src/zlib/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 */

};


#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateReset(z_streamp z)
#else
int ZEXPORT inflateReset(z)
z_streamp z;
#endif
{
  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;
}


#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateEnd(z_streamp z)
#else
int ZEXPORT inflateEnd(z)
z_streamp z;
#endif
{
  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;
}

#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateInit2_(z_streamp z, int w, const char* version, int stream_size)
#else
int ZEXPORT inflateInit2_(z, w, version, stream_size)
z_streamp z;
int w;
const char *version;
int stream_size;
#endif
{
  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;
}

#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateInit_(z_streamp z, const char* version, int stream_size)
#else
int ZEXPORT inflateInit_(z, version, stream_size)
z_streamp z;
const char *version;
int stream_size;
#endif
{
  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++)

#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflate(z_streamp z, int f)
#else
int ZEXPORT inflate(z, f)
z_streamp z;
int f;
#endif
{
  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
}

#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateSetDictionary(z_streamp z, const Bytef* dictionary, uInt dictLength)
#else
int ZEXPORT inflateSetDictionary(z, dictionary, dictLength)
z_streamp z;
const Bytef *dictionary;
uInt  dictLength;
#endif
{
  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<<z->state->wbits))
  {
    length = (1<<z->state->wbits)-1;
    dictionary += dictLength - length;
  }
  inflate_set_dictionary(z->state->blocks, dictionary, length);
  z->state->mode = BLOCKS;
  return Z_OK;
}

#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateSync(z_streamp z)
#else
int ZEXPORT inflateSync(z)
z_streamp z;
#endif
{
  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.
 */
#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
int ZEXPORT inflateSyncPoint(z_streamp z)
#else
int ZEXPORT inflateSyncPoint(z)
z_streamp z;
#endif
{
  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);
}
Commit	Line	Data
	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	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	}