| 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 | #include "inffast.h" |
| 12 | |
| 13 | /* simplify the use of the inflate_huft type with some defines */ |
| 14 | #define exop word.what.Exop |
| 15 | #define bits word.what.Bits |
| 16 | |
| 17 | typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */ |
| 18 | START, /* x: set up for LEN */ |
| 19 | LEN, /* i: get length/literal/eob next */ |
| 20 | LENEXT, /* i: getting length extra (have base) */ |
| 21 | DIST, /* i: get distance next */ |
| 22 | DISTEXT, /* i: getting distance extra */ |
| 23 | COPY, /* o: copying bytes in window, waiting for space */ |
| 24 | LIT, /* o: got literal, waiting for output space */ |
| 25 | WASH, /* o: got eob, possibly still output waiting */ |
| 26 | END, /* x: got eob and all data flushed */ |
| 27 | BADCODE} /* x: got error */ |
| 28 | inflate_codes_mode; |
| 29 | |
| 30 | /* inflate codes private state */ |
| 31 | struct inflate_codes_state { |
| 32 | |
| 33 | /* mode */ |
| 34 | inflate_codes_mode mode; /* current inflate_codes mode */ |
| 35 | |
| 36 | /* mode dependent information */ |
| 37 | uInt len; |
| 38 | union { |
| 39 | struct { |
| 40 | inflate_huft *tree; /* pointer into tree */ |
| 41 | uInt need; /* bits needed */ |
| 42 | } code; /* if LEN or DIST, where in tree */ |
| 43 | uInt lit; /* if LIT, literal */ |
| 44 | struct { |
| 45 | uInt get; /* bits to get for extra */ |
| 46 | uInt dist; /* distance back to copy from */ |
| 47 | } copy; /* if EXT or COPY, where and how much */ |
| 48 | } sub; /* submode */ |
| 49 | |
| 50 | /* mode independent information */ |
| 51 | Byte lbits; /* ltree bits decoded per branch */ |
| 52 | Byte dbits; /* dtree bits decoder per branch */ |
| 53 | inflate_huft *ltree; /* literal/length/eob tree */ |
| 54 | inflate_huft *dtree; /* distance tree */ |
| 55 | |
| 56 | }; |
| 57 | |
| 58 | |
| 59 | inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z) |
| 60 | uInt bl, bd; |
| 61 | inflate_huft *tl; |
| 62 | inflate_huft *td; /* need separate declaration for Borland C++ */ |
| 63 | z_streamp z; |
| 64 | { |
| 65 | inflate_codes_statef *c; |
| 66 | |
| 67 | if ((c = (inflate_codes_statef *) |
| 68 | ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL) |
| 69 | { |
| 70 | c->mode = START; |
| 71 | c->lbits = (Byte)bl; |
| 72 | c->dbits = (Byte)bd; |
| 73 | c->ltree = tl; |
| 74 | c->dtree = td; |
| 75 | Tracev((stderr, "inflate: codes new\n")); |
| 76 | } |
| 77 | return c; |
| 78 | } |
| 79 | |
| 80 | |
| 81 | int inflate_codes(s, z, r) |
| 82 | inflate_blocks_statef *s; |
| 83 | z_streamp z; |
| 84 | int r; |
| 85 | { |
| 86 | uInt j; /* temporary storage */ |
| 87 | inflate_huft *t; /* temporary pointer */ |
| 88 | uInt e; /* extra bits or operation */ |
| 89 | uLong b; /* bit buffer */ |
| 90 | uInt k; /* bits in bit buffer */ |
| 91 | Bytef *p; /* input data pointer */ |
| 92 | uInt n; /* bytes available there */ |
| 93 | Bytef *q; /* output window write pointer */ |
| 94 | uInt m; /* bytes to end of window or read pointer */ |
| 95 | Bytef *f; /* pointer to copy strings from */ |
| 96 | inflate_codes_statef *c = s->sub.decode.codes; /* codes state */ |
| 97 | |
| 98 | /* copy input/output information to locals (UPDATE macro restores) */ |
| 99 | LOAD |
| 100 | |
| 101 | /* process input and output based on current state */ |
| 102 | while (1) switch (c->mode) |
| 103 | { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */ |
| 104 | case START: /* x: set up for LEN */ |
| 105 | #ifndef SLOW |
| 106 | if (m >= 258 && n >= 10) |
| 107 | { |
| 108 | UPDATE |
| 109 | r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z); |
| 110 | LOAD |
| 111 | if (r != Z_OK) |
| 112 | { |
| 113 | c->mode = r == Z_STREAM_END ? WASH : BADCODE; |
| 114 | break; |
| 115 | } |
| 116 | } |
| 117 | #endif /* !SLOW */ |
| 118 | c->sub.code.need = c->lbits; |
| 119 | c->sub.code.tree = c->ltree; |
| 120 | c->mode = LEN; |
| 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 | case DIST: /* i: get distance next */ |
| 169 | j = c->sub.code.need; |
| 170 | NEEDBITS(j) |
| 171 | t = c->sub.code.tree + ((uInt)b & inflate_mask[j]); |
| 172 | DUMPBITS(t->bits) |
| 173 | e = (uInt)(t->exop); |
| 174 | if (e & 16) /* distance */ |
| 175 | { |
| 176 | c->sub.copy.get = e & 15; |
| 177 | c->sub.copy.dist = t->base; |
| 178 | c->mode = DISTEXT; |
| 179 | break; |
| 180 | } |
| 181 | if ((e & 64) == 0) /* next table */ |
| 182 | { |
| 183 | c->sub.code.need = e; |
| 184 | c->sub.code.tree = t + t->base; |
| 185 | break; |
| 186 | } |
| 187 | c->mode = BADCODE; /* invalid code */ |
| 188 | z->msg = (char*)"invalid distance code"; |
| 189 | r = Z_DATA_ERROR; |
| 190 | LEAVE |
| 191 | case DISTEXT: /* i: getting distance extra */ |
| 192 | j = c->sub.copy.get; |
| 193 | NEEDBITS(j) |
| 194 | c->sub.copy.dist += (uInt)b & inflate_mask[j]; |
| 195 | DUMPBITS(j) |
| 196 | Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist)); |
| 197 | c->mode = COPY; |
| 198 | case COPY: /* o: copying bytes in window, waiting for space */ |
| 199 | f = q - c->sub.copy.dist; |
| 200 | while (f < s->window) /* modulo window size-"while" instead */ |
| 201 | f += s->end - s->window; /* of "if" handles invalid distances */ |
| 202 | while (c->len) |
| 203 | { |
| 204 | NEEDOUT |
| 205 | OUTBYTE(*f++) |
| 206 | if (f == s->end) |
| 207 | f = s->window; |
| 208 | c->len--; |
| 209 | } |
| 210 | c->mode = START; |
| 211 | break; |
| 212 | case LIT: /* o: got literal, waiting for output space */ |
| 213 | NEEDOUT |
| 214 | OUTBYTE(c->sub.lit) |
| 215 | c->mode = START; |
| 216 | break; |
| 217 | case WASH: /* o: got eob, possibly more output */ |
| 218 | if (k > 7) /* return unused byte, if any */ |
| 219 | { |
| 220 | Assert(k < 16, "inflate_codes grabbed too many bytes") |
| 221 | k -= 8; |
| 222 | n++; |
| 223 | p--; /* can always return one */ |
| 224 | } |
| 225 | FLUSH |
| 226 | if (s->read != s->write) |
| 227 | LEAVE |
| 228 | c->mode = END; |
| 229 | case END: |
| 230 | r = Z_STREAM_END; |
| 231 | LEAVE |
| 232 | case BADCODE: /* x: got error */ |
| 233 | r = Z_DATA_ERROR; |
| 234 | LEAVE |
| 235 | default: |
| 236 | r = Z_STREAM_ERROR; |
| 237 | LEAVE |
| 238 | } |
| 239 | #ifdef NEED_DUMMY_RETURN |
| 240 | return Z_STREAM_ERROR; /* Some dumb compilers complain without this */ |
| 241 | #endif |
| 242 | } |
| 243 | |
| 244 | |
| 245 | void inflate_codes_free(c, z) |
| 246 | inflate_codes_statef *c; |
| 247 | z_streamp z; |
| 248 | { |
| 249 | ZFREE(z, c); |
| 250 | Tracev((stderr, "inflate: codes free\n")); |
| 251 | } |