1 /* $OpenBSD: zopen.c,v 1.17 2005/08/25 17:07:56 millert Exp $ */ 2 /* $NetBSD: zopen.c,v 1.5 1995/03/26 09:44:53 glass Exp $ */ 3 4 /*- 5 * Copyright (c) 1985, 1986, 1992, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Diomidis Spinellis and James A. Woods, derived from original 10 * work by Spencer Thomas and Joseph Orost. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * From: @(#)zopen.c 8.1 (Berkeley) 6/27/93 37 */ 38 39 #if 0 40 static char sccsid[] = "@(#)zopen.c 8.1 (Berkeley) 6/27/93"; 41 #else 42 const char z_rcsid[] = 43 "$OpenBSD: zopen.c,v 1.17 2005/08/25 17:07:56 millert Exp $"; 44 #endif 45 46 /*- 47 * fcompress.c - File compression ala IEEE Computer, June 1984. 48 * 49 * Compress authors: 50 * Spencer W. Thomas (decvax!utah-cs!thomas) 51 * Jim McKie (decvax!mcvax!jim) 52 * Steve Davies (decvax!vax135!petsd!peora!srd) 53 * Ken Turkowski (decvax!decwrl!turtlevax!ken) 54 * James A. Woods (decvax!ihnp4!ames!jaw) 55 * Joe Orost (decvax!vax135!petsd!joe) 56 * 57 * Cleaned up and converted to library returning I/O streams by 58 * Diomidis Spinellis <dds@doc.ic.ac.uk>. 59 * 60 * zopen(filename, mode, bits) 61 * Returns a FILE * that can be used for read or write. The modes 62 * supported are only "r" and "w". Seeking is not allowed. On 63 * reading the file is decompressed, on writing it is compressed. 64 * The output is compatible with compress(1) with 16 bit tables. 65 * Any file produced by compress(1) can be read. 66 */ 67 68 #include <sys/param.h> 69 #include <sys/stat.h> 70 71 #include <ctype.h> 72 #include <errno.h> 73 #include <signal.h> 74 #include <stdio.h> 75 #include <stdlib.h> 76 #include <string.h> 77 #include <unistd.h> 78 #include <fcntl.h> 79 #include "compress.h" 80 81 #define BITS 16 /* Default bits. */ 82 #define HSIZE 69001 /* 95% occupancy */ 83 #define ZBUFSIZ 8192 /* I/O buffer size */ 84 85 /* A code_int must be able to hold 2**BITS values of type int, and also -1. */ 86 typedef long code_int; 87 typedef long count_int; 88 89 static const u_char z_magic[] = 90 {'\037', '\235'}; /* 1F 9D */ 91 92 #define BIT_MASK 0x1f /* Defines for third byte of header. */ 93 #define BLOCK_MASK 0x80 94 95 /* 96 * Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is 97 * a fourth header byte (for expansion). 98 */ 99 #define INIT_BITS 9 /* Initial number of bits/code. */ 100 101 #define MAXCODE(n_bits) ((1 << (n_bits)) - 1) 102 103 struct s_zstate { 104 int zs_fd; /* File stream for I/O */ 105 char zs_mode; /* r or w */ 106 enum { 107 S_START, S_MAGIC, S_MIDDLE, S_EOF 108 } zs_state; /* State of computation */ 109 int zs_n_bits; /* Number of bits/code. */ 110 int zs_maxbits; /* User settable max # bits/code. */ 111 code_int zs_maxcode; /* Maximum code, given n_bits. */ 112 code_int zs_maxmaxcode; /* Should NEVER generate this code. */ 113 count_int zs_htab[HSIZE]; 114 u_short zs_codetab[HSIZE]; 115 code_int zs_hsize; /* For dynamic table sizing. */ 116 code_int zs_free_ent; /* First unused entry. */ 117 /* 118 * Block compression parameters -- after all codes are used up, 119 * and compression rate changes, start over. 120 */ 121 int zs_block_compress; 122 int zs_clear_flg; 123 long zs_ratio; 124 count_int zs_checkpoint; 125 long zs_in_count; /* Length of input. */ 126 long zs_bytes_out; /* Length of output. */ 127 long zs_out_count; /* # of codes output (for debugging).*/ 128 u_char zs_buf[ZBUFSIZ]; /* I/O buffer */ 129 u_char *zs_bp; /* Current I/O window in the zs_buf */ 130 int zs_offset; /* Number of bits in the zs_buf */ 131 union { 132 struct { 133 long zs_fcode; 134 code_int zs_ent; 135 code_int zs_hsize_reg; 136 int zs_hshift; 137 } w; /* Write parameters */ 138 struct { 139 u_char *zs_stackp, *zs_ebp; 140 int zs_finchar; 141 code_int zs_code, zs_oldcode, zs_incode; 142 int zs_size; 143 } r; /* Read parameters */ 144 } u; 145 }; 146 147 /* Definitions to retain old variable names */ 148 #define zs_fcode u.w.zs_fcode 149 #define zs_ent u.w.zs_ent 150 #define zs_hsize_reg u.w.zs_hsize_reg 151 #define zs_hshift u.w.zs_hshift 152 #define zs_stackp u.r.zs_stackp 153 #define zs_finchar u.r.zs_finchar 154 #define zs_code u.r.zs_code 155 #define zs_oldcode u.r.zs_oldcode 156 #define zs_incode u.r.zs_incode 157 #define zs_size u.r.zs_size 158 #define zs_ebp u.r.zs_ebp 159 160 /* 161 * To save much memory, we overlay the table used by compress() with those 162 * used by decompress(). The tab_prefix table is the same size and type as 163 * the codetab. The tab_suffix table needs 2**BITS characters. We get this 164 * from the beginning of htab. The output stack uses the rest of htab, and 165 * contains characters. There is plenty of room for any possible stack 166 * (stack used to be 8000 characters). 167 */ 168 169 #define htabof(i) zs->zs_htab[i] 170 #define codetabof(i) zs->zs_codetab[i] 171 172 #define tab_prefixof(i) codetabof(i) 173 #define tab_suffixof(i) ((u_char *)(zs->zs_htab))[i] 174 #define de_stack ((u_char *)&tab_suffixof(1 << BITS)) 175 176 #define CHECK_GAP 10000 /* Ratio check interval. */ 177 178 /* 179 * the next two codes should not be changed lightly, as they must not 180 * lie within the contiguous general code space. 181 */ 182 #define FIRST 257 /* First free entry. */ 183 #define CLEAR 256 /* Table clear output code. */ 184 185 static int cl_block(struct s_zstate *); 186 static void cl_hash(struct s_zstate *, count_int); 187 static code_int getcode(struct s_zstate *); 188 static int output(struct s_zstate *, code_int); 189 190 /*- 191 * Algorithm from "A Technique for High Performance Data Compression", 192 * Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19. 193 * 194 * Algorithm: 195 * Modified Lempel-Ziv method (LZW). Basically finds common 196 * substrings and replaces them with a variable size code. This is 197 * deterministic, and can be done on the fly. Thus, the decompression 198 * procedure needs no input table, but tracks the way the table was built. 199 */ 200 201 /*- 202 * compress write 203 * 204 * Algorithm: use open addressing double hashing (no chaining) on the 205 * prefix code / next character combination. We do a variant of Knuth's 206 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime 207 * secondary probe. Here, the modular division first probe is gives way 208 * to a faster exclusive-or manipulation. Also do block compression with 209 * an adaptive reset, whereby the code table is cleared when the compression 210 * ratio decreases, but after the table fills. The variable-length output 211 * codes are re-sized at this point, and a special CLEAR code is generated 212 * for the decompressor. Late addition: construct the table according to 213 * file size for noticeable speed improvement on small files. Please direct 214 * questions about this implementation to ames!jaw. 215 */ 216 int 217 zwrite(void *cookie, const char *wbp, int num) 218 { 219 code_int i; 220 int c, disp; 221 struct s_zstate *zs; 222 const u_char *bp; 223 u_char tmp; 224 int count; 225 226 zs = cookie; 227 count = num; 228 bp = (u_char *)wbp; 229 switch (zs->zs_state) { 230 case S_MAGIC: 231 return -1; 232 case S_EOF: 233 return 0; 234 case S_START: 235 zs->zs_state = S_MIDDLE; 236 237 zs->zs_maxmaxcode = 1L << zs->zs_maxbits; 238 if (write(zs->zs_fd, z_magic, sizeof(z_magic)) != 239 sizeof(z_magic)) 240 return (-1); 241 tmp = (u_char)(zs->zs_maxbits | zs->zs_block_compress); 242 if (write(zs->zs_fd, &tmp, sizeof(tmp)) != sizeof(tmp)) 243 return (-1); 244 245 zs->zs_bp = zs->zs_buf; 246 zs->zs_offset = 0; 247 zs->zs_bytes_out = 3; /* Includes 3-byte header mojo. */ 248 zs->zs_out_count = 0; 249 zs->zs_clear_flg = 0; 250 zs->zs_ratio = 0; 251 zs->zs_in_count = 1; 252 zs->zs_checkpoint = CHECK_GAP; 253 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 254 zs->zs_free_ent = ((zs->zs_block_compress) ? FIRST : 256); 255 256 zs->zs_ent = *bp++; 257 --count; 258 259 zs->zs_hshift = 0; 260 for (zs->zs_fcode = (long)zs->zs_hsize; zs->zs_fcode < 65536L; 261 zs->zs_fcode *= 2L) 262 zs->zs_hshift++; 263 /* Set hash code range bound. */ 264 zs->zs_hshift = 8 - zs->zs_hshift; 265 266 zs->zs_hsize_reg = zs->zs_hsize; 267 /* Clear hash table. */ 268 cl_hash(zs, (count_int)zs->zs_hsize_reg); 269 270 case S_MIDDLE: 271 for (i = 0; count-- > 0;) { 272 c = *bp++; 273 zs->zs_in_count++; 274 zs->zs_fcode = (long)(((long)c << zs->zs_maxbits) + 275 zs->zs_ent); 276 /* Xor hashing. */ 277 i = ((c << zs->zs_hshift) ^ zs->zs_ent); 278 279 if (htabof(i) == zs->zs_fcode) { 280 zs->zs_ent = codetabof(i); 281 continue; 282 } else if ((long)htabof(i) < 0) /* Empty slot. */ 283 goto nomatch; 284 /* Secondary hash (after G. Knott). */ 285 disp = zs->zs_hsize_reg - i; 286 if (i == 0) 287 disp = 1; 288 probe: if ((i -= disp) < 0) 289 i += zs->zs_hsize_reg; 290 291 if (htabof(i) == zs->zs_fcode) { 292 zs->zs_ent = codetabof(i); 293 continue; 294 } 295 if ((long)htabof(i) >= 0) 296 goto probe; 297 nomatch: if (output(zs, (code_int) zs->zs_ent) == -1) 298 return (-1); 299 zs->zs_out_count++; 300 zs->zs_ent = c; 301 if (zs->zs_free_ent < zs->zs_maxmaxcode) { 302 /* code -> hashtable */ 303 codetabof(i) = zs->zs_free_ent++; 304 htabof(i) = zs->zs_fcode; 305 } else if ((count_int)zs->zs_in_count >= 306 zs->zs_checkpoint && zs->zs_block_compress) { 307 if (cl_block(zs) == -1) 308 return (-1); 309 } 310 } 311 } 312 return (num); 313 } 314 315 int 316 z_close(void *cookie, struct z_info *info, const char *name, struct stat *sb) 317 { 318 struct s_zstate *zs; 319 int rval; 320 321 zs = cookie; 322 if (zs->zs_mode == 'w') { /* Put out the final code. */ 323 if (output(zs, (code_int) zs->zs_ent) == -1) { 324 (void)close(zs->zs_fd); 325 free(zs); 326 return (-1); 327 } 328 zs->zs_out_count++; 329 if (output(zs, (code_int) - 1) == -1) { 330 (void)close(zs->zs_fd); 331 free(zs); 332 return (-1); 333 } 334 } 335 336 if (info != NULL) { 337 info->mtime = 0; 338 info->crc = (u_int32_t)-1; 339 info->hlen = 0; 340 info->total_in = (off_t)zs->zs_in_count; 341 info->total_out = (off_t)zs->zs_bytes_out; 342 } 343 344 #ifndef SAVECORE 345 setfile(name, zs->zs_fd, sb); 346 #endif 347 rval = close(zs->zs_fd); 348 free(zs); 349 return (rval); 350 } 351 352 static int 353 zclose(void *cookie) 354 { 355 return z_close(cookie, NULL, NULL, NULL); 356 } 357 358 /*- 359 * Output the given code. 360 * Inputs: 361 * code: A n_bits-bit integer. If == -1, then EOF. This assumes 362 * that n_bits =< (long)wordsize - 1. 363 * Outputs: 364 * Outputs code to the file. 365 * Assumptions: 366 * Chars are 8 bits long. 367 * Algorithm: 368 * Maintain a BITS character long buffer (so that 8 codes will 369 * fit in it exactly). Use the VAX insv instruction to insert each 370 * code in turn. When the buffer fills up empty it and start over. 371 */ 372 373 static const u_char lmask[9] = 374 {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00}; 375 static const u_char rmask[9] = 376 {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}; 377 378 static int 379 output(struct s_zstate *zs, code_int ocode) 380 { 381 int bits; 382 383 if (ocode >= 0) { 384 int r_off; 385 u_char *bp; 386 387 /* Get to the first byte. */ 388 bp = zs->zs_bp + (zs->zs_offset >> 3); 389 r_off = zs->zs_offset & 7; 390 bits = zs->zs_n_bits; 391 392 /* 393 * Since ocode is always >= 8 bits, only need to mask the first 394 * hunk on the left. 395 */ 396 *bp = (*bp & rmask[r_off]) | ((ocode << r_off) & lmask[r_off]); 397 bp++; 398 bits -= (8 - r_off); 399 ocode >>= 8 - r_off; 400 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits) */ 401 if (bits >= 8) { 402 *bp++ = ocode; 403 ocode >>= 8; 404 bits -= 8; 405 } 406 /* Last bits. */ 407 if (bits) 408 *bp = ocode; 409 zs->zs_offset += zs->zs_n_bits; 410 if (zs->zs_offset == (zs->zs_n_bits << 3)) { 411 zs->zs_bp += zs->zs_n_bits; 412 zs->zs_offset = 0; 413 } 414 /* 415 * If the next entry is going to be too big for the ocode size, 416 * then increase it, if possible. 417 */ 418 if (zs->zs_free_ent > zs->zs_maxcode || 419 (zs->zs_clear_flg > 0)) { 420 /* 421 * Write the whole buffer, because the input side won't 422 * discover the size increase until after it has read it 423 */ 424 if (zs->zs_offset > 0) { 425 zs->zs_bp += zs->zs_n_bits; 426 zs->zs_offset = 0; 427 } 428 429 if (zs->zs_clear_flg) { 430 zs->zs_maxcode = 431 MAXCODE(zs->zs_n_bits = INIT_BITS); 432 zs->zs_clear_flg = 0; 433 } else { 434 zs->zs_n_bits++; 435 if (zs->zs_n_bits == zs->zs_maxbits) 436 zs->zs_maxcode = zs->zs_maxmaxcode; 437 else 438 zs->zs_maxcode = 439 MAXCODE(zs->zs_n_bits); 440 } 441 } 442 443 if (zs->zs_bp + zs->zs_n_bits > &zs->zs_buf[ZBUFSIZ]) { 444 bits = zs->zs_bp - zs->zs_buf; 445 if (write(zs->zs_fd, zs->zs_buf, bits) != bits) 446 return (-1); 447 zs->zs_bytes_out += bits; 448 if (zs->zs_offset > 0) 449 fprintf (stderr, "zs_offset != 0\n"); 450 zs->zs_bp = zs->zs_buf; 451 } 452 } else { 453 /* At EOF, write the rest of the buffer. */ 454 if (zs->zs_offset > 0) 455 zs->zs_bp += (zs->zs_offset + 7) / 8; 456 if (zs->zs_bp > zs->zs_buf) { 457 bits = zs->zs_bp - zs->zs_buf; 458 if (write(zs->zs_fd, zs->zs_buf, bits) != bits) 459 return (-1); 460 zs->zs_bytes_out += bits; 461 } 462 zs->zs_offset = 0; 463 zs->zs_bp = zs->zs_buf; 464 } 465 return (0); 466 } 467 468 /* 469 * Decompress read. This routine adapts to the codes in the file building 470 * the "string" table on-the-fly; requiring no table to be stored in the 471 * compressed file. The tables used herein are shared with those of the 472 * compress() routine. See the definitions above. 473 */ 474 int 475 zread(void *cookie, char *rbp, int num) 476 { 477 u_int count; 478 struct s_zstate *zs; 479 u_char *bp, header[3]; 480 481 if (num == 0) 482 return (0); 483 484 zs = cookie; 485 count = num; 486 bp = (u_char *)rbp; 487 switch (zs->zs_state) { 488 case S_START: 489 zs->zs_state = S_MIDDLE; 490 zs->zs_bp = zs->zs_buf; 491 header[0] = header[1] = header[2] = '\0'; 492 read(zs->zs_fd, header, sizeof(header)); 493 break; 494 case S_MAGIC: 495 zs->zs_state = S_MIDDLE; 496 zs->zs_bp = zs->zs_buf; 497 header[0] = z_magic[0]; 498 header[1] = z_magic[1]; 499 header[2] = '\0'; 500 read(zs->zs_fd, &header[2], 1); 501 break; 502 case S_MIDDLE: 503 goto middle; 504 case S_EOF: 505 goto eof; 506 } 507 508 /* Check the magic number */ 509 if (header[0] != z_magic[0] || header[1] != z_magic[1]) { 510 errno = EFTYPE; 511 return (-1); 512 } 513 zs->zs_maxbits = header[2]; /* Set -b from file. */ 514 zs->zs_in_count += sizeof(header); 515 zs->zs_block_compress = zs->zs_maxbits & BLOCK_MASK; 516 zs->zs_maxbits &= BIT_MASK; 517 zs->zs_maxmaxcode = 1L << zs->zs_maxbits; 518 if (zs->zs_maxbits > BITS) { 519 errno = EFTYPE; 520 return (-1); 521 } 522 /* As above, initialize the first 256 entries in the table. */ 523 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 524 for (zs->zs_code = 255; zs->zs_code >= 0; zs->zs_code--) { 525 tab_prefixof(zs->zs_code) = 0; 526 tab_suffixof(zs->zs_code) = (u_char) zs->zs_code; 527 } 528 zs->zs_free_ent = zs->zs_block_compress ? FIRST : 256; 529 530 zs->zs_finchar = zs->zs_oldcode = getcode(zs); 531 if (zs->zs_oldcode == -1) /* EOF already? */ 532 return (0); /* Get out of here */ 533 534 /* First code must be 8 bits = char. */ 535 *bp++ = (u_char)zs->zs_finchar; 536 count--; 537 zs->zs_stackp = de_stack; 538 539 while ((zs->zs_code = getcode(zs)) > -1) { 540 541 if ((zs->zs_code == CLEAR) && zs->zs_block_compress) { 542 for (zs->zs_code = 255; zs->zs_code >= 0; 543 zs->zs_code--) 544 tab_prefixof(zs->zs_code) = 0; 545 zs->zs_clear_flg = 1; 546 zs->zs_free_ent = FIRST - 1; 547 if ((zs->zs_code = getcode(zs)) == -1) /* O, untimely death! */ 548 break; 549 } 550 zs->zs_incode = zs->zs_code; 551 552 /* Special case for KwKwK string. */ 553 if (zs->zs_code >= zs->zs_free_ent) { 554 *zs->zs_stackp++ = zs->zs_finchar; 555 zs->zs_code = zs->zs_oldcode; 556 } 557 558 /* Generate output characters in reverse order. */ 559 while (zs->zs_code >= 256) { 560 /* 561 * Bad input file may cause zs_stackp to overflow 562 * zs_htab; check here and abort decompression, 563 * that's better than dumping core. 564 */ 565 if (zs->zs_stackp >= (u_char *)&zs->zs_htab[HSIZE]) { 566 errno = EINVAL; 567 return (-1); 568 } 569 *zs->zs_stackp++ = tab_suffixof(zs->zs_code); 570 zs->zs_code = tab_prefixof(zs->zs_code); 571 } 572 *zs->zs_stackp++ = zs->zs_finchar = tab_suffixof(zs->zs_code); 573 574 /* And put them out in forward order. */ 575 middle: do { 576 if (count-- == 0) { 577 zs->zs_bytes_out += num; 578 return (num); 579 } 580 *bp++ = *--zs->zs_stackp; 581 } while (zs->zs_stackp > de_stack); 582 583 /* Generate the new entry. */ 584 if ((zs->zs_code = zs->zs_free_ent) < zs->zs_maxmaxcode) { 585 tab_prefixof(zs->zs_code) = (u_short) zs->zs_oldcode; 586 tab_suffixof(zs->zs_code) = zs->zs_finchar; 587 zs->zs_free_ent = zs->zs_code + 1; 588 } 589 590 /* Remember previous code. */ 591 zs->zs_oldcode = zs->zs_incode; 592 } 593 zs->zs_state = S_EOF; 594 zs->zs_bytes_out += num - count; 595 eof: return (num - count); 596 } 597 598 /*- 599 * Read one code from the standard input. If EOF, return -1. 600 * Inputs: 601 * stdin 602 * Outputs: 603 * code or -1 is returned. 604 */ 605 static code_int 606 getcode(struct s_zstate *zs) 607 { 608 code_int gcode; 609 int r_off, bits; 610 u_char *bp; 611 612 if (zs->zs_clear_flg > 0 || zs->zs_offset >= zs->zs_size || 613 zs->zs_free_ent > zs->zs_maxcode) { 614 615 zs->zs_bp += zs->zs_n_bits; 616 /* 617 * If the next entry will be too big for the current gcode 618 * size, then we must increase the size. This implies reading 619 * a new buffer full, too. 620 */ 621 if (zs->zs_free_ent > zs->zs_maxcode) { 622 zs->zs_n_bits++; 623 if (zs->zs_n_bits == zs->zs_maxbits) { 624 /* Won't get any bigger now. */ 625 zs->zs_maxcode = zs->zs_maxmaxcode; 626 } else 627 zs->zs_maxcode = MAXCODE(zs->zs_n_bits); 628 } 629 if (zs->zs_clear_flg > 0) { 630 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 631 zs->zs_clear_flg = 0; 632 } 633 634 /* fill the buffer up to the neck */ 635 if (zs->zs_bp + zs->zs_n_bits > zs->zs_ebp) { 636 for (bp = zs->zs_buf; zs->zs_bp < zs->zs_ebp; 637 *bp++ = *zs->zs_bp++); 638 if ((bits = read(zs->zs_fd, bp, ZBUFSIZ - 639 (bp - zs->zs_buf))) < 0) 640 return -1; 641 zs->zs_in_count += bits; 642 zs->zs_bp = zs->zs_buf; 643 zs->zs_ebp = bp + bits; 644 } 645 zs->zs_offset = 0; 646 zs->zs_size = MIN(zs->zs_n_bits, zs->zs_ebp - zs->zs_bp); 647 if (zs->zs_size == 0) 648 return -1; 649 /* Round size down to integral number of codes. */ 650 zs->zs_size = (zs->zs_size << 3) - (zs->zs_n_bits - 1); 651 } 652 653 bp = zs->zs_bp; 654 r_off = zs->zs_offset; 655 bits = zs->zs_n_bits; 656 657 /* Get to the first byte. */ 658 bp += (r_off >> 3); 659 r_off &= 7; 660 661 /* Get first part (low order bits). */ 662 gcode = (*bp++ >> r_off); 663 bits -= (8 - r_off); 664 r_off = 8 - r_off; /* Now, roffset into gcode word. */ 665 666 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */ 667 if (bits >= 8) { 668 gcode |= *bp++ << r_off; 669 r_off += 8; 670 bits -= 8; 671 } 672 673 /* High order bits. */ 674 gcode |= (*bp & rmask[bits]) << r_off; 675 zs->zs_offset += zs->zs_n_bits; 676 677 return (gcode); 678 } 679 680 /* Table clear for block compress. */ 681 static int 682 cl_block(struct s_zstate *zs) 683 { 684 long rat; 685 686 zs->zs_checkpoint = zs->zs_in_count + CHECK_GAP; 687 688 if (zs->zs_in_count > 0x007fffff) { /* Shift will overflow. */ 689 rat = zs->zs_bytes_out >> 8; 690 if (rat == 0) /* Don't divide by zero. */ 691 rat = 0x7fffffff; 692 else 693 rat = zs->zs_in_count / rat; 694 } else { 695 /* 8 fractional bits. */ 696 rat = (zs->zs_in_count << 8) / zs->zs_bytes_out; 697 } 698 if (rat > zs->zs_ratio) 699 zs->zs_ratio = rat; 700 else { 701 zs->zs_ratio = 0; 702 cl_hash(zs, (count_int) zs->zs_hsize); 703 zs->zs_free_ent = FIRST; 704 zs->zs_clear_flg = 1; 705 if (output(zs, (code_int) CLEAR) == -1) 706 return (-1); 707 } 708 return (0); 709 } 710 711 /* Reset code table. */ 712 static void 713 cl_hash(struct s_zstate *zs, count_int cl_hsize) 714 { 715 count_int *htab_p; 716 long i, m1; 717 718 m1 = -1; 719 htab_p = zs->zs_htab + cl_hsize; 720 i = cl_hsize - 16; 721 do { /* Might use Sys V memset(3) here. */ 722 *(htab_p - 16) = m1; 723 *(htab_p - 15) = m1; 724 *(htab_p - 14) = m1; 725 *(htab_p - 13) = m1; 726 *(htab_p - 12) = m1; 727 *(htab_p - 11) = m1; 728 *(htab_p - 10) = m1; 729 *(htab_p - 9) = m1; 730 *(htab_p - 8) = m1; 731 *(htab_p - 7) = m1; 732 *(htab_p - 6) = m1; 733 *(htab_p - 5) = m1; 734 *(htab_p - 4) = m1; 735 *(htab_p - 3) = m1; 736 *(htab_p - 2) = m1; 737 *(htab_p - 1) = m1; 738 htab_p -= 16; 739 } while ((i -= 16) >= 0); 740 for (i += 16; i > 0; i--) 741 *--htab_p = m1; 742 } 743 744 FILE * 745 zopen(const char *name, const char *mode, int bits) 746 { 747 int fd; 748 void *cookie; 749 if ((fd = open(name, (*mode=='r'? O_RDONLY:O_WRONLY|O_CREAT), 750 S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1) 751 return NULL; 752 if ((cookie = z_open(fd, mode, NULL, bits, 0, 0)) == NULL) { 753 close(fd); 754 return NULL; 755 } 756 return funopen(cookie, (*mode == 'r'?zread:NULL), 757 (*mode == 'w'?zwrite:NULL), NULL, zclose); 758 } 759 760 void * 761 z_open(int fd, const char *mode, char *name, int bits, 762 u_int32_t mtime, int gotmagic) 763 { 764 struct s_zstate *zs; 765 766 if ((mode[0] != 'r' && mode[0] != 'w') || mode[1] != '\0' || 767 bits < 0 || bits > BITS) { 768 errno = EINVAL; 769 return (NULL); 770 } 771 772 if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL) 773 return (NULL); 774 775 /* User settable max # bits/code. */ 776 zs->zs_maxbits = bits ? bits : BITS; 777 /* Should NEVER generate this code. */ 778 zs->zs_maxmaxcode = 1 << zs->zs_maxbits; 779 zs->zs_hsize = HSIZE; /* For dynamic table sizing. */ 780 zs->zs_free_ent = 0; /* First unused entry. */ 781 zs->zs_block_compress = BLOCK_MASK; 782 zs->zs_clear_flg = 0; 783 zs->zs_ratio = 0; 784 zs->zs_checkpoint = CHECK_GAP; 785 zs->zs_in_count = 0; /* Length of input. */ 786 zs->zs_out_count = 0; /* # of codes output (for debugging).*/ 787 zs->zs_state = gotmagic ? S_MAGIC : S_START; 788 zs->zs_offset = 0; 789 zs->zs_size = 0; 790 zs->zs_mode = mode[0]; 791 zs->zs_bp = zs->zs_ebp = zs->zs_buf; 792 793 zs->zs_fd = fd; 794 return zs; 795 } 796