File: /usr/src/linux/fs/cramfs/inflate/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 int ZEXPORT cramfs_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 cramfs_inflate_blocks_reset(z->state->blocks, z, Z_NULL);
62 return Z_OK;
63 }
64
65
66 int ZEXPORT cramfs_inflateEnd(z)
67 z_streamp z;
68 {
69 if (z == Z_NULL || z->state == Z_NULL)
70 return Z_STREAM_ERROR;
71 if (z->state->blocks != Z_NULL)
72 cramfs_inflate_blocks_free(z->state->blocks, z);
73 z->state = Z_NULL;
74 return Z_OK;
75 }
76
77
78 int ZEXPORT cramfs_inflateInit2_(z, w, version, stream_size)
79 z_streamp z;
80 int w;
81 const char *version;
82 int stream_size;
83 {
84 static struct internal_state internal_state;
85
86 if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
87 stream_size != sizeof(z_stream))
88 return Z_VERSION_ERROR;
89
90 /* initialize state */
91 if (z == Z_NULL)
92 return Z_STREAM_ERROR;
93 z->msg = Z_NULL;
94 z->state = &internal_state;
95 z->state->blocks = Z_NULL;
96
97 /* handle undocumented nowrap option (no zlib header or check) */
98 z->state->nowrap = 0;
99 if (w < 0)
100 {
101 w = - w;
102 z->state->nowrap = 1;
103 }
104
105 /* set window size */
106 if (w < 8 || w > 15)
107 {
108 cramfs_inflateEnd(z);
109 return Z_STREAM_ERROR;
110 }
111 z->state->wbits = (uInt)w;
112
113 /* create inflate_blocks state */
114 if ((z->state->blocks =
115 cramfs_inflate_blocks_new(z, z->state->nowrap ? Z_NULL : cramfs_adler32, (uInt)1 << w))
116 == Z_NULL)
117 {
118 cramfs_inflateEnd(z);
119 return Z_MEM_ERROR;
120 }
121
122 /* reset state */
123 cramfs_inflateReset(z);
124 return Z_OK;
125 }
126
127
128 int ZEXPORT cramfs_inflateInit_(z, version, stream_size)
129 z_streamp z;
130 const char *version;
131 int stream_size;
132 {
133 return cramfs_inflateInit2_(z, DEF_WBITS, version, stream_size);
134 }
135
136
137 #define NEEDBYTE {if(z->avail_in==0)return r;r=f;}
138 #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
139
140 int ZEXPORT cramfs_inflate(z, f)
141 z_streamp z;
142 int f;
143 {
144 int r;
145 uInt b;
146
147 if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
148 return Z_STREAM_ERROR;
149 f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
150 r = Z_BUF_ERROR;
151 while (1) switch (z->state->mode)
152 {
153 case METHOD:
154 NEEDBYTE
155 if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
156 {
157 z->state->mode = BAD;
158 z->msg = (char*)"unknown compression method";
159 z->state->sub.marker = 5; /* can't try inflateSync */
160 break;
161 }
162 if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
163 {
164 z->state->mode = BAD;
165 z->msg = (char*)"invalid window size";
166 z->state->sub.marker = 5; /* can't try inflateSync */
167 break;
168 }
169 z->state->mode = FLAG;
170 case FLAG:
171 NEEDBYTE
172 b = NEXTBYTE;
173 if (((z->state->sub.method << 8) + b) % 31)
174 {
175 z->state->mode = BAD;
176 z->msg = (char*)"incorrect header check";
177 z->state->sub.marker = 5; /* can't try inflateSync */
178 break;
179 }
180 if (!(b & PRESET_DICT))
181 {
182 z->state->mode = BLOCKS;
183 break;
184 }
185 z->state->mode = DICT4;
186 case DICT4:
187 NEEDBYTE
188 z->state->sub.check.need = (uLong)NEXTBYTE << 24;
189 z->state->mode = DICT3;
190 case DICT3:
191 NEEDBYTE
192 z->state->sub.check.need += (uLong)NEXTBYTE << 16;
193 z->state->mode = DICT2;
194 case DICT2:
195 NEEDBYTE
196 z->state->sub.check.need += (uLong)NEXTBYTE << 8;
197 z->state->mode = DICT1;
198 case DICT1:
199 NEEDBYTE
200 z->state->sub.check.need += (uLong)NEXTBYTE;
201 z->adler = z->state->sub.check.need;
202 z->state->mode = DICT0;
203 return Z_NEED_DICT;
204 case DICT0:
205 z->state->mode = BAD;
206 z->msg = (char*)"need dictionary";
207 z->state->sub.marker = 0; /* can try inflateSync */
208 return Z_STREAM_ERROR;
209 case BLOCKS:
210 r = cramfs_inflate_blocks(z->state->blocks, z, r);
211 if (r == Z_DATA_ERROR)
212 {
213 z->state->mode = BAD;
214 z->state->sub.marker = 0; /* can try inflateSync */
215 break;
216 }
217 if (r == Z_OK)
218 r = f;
219 if (r != Z_STREAM_END)
220 return r;
221 r = f;
222 cramfs_inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
223 if (z->state->nowrap)
224 {
225 z->state->mode = DONE;
226 break;
227 }
228 z->state->mode = CHECK4;
229 case CHECK4:
230 NEEDBYTE
231 z->state->sub.check.need = (uLong)NEXTBYTE << 24;
232 z->state->mode = CHECK3;
233 case CHECK3:
234 NEEDBYTE
235 z->state->sub.check.need += (uLong)NEXTBYTE << 16;
236 z->state->mode = CHECK2;
237 case CHECK2:
238 NEEDBYTE
239 z->state->sub.check.need += (uLong)NEXTBYTE << 8;
240 z->state->mode = CHECK1;
241 case CHECK1:
242 NEEDBYTE
243 z->state->sub.check.need += (uLong)NEXTBYTE;
244
245 if (z->state->sub.check.was != z->state->sub.check.need)
246 {
247 z->state->mode = BAD;
248 z->msg = (char*)"incorrect data check";
249 z->state->sub.marker = 5; /* can't try inflateSync */
250 break;
251 }
252 z->state->mode = DONE;
253 case DONE:
254 return Z_STREAM_END;
255 case BAD:
256 return Z_DATA_ERROR;
257 default:
258 return Z_STREAM_ERROR;
259 }
260 #ifdef NEED_DUMMY_RETURN
261 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
262 #endif
263 }
264
265
266 int ZEXPORT cramfs_inflateSync(z)
267 z_streamp z;
268 {
269 uInt n; /* number of bytes to look at */
270 Bytef *p; /* pointer to bytes */
271 uInt m; /* number of marker bytes found in a row */
272 uLong r, w; /* temporaries to save total_in and total_out */
273
274 /* set up */
275 if (z == Z_NULL || z->state == Z_NULL)
276 return Z_STREAM_ERROR;
277 if (z->state->mode != BAD)
278 {
279 z->state->mode = BAD;
280 z->state->sub.marker = 0;
281 }
282 if ((n = z->avail_in) == 0)
283 return Z_BUF_ERROR;
284 p = z->next_in;
285 m = z->state->sub.marker;
286
287 /* search */
288 while (n && m < 4)
289 {
290 static const Byte mark[4] = {0, 0, 0xff, 0xff};
291 if (*p == mark[m])
292 m++;
293 else if (*p)
294 m = 0;
295 else
296 m = 4 - m;
297 p++, n--;
298 }
299
300 /* restore */
301 z->total_in += p - z->next_in;
302 z->next_in = p;
303 z->avail_in = n;
304 z->state->sub.marker = m;
305
306 /* return no joy or set up to restart on a new block */
307 if (m != 4)
308 return Z_DATA_ERROR;
309 r = z->total_in; w = z->total_out;
310 cramfs_inflateReset(z);
311 z->total_in = r; z->total_out = w;
312 z->state->mode = BLOCKS;
313 return Z_OK;
314 }
315
316
317 /* Returns true if inflate is currently at the end of a block generated
318 * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
319 * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
320 * but removes the length bytes of the resulting empty stored block. When
321 * decompressing, PPP checks that at the end of input packet, inflate is
322 * waiting for these length bytes.
323 */
324 int ZEXPORT cramfs_inflateSyncPoint(z)
325 z_streamp z;
326 {
327 if (z == Z_NULL || z->state == Z_NULL || z->state->blocks == Z_NULL)
328 return Z_STREAM_ERROR;
329 return inflate_blocks_sync_point(z->state->blocks);
330 }
331