = Z_BUF_ERROR; 
  while (1) switch (z->state->mode) 
  { 
    case METHOD: 
      NEEDBYTE 
      if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED) 
      { 
        z->state->mode = BAD; 
        z->msg = (char*)"unknown compression method"; 
        z->state->sub.marker = 5;       /* can't try inflateSync */ 
        break; 
      } 
      if ((z->state->sub.method >> 4) + 8 > z->state->wbits) 
      { 
        z->state->mode = BAD; 
        z->msg = (char*)"invalid window size"; 
        z->state->sub.marker = 5;       /* can't try inflateSync */ 
        break; 
      } 
      z->state->mode = FLAG; 
    case FLAG: 
      NEEDBYTE 
      b = NEXTBYTE; 
      if (((z->state->sub.method << 8) + b) % 31) 
      { 
        z->state->mode = BAD; 
        z->msg = (char*)"incorrect header check"; 
        z->state->sub.marker = 5;       /* can't try inflateSync */ 
        break; 
      } 
      Tracev((stderr, "inflate: zlib header ok\n")); 
      if (!(b & PRESET_DICT)) 
      { 
        z->state->mode = BLOCKS; 
        break; 
      } 
      z->state->mode = DICT4; 
    case DICT4: 
      NEEDBYTE 
      z->state->sub.check.need = (uLong)NEXTBYTE << 24; 
      z->state->mode = DICT3; 
    case DICT3: 
      NEEDBYTE 
      z->state->sub.check.need += (uLong)NEXTBYTE << 16; 
      z->state->mode = DICT2; 
    case DICT2: 
      NEEDBYTE 
      z->state->sub.check.need += (uLong)NEXTBYTE << 8; 
      z->state->mode = DICT1; 
    case DICT1: 
      NEEDBYTE 
      z->state->sub.check.need += (uLong)NEXTBYTE; 
      z->adler = z->state->sub.check.need; 
      z->state->mode = DICT0; 
      return Z_NEED_DICT; 
    case DICT0: 
      z->state->mode = BAD; 
      z->msg = (char*)"need dictionary"; 
      z->state->sub.marker = 0;       /* can try inflateSync */ 
      return Z_STREAM_ERROR; 
    case BLOCKS: 
      r = inflate_blocks(z->state->blocks, z, r); 
      if (r == Z_DATA_ERROR) 
      { 
        z->state->mode = BAD; 
        z->state->sub.marker = 0;       /* can try inflateSync */ 
        break; 
      } 
      if (r == Z_OK) 
        r = f; 
      if (r != Z_STREAM_END) 
        return r; 
      r = f; 
      inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was); 
      if (z->state->nowrap) 
      { 
        z->state->mode = DONE; 
        break; 
      } 
      z->state->mode = CHECK4; 
    case CHECK4: 
      NEEDBYTE 
      z->state->sub.check.need = (uLong)NEXTBYTE << 24; 
      z->state->mode = CHECK3; 
    case CHECK3: 
      NEEDBYTE 
      z->state->sub.check.need += (uLong)NEXTBYTE << 16; 
      z->state->mode = CHECK2; 
    case CHECK2: 
      NEEDBYTE 
      z->state->sub.check.need += (uLong)NEXTBYTE << 8; 
      z->state->mode = CHECK1; 
    case CHECK1: 
      NEEDBYTE 
      z->state->sub.check.need += (uLong)NEXTBYTE; 
 
      if (z->state->sub.check.was != z->state->sub.check.need) 
      { 
        z->state->mode = BAD; 
        z->msg = (char*)"incorrect data check"; 
        z->state->sub.marker = 5;       /* can't try inflateSync */ 
        break; 
      } 
      Tracev((stderr, "inflate: zlib check ok\n")); 
      z->state->mode = DONE; 
    case DONE: 
      return Z_STREAM_END; 
    case BAD: 
      return Z_DATA_ERROR; 
    default: 
      return Z_STREAM_ERROR; 
  } 
#ifdef NEED_DUMMY_RETURN 
  return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */ 
#endif 
} 
 
 
int ZEXPORT inflateSetDictionary(z, dictionary, dictLength) 
z_streamp z; 
const Bytef *dictionary; 
uInt  dictLength; 
{ 
  uInt length = dictLength; 
 
  if (z == Z_NULL || z->state == Z_NULL || z->state->mode != DICT0) 
    return Z_STREAM_ERROR; 
 
  if (adler32(1L, dictionary, dictLength) != z->adler) return Z_DATA_ERROR; 
  z->adler = 1L; 
 
  if (length >= ((uInt)1<state->wbits)) 
  { 
    length = (1<state->wbits)-1; 
    dictionary += dictLength - length; 
  } 
  inflate_set_dictionary(z->state->blocks, dictionary, length); 
  z->state->mode = BLOCKS; 
  return Z_OK; 
} 
 
 
int ZEXPORT inflateSync(z) 
z_streamp z; 
{ 
  uInt n;       /* number of bytes to look at */ 
  Bytef *p;     /* pointer to bytes */ 
  uInt m;       /* number of marker bytes found in a row */ 
  uLong r, w;   /* temporaries to save total_in and total_out */ 
 
  /* set up */ 
  if (z == Z_NULL || z->state == Z_NULL) 
    return Z_STREAM_ERROR; 
  if (z->state->mode != BAD) 
  { 
    z->state->mode = BAD; 
    z->state->sub.marker = 0; 
  } 
  if ((n = z->avail_in) == 0) 
    return Z_BUF_ERROR; 
  p = z->next_in; 
  m = z->state->sub.marker; 
 
  /* search */ 
  while (n && m < 4) 
  { 
    static const Byte mark[4] = {0, 0, 0xff, 0xff}; 
    if (*p == mark[m]) 
      m++; 
    else if (*p) 
      m = 0; 
    else 
      m = 4 - m; 
    p++, n--; 
  } 
 
  /* restore */ 
  z->total_in += p - z->next_in; 
  z->next_in = p; 
  z->avail_in = n; 
  z->state->sub.marker = m; 
 
  /* return no joy or set up to restart on a new block */ 
  if (m != 4) 
    return Z_DATA_ERROR; 
  r = z->total_in;  w = z->total_out; 
  inflateReset(z); 
  z->total_in = r;  z->total_out = w; 
  z->state->mode = BLOCKS; 
  return Z_OK; 
} 
 
 
/* Returns true if inflate is currently at the end of a block generated 
 * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP 
 * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH 
 * but removes the length bytes of the resulting empty stored block. When 
 * decompressing, PPP checks that at the end of input packet, inflate is 
 * waiting for these length bytes. 
 */ 
int ZEXPORT inflateSyncPoint(z) 
z_streamp z; 
{ 
  if (z == Z_NULL || z->state == Z_NULL || z->state->blocks == Z_NULL) 
    return Z_STREAM_ERROR; 
  return inflate_blocks_sync_point(z->state->blocks); 
}