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