1 /* infcodes.c -- process literals and length/distance pairs
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 "inftrees.h"
8 #include "infblock.h"
9 #include "infcodes.h"
10 #include "infutil.h"
11
12 /* simplify the use of the inflate_huft type with some defines */
13 #define exop word.what.Exop
14 #define bits word.what.Bits
15
16 typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
17 START, /* x: set up for LEN */
18 LEN, /* i: get length/literal/eob next */
19 LENEXT, /* i: getting length extra (have base) */
20 DIST, /* i: get distance next */
21 DISTEXT, /* i: getting distance extra */
22 COPY, /* o: copying bytes in window, waiting for space */
23 LIT, /* o: got literal, waiting for output space */
24 WASH, /* o: got eob, possibly still output waiting */
25 END, /* x: got eob and all data flushed */
26 BADCODE} /* x: got error */
27 inflate_codes_mode;
28
29 /* inflate codes private state */
30 struct inflate_codes_state {
31
32 /* mode */
33 inflate_codes_mode mode; /* current inflate_codes mode */
34
35 /* mode dependent information */
36 uInt len;
37 union {
38 struct {
39 inflate_huft *tree; /* pointer into tree */
40 uInt need; /* bits needed */
41 } code; /* if LEN or DIST, where in tree */
42 uInt lit; /* if LIT, literal */
43 struct {
44 uInt get; /* bits to get for extra */
45 uInt dist; /* distance back to copy from */
46 } copy; /* if EXT or COPY, where and how much */
47 } sub; /* submode */
48
49 /* mode independent information */
50 Byte lbits; /* ltree bits decoded per branch */
51 Byte dbits; /* dtree bits decoder per branch */
52 inflate_huft *ltree; /* literal/length/eob tree */
53 inflate_huft *dtree; /* distance tree */
54
55 };
56
57
inflate_codes_new(uInt bl,uInt bd,inflate_huft * tl,inflate_huft * td,z_streamp z)58 local inflate_codes_statef *inflate_codes_new( /* bl, bd, tl, td, z) */
59 uInt bl, uInt bd,
60 inflate_huft *tl,
61 inflate_huft *td, /* need separate declaration for Borland C++ */
62 z_streamp z )
63 {
64 inflate_codes_statef *c;
65
66 if ((c = (inflate_codes_statef *)
67 ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
68 {
69 c->mode = START;
70 c->lbits = (Byte)bl;
71 c->dbits = (Byte)bd;
72 c->ltree = tl;
73 c->dtree = td;
74 Tracev((stderr, "inflate: codes new\n"));
75 }
76 return c;
77 }
78
79
inflate_codes(inflate_blocks_statef * s,z_streamp z,int r)80 local int inflate_codes( /* s, z, r) */
81 inflate_blocks_statef *s,
82 z_streamp z,
83 int r )
84 {
85 uInt j; /* temporary storage */
86 inflate_huft *t; /* temporary pointer */
87 uInt e; /* extra bits or operation */
88 uLong b; /* bit buffer */
89 uInt k; /* bits in bit buffer */
90 Bytef *p; /* input data pointer */
91 uInt n; /* bytes available there */
92 Bytef *q; /* output window write pointer */
93 uInt m; /* bytes to end of window or read pointer */
94 Bytef *f; /* pointer to copy strings from */
95 inflate_codes_statef *c = s->sub.decode.codes; /* codes state */
96
97 /* copy input/output information to locals (UPDATE macro restores) */
98 LOAD
99
100 /* process input and output based on current state */
101 while (1) switch (c->mode)
102 { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
103 case START: /* x: set up for LEN */
104 #ifndef SLOW
105 if (m >= 258 && n >= 10)
106 {
107 UPDATE
108 r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
109 LOAD
110 if (r != Z_OK)
111 {
112 c->mode = r == Z_STREAM_END ? WASH : BADCODE;
113 break;
114 }
115 }
116 #endif /* !SLOW */
117 c->sub.code.need = c->lbits;
118 c->sub.code.tree = c->ltree;
119 c->mode = LEN;
120 /* fall through */
121 case LEN: /* i: get length/literal/eob next */
122 j = c->sub.code.need;
123 NEEDBITS(j)
124 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
125 DUMPBITS(t->bits)
126 e = (uInt)(t->exop);
127 if (e == 0) /* literal */
128 {
129 c->sub.lit = t->base;
130 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
131 "inflate: literal '%c'\n" :
132 "inflate: literal 0x%02x\n", t->base));
133 c->mode = LIT;
134 break;
135 }
136 if (e & 16) /* length */
137 {
138 c->sub.copy.get = e & 15;
139 c->len = t->base;
140 c->mode = LENEXT;
141 break;
142 }
143 if ((e & 64) == 0) /* next table */
144 {
145 c->sub.code.need = e;
146 c->sub.code.tree = t + t->base;
147 break;
148 }
149 if (e & 32) /* end of block */
150 {
151 Tracevv((stderr, "inflate: end of block\n"));
152 c->mode = WASH;
153 break;
154 }
155 c->mode = BADCODE; /* invalid code */
156 z->msg = (char*)"invalid literal/length code";
157 r = Z_DATA_ERROR;
158 LEAVE
159 case LENEXT: /* i: getting length extra (have base) */
160 j = c->sub.copy.get;
161 NEEDBITS(j)
162 c->len += (uInt)b & inflate_mask[j];
163 DUMPBITS(j)
164 c->sub.code.need = c->dbits;
165 c->sub.code.tree = c->dtree;
166 Tracevv((stderr, "inflate: length %u\n", c->len));
167 c->mode = DIST;
168 /* fall through */
169 case DIST: /* i: get distance next */
170 j = c->sub.code.need;
171 NEEDBITS(j)
172 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
173 DUMPBITS(t->bits)
174 e = (uInt)(t->exop);
175 if (e & 16) /* distance */
176 {
177 c->sub.copy.get = e & 15;
178 c->sub.copy.dist = t->base;
179 c->mode = DISTEXT;
180 break;
181 }
182 if ((e & 64) == 0) /* next table */
183 {
184 c->sub.code.need = e;
185 c->sub.code.tree = t + t->base;
186 break;
187 }
188 c->mode = BADCODE; /* invalid code */
189 z->msg = (char*)"invalid distance code";
190 r = Z_DATA_ERROR;
191 LEAVE
192 case DISTEXT: /* i: getting distance extra */
193 j = c->sub.copy.get;
194 NEEDBITS(j)
195 c->sub.copy.dist += (uInt)b & inflate_mask[j];
196 DUMPBITS(j)
197 Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist));
198 c->mode = COPY;
199 /* fall through */
200 case COPY: /* o: copying bytes in window, waiting for space */
201 f = q - c->sub.copy.dist;
202 while (f < s->window) /* modulo window size-"while" instead */
203 f += s->end - s->window; /* of "if" handles invalid distances */
204 while (c->len)
205 {
206 NEEDOUT
207 OUTBYTE(*f++)
208 if (f == s->end)
209 f = s->window;
210 c->len--;
211 }
212 c->mode = START;
213 break;
214 case LIT: /* o: got literal, waiting for output space */
215 NEEDOUT
216 OUTBYTE(c->sub.lit)
217 c->mode = START;
218 break;
219 case WASH: /* o: got eob, possibly more output */
220 if (k > 7) /* return unused byte, if any */
221 {
222 Assert(k < 16, "inflate_codes grabbed too many bytes")
223 k -= 8;
224 n++;
225 p--; /* can always return one */
226 }
227 FLUSH
228 if (s->read != s->write)
229 LEAVE
230 c->mode = END;
231 /* fall through */
232 case END:
233 r = Z_STREAM_END;
234 LEAVE
235 case BADCODE: /* x: got error */
236 r = Z_DATA_ERROR;
237 LEAVE
238 default:
239 r = Z_STREAM_ERROR;
240 LEAVE
241 }
242 #ifdef NEED_DUMMY_RETURN
243 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
244 #endif
245 }
246
247
inflate_codes_free(inflate_codes_statef * c,z_streamp z)248 local void inflate_codes_free( /* c, z) */
249 inflate_codes_statef *c,
250 z_streamp z )
251 {
252 ZFREE(z, c);
253 Tracev((stderr, "inflate: codes free\n"));
254 }
255