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