inflate.c revision 1.3 
1/*	$OpenBSD: inflate.c,v 1.3 2002/03/12 00:25:57 millert Exp $	*/
2/* inflate.c -- zlib interface to inflate modules
3 * Copyright (C) 1995-2002 Mark Adler
4 * For conditions of distribution and use, see copyright notice in zlib.h
5 */
6
7#include "zutil.h"
8#include "infblock.h"
9
10struct inflate_blocks_state {int dummy;}; /* for buggy compilers */
11
12typedef enum {
13      METHOD,   /* waiting for method byte */
14      FLAG,     /* waiting for flag byte */
15      DICT4,    /* four dictionary check bytes to go */
16      DICT3,    /* three dictionary check bytes to go */
17      DICT2,    /* two dictionary check bytes to go */
18      DICT1,    /* one dictionary check byte to go */
19      DICT0,    /* waiting for inflateSetDictionary */
20      BLOCKS,   /* decompressing blocks */
21      CHECK4,   /* four check bytes to go */
22      CHECK3,   /* three check bytes to go */
23      CHECK2,   /* two check bytes to go */
24      CHECK1,   /* one check byte to go */
25      DONE,     /* finished check, done */
26      BAD}      /* got an error--stay here */
27inflate_mode;
28
29/* inflate private state */
30struct internal_state {
31
32  /* mode */
33  inflate_mode  mode;   /* current inflate mode */
34
35  /* mode dependent information */
36  union {
37    uInt method;        /* if FLAGS, method byte */
38    struct {
39      uLong was;                /* computed check value */
40      uLong need;               /* stream check value */
41    } check;            /* if CHECK, check values to compare */
42    uInt marker;        /* if BAD, inflateSync's marker bytes count */
43  } sub;        /* submode */
44
45  /* mode independent information */
46  int  nowrap;          /* flag for no wrapper */
47  uInt wbits;           /* log2(window size)  (8..15, defaults to 15) */
48  inflate_blocks_statef
49    *blocks;            /* current inflate_blocks state */
50
51};
52
53
54int ZEXPORT inflateReset(z)
55z_streamp z;
56{
57  if (z == Z_NULL || z->state == Z_NULL)
58    return Z_STREAM_ERROR;
59  z->total_in = z->total_out = 0;
60  z->msg = Z_NULL;
61  z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
62  inflate_blocks_reset(z->state->blocks, z, Z_NULL);
63  Tracev((stderr, "inflate: reset\n"));
64  return Z_OK;
65}
66
67
68int ZEXPORT inflateEnd(z)
69z_streamp z;
70{
71  if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
72    return Z_STREAM_ERROR;
73  if (z->state->blocks != Z_NULL)
74    inflate_blocks_free(z->state->blocks, z);
75  ZFREE(z, z->state);
76  z->state = Z_NULL;
77  Tracev((stderr, "inflate: end\n"));
78  return Z_OK;
79}
80
81
82int ZEXPORT inflateInit2_(z, w, version, stream_size)
83z_streamp z;
84int w;
85const char *version;
86int stream_size;
87{
88  if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
89      stream_size != sizeof(z_stream))
90      return Z_VERSION_ERROR;
91
92  /* initialize state */
93  if (z == Z_NULL)
94    return Z_STREAM_ERROR;
95  z->msg = Z_NULL;
96  if (z->zalloc == Z_NULL)
97  {
98    z->zalloc = zcalloc;
99    z->opaque = (voidpf)0;
100  }
101  if (z->zfree == Z_NULL) z->zfree = zcfree;
102  if ((z->state = (struct internal_state FAR *)
103       ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
104    return Z_MEM_ERROR;
105  z->state->blocks = Z_NULL;
106
107  /* handle undocumented nowrap option (no zlib header or check) */
108  z->state->nowrap = 0;
109  if (w < 0)
110  {
111    w = - w;
112    z->state->nowrap = 1;
113  }
114
115  /* set window size */
116  if (w < 8 || w > 15)
117  {
118    inflateEnd(z);
119    return Z_STREAM_ERROR;
120  }
121  z->state->wbits = (uInt)w;
122
123  /* create inflate_blocks state */
124  if ((z->state->blocks =
125      inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w))
126      == Z_NULL)
127  {
128    inflateEnd(z);
129    return Z_MEM_ERROR;
130  }
131  Tracev((stderr, "inflate: allocated\n"));
132
133  /* reset state */
134  inflateReset(z);
135  return Z_OK;
136}
137
138
139int ZEXPORT inflateInit_(z, version, stream_size)
140z_streamp z;
141const char *version;
142int stream_size;
143{
144  return inflateInit2_(z, DEF_WBITS, version, stream_size);
145}
146
147
148#define NEEDBYTE {if(z->avail_in==0)return r;r=f;}
149#define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
150
151int ZEXPORT inflate(z, f)
152z_streamp z;
153int f;
154{
155  int r;
156  uInt b;
157
158  if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
159    return Z_STREAM_ERROR;
160  f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
161  r = Z_BUF_ERROR;
162  while (1) switch (z->state->mode)
163  {
164    case METHOD:
165      NEEDBYTE
166      if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
167      {
168        z->state->mode = BAD;
169        z->msg = (char*)"unknown compression method";
170        z->state->sub.marker = 5;       /* can't try inflateSync */
171        break;
172      }
173      if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
174      {
175        z->state->mode = BAD;
176        z->msg = (char*)"invalid window size";
177        z->state->sub.marker = 5;       /* can't try inflateSync */
178        break;
179      }
180      z->state->mode = FLAG;
181    case FLAG:
182      NEEDBYTE
183      b = NEXTBYTE;
184      if (((z->state->sub.method << 8) + b) % 31)
185      {
186        z->state->mode = BAD;
187        z->msg = (char*)"incorrect header check";
188        z->state->sub.marker = 5;       /* can't try inflateSync */
189        break;
190      }
191      Tracev((stderr, "inflate: zlib header ok\n"));
192      if (!(b & PRESET_DICT))
193      {
194        z->state->mode = BLOCKS;
195        break;
196      }
197      z->state->mode = DICT4;
198    case DICT4:
199      NEEDBYTE
200      z->state->sub.check.need = (uLong)NEXTBYTE << 24;
201      z->state->mode = DICT3;
202    case DICT3:
203      NEEDBYTE
204      z->state->sub.check.need += (uLong)NEXTBYTE << 16;
205      z->state->mode = DICT2;
206    case DICT2:
207      NEEDBYTE
208      z->state->sub.check.need += (uLong)NEXTBYTE << 8;
209      z->state->mode = DICT1;
210    case DICT1:
211      NEEDBYTE
212      z->state->sub.check.need += (uLong)NEXTBYTE;
213      z->adler = z->state->sub.check.need;
214      z->state->mode = DICT0;
215      return Z_NEED_DICT;
216    case DICT0:
217      z->state->mode = BAD;
218      z->msg = (char*)"need dictionary";
219      z->state->sub.marker = 0;       /* can try inflateSync */
220      return Z_STREAM_ERROR;
221    case BLOCKS:
222      r = inflate_blocks(z->state->blocks, z, r);
223      if (r == Z_DATA_ERROR)
224      {
225        z->state->mode = BAD;
226        z->state->sub.marker = 0;       /* can try inflateSync */
227        break;
228      }
229      if (r == Z_OK)
230        r = f;
231      if (r != Z_STREAM_END)
232        return r;
233      r = f;
234      inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
235      if (z->state->nowrap)
236      {
237        z->state->mode = DONE;
238        break;
239      }
240      z->state->mode = CHECK4;
241    case CHECK4:
242      NEEDBYTE
243      z->state->sub.check.need = (uLong)NEXTBYTE << 24;
244      z->state->mode = CHECK3;
245    case CHECK3:
246      NEEDBYTE
247      z->state->sub.check.need += (uLong)NEXTBYTE << 16;
248      z->state->mode = CHECK2;
249    case CHECK2:
250      NEEDBYTE
251      z->state->sub.check.need += (uLong)NEXTBYTE << 8;
252      z->state->mode = CHECK1;
253    case CHECK1:
254      NEEDBYTE
255      z->state->sub.check.need += (uLong)NEXTBYTE;
256
257      if (z->state->sub.check.was != z->state->sub.check.need)
258      {
259        z->state->mode = BAD;
260        z->msg = (char*)"incorrect data check";
261        z->state->sub.marker = 5;       /* can't try inflateSync */
262        break;
263      }
264      Tracev((stderr, "inflate: zlib check ok\n"));
265      z->state->mode = DONE;
266    case DONE:
267      return Z_STREAM_END;
268    case BAD:
269      return Z_DATA_ERROR;
270    default:
271      return Z_STREAM_ERROR;
272  }
273#ifdef NEED_DUMMY_RETURN
274  return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
275#endif
276}
277
278
279int ZEXPORT inflateSetDictionary(z, dictionary, dictLength)
280z_streamp z;
281const Bytef *dictionary;
282uInt  dictLength;
283{
284  uInt length = dictLength;
285
286  if (z == Z_NULL || z->state == Z_NULL || z->state->mode != DICT0)
287    return Z_STREAM_ERROR;
288
289  if (adler32(1L, dictionary, dictLength) != z->adler) return Z_DATA_ERROR;
290  z->adler = 1L;
291
292  if (length >= ((uInt)1<<z->state->wbits))
293  {
294    length = (1<<z->state->wbits)-1;
295    dictionary += dictLength - length;
296  }
297  inflate_set_dictionary(z->state->blocks, dictionary, length);
298  z->state->mode = BLOCKS;
299  return Z_OK;
300}
301
302
303int ZEXPORT inflateSync(z)
304z_streamp z;
305{
306  uInt n;       /* number of bytes to look at */
307  Bytef *p;     /* pointer to bytes */
308  uInt m;       /* number of marker bytes found in a row */
309  uLong r, w;   /* temporaries to save total_in and total_out */
310
311  /* set up */
312  if (z == Z_NULL || z->state == Z_NULL)
313    return Z_STREAM_ERROR;
314  if (z->state->mode != BAD)
315  {
316    z->state->mode = BAD;
317    z->state->sub.marker = 0;
318  }
319  if ((n = z->avail_in) == 0)
320    return Z_BUF_ERROR;
321  p = z->next_in;
322  m = z->state->sub.marker;
323
324  /* search */
325  while (n && m < 4)
326  {
327    static const Byte mark[4] = {0, 0, 0xff, 0xff};
328    if (*p == mark[m])
329      m++;
330    else if (*p)
331      m = 0;
332    else
333      m = 4 - m;
334    p++, n--;
335  }
336
337  /* restore */
338  z->total_in += p - z->next_in;
339  z->next_in = p;
340  z->avail_in = n;
341  z->state->sub.marker = m;
342
343  /* return no joy or set up to restart on a new block */
344  if (m != 4)
345    return Z_DATA_ERROR;
346  r = z->total_in;  w = z->total_out;
347  inflateReset(z);
348  z->total_in = r;  z->total_out = w;
349  z->state->mode = BLOCKS;
350  return Z_OK;
351}
352
353
354/* Returns true if inflate is currently at the end of a block generated
355 * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
356 * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
357 * but removes the length bytes of the resulting empty stored block. When
358 * decompressing, PPP checks that at the end of input packet, inflate is
359 * waiting for these length bytes.
360 */
361int ZEXPORT inflateSyncPoint(z)
362z_streamp z;
363{
364  if (z == Z_NULL || z->state == Z_NULL || z->state->blocks == Z_NULL)
365    return Z_STREAM_ERROR;
366  return inflate_blocks_sync_point(z->state->blocks);
367}
368