1 /* $OpenBSD: zopen.c,v 1.22 2017/05/29 14:41:16 fcambus 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 /*- 40 * fcompress.c - File compression ala IEEE Computer, June 1984. 41 * 42 * Compress authors: 43 * Spencer W. Thomas (decvax!utah-cs!thomas) 44 * Jim McKie (decvax!mcvax!jim) 45 * Steve Davies (decvax!vax135!petsd!peora!srd) 46 * Ken Turkowski (decvax!decwrl!turtlevax!ken) 47 * James A. Woods (decvax!ihnp4!ames!jaw) 48 * Joe Orost (decvax!vax135!petsd!joe) 49 * 50 * Cleaned up and converted to library returning I/O streams by 51 * Diomidis Spinellis <dds@doc.ic.ac.uk>. 52 * 53 * zopen(filename, mode, bits) 54 * Returns a FILE * that can be used for read or write. The modes 55 * supported are only "r" and "w". Seeking is not allowed. On 56 * reading the file is decompressed, on writing it is compressed. 57 * The output is compatible with compress(1) with 16 bit tables. 58 * Any file produced by compress(1) can be read. 59 */ 60 61 #include <sys/stat.h> 62 63 #include <ctype.h> 64 #include <errno.h> 65 #include <signal.h> 66 #include <stdio.h> 67 #include <stdlib.h> 68 #include <string.h> 69 #include <unistd.h> 70 #include <fcntl.h> 71 #include "compress.h" 72 73 #define MINIMUM(a, b) (((a) < (b)) ? (a) : (b)) 74 75 #define BITS 16 /* Default bits. */ 76 #define HSIZE 69001 /* 95% occupancy */ 77 #define ZBUFSIZ 8192 /* I/O buffer size */ 78 79 /* A code_int must be able to hold 2**BITS values of type int, and also -1. */ 80 typedef long code_int; 81 typedef long count_int; 82 83 static const u_char z_magic[] = 84 {'\037', '\235'}; /* 1F 9D */ 85 86 #define BIT_MASK 0x1f /* Defines for third byte of header. */ 87 #define BLOCK_MASK 0x80 88 89 /* 90 * Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is 91 * a fourth header byte (for expansion). 92 */ 93 #define INIT_BITS 9 /* Initial number of bits/code. */ 94 95 #define MAXCODE(n_bits) ((1 << (n_bits)) - 1) 96 97 struct s_zstate { 98 int zs_fd; /* File stream for I/O */ 99 char zs_mode; /* r or w */ 100 enum { 101 S_START, S_MAGIC, S_MIDDLE, S_EOF 102 } zs_state; /* State of computation */ 103 int zs_n_bits; /* Number of bits/code. */ 104 int zs_maxbits; /* User settable max # bits/code. */ 105 code_int zs_maxcode; /* Maximum code, given n_bits. */ 106 code_int zs_maxmaxcode; /* Should NEVER generate this code. */ 107 count_int zs_htab[HSIZE]; 108 u_short zs_codetab[HSIZE]; 109 code_int zs_hsize; /* For dynamic table sizing. */ 110 code_int zs_free_ent; /* First unused entry. */ 111 /* 112 * Block compression parameters -- after all codes are used up, 113 * and compression rate changes, start over. 114 */ 115 int zs_block_compress; 116 int zs_clear_flg; 117 long zs_ratio; 118 count_int zs_checkpoint; 119 long zs_in_count; /* Length of input. */ 120 long zs_bytes_out; /* Length of output. */ 121 long zs_out_count; /* # of codes output (for debugging).*/ 122 u_char zs_buf[ZBUFSIZ]; /* I/O buffer */ 123 u_char *zs_bp; /* Current I/O window in the zs_buf */ 124 int zs_offset; /* Number of bits in the zs_buf */ 125 union { 126 struct { 127 long zs_fcode; 128 code_int zs_ent; 129 code_int zs_hsize_reg; 130 int zs_hshift; 131 } w; /* Write parameters */ 132 struct { 133 u_char *zs_stackp, *zs_ebp; 134 int zs_finchar; 135 code_int zs_code, zs_oldcode, zs_incode; 136 int zs_size; 137 } r; /* Read parameters */ 138 } u; 139 }; 140 141 /* Definitions to retain old variable names */ 142 #define zs_fcode u.w.zs_fcode 143 #define zs_ent u.w.zs_ent 144 #define zs_hsize_reg u.w.zs_hsize_reg 145 #define zs_hshift u.w.zs_hshift 146 #define zs_stackp u.r.zs_stackp 147 #define zs_finchar u.r.zs_finchar 148 #define zs_code u.r.zs_code 149 #define zs_oldcode u.r.zs_oldcode 150 #define zs_incode u.r.zs_incode 151 #define zs_size u.r.zs_size 152 #define zs_ebp u.r.zs_ebp 153 154 /* 155 * To save much memory, we overlay the table used by compress() with those 156 * used by decompress(). The tab_prefix table is the same size and type as 157 * the codetab. The tab_suffix table needs 2**BITS characters. We get this 158 * from the beginning of htab. The output stack uses the rest of htab, and 159 * contains characters. There is plenty of room for any possible stack 160 * (stack used to be 8000 characters). 161 */ 162 163 #define htabof(i) zs->zs_htab[i] 164 #define codetabof(i) zs->zs_codetab[i] 165 166 #define tab_prefixof(i) codetabof(i) 167 #define tab_suffixof(i) ((u_char *)(zs->zs_htab))[i] 168 #define de_stack ((u_char *)&tab_suffixof(1 << BITS)) 169 170 #define CHECK_GAP 10000 /* Ratio check interval. */ 171 172 /* 173 * the next two codes should not be changed lightly, as they must not 174 * lie within the contiguous general code space. 175 */ 176 #define FIRST 257 /* First free entry. */ 177 #define CLEAR 256 /* Table clear output code. */ 178 179 static int cl_block(struct s_zstate *); 180 static void cl_hash(struct s_zstate *, count_int); 181 static code_int getcode(struct s_zstate *); 182 static int output(struct s_zstate *, code_int); 183 184 /*- 185 * Algorithm from "A Technique for High Performance Data Compression", 186 * Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19. 187 * 188 * Algorithm: 189 * Modified Lempel-Ziv method (LZW). Basically finds common 190 * substrings and replaces them with a variable size code. This is 191 * deterministic, and can be done on the fly. Thus, the decompression 192 * procedure needs no input table, but tracks the way the table was built. 193 */ 194 195 /*- 196 * compress write 197 * 198 * Algorithm: use open addressing double hashing (no chaining) on the 199 * prefix code / next character combination. We do a variant of Knuth's 200 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime 201 * secondary probe. Here, the modular division first probe is gives way 202 * to a faster exclusive-or manipulation. Also do block compression with 203 * an adaptive reset, whereby the code table is cleared when the compression 204 * ratio decreases, but after the table fills. The variable-length output 205 * codes are re-sized at this point, and a special CLEAR code is generated 206 * for the decompressor. Late addition: construct the table according to 207 * file size for noticeable speed improvement on small files. Please direct 208 * questions about this implementation to ames!jaw. 209 */ 210 int 211 zwrite(void *cookie, const char *wbp, int num) 212 { 213 code_int i; 214 int c, disp; 215 struct s_zstate *zs; 216 const u_char *bp; 217 u_char tmp; 218 int count; 219 220 zs = cookie; 221 count = num; 222 bp = (u_char *)wbp; 223 switch (zs->zs_state) { 224 case S_MAGIC: 225 return -1; 226 case S_EOF: 227 return 0; 228 case S_START: 229 zs->zs_state = S_MIDDLE; 230 231 zs->zs_maxmaxcode = 1L << zs->zs_maxbits; 232 if (write(zs->zs_fd, z_magic, sizeof(z_magic)) != 233 sizeof(z_magic)) 234 return (-1); 235 tmp = (u_char)(zs->zs_maxbits | zs->zs_block_compress); 236 if (write(zs->zs_fd, &tmp, sizeof(tmp)) != sizeof(tmp)) 237 return (-1); 238 239 zs->zs_bp = zs->zs_buf; 240 zs->zs_offset = 0; 241 zs->zs_bytes_out = 3; /* Includes 3-byte header mojo. */ 242 zs->zs_out_count = 0; 243 zs->zs_clear_flg = 0; 244 zs->zs_ratio = 0; 245 zs->zs_in_count = 1; 246 zs->zs_checkpoint = CHECK_GAP; 247 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 248 zs->zs_free_ent = ((zs->zs_block_compress) ? FIRST : 256); 249 250 zs->zs_ent = *bp++; 251 --count; 252 253 zs->zs_hshift = 0; 254 for (zs->zs_fcode = (long)zs->zs_hsize; zs->zs_fcode < 65536L; 255 zs->zs_fcode *= 2L) 256 zs->zs_hshift++; 257 /* Set hash code range bound. */ 258 zs->zs_hshift = 8 - zs->zs_hshift; 259 260 zs->zs_hsize_reg = zs->zs_hsize; 261 /* Clear hash table. */ 262 cl_hash(zs, (count_int)zs->zs_hsize_reg); 263 264 case S_MIDDLE: 265 for (i = 0; count-- > 0;) { 266 c = *bp++; 267 zs->zs_in_count++; 268 zs->zs_fcode = (long)(((long)c << zs->zs_maxbits) + 269 zs->zs_ent); 270 /* Xor hashing. */ 271 i = ((c << zs->zs_hshift) ^ zs->zs_ent); 272 273 if (htabof(i) == zs->zs_fcode) { 274 zs->zs_ent = codetabof(i); 275 continue; 276 } else if ((long)htabof(i) < 0) /* Empty slot. */ 277 goto nomatch; 278 /* Secondary hash (after G. Knott). */ 279 disp = zs->zs_hsize_reg - i; 280 if (i == 0) 281 disp = 1; 282 probe: if ((i -= disp) < 0) 283 i += zs->zs_hsize_reg; 284 285 if (htabof(i) == zs->zs_fcode) { 286 zs->zs_ent = codetabof(i); 287 continue; 288 } 289 if ((long)htabof(i) >= 0) 290 goto probe; 291 nomatch: if (output(zs, (code_int) zs->zs_ent) == -1) 292 return (-1); 293 zs->zs_out_count++; 294 zs->zs_ent = c; 295 if (zs->zs_free_ent < zs->zs_maxmaxcode) { 296 /* code -> hashtable */ 297 codetabof(i) = zs->zs_free_ent++; 298 htabof(i) = zs->zs_fcode; 299 } else if ((count_int)zs->zs_in_count >= 300 zs->zs_checkpoint && zs->zs_block_compress) { 301 if (cl_block(zs) == -1) 302 return (-1); 303 } 304 } 305 } 306 return (num); 307 } 308 309 int 310 z_close(void *cookie, struct z_info *info, const char *name, struct stat *sb) 311 { 312 struct s_zstate *zs; 313 int rval; 314 315 zs = cookie; 316 if (zs->zs_mode == 'w') { /* Put out the final code. */ 317 if (output(zs, (code_int) zs->zs_ent) == -1) { 318 (void)close(zs->zs_fd); 319 free(zs); 320 return (-1); 321 } 322 zs->zs_out_count++; 323 if (output(zs, (code_int) - 1) == -1) { 324 (void)close(zs->zs_fd); 325 free(zs); 326 return (-1); 327 } 328 } 329 330 if (info != NULL) { 331 info->mtime = 0; 332 info->crc = (u_int32_t)-1; 333 info->hlen = 0; 334 info->total_in = (off_t)zs->zs_in_count; 335 info->total_out = (off_t)zs->zs_bytes_out; 336 } 337 338 #ifndef SAVECORE 339 setfile(name, zs->zs_fd, sb); 340 #endif 341 rval = close(zs->zs_fd); 342 free(zs); 343 return (rval); 344 } 345 346 /*- 347 * Output the given code. 348 * Inputs: 349 * code: A n_bits-bit integer. If == -1, then EOF. This assumes 350 * that n_bits =< (long)wordsize - 1. 351 * Outputs: 352 * Outputs code to the file. 353 * Assumptions: 354 * Chars are 8 bits long. 355 * Algorithm: 356 * Maintain a BITS character long buffer (so that 8 codes will 357 * fit in it exactly). Use the VAX insv instruction to insert each 358 * code in turn. When the buffer fills up empty it and start over. 359 */ 360 361 static const u_char lmask[9] = 362 {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00}; 363 static const u_char rmask[9] = 364 {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}; 365 366 static int 367 output(struct s_zstate *zs, code_int ocode) 368 { 369 int bits; 370 371 if (ocode >= 0) { 372 int r_off; 373 u_char *bp; 374 375 /* Get to the first byte. */ 376 bp = zs->zs_bp + (zs->zs_offset >> 3); 377 r_off = zs->zs_offset & 7; 378 bits = zs->zs_n_bits; 379 380 /* 381 * Since ocode is always >= 8 bits, only need to mask the first 382 * hunk on the left. 383 */ 384 *bp = (*bp & rmask[r_off]) | ((ocode << r_off) & lmask[r_off]); 385 bp++; 386 bits -= (8 - r_off); 387 ocode >>= 8 - r_off; 388 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits) */ 389 if (bits >= 8) { 390 *bp++ = ocode; 391 ocode >>= 8; 392 bits -= 8; 393 } 394 /* Last bits. */ 395 if (bits) 396 *bp = ocode; 397 zs->zs_offset += zs->zs_n_bits; 398 if (zs->zs_offset == (zs->zs_n_bits << 3)) { 399 zs->zs_bp += zs->zs_n_bits; 400 zs->zs_offset = 0; 401 } 402 /* 403 * If the next entry is going to be too big for the ocode size, 404 * then increase it, if possible. 405 */ 406 if (zs->zs_free_ent > zs->zs_maxcode || 407 (zs->zs_clear_flg > 0)) { 408 /* 409 * Write the whole buffer, because the input side won't 410 * discover the size increase until after it has read it 411 */ 412 if (zs->zs_offset > 0) { 413 zs->zs_bp += zs->zs_n_bits; 414 zs->zs_offset = 0; 415 } 416 417 if (zs->zs_clear_flg) { 418 zs->zs_maxcode = 419 MAXCODE(zs->zs_n_bits = INIT_BITS); 420 zs->zs_clear_flg = 0; 421 } else { 422 zs->zs_n_bits++; 423 if (zs->zs_n_bits == zs->zs_maxbits) 424 zs->zs_maxcode = zs->zs_maxmaxcode; 425 else 426 zs->zs_maxcode = 427 MAXCODE(zs->zs_n_bits); 428 } 429 } 430 431 if (zs->zs_bp + zs->zs_n_bits > &zs->zs_buf[ZBUFSIZ]) { 432 bits = zs->zs_bp - zs->zs_buf; 433 if (write(zs->zs_fd, zs->zs_buf, bits) != bits) 434 return (-1); 435 zs->zs_bytes_out += bits; 436 if (zs->zs_offset > 0) 437 fprintf (stderr, "zs_offset != 0\n"); 438 zs->zs_bp = zs->zs_buf; 439 } 440 } else { 441 /* At EOF, write the rest of the buffer. */ 442 if (zs->zs_offset > 0) 443 zs->zs_bp += (zs->zs_offset + 7) / 8; 444 if (zs->zs_bp > zs->zs_buf) { 445 bits = zs->zs_bp - zs->zs_buf; 446 if (write(zs->zs_fd, zs->zs_buf, bits) != bits) 447 return (-1); 448 zs->zs_bytes_out += bits; 449 } 450 zs->zs_offset = 0; 451 zs->zs_bp = zs->zs_buf; 452 } 453 return (0); 454 } 455 456 /* 457 * Decompress read. This routine adapts to the codes in the file building 458 * the "string" table on-the-fly; requiring no table to be stored in the 459 * compressed file. The tables used herein are shared with those of the 460 * compress() routine. See the definitions above. 461 */ 462 int 463 zread(void *cookie, char *rbp, int num) 464 { 465 u_int count; 466 struct s_zstate *zs; 467 u_char *bp, header[3]; 468 469 if (num == 0) 470 return (0); 471 472 zs = cookie; 473 count = num; 474 bp = (u_char *)rbp; 475 switch (zs->zs_state) { 476 case S_START: 477 zs->zs_state = S_MIDDLE; 478 zs->zs_bp = zs->zs_buf; 479 header[0] = header[1] = header[2] = '\0'; 480 read(zs->zs_fd, header, sizeof(header)); 481 break; 482 case S_MAGIC: 483 zs->zs_state = S_MIDDLE; 484 zs->zs_bp = zs->zs_buf; 485 header[0] = z_magic[0]; 486 header[1] = z_magic[1]; 487 header[2] = '\0'; 488 read(zs->zs_fd, &header[2], 1); 489 break; 490 case S_MIDDLE: 491 goto middle; 492 case S_EOF: 493 goto eof; 494 } 495 496 /* Check the magic number */ 497 if (header[0] != z_magic[0] || header[1] != z_magic[1]) { 498 errno = EFTYPE; 499 return (-1); 500 } 501 zs->zs_maxbits = header[2]; /* Set -b from file. */ 502 zs->zs_in_count += sizeof(header); 503 zs->zs_block_compress = zs->zs_maxbits & BLOCK_MASK; 504 zs->zs_maxbits &= BIT_MASK; 505 zs->zs_maxmaxcode = 1L << zs->zs_maxbits; 506 if (zs->zs_maxbits > BITS) { 507 errno = EFTYPE; 508 return (-1); 509 } 510 /* As above, initialize the first 256 entries in the table. */ 511 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 512 for (zs->zs_code = 255; zs->zs_code >= 0; zs->zs_code--) { 513 tab_prefixof(zs->zs_code) = 0; 514 tab_suffixof(zs->zs_code) = (u_char) zs->zs_code; 515 } 516 zs->zs_free_ent = zs->zs_block_compress ? FIRST : 256; 517 518 zs->zs_finchar = zs->zs_oldcode = getcode(zs); 519 if (zs->zs_oldcode == -1) /* EOF already? */ 520 return (0); /* Get out of here */ 521 522 /* First code must be 8 bits = char. */ 523 *bp++ = (u_char)zs->zs_finchar; 524 count--; 525 zs->zs_stackp = de_stack; 526 527 while ((zs->zs_code = getcode(zs)) > -1) { 528 529 if ((zs->zs_code == CLEAR) && zs->zs_block_compress) { 530 for (zs->zs_code = 255; zs->zs_code >= 0; 531 zs->zs_code--) 532 tab_prefixof(zs->zs_code) = 0; 533 zs->zs_clear_flg = 1; 534 zs->zs_free_ent = FIRST - 1; 535 if ((zs->zs_code = getcode(zs)) == -1) /* O, untimely death! */ 536 break; 537 } 538 zs->zs_incode = zs->zs_code; 539 540 /* Special case for KwKwK string. */ 541 if (zs->zs_code >= zs->zs_free_ent) { 542 *zs->zs_stackp++ = zs->zs_finchar; 543 zs->zs_code = zs->zs_oldcode; 544 } 545 546 /* Generate output characters in reverse order. */ 547 while (zs->zs_code >= 256) { 548 /* 549 * Bad input file may cause zs_stackp to overflow 550 * zs_htab; check here and abort decompression, 551 * that's better than dumping core. 552 */ 553 if (zs->zs_stackp >= (u_char *)&zs->zs_htab[HSIZE]) { 554 errno = EINVAL; 555 return (-1); 556 } 557 *zs->zs_stackp++ = tab_suffixof(zs->zs_code); 558 zs->zs_code = tab_prefixof(zs->zs_code); 559 } 560 *zs->zs_stackp++ = zs->zs_finchar = tab_suffixof(zs->zs_code); 561 562 /* And put them out in forward order. */ 563 middle: do { 564 if (count-- == 0) { 565 zs->zs_bytes_out += num; 566 return (num); 567 } 568 *bp++ = *--zs->zs_stackp; 569 } while (zs->zs_stackp > de_stack); 570 571 /* Generate the new entry. */ 572 if ((zs->zs_code = zs->zs_free_ent) < zs->zs_maxmaxcode) { 573 tab_prefixof(zs->zs_code) = (u_short) zs->zs_oldcode; 574 tab_suffixof(zs->zs_code) = zs->zs_finchar; 575 zs->zs_free_ent = zs->zs_code + 1; 576 } 577 578 /* Remember previous code. */ 579 zs->zs_oldcode = zs->zs_incode; 580 } 581 zs->zs_state = S_EOF; 582 zs->zs_bytes_out += num - count; 583 eof: return (num - count); 584 } 585 586 /*- 587 * Read one code from the standard input. If EOF, return -1. 588 * Inputs: 589 * stdin 590 * Outputs: 591 * code or -1 is returned. 592 */ 593 static code_int 594 getcode(struct s_zstate *zs) 595 { 596 code_int gcode; 597 int r_off, bits; 598 u_char *bp; 599 600 if (zs->zs_clear_flg > 0 || zs->zs_offset >= zs->zs_size || 601 zs->zs_free_ent > zs->zs_maxcode) { 602 603 zs->zs_bp += zs->zs_n_bits; 604 /* 605 * If the next entry will be too big for the current gcode 606 * size, then we must increase the size. This implies reading 607 * a new buffer full, too. 608 */ 609 if (zs->zs_free_ent > zs->zs_maxcode) { 610 zs->zs_n_bits++; 611 if (zs->zs_n_bits == zs->zs_maxbits) { 612 /* Won't get any bigger now. */ 613 zs->zs_maxcode = zs->zs_maxmaxcode; 614 } else 615 zs->zs_maxcode = MAXCODE(zs->zs_n_bits); 616 } 617 if (zs->zs_clear_flg > 0) { 618 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 619 zs->zs_clear_flg = 0; 620 } 621 622 /* fill the buffer up to the neck */ 623 if (zs->zs_bp + zs->zs_n_bits > zs->zs_ebp) { 624 for (bp = zs->zs_buf; zs->zs_bp < zs->zs_ebp; 625 *bp++ = *zs->zs_bp++); 626 if ((bits = read(zs->zs_fd, bp, ZBUFSIZ - 627 (bp - zs->zs_buf))) < 0) 628 return -1; 629 zs->zs_in_count += bits; 630 zs->zs_bp = zs->zs_buf; 631 zs->zs_ebp = bp + bits; 632 } 633 zs->zs_offset = 0; 634 zs->zs_size = MINIMUM(zs->zs_n_bits, zs->zs_ebp - zs->zs_bp); 635 if (zs->zs_size == 0) 636 return -1; 637 /* Round size down to integral number of codes. */ 638 zs->zs_size = (zs->zs_size << 3) - (zs->zs_n_bits - 1); 639 } 640 641 bp = zs->zs_bp; 642 r_off = zs->zs_offset; 643 bits = zs->zs_n_bits; 644 645 /* Get to the first byte. */ 646 bp += (r_off >> 3); 647 r_off &= 7; 648 649 /* Get first part (low order bits). */ 650 gcode = (*bp++ >> r_off); 651 bits -= (8 - r_off); 652 r_off = 8 - r_off; /* Now, roffset into gcode word. */ 653 654 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */ 655 if (bits >= 8) { 656 gcode |= *bp++ << r_off; 657 r_off += 8; 658 bits -= 8; 659 } 660 661 /* High order bits. */ 662 gcode |= (*bp & rmask[bits]) << r_off; 663 zs->zs_offset += zs->zs_n_bits; 664 665 return (gcode); 666 } 667 668 /* Table clear for block compress. */ 669 static int 670 cl_block(struct s_zstate *zs) 671 { 672 long rat; 673 674 zs->zs_checkpoint = zs->zs_in_count + CHECK_GAP; 675 676 if (zs->zs_in_count > 0x007fffff) { /* Shift will overflow. */ 677 rat = zs->zs_bytes_out >> 8; 678 if (rat == 0) /* Don't divide by zero. */ 679 rat = 0x7fffffff; 680 else 681 rat = zs->zs_in_count / rat; 682 } else { 683 /* 8 fractional bits. */ 684 rat = (zs->zs_in_count << 8) / zs->zs_bytes_out; 685 } 686 if (rat > zs->zs_ratio) 687 zs->zs_ratio = rat; 688 else { 689 zs->zs_ratio = 0; 690 cl_hash(zs, (count_int) zs->zs_hsize); 691 zs->zs_free_ent = FIRST; 692 zs->zs_clear_flg = 1; 693 if (output(zs, (code_int) CLEAR) == -1) 694 return (-1); 695 } 696 return (0); 697 } 698 699 /* Reset code table. */ 700 static void 701 cl_hash(struct s_zstate *zs, count_int cl_hsize) 702 { 703 count_int *htab_p; 704 long i, m1; 705 706 m1 = -1; 707 htab_p = zs->zs_htab + cl_hsize; 708 i = cl_hsize - 16; 709 do { /* Might use Sys V memset(3) here. */ 710 *(htab_p - 16) = m1; 711 *(htab_p - 15) = m1; 712 *(htab_p - 14) = m1; 713 *(htab_p - 13) = m1; 714 *(htab_p - 12) = m1; 715 *(htab_p - 11) = m1; 716 *(htab_p - 10) = m1; 717 *(htab_p - 9) = m1; 718 *(htab_p - 8) = m1; 719 *(htab_p - 7) = m1; 720 *(htab_p - 6) = m1; 721 *(htab_p - 5) = m1; 722 *(htab_p - 4) = m1; 723 *(htab_p - 3) = m1; 724 *(htab_p - 2) = m1; 725 *(htab_p - 1) = m1; 726 htab_p -= 16; 727 } while ((i -= 16) >= 0); 728 for (i += 16; i > 0; i--) 729 *--htab_p = m1; 730 } 731 732 void * 733 z_wopen(int fd, char *name, int bits, u_int32_t mtime) 734 { 735 struct s_zstate *zs; 736 737 if (bits < 0 || bits > BITS) { 738 errno = EINVAL; 739 return (NULL); 740 } 741 742 if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL) 743 return (NULL); 744 745 /* User settable max # bits/code. */ 746 zs->zs_maxbits = bits ? bits : BITS; 747 /* Should NEVER generate this code. */ 748 zs->zs_maxmaxcode = 1 << zs->zs_maxbits; 749 zs->zs_hsize = HSIZE; /* For dynamic table sizing. */ 750 zs->zs_free_ent = 0; /* First unused entry. */ 751 zs->zs_block_compress = BLOCK_MASK; 752 zs->zs_clear_flg = 0; 753 zs->zs_ratio = 0; 754 zs->zs_checkpoint = CHECK_GAP; 755 zs->zs_in_count = 0; /* Length of input. */ 756 zs->zs_out_count = 0; /* # of codes output (for debugging).*/ 757 zs->zs_state = S_START; 758 zs->zs_offset = 0; 759 zs->zs_size = 0; 760 zs->zs_mode = 'w'; 761 zs->zs_bp = zs->zs_ebp = zs->zs_buf; 762 763 zs->zs_fd = fd; 764 return zs; 765 } 766 767 void * 768 z_ropen(int fd, char *name, int gotmagic) 769 { 770 struct s_zstate *zs; 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; 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 = 'r'; 791 zs->zs_bp = zs->zs_ebp = zs->zs_buf; 792 793 zs->zs_fd = fd; 794 return zs; 795 } 796