1 /* $NetBSD: zuncompress.c,v 1.11 2011/08/16 13:55:02 joerg Exp $ */ 2 3 /*- 4 * Copyright (c) 1985, 1986, 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Diomidis Spinellis and James A. Woods, derived from original 9 * work by Spencer Thomas and Joseph Orost. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * from: NetBSD: zopen.c,v 1.8 2003/08/07 11:13:29 agc Exp 36 * $FreeBSD$ 37 */ 38 39 /* This file is #included by gzip.c */ 40 41 static int zread(void *, char *, int); 42 43 #define tab_prefixof(i) (zs->zs_codetab[i]) 44 #define tab_suffixof(i) ((char_type *)(zs->zs_htab))[i] 45 #define de_stack ((char_type *)&tab_suffixof(1 << BITS)) 46 47 #define BITS 16 /* Default bits. */ 48 #define HSIZE 69001 /* 95% occupancy */ /* XXX may not need HSIZE */ 49 #define BIT_MASK 0x1f /* Defines for third byte of header. */ 50 #define BLOCK_MASK 0x80 51 #define CHECK_GAP 10000 /* Ratio check interval. */ 52 #define BUFSIZE (64 * 1024) 53 54 /* 55 * Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is 56 * a fourth header byte (for expansion). 57 */ 58 #define INIT_BITS 9 /* Initial number of bits/code. */ 59 60 /* 61 * the next two codes should not be changed lightly, as they must not 62 * lie within the contiguous general code space. 63 */ 64 #define FIRST 257 /* First free entry. */ 65 #define CLEAR 256 /* Table clear output code. */ 66 67 68 #define MAXCODE(n_bits) ((1 << (n_bits)) - 1) 69 70 typedef long code_int; 71 typedef long count_int; 72 typedef u_char char_type; 73 74 static char_type magic_header[] = 75 {'\037', '\235'}; /* 1F 9D */ 76 77 static char_type rmask[9] = 78 {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}; 79 80 static off_t total_compressed_bytes; 81 static size_t compressed_prelen; 82 static char *compressed_pre; 83 84 struct s_zstate { 85 FILE *zs_fp; /* File stream for I/O */ 86 char zs_mode; /* r or w */ 87 enum { 88 S_START, S_MIDDLE, S_EOF 89 } zs_state; /* State of computation */ 90 int zs_n_bits; /* Number of bits/code. */ 91 int zs_maxbits; /* User settable max # bits/code. */ 92 code_int zs_maxcode; /* Maximum code, given n_bits. */ 93 code_int zs_maxmaxcode; /* Should NEVER generate this code. */ 94 count_int zs_htab [HSIZE]; 95 u_short zs_codetab [HSIZE]; 96 code_int zs_hsize; /* For dynamic table sizing. */ 97 code_int zs_free_ent; /* First unused entry. */ 98 /* 99 * Block compression parameters -- after all codes are used up, 100 * and compression rate changes, start over. 101 */ 102 int zs_block_compress; 103 int zs_clear_flg; 104 long zs_ratio; 105 count_int zs_checkpoint; 106 int zs_offset; 107 long zs_in_count; /* Length of input. */ 108 long zs_bytes_out; /* Length of compressed output. */ 109 long zs_out_count; /* # of codes output (for debugging). */ 110 char_type zs_buf[BITS]; 111 union { 112 struct { 113 long zs_fcode; 114 code_int zs_ent; 115 code_int zs_hsize_reg; 116 int zs_hshift; 117 } w; /* Write parameters */ 118 struct { 119 char_type *zs_stackp; 120 int zs_finchar; 121 code_int zs_code, zs_oldcode, zs_incode; 122 int zs_roffset, zs_size; 123 char_type zs_gbuf[BITS]; 124 } r; /* Read parameters */ 125 } u; 126 }; 127 128 static code_int getcode(struct s_zstate *zs); 129 130 static off_t 131 zuncompress(FILE *in, FILE *out, char *pre, size_t prelen, 132 off_t *compressed_bytes) 133 { 134 off_t bin, bout = 0; 135 char *buf; 136 137 buf = malloc(BUFSIZE); 138 if (buf == NULL) 139 return -1; 140 141 /* XXX */ 142 compressed_prelen = prelen; 143 if (prelen != 0) 144 compressed_pre = pre; 145 else 146 compressed_pre = NULL; 147 148 while ((bin = fread(buf, 1, sizeof(buf), in)) != 0) { 149 if (tflag == 0 && (off_t)fwrite(buf, 1, bin, out) != bin) { 150 free(buf); 151 return -1; 152 } 153 bout += bin; 154 } 155 156 if (compressed_bytes) 157 *compressed_bytes = total_compressed_bytes; 158 159 free(buf); 160 return bout; 161 } 162 163 static int 164 zclose(void *zs) 165 { 166 free(zs); 167 /* We leave the caller to close the fd passed to zdopen() */ 168 return 0; 169 } 170 171 FILE * 172 zdopen(int fd) 173 { 174 struct s_zstate *zs; 175 176 if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL) 177 return (NULL); 178 179 zs->zs_state = S_START; 180 181 /* XXX we can get rid of some of these */ 182 zs->zs_hsize = HSIZE; /* For dynamic table sizing. */ 183 zs->zs_free_ent = 0; /* First unused entry. */ 184 zs->zs_block_compress = BLOCK_MASK; 185 zs->zs_clear_flg = 0; /* XXX we calloc()'d this structure why = 0? */ 186 zs->zs_ratio = 0; 187 zs->zs_checkpoint = CHECK_GAP; 188 zs->zs_in_count = 1; /* Length of input. */ 189 zs->zs_out_count = 0; /* # of codes output (for debugging). */ 190 zs->u.r.zs_roffset = 0; 191 zs->u.r.zs_size = 0; 192 193 /* 194 * Layering compress on top of stdio in order to provide buffering, 195 * and ensure that reads and write work with the data specified. 196 */ 197 if ((zs->zs_fp = fdopen(fd, "r")) == NULL) { 198 free(zs); 199 return NULL; 200 } 201 202 return funopen(zs, zread, NULL, NULL, zclose); 203 } 204 205 /* 206 * Decompress read. This routine adapts to the codes in the file building 207 * the "string" table on-the-fly; requiring no table to be stored in the 208 * compressed file. The tables used herein are shared with those of the 209 * compress() routine. See the definitions above. 210 */ 211 static int 212 zread(void *cookie, char *rbp, int num) 213 { 214 u_int count, i; 215 struct s_zstate *zs; 216 u_char *bp, header[3]; 217 218 if (num == 0) 219 return (0); 220 221 zs = cookie; 222 count = num; 223 bp = (u_char *)rbp; 224 switch (zs->zs_state) { 225 case S_START: 226 zs->zs_state = S_MIDDLE; 227 break; 228 case S_MIDDLE: 229 goto middle; 230 case S_EOF: 231 goto eof; 232 } 233 234 /* Check the magic number */ 235 for (i = 0; i < 3 && compressed_prelen; i++, compressed_prelen--) 236 header[i] = *compressed_pre++; 237 238 if (fread(header + i, 1, sizeof(header) - i, zs->zs_fp) != 239 sizeof(header) - i || 240 memcmp(header, magic_header, sizeof(magic_header)) != 0) { 241 errno = EFTYPE; 242 return (-1); 243 } 244 total_compressed_bytes = 0; 245 zs->zs_maxbits = header[2]; /* Set -b from file. */ 246 zs->zs_block_compress = zs->zs_maxbits & BLOCK_MASK; 247 zs->zs_maxbits &= BIT_MASK; 248 zs->zs_maxmaxcode = 1L << zs->zs_maxbits; 249 if (zs->zs_maxbits > BITS || zs->zs_maxbits < 12) { 250 errno = EFTYPE; 251 return (-1); 252 } 253 /* As above, initialize the first 256 entries in the table. */ 254 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 255 for (zs->u.r.zs_code = 255; zs->u.r.zs_code >= 0; zs->u.r.zs_code--) { 256 tab_prefixof(zs->u.r.zs_code) = 0; 257 tab_suffixof(zs->u.r.zs_code) = (char_type) zs->u.r.zs_code; 258 } 259 zs->zs_free_ent = zs->zs_block_compress ? FIRST : 256; 260 261 zs->u.r.zs_oldcode = -1; 262 zs->u.r.zs_stackp = de_stack; 263 264 while ((zs->u.r.zs_code = getcode(zs)) > -1) { 265 266 if ((zs->u.r.zs_code == CLEAR) && zs->zs_block_compress) { 267 for (zs->u.r.zs_code = 255; zs->u.r.zs_code >= 0; 268 zs->u.r.zs_code--) 269 tab_prefixof(zs->u.r.zs_code) = 0; 270 zs->zs_clear_flg = 1; 271 zs->zs_free_ent = FIRST; 272 zs->u.r.zs_oldcode = -1; 273 continue; 274 } 275 zs->u.r.zs_incode = zs->u.r.zs_code; 276 277 /* Special case for KwKwK string. */ 278 if (zs->u.r.zs_code >= zs->zs_free_ent) { 279 if (zs->u.r.zs_code > zs->zs_free_ent || 280 zs->u.r.zs_oldcode == -1) { 281 /* Bad stream. */ 282 errno = EINVAL; 283 return (-1); 284 } 285 *zs->u.r.zs_stackp++ = zs->u.r.zs_finchar; 286 zs->u.r.zs_code = zs->u.r.zs_oldcode; 287 } 288 /* 289 * The above condition ensures that code < free_ent. 290 * The construction of tab_prefixof in turn guarantees that 291 * each iteration decreases code and therefore stack usage is 292 * bound by 1 << BITS - 256. 293 */ 294 295 /* Generate output characters in reverse order. */ 296 while (zs->u.r.zs_code >= 256) { 297 *zs->u.r.zs_stackp++ = tab_suffixof(zs->u.r.zs_code); 298 zs->u.r.zs_code = tab_prefixof(zs->u.r.zs_code); 299 } 300 *zs->u.r.zs_stackp++ = zs->u.r.zs_finchar = tab_suffixof(zs->u.r.zs_code); 301 302 /* And put them out in forward order. */ 303 middle: do { 304 if (count-- == 0) 305 return (num); 306 *bp++ = *--zs->u.r.zs_stackp; 307 } while (zs->u.r.zs_stackp > de_stack); 308 309 /* Generate the new entry. */ 310 if ((zs->u.r.zs_code = zs->zs_free_ent) < zs->zs_maxmaxcode && 311 zs->u.r.zs_oldcode != -1) { 312 tab_prefixof(zs->u.r.zs_code) = (u_short) zs->u.r.zs_oldcode; 313 tab_suffixof(zs->u.r.zs_code) = zs->u.r.zs_finchar; 314 zs->zs_free_ent = zs->u.r.zs_code + 1; 315 } 316 317 /* Remember previous code. */ 318 zs->u.r.zs_oldcode = zs->u.r.zs_incode; 319 } 320 zs->zs_state = S_EOF; 321 eof: return (num - count); 322 } 323 324 /*- 325 * Read one code from the standard input. If EOF, return -1. 326 * Inputs: 327 * stdin 328 * Outputs: 329 * code or -1 is returned. 330 */ 331 static code_int 332 getcode(struct s_zstate *zs) 333 { 334 code_int gcode; 335 int r_off, bits, i; 336 char_type *bp; 337 338 bp = zs->u.r.zs_gbuf; 339 if (zs->zs_clear_flg > 0 || zs->u.r.zs_roffset >= zs->u.r.zs_size || 340 zs->zs_free_ent > zs->zs_maxcode) { 341 /* 342 * If the next entry will be too big for the current gcode 343 * size, then we must increase the size. This implies reading 344 * a new buffer full, too. 345 */ 346 if (zs->zs_free_ent > zs->zs_maxcode) { 347 zs->zs_n_bits++; 348 if (zs->zs_n_bits == zs->zs_maxbits) /* Won't get any bigger now. */ 349 zs->zs_maxcode = zs->zs_maxmaxcode; 350 else 351 zs->zs_maxcode = MAXCODE(zs->zs_n_bits); 352 } 353 if (zs->zs_clear_flg > 0) { 354 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 355 zs->zs_clear_flg = 0; 356 } 357 /* XXX */ 358 for (i = 0; i < zs->zs_n_bits && compressed_prelen; i++, compressed_prelen--) 359 zs->u.r.zs_gbuf[i] = *compressed_pre++; 360 zs->u.r.zs_size = fread(zs->u.r.zs_gbuf + i, 1, zs->zs_n_bits - i, zs->zs_fp); 361 zs->u.r.zs_size += i; 362 if (zs->u.r.zs_size <= 0) /* End of file. */ 363 return (-1); 364 zs->u.r.zs_roffset = 0; 365 366 total_compressed_bytes += zs->u.r.zs_size; 367 368 /* Round size down to integral number of codes. */ 369 zs->u.r.zs_size = (zs->u.r.zs_size << 3) - (zs->zs_n_bits - 1); 370 } 371 r_off = zs->u.r.zs_roffset; 372 bits = zs->zs_n_bits; 373 374 /* Get to the first byte. */ 375 bp += (r_off >> 3); 376 r_off &= 7; 377 378 /* Get first part (low order bits). */ 379 gcode = (*bp++ >> r_off); 380 bits -= (8 - r_off); 381 r_off = 8 - r_off; /* Now, roffset into gcode word. */ 382 383 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */ 384 if (bits >= 8) { 385 gcode |= *bp++ << r_off; 386 r_off += 8; 387 bits -= 8; 388 } 389 390 /* High order bits. */ 391 gcode |= (*bp & rmask[bits]) << r_off; 392 zs->u.r.zs_roffset += zs->zs_n_bits; 393 394 return (gcode); 395 } 396 397