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
zwrite(void * cookie,const char * wbp,int num)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
z_close(void * cookie,struct z_info * info,const char * name,struct stat * sb)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
output(struct s_zstate * zs,code_int ocode)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
zread(void * cookie,char * rbp,int num)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
getcode(struct s_zstate * zs)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
cl_block(struct s_zstate * zs)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
cl_hash(struct s_zstate * zs,count_int cl_hsize)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 *
z_wopen(int fd,char * name,int bits,u_int32_t mtime)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 *
z_ropen(int fd,char * name,int gotmagic)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