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 #define  DONE  INFLATE_DONE
10 #define  BAD   INFLATE_BAD
11 
12 typedef 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 */
27 inflate_mode;
28 
29 /* inflate private state */
30 struct 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 
inflateReset(z_streamp z)54 ZEXPORT(int) inflateReset( /* z) */
55 z_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 
inflateEnd(z_streamp z)68 ZEXPORT(int) inflateEnd( /* z) */
69 z_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 
inflateInit2_(z_streamp z,int w,const char * version,int stream_size)82 ZEXPORT(int) inflateInit2_( /* z, w, version, stream_size) */
83 z_streamp z,
84 int w,
85 const char *version,
86 int 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 
139 
140 #undef  NEEDBYTE
141 #define NEEDBYTE {if(z->avail_in==0)return r;r=f;}
142 
143 #undef  NEXTBYTE
144 #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
145 
146 
inflate(z_streamp z,int f)147 ZEXPORT(int) inflate( /* z, f) */
148 z_streamp z,
149 int f )
150 {
151   int r;
152   uInt b;
153 
154   if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
155     return Z_STREAM_ERROR;
156   f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
157   r = Z_BUF_ERROR;
158   while (1) switch (z->state->mode)
159   {
160     case METHOD:
161       NEEDBYTE
162       if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
163       {
164         z->state->mode = BAD;
165         z->msg = (char*)"unknown compression method";
166         z->state->sub.marker = 5;       /* can't try inflateSync */
167         break;
168       }
169       if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
170       {
171         z->state->mode = BAD;
172         z->msg = (char*)"invalid window size";
173         z->state->sub.marker = 5;       /* can't try inflateSync */
174         break;
175       }
176       z->state->mode = FLAG;
177     case FLAG:
178       NEEDBYTE
179       b = NEXTBYTE;
180       if (((z->state->sub.method << 8) + b) % 31)
181       {
182         z->state->mode = BAD;
183         z->msg = (char*)"incorrect header check";
184         z->state->sub.marker = 5;       /* can't try inflateSync */
185         break;
186       }
187       Tracev((stderr, "inflate: zlib header ok\n"));
188       if (!(b & PRESET_DICT))
189       {
190         z->state->mode = BLOCKS;
191         break;
192       }
193       z->state->mode = DICT4;
194     case DICT4:
195       NEEDBYTE
196       z->state->sub.check.need = (uLong)NEXTBYTE << 24;
197       z->state->mode = DICT3;
198     case DICT3:
199       NEEDBYTE
200       z->state->sub.check.need += (uLong)NEXTBYTE << 16;
201       z->state->mode = DICT2;
202     case DICT2:
203       NEEDBYTE
204       z->state->sub.check.need += (uLong)NEXTBYTE << 8;
205       z->state->mode = DICT1;
206     case DICT1:
207       NEEDBYTE
208       z->state->sub.check.need += (uLong)NEXTBYTE;
209       z->adler = z->state->sub.check.need;
210       z->state->mode = DICT0;
211       return Z_NEED_DICT;
212     case DICT0:
213       z->state->mode = BAD;
214       z->msg = (char*)"need dictionary";
215       z->state->sub.marker = 0;       /* can try inflateSync */
216       return Z_STREAM_ERROR;
217     case BLOCKS:
218       r = inflate_blocks(z->state->blocks, z, r);
219       if (r == Z_DATA_ERROR)
220       {
221         z->state->mode = BAD;
222         z->state->sub.marker = 0;       /* can try inflateSync */
223         break;
224       }
225       if (r == Z_OK)
226         r = f;
227       if (r != Z_STREAM_END)
228         return r;
229       r = f;
230       inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
231       if (z->state->nowrap)
232       {
233         z->state->mode = DONE;
234         break;
235       }
236       z->state->mode = CHECK4;
237     case CHECK4:
238       NEEDBYTE
239       z->state->sub.check.need = (uLong)NEXTBYTE << 24;
240       z->state->mode = CHECK3;
241     case CHECK3:
242       NEEDBYTE
243       z->state->sub.check.need += (uLong)NEXTBYTE << 16;
244       z->state->mode = CHECK2;
245     case CHECK2:
246       NEEDBYTE
247       z->state->sub.check.need += (uLong)NEXTBYTE << 8;
248       z->state->mode = CHECK1;
249     case CHECK1:
250       NEEDBYTE
251       z->state->sub.check.need += (uLong)NEXTBYTE;
252 
253       if (z->state->sub.check.was != z->state->sub.check.need)
254       {
255         z->state->mode = BAD;
256         z->msg = (char*)"incorrect data check";
257         z->state->sub.marker = 5;       /* can't try inflateSync */
258         break;
259       }
260       Tracev((stderr, "inflate: zlib check ok\n"));
261       z->state->mode = DONE;
262     case DONE:
263       return Z_STREAM_END;
264     case BAD:
265       return Z_DATA_ERROR;
266     default:
267       return Z_STREAM_ERROR;
268   }
269 #ifdef NEED_DUMMY_RETURN
270   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
271 #endif
272 }
273 
274