1 /* $OpenBSD: zopen.c,v 1.13 2003/07/17 20:06:01 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 1.13 2003/07/17 20:06:01 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 paramenters */ 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) 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 rval = close(zs->zs_fd); 345 free(zs); 346 return (rval); 347 } 348 349 int 350 zclose(void *cookie) 351 { 352 return z_close(cookie, NULL); 353 } 354 355 /*- 356 * Output the given code. 357 * Inputs: 358 * code: A n_bits-bit integer. If == -1, then EOF. This assumes 359 * that n_bits =< (long)wordsize - 1. 360 * Outputs: 361 * Outputs code to the file. 362 * Assumptions: 363 * Chars are 8 bits long. 364 * Algorithm: 365 * Maintain a BITS character long buffer (so that 8 codes will 366 * fit in it exactly). Use the VAX insv instruction to insert each 367 * code in turn. When the buffer fills up empty it and start over. 368 */ 369 370 static const u_char lmask[9] = 371 {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00}; 372 static const u_char rmask[9] = 373 {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}; 374 375 static int 376 output(struct s_zstate *zs, code_int ocode) 377 { 378 int bits; 379 380 if (ocode >= 0) { 381 int r_off; 382 u_char *bp; 383 384 /* Get to the first byte. */ 385 bp = zs->zs_bp + (zs->zs_offset >> 3); 386 r_off = zs->zs_offset & 7; 387 bits = zs->zs_n_bits; 388 389 /* 390 * Since ocode is always >= 8 bits, only need to mask the first 391 * hunk on the left. 392 */ 393 *bp = (*bp & rmask[r_off]) | ((ocode << r_off) & lmask[r_off]); 394 bp++; 395 bits -= (8 - r_off); 396 ocode >>= 8 - r_off; 397 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits) */ 398 if (bits >= 8) { 399 *bp++ = ocode; 400 ocode >>= 8; 401 bits -= 8; 402 } 403 /* Last bits. */ 404 if (bits) 405 *bp = ocode; 406 zs->zs_offset += zs->zs_n_bits; 407 if (zs->zs_offset == (zs->zs_n_bits << 3)) { 408 zs->zs_bp += zs->zs_n_bits; 409 zs->zs_offset = 0; 410 } 411 /* 412 * If the next entry is going to be too big for the ocode size, 413 * then increase it, if possible. 414 */ 415 if (zs->zs_free_ent > zs->zs_maxcode || 416 (zs->zs_clear_flg > 0)) { 417 /* 418 * Write the whole buffer, because the input side won't 419 * discover the size increase until after it has read it 420 */ 421 if (zs->zs_offset > 0) { 422 zs->zs_bp += zs->zs_n_bits; 423 zs->zs_offset = 0; 424 } 425 426 if (zs->zs_clear_flg) { 427 zs->zs_maxcode = 428 MAXCODE(zs->zs_n_bits = INIT_BITS); 429 zs->zs_clear_flg = 0; 430 } else { 431 zs->zs_n_bits++; 432 if (zs->zs_n_bits == zs->zs_maxbits) 433 zs->zs_maxcode = zs->zs_maxmaxcode; 434 else 435 zs->zs_maxcode = 436 MAXCODE(zs->zs_n_bits); 437 } 438 } 439 440 if (zs->zs_bp + zs->zs_n_bits > &zs->zs_buf[ZBUFSIZ]) { 441 bits = zs->zs_bp - zs->zs_buf; 442 if (write(zs->zs_fd, zs->zs_buf, bits) != bits) 443 return (-1); 444 zs->zs_bytes_out += bits; 445 if (zs->zs_offset > 0) 446 fprintf (stderr, "zs_offset != 0\n"); 447 zs->zs_bp = zs->zs_buf; 448 } 449 } else { 450 /* At EOF, write the rest of the buffer. */ 451 if (zs->zs_offset > 0) 452 zs->zs_bp += (zs->zs_offset + 7) / 8; 453 if (zs->zs_bp > zs->zs_buf) { 454 bits = zs->zs_bp - zs->zs_buf; 455 if (write(zs->zs_fd, zs->zs_buf, bits) != bits) 456 return (-1); 457 zs->zs_bytes_out += bits; 458 } 459 zs->zs_offset = 0; 460 zs->zs_bp = zs->zs_buf; 461 } 462 return (0); 463 } 464 465 /* 466 * Decompress read. This routine adapts to the codes in the file building 467 * the "string" table on-the-fly; requiring no table to be stored in the 468 * compressed file. The tables used herein are shared with those of the 469 * compress() routine. See the definitions above. 470 */ 471 int 472 zread(void *cookie, char *rbp, int num) 473 { 474 u_int count; 475 struct s_zstate *zs; 476 u_char *bp, header[3]; 477 478 if (num == 0) 479 return (0); 480 481 zs = cookie; 482 count = num; 483 bp = (u_char *)rbp; 484 switch (zs->zs_state) { 485 case S_START: 486 zs->zs_state = S_MIDDLE; 487 zs->zs_bp = zs->zs_buf; 488 header[0] = header[1] = header[2] = '\0'; 489 read(zs->zs_fd, header, sizeof(header)); 490 break; 491 case S_MAGIC: 492 zs->zs_state = S_MIDDLE; 493 zs->zs_bp = zs->zs_buf; 494 header[0] = z_magic[0]; 495 header[1] = z_magic[1]; 496 header[2] = '\0'; 497 read(zs->zs_fd, &header[2], 1); 498 break; 499 case S_MIDDLE: 500 goto middle; 501 case S_EOF: 502 goto eof; 503 } 504 505 /* Check the magic number */ 506 if (header[0] != z_magic[0] || header[1] != z_magic[1]) { 507 errno = EFTYPE; 508 return (-1); 509 } 510 zs->zs_maxbits = header[2]; /* Set -b from file. */ 511 zs->zs_in_count += sizeof(header); 512 zs->zs_block_compress = zs->zs_maxbits & BLOCK_MASK; 513 zs->zs_maxbits &= BIT_MASK; 514 zs->zs_maxmaxcode = 1L << zs->zs_maxbits; 515 if (zs->zs_maxbits > BITS) { 516 errno = EFTYPE; 517 return (-1); 518 } 519 /* As above, initialize the first 256 entries in the table. */ 520 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS); 521 for (zs->zs_code = 255; zs->zs_code >= 0; zs->zs_code--) { 522 tab_prefixof(zs->zs_code) = 0; 523 tab_suffixof(zs->zs_code) = (u_char) zs->zs_code; 524 } 525 zs->zs_free_ent = zs->zs_block_compress ? FIRST : 256; 526 527 zs->zs_finchar = zs->zs_oldcode = getcode(zs); 528 if (zs->zs_oldcode == -1) /* EOF already? */ 529 return (0); /* Get out of here */ 530 531 /* First code must be 8 bits = char. */ 532 *bp++ = (u_char)zs->zs_finchar; 533 count--; 534 zs->zs_stackp = de_stack; 535 536 while ((zs->zs_code = getcode(zs)) > -1) { 537 538 if ((zs->zs_code == CLEAR) && zs->zs_block_compress) { 539 for (zs->zs_code = 255; zs->zs_code >= 0; 540 zs->zs_code--) 541 tab_prefixof(zs->zs_code) = 0; 542 zs->zs_clear_flg = 1; 543 zs->zs_free_ent = FIRST - 1; 544 if ((zs->zs_code = getcode(zs)) == -1) /* O, untimely death! */ 545 break; 546 } 547 zs->zs_incode = zs->zs_code; 548 549 /* Special case for KwKwK string. */ 550 if (zs->zs_code >= zs->zs_free_ent) { 551 *zs->zs_stackp++ = zs->zs_finchar; 552 zs->zs_code = zs->zs_oldcode; 553 } 554 555 /* Generate output characters in reverse order. */ 556 while (zs->zs_code >= 256) { 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 = MIN(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 FILE * 733 zopen(const char *name, const char *mode, int bits) 734 { 735 int fd; 736 void *cookie; 737 if ((fd = open(name, (*mode=='r'? O_RDONLY:O_WRONLY|O_CREAT), 738 S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1) 739 return NULL; 740 if ((cookie = z_open(fd, mode, NULL, bits, 0, 0)) == NULL) { 741 close(fd); 742 return NULL; 743 } 744 return funopen(cookie, (*mode == 'r'?zread:NULL), 745 (*mode == 'w'?zwrite:NULL), NULL, zclose); 746 } 747 748 void * 749 z_open(int fd, const char *mode, char *name, int bits, 750 u_int32_t mtime, int gotmagic) 751 { 752 struct s_zstate *zs; 753 754 if ((mode[0] != 'r' && mode[0] != 'w') || mode[1] != '\0' || 755 bits < 0 || bits > BITS) { 756 errno = EINVAL; 757 return (NULL); 758 } 759 760 if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL) 761 return (NULL); 762 763 /* User settable max # bits/code. */ 764 zs->zs_maxbits = bits ? bits : BITS; 765 /* Should NEVER generate this code. */ 766 zs->zs_maxmaxcode = 1 << zs->zs_maxbits; 767 zs->zs_hsize = HSIZE; /* For dynamic table sizing. */ 768 zs->zs_free_ent = 0; /* First unused entry. */ 769 zs->zs_block_compress = BLOCK_MASK; 770 zs->zs_clear_flg = 0; 771 zs->zs_ratio = 0; 772 zs->zs_checkpoint = CHECK_GAP; 773 zs->zs_in_count = 0; /* Length of input. */ 774 zs->zs_out_count = 0; /* # of codes output (for debugging).*/ 775 zs->zs_state = gotmagic ? S_MAGIC : S_START; 776 zs->zs_offset = 0; 777 zs->zs_size = 0; 778 zs->zs_mode = mode[0]; 779 zs->zs_bp = zs->zs_ebp = zs->zs_buf; 780 781 zs->zs_fd = fd; 782 return zs; 783 } 784