Branch data Line data Source code
1 : : /* +++ deflate.c */
2 : : /* deflate.c -- compress data using the deflation algorithm
3 : : * Copyright (C) 1995-1996 Jean-loup Gailly.
4 : : * For conditions of distribution and use, see copyright notice in zlib.h
5 : : */
6 : :
7 : : /*
8 : : * ALGORITHM
9 : : *
10 : : * The "deflation" process depends on being able to identify portions
11 : : * of the input text which are identical to earlier input (within a
12 : : * sliding window trailing behind the input currently being processed).
13 : : *
14 : : * The most straightforward technique turns out to be the fastest for
15 : : * most input files: try all possible matches and select the longest.
16 : : * The key feature of this algorithm is that insertions into the string
17 : : * dictionary are very simple and thus fast, and deletions are avoided
18 : : * completely. Insertions are performed at each input character, whereas
19 : : * string matches are performed only when the previous match ends. So it
20 : : * is preferable to spend more time in matches to allow very fast string
21 : : * insertions and avoid deletions. The matching algorithm for small
22 : : * strings is inspired from that of Rabin & Karp. A brute force approach
23 : : * is used to find longer strings when a small match has been found.
24 : : * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
25 : : * (by Leonid Broukhis).
26 : : * A previous version of this file used a more sophisticated algorithm
27 : : * (by Fiala and Greene) which is guaranteed to run in linear amortized
28 : : * time, but has a larger average cost, uses more memory and is patented.
29 : : * However the F&G algorithm may be faster for some highly redundant
30 : : * files if the parameter max_chain_length (described below) is too large.
31 : : *
32 : : * ACKNOWLEDGEMENTS
33 : : *
34 : : * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
35 : : * I found it in 'freeze' written by Leonid Broukhis.
36 : : * Thanks to many people for bug reports and testing.
37 : : *
38 : : * REFERENCES
39 : : *
40 : : * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
41 : : * Available in ftp://ds.internic.net/rfc/rfc1951.txt
42 : : *
43 : : * A description of the Rabin and Karp algorithm is given in the book
44 : : * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
45 : : *
46 : : * Fiala,E.R., and Greene,D.H.
47 : : * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
48 : : *
49 : : */
50 : :
51 : : #include <linux/module.h>
52 : : #include <linux/zutil.h>
53 : : #include "defutil.h"
54 : :
55 : :
56 : : /* ===========================================================================
57 : : * Function prototypes.
58 : : */
59 : : typedef enum {
60 : : need_more, /* block not completed, need more input or more output */
61 : : block_done, /* block flush performed */
62 : : finish_started, /* finish started, need only more output at next deflate */
63 : : finish_done /* finish done, accept no more input or output */
64 : : } block_state;
65 : :
66 : : typedef block_state (*compress_func) (deflate_state *s, int flush);
67 : : /* Compression function. Returns the block state after the call. */
68 : :
69 : : static void fill_window (deflate_state *s);
70 : : static block_state deflate_stored (deflate_state *s, int flush);
71 : : static block_state deflate_fast (deflate_state *s, int flush);
72 : : static block_state deflate_slow (deflate_state *s, int flush);
73 : : static void lm_init (deflate_state *s);
74 : : static void putShortMSB (deflate_state *s, uInt b);
75 : : static void flush_pending (z_streamp strm);
76 : : static int read_buf (z_streamp strm, Byte *buf, unsigned size);
77 : : static uInt longest_match (deflate_state *s, IPos cur_match);
78 : :
79 : : #ifdef DEBUG_ZLIB
80 : : static void check_match (deflate_state *s, IPos start, IPos match,
81 : : int length);
82 : : #endif
83 : :
84 : : /* ===========================================================================
85 : : * Local data
86 : : */
87 : :
88 : : #define NIL 0
89 : : /* Tail of hash chains */
90 : :
91 : : #ifndef TOO_FAR
92 : : # define TOO_FAR 4096
93 : : #endif
94 : : /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
95 : :
96 : : #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
97 : : /* Minimum amount of lookahead, except at the end of the input file.
98 : : * See deflate.c for comments about the MIN_MATCH+1.
99 : : */
100 : :
101 : : /* Values for max_lazy_match, good_match and max_chain_length, depending on
102 : : * the desired pack level (0..9). The values given below have been tuned to
103 : : * exclude worst case performance for pathological files. Better values may be
104 : : * found for specific files.
105 : : */
106 : : typedef struct config_s {
107 : : ush good_length; /* reduce lazy search above this match length */
108 : : ush max_lazy; /* do not perform lazy search above this match length */
109 : : ush nice_length; /* quit search above this match length */
110 : : ush max_chain;
111 : : compress_func func;
112 : : } config;
113 : :
114 : : static const config configuration_table[10] = {
115 : : /* good lazy nice chain */
116 : : /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
117 : : /* 1 */ {4, 4, 8, 4, deflate_fast}, /* maximum speed, no lazy matches */
118 : : /* 2 */ {4, 5, 16, 8, deflate_fast},
119 : : /* 3 */ {4, 6, 32, 32, deflate_fast},
120 : :
121 : : /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
122 : : /* 5 */ {8, 16, 32, 32, deflate_slow},
123 : : /* 6 */ {8, 16, 128, 128, deflate_slow},
124 : : /* 7 */ {8, 32, 128, 256, deflate_slow},
125 : : /* 8 */ {32, 128, 258, 1024, deflate_slow},
126 : : /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
127 : :
128 : : /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
129 : : * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
130 : : * meaning.
131 : : */
132 : :
133 : : #define EQUAL 0
134 : : /* result of memcmp for equal strings */
135 : :
136 : : /* ===========================================================================
137 : : * Update a hash value with the given input byte
138 : : * IN assertion: all calls to UPDATE_HASH are made with consecutive
139 : : * input characters, so that a running hash key can be computed from the
140 : : * previous key instead of complete recalculation each time.
141 : : */
142 : : #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
143 : :
144 : :
145 : : /* ===========================================================================
146 : : * Insert string str in the dictionary and set match_head to the previous head
147 : : * of the hash chain (the most recent string with same hash key). Return
148 : : * the previous length of the hash chain.
149 : : * IN assertion: all calls to INSERT_STRING are made with consecutive
150 : : * input characters and the first MIN_MATCH bytes of str are valid
151 : : * (except for the last MIN_MATCH-1 bytes of the input file).
152 : : */
153 : : #define INSERT_STRING(s, str, match_head) \
154 : : (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
155 : : s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
156 : : s->head[s->ins_h] = (Pos)(str))
157 : :
158 : : /* ===========================================================================
159 : : * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
160 : : * prev[] will be initialized on the fly.
161 : : */
162 : : #define CLEAR_HASH(s) \
163 : : s->head[s->hash_size-1] = NIL; \
164 : : memset((char *)s->head, 0, (unsigned)(s->hash_size-1)*sizeof(*s->head));
165 : :
166 : : /* ========================================================================= */
167 : 0 : int zlib_deflateInit2(
168 : : z_streamp strm,
169 : : int level,
170 : : int method,
171 : : int windowBits,
172 : : int memLevel,
173 : : int strategy
174 : : )
175 : : {
176 : : deflate_state *s;
177 : : int noheader = 0;
178 : : deflate_workspace *mem;
179 : : char *next;
180 : :
181 : : ush *overlay;
182 : : /* We overlay pending_buf and d_buf+l_buf. This works since the average
183 : : * output size for (length,distance) codes is <= 24 bits.
184 : : */
185 : :
186 [ # # ]: 0 : if (strm == NULL) return Z_STREAM_ERROR;
187 : :
188 : 0 : strm->msg = NULL;
189 : :
190 [ # # ]: 0 : if (level == Z_DEFAULT_COMPRESSION) level = 6;
191 : :
192 : 0 : mem = (deflate_workspace *) strm->workspace;
193 : :
194 [ # # ]: 0 : if (windowBits < 0) { /* undocumented feature: suppress zlib header */
195 : : noheader = 1;
196 : 0 : windowBits = -windowBits;
197 : : }
198 [ # # ][ # # ]: 0 : if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
199 [ # # ][ # # ]: 0 : windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
200 [ # # ]: 0 : strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
201 : : return Z_STREAM_ERROR;
202 : : }
203 : :
204 : : /*
205 : : * Direct the workspace's pointers to the chunks that were allocated
206 : : * along with the deflate_workspace struct.
207 : : */
208 : : next = (char *) mem;
209 : 0 : next += sizeof(*mem);
210 : 0 : mem->window_memory = (Byte *) next;
211 : 0 : next += zlib_deflate_window_memsize(windowBits);
212 : 0 : mem->prev_memory = (Pos *) next;
213 : 0 : next += zlib_deflate_prev_memsize(windowBits);
214 : 0 : mem->head_memory = (Pos *) next;
215 : 0 : next += zlib_deflate_head_memsize(memLevel);
216 : 0 : mem->overlay_memory = next;
217 : :
218 : 0 : s = (deflate_state *) &(mem->deflate_memory);
219 : 0 : strm->state = (struct internal_state *)s;
220 : 0 : s->strm = strm;
221 : :
222 : 0 : s->noheader = noheader;
223 : 0 : s->w_bits = windowBits;
224 : 0 : s->w_size = 1 << s->w_bits;
225 : 0 : s->w_mask = s->w_size - 1;
226 : :
227 : 0 : s->hash_bits = memLevel + 7;
228 : 0 : s->hash_size = 1 << s->hash_bits;
229 : 0 : s->hash_mask = s->hash_size - 1;
230 : 0 : s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
231 : :
232 : 0 : s->window = (Byte *) mem->window_memory;
233 : 0 : s->prev = (Pos *) mem->prev_memory;
234 : 0 : s->head = (Pos *) mem->head_memory;
235 : :
236 : 0 : s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
237 : :
238 : 0 : overlay = (ush *) mem->overlay_memory;
239 : 0 : s->pending_buf = (uch *) overlay;
240 : 0 : s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
241 : :
242 : 0 : s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
243 : 0 : s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
244 : :
245 : 0 : s->level = level;
246 : 0 : s->strategy = strategy;
247 : 0 : s->method = (Byte)method;
248 : :
249 : 0 : return zlib_deflateReset(strm);
250 : : }
251 : :
252 : : /* ========================================================================= */
253 : : #if 0
254 : : int zlib_deflateSetDictionary(
255 : : z_streamp strm,
256 : : const Byte *dictionary,
257 : : uInt dictLength
258 : : )
259 : : {
260 : : deflate_state *s;
261 : : uInt length = dictLength;
262 : : uInt n;
263 : : IPos hash_head = 0;
264 : :
265 : : if (strm == NULL || strm->state == NULL || dictionary == NULL)
266 : : return Z_STREAM_ERROR;
267 : :
268 : : s = (deflate_state *) strm->state;
269 : : if (s->status != INIT_STATE) return Z_STREAM_ERROR;
270 : :
271 : : strm->adler = zlib_adler32(strm->adler, dictionary, dictLength);
272 : :
273 : : if (length < MIN_MATCH) return Z_OK;
274 : : if (length > MAX_DIST(s)) {
275 : : length = MAX_DIST(s);
276 : : #ifndef USE_DICT_HEAD
277 : : dictionary += dictLength - length; /* use the tail of the dictionary */
278 : : #endif
279 : : }
280 : : memcpy((char *)s->window, dictionary, length);
281 : : s->strstart = length;
282 : : s->block_start = (long)length;
283 : :
284 : : /* Insert all strings in the hash table (except for the last two bytes).
285 : : * s->lookahead stays null, so s->ins_h will be recomputed at the next
286 : : * call of fill_window.
287 : : */
288 : : s->ins_h = s->window[0];
289 : : UPDATE_HASH(s, s->ins_h, s->window[1]);
290 : : for (n = 0; n <= length - MIN_MATCH; n++) {
291 : : INSERT_STRING(s, n, hash_head);
292 : : }
293 : : if (hash_head) hash_head = 0; /* to make compiler happy */
294 : : return Z_OK;
295 : : }
296 : : #endif /* 0 */
297 : :
298 : : /* ========================================================================= */
299 : 0 : int zlib_deflateReset(
300 : : z_streamp strm
301 : : )
302 : : {
303 : : deflate_state *s;
304 : :
305 [ # # ][ # # ]: 0 : if (strm == NULL || strm->state == NULL)
306 : : return Z_STREAM_ERROR;
307 : :
308 : 0 : strm->total_in = strm->total_out = 0;
309 : 0 : strm->msg = NULL;
310 : 0 : strm->data_type = Z_UNKNOWN;
311 : :
312 : : s = (deflate_state *)strm->state;
313 : 0 : s->pending = 0;
314 : 0 : s->pending_out = s->pending_buf;
315 : :
316 [ # # ]: 0 : if (s->noheader < 0) {
317 : 0 : s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
318 : : }
319 [ # # ]: 0 : s->status = s->noheader ? BUSY_STATE : INIT_STATE;
320 : 0 : strm->adler = 1;
321 : 0 : s->last_flush = Z_NO_FLUSH;
322 : :
323 : 0 : zlib_tr_init(s);
324 : 0 : lm_init(s);
325 : :
326 : 0 : return Z_OK;
327 : : }
328 : :
329 : : /* ========================================================================= */
330 : : #if 0
331 : : int zlib_deflateParams(
332 : : z_streamp strm,
333 : : int level,
334 : : int strategy
335 : : )
336 : : {
337 : : deflate_state *s;
338 : : compress_func func;
339 : : int err = Z_OK;
340 : :
341 : : if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
342 : : s = (deflate_state *) strm->state;
343 : :
344 : : if (level == Z_DEFAULT_COMPRESSION) {
345 : : level = 6;
346 : : }
347 : : if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
348 : : return Z_STREAM_ERROR;
349 : : }
350 : : func = configuration_table[s->level].func;
351 : :
352 : : if (func != configuration_table[level].func && strm->total_in != 0) {
353 : : /* Flush the last buffer: */
354 : : err = zlib_deflate(strm, Z_PARTIAL_FLUSH);
355 : : }
356 : : if (s->level != level) {
357 : : s->level = level;
358 : : s->max_lazy_match = configuration_table[level].max_lazy;
359 : : s->good_match = configuration_table[level].good_length;
360 : : s->nice_match = configuration_table[level].nice_length;
361 : : s->max_chain_length = configuration_table[level].max_chain;
362 : : }
363 : : s->strategy = strategy;
364 : : return err;
365 : : }
366 : : #endif /* 0 */
367 : :
368 : : /* =========================================================================
369 : : * Put a short in the pending buffer. The 16-bit value is put in MSB order.
370 : : * IN assertion: the stream state is correct and there is enough room in
371 : : * pending_buf.
372 : : */
373 : : static void putShortMSB(
374 : : deflate_state *s,
375 : : uInt b
376 : : )
377 : : {
378 : 0 : put_byte(s, (Byte)(b >> 8));
379 : 0 : put_byte(s, (Byte)(b & 0xff));
380 : : }
381 : :
382 : : /* =========================================================================
383 : : * Flush as much pending output as possible. All deflate() output goes
384 : : * through this function so some applications may wish to modify it
385 : : * to avoid allocating a large strm->next_out buffer and copying into it.
386 : : * (See also read_buf()).
387 : : */
388 : 0 : static void flush_pending(
389 : : z_streamp strm
390 : : )
391 : : {
392 : 0 : deflate_state *s = (deflate_state *) strm->state;
393 : 0 : unsigned len = s->pending;
394 : :
395 [ # # ]: 0 : if (len > strm->avail_out) len = strm->avail_out;
396 [ # # ]: 0 : if (len == 0) return;
397 : :
398 [ # # ]: 0 : if (strm->next_out != NULL) {
399 : 0 : memcpy(strm->next_out, s->pending_out, len);
400 : 0 : strm->next_out += len;
401 : : }
402 : 0 : s->pending_out += len;
403 : 0 : strm->total_out += len;
404 : 0 : strm->avail_out -= len;
405 : 0 : s->pending -= len;
406 [ # # ]: 0 : if (s->pending == 0) {
407 : 0 : s->pending_out = s->pending_buf;
408 : : }
409 : : }
410 : :
411 : : /* ========================================================================= */
412 : 0 : int zlib_deflate(
413 : : z_streamp strm,
414 : : int flush
415 : : )
416 : : {
417 : : int old_flush; /* value of flush param for previous deflate call */
418 : : deflate_state *s;
419 : :
420 [ # # ][ # # ]: 0 : if (strm == NULL || strm->state == NULL ||
421 [ # # ]: 0 : flush > Z_FINISH || flush < 0) {
422 : : return Z_STREAM_ERROR;
423 : : }
424 : : s = (deflate_state *) strm->state;
425 : :
426 [ # # ][ # # ]: 0 : if ((strm->next_in == NULL && strm->avail_in != 0) ||
[ # # ]
427 [ # # ]: 0 : (s->status == FINISH_STATE && flush != Z_FINISH)) {
428 : : return Z_STREAM_ERROR;
429 : : }
430 [ # # ]: 0 : if (strm->avail_out == 0) return Z_BUF_ERROR;
431 : :
432 : 0 : s->strm = strm; /* just in case */
433 : 0 : old_flush = s->last_flush;
434 : 0 : s->last_flush = flush;
435 : :
436 : : /* Write the zlib header */
437 [ # # ]: 0 : if (s->status == INIT_STATE) {
438 : :
439 : 0 : uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
440 : 0 : uInt level_flags = (s->level-1) >> 1;
441 : :
442 [ # # ]: 0 : if (level_flags > 3) level_flags = 3;
443 : 0 : header |= (level_flags << 6);
444 [ # # ]: 0 : if (s->strstart != 0) header |= PRESET_DICT;
445 : 0 : header += 31 - (header % 31);
446 : :
447 : 0 : s->status = BUSY_STATE;
448 : : putShortMSB(s, header);
449 : :
450 : : /* Save the adler32 of the preset dictionary: */
451 [ # # ]: 0 : if (s->strstart != 0) {
452 : 0 : putShortMSB(s, (uInt)(strm->adler >> 16));
453 : 0 : putShortMSB(s, (uInt)(strm->adler & 0xffff));
454 : : }
455 : 0 : strm->adler = 1L;
456 : : }
457 : :
458 : : /* Flush as much pending output as possible */
459 [ # # ]: 0 : if (s->pending != 0) {
460 : 0 : flush_pending(strm);
461 [ # # ]: 0 : if (strm->avail_out == 0) {
462 : : /* Since avail_out is 0, deflate will be called again with
463 : : * more output space, but possibly with both pending and
464 : : * avail_in equal to zero. There won't be anything to do,
465 : : * but this is not an error situation so make sure we
466 : : * return OK instead of BUF_ERROR at next call of deflate:
467 : : */
468 : 0 : s->last_flush = -1;
469 : 0 : return Z_OK;
470 : : }
471 : :
472 : : /* Make sure there is something to do and avoid duplicate consecutive
473 : : * flushes. For repeated and useless calls with Z_FINISH, we keep
474 : : * returning Z_STREAM_END instead of Z_BUFF_ERROR.
475 : : */
476 [ # # ][ # # ]: 0 : } else if (strm->avail_in == 0 && flush <= old_flush &&
477 : 0 : flush != Z_FINISH) {
478 : : return Z_BUF_ERROR;
479 : : }
480 : :
481 : : /* User must not provide more input after the first FINISH: */
482 [ # # ][ # # ]: 0 : if (s->status == FINISH_STATE && strm->avail_in != 0) {
483 : : return Z_BUF_ERROR;
484 : : }
485 : :
486 : : /* Start a new block or continue the current one.
487 : : */
488 [ # # ][ # # ]: 0 : if (strm->avail_in != 0 || s->lookahead != 0 ||
[ # # ]
489 [ # # ]: 0 : (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
490 : : block_state bstate;
491 : :
492 : 0 : bstate = (*(configuration_table[s->level].func))(s, flush);
493 : :
494 [ # # ]: 0 : if (bstate == finish_started || bstate == finish_done) {
495 : 0 : s->status = FINISH_STATE;
496 : : }
497 [ # # ]: 0 : if (bstate == need_more || bstate == finish_started) {
498 [ # # ]: 0 : if (strm->avail_out == 0) {
499 : 0 : s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
500 : : }
501 : : return Z_OK;
502 : : /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
503 : : * of deflate should use the same flush parameter to make sure
504 : : * that the flush is complete. So we don't have to output an
505 : : * empty block here, this will be done at next call. This also
506 : : * ensures that for a very small output buffer, we emit at most
507 : : * one empty block.
508 : : */
509 : : }
510 [ # # ]: 0 : if (bstate == block_done) {
511 [ # # ]: 0 : if (flush == Z_PARTIAL_FLUSH) {
512 : 0 : zlib_tr_align(s);
513 [ # # ]: 0 : } else if (flush == Z_PACKET_FLUSH) {
514 : : /* Output just the 3-bit `stored' block type value,
515 : : but not a zero length. */
516 : 0 : zlib_tr_stored_type_only(s);
517 : : } else { /* FULL_FLUSH or SYNC_FLUSH */
518 : 0 : zlib_tr_stored_block(s, (char*)0, 0L, 0);
519 : : /* For a full flush, this empty block will be recognized
520 : : * as a special marker by inflate_sync().
521 : : */
522 [ # # ]: 0 : if (flush == Z_FULL_FLUSH) {
523 [ # # ]: 0 : CLEAR_HASH(s); /* forget history */
524 : : }
525 : : }
526 : 0 : flush_pending(strm);
527 [ # # ]: 0 : if (strm->avail_out == 0) {
528 : 0 : s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
529 : 0 : return Z_OK;
530 : : }
531 : : }
532 : : }
533 : : Assert(strm->avail_out > 0, "bug2");
534 : :
535 [ # # ]: 0 : if (flush != Z_FINISH) return Z_OK;
536 [ # # ]: 0 : if (s->noheader) return Z_STREAM_END;
537 : :
538 : : /* Write the zlib trailer (adler32) */
539 : 0 : putShortMSB(s, (uInt)(strm->adler >> 16));
540 : 0 : putShortMSB(s, (uInt)(strm->adler & 0xffff));
541 : 0 : flush_pending(strm);
542 : : /* If avail_out is zero, the application will call deflate again
543 : : * to flush the rest.
544 : : */
545 : 0 : s->noheader = -1; /* write the trailer only once! */
546 : 0 : return s->pending != 0 ? Z_OK : Z_STREAM_END;
547 : : }
548 : :
549 : : /* ========================================================================= */
550 : 0 : int zlib_deflateEnd(
551 : : z_streamp strm
552 : : )
553 : : {
554 : : int status;
555 : : deflate_state *s;
556 : :
557 [ # # ][ # # ]: 0 : if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
558 : : s = (deflate_state *) strm->state;
559 : :
560 : 0 : status = s->status;
561 [ # # ][ # # ]: 0 : if (status != INIT_STATE && status != BUSY_STATE &&
562 : : status != FINISH_STATE) {
563 : : return Z_STREAM_ERROR;
564 : : }
565 : :
566 : 0 : strm->state = NULL;
567 : :
568 [ # # ]: 0 : return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
569 : : }
570 : :
571 : : /* =========================================================================
572 : : * Copy the source state to the destination state.
573 : : */
574 : : #if 0
575 : : int zlib_deflateCopy (
576 : : z_streamp dest,
577 : : z_streamp source
578 : : )
579 : : {
580 : : #ifdef MAXSEG_64K
581 : : return Z_STREAM_ERROR;
582 : : #else
583 : : deflate_state *ds;
584 : : deflate_state *ss;
585 : : ush *overlay;
586 : : deflate_workspace *mem;
587 : :
588 : :
589 : : if (source == NULL || dest == NULL || source->state == NULL) {
590 : : return Z_STREAM_ERROR;
591 : : }
592 : :
593 : : ss = (deflate_state *) source->state;
594 : :
595 : : *dest = *source;
596 : :
597 : : mem = (deflate_workspace *) dest->workspace;
598 : :
599 : : ds = &(mem->deflate_memory);
600 : :
601 : : dest->state = (struct internal_state *) ds;
602 : : *ds = *ss;
603 : : ds->strm = dest;
604 : :
605 : : ds->window = (Byte *) mem->window_memory;
606 : : ds->prev = (Pos *) mem->prev_memory;
607 : : ds->head = (Pos *) mem->head_memory;
608 : : overlay = (ush *) mem->overlay_memory;
609 : : ds->pending_buf = (uch *) overlay;
610 : :
611 : : memcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
612 : : memcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
613 : : memcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
614 : : memcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
615 : :
616 : : ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
617 : : ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
618 : : ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
619 : :
620 : : ds->l_desc.dyn_tree = ds->dyn_ltree;
621 : : ds->d_desc.dyn_tree = ds->dyn_dtree;
622 : : ds->bl_desc.dyn_tree = ds->bl_tree;
623 : :
624 : : return Z_OK;
625 : : #endif
626 : : }
627 : : #endif /* 0 */
628 : :
629 : : /* ===========================================================================
630 : : * Read a new buffer from the current input stream, update the adler32
631 : : * and total number of bytes read. All deflate() input goes through
632 : : * this function so some applications may wish to modify it to avoid
633 : : * allocating a large strm->next_in buffer and copying from it.
634 : : * (See also flush_pending()).
635 : : */
636 : 0 : static int read_buf(
637 : : z_streamp strm,
638 : : Byte *buf,
639 : : unsigned size
640 : : )
641 : : {
642 : 0 : unsigned len = strm->avail_in;
643 : :
644 [ # # ]: 0 : if (len > size) len = size;
645 [ # # ]: 0 : if (len == 0) return 0;
646 : :
647 : 0 : strm->avail_in -= len;
648 : :
649 [ # # ]: 0 : if (!((deflate_state *)(strm->state))->noheader) {
650 : 0 : strm->adler = zlib_adler32(strm->adler, strm->next_in, len);
651 : : }
652 : 0 : memcpy(buf, strm->next_in, len);
653 : 0 : strm->next_in += len;
654 : 0 : strm->total_in += len;
655 : :
656 : 0 : return (int)len;
657 : : }
658 : :
659 : : /* ===========================================================================
660 : : * Initialize the "longest match" routines for a new zlib stream
661 : : */
662 : 0 : static void lm_init(
663 : : deflate_state *s
664 : : )
665 : : {
666 : 0 : s->window_size = (ulg)2L*s->w_size;
667 : :
668 [ # # ]: 0 : CLEAR_HASH(s);
669 : :
670 : : /* Set the default configuration parameters:
671 : : */
672 : 0 : s->max_lazy_match = configuration_table[s->level].max_lazy;
673 : 0 : s->good_match = configuration_table[s->level].good_length;
674 : 0 : s->nice_match = configuration_table[s->level].nice_length;
675 : 0 : s->max_chain_length = configuration_table[s->level].max_chain;
676 : :
677 : 0 : s->strstart = 0;
678 : 0 : s->block_start = 0L;
679 : 0 : s->lookahead = 0;
680 : 0 : s->match_length = s->prev_length = MIN_MATCH-1;
681 : 0 : s->match_available = 0;
682 : 0 : s->ins_h = 0;
683 : 0 : }
684 : :
685 : : /* ===========================================================================
686 : : * Set match_start to the longest match starting at the given string and
687 : : * return its length. Matches shorter or equal to prev_length are discarded,
688 : : * in which case the result is equal to prev_length and match_start is
689 : : * garbage.
690 : : * IN assertions: cur_match is the head of the hash chain for the current
691 : : * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
692 : : * OUT assertion: the match length is not greater than s->lookahead.
693 : : */
694 : : /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
695 : : * match.S. The code will be functionally equivalent.
696 : : */
697 : 0 : static uInt longest_match(
698 : : deflate_state *s,
699 : : IPos cur_match /* current match */
700 : : )
701 : : {
702 : 0 : unsigned chain_length = s->max_chain_length;/* max hash chain length */
703 : 0 : register Byte *scan = s->window + s->strstart; /* current string */
704 : : register Byte *match; /* matched string */
705 : : register int len; /* length of current match */
706 : 0 : int best_len = s->prev_length; /* best match length so far */
707 : 0 : int nice_match = s->nice_match; /* stop if match long enough */
708 : 0 : IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
709 [ # # ]: 0 : s->strstart - (IPos)MAX_DIST(s) : NIL;
710 : : /* Stop when cur_match becomes <= limit. To simplify the code,
711 : : * we prevent matches with the string of window index 0.
712 : : */
713 : 0 : Pos *prev = s->prev;
714 : 0 : uInt wmask = s->w_mask;
715 : :
716 : : #ifdef UNALIGNED_OK
717 : : /* Compare two bytes at a time. Note: this is not always beneficial.
718 : : * Try with and without -DUNALIGNED_OK to check.
719 : : */
720 : : register Byte *strend = s->window + s->strstart + MAX_MATCH - 1;
721 : : register ush scan_start = *(ush*)scan;
722 : : register ush scan_end = *(ush*)(scan+best_len-1);
723 : : #else
724 : 0 : register Byte *strend = s->window + s->strstart + MAX_MATCH;
725 : 0 : register Byte scan_end1 = scan[best_len-1];
726 : 0 : register Byte scan_end = scan[best_len];
727 : : #endif
728 : :
729 : : /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
730 : : * It is easy to get rid of this optimization if necessary.
731 : : */
732 : : Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
733 : :
734 : : /* Do not waste too much time if we already have a good match: */
735 [ # # ]: 0 : if (s->prev_length >= s->good_match) {
736 : 0 : chain_length >>= 2;
737 : : }
738 : : /* Do not look for matches beyond the end of the input. This is necessary
739 : : * to make deflate deterministic.
740 : : */
741 [ # # ]: 0 : if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
742 : :
743 : : Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
744 : :
745 : : do {
746 : : Assert(cur_match < s->strstart, "no future");
747 : 0 : match = s->window + cur_match;
748 : :
749 : : /* Skip to next match if the match length cannot increase
750 : : * or if the match length is less than 2:
751 : : */
752 : : #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
753 : : /* This code assumes sizeof(unsigned short) == 2. Do not use
754 : : * UNALIGNED_OK if your compiler uses a different size.
755 : : */
756 : : if (*(ush*)(match+best_len-1) != scan_end ||
757 : : *(ush*)match != scan_start) continue;
758 : :
759 : : /* It is not necessary to compare scan[2] and match[2] since they are
760 : : * always equal when the other bytes match, given that the hash keys
761 : : * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
762 : : * strstart+3, +5, ... up to strstart+257. We check for insufficient
763 : : * lookahead only every 4th comparison; the 128th check will be made
764 : : * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
765 : : * necessary to put more guard bytes at the end of the window, or
766 : : * to check more often for insufficient lookahead.
767 : : */
768 : : Assert(scan[2] == match[2], "scan[2]?");
769 : : scan++, match++;
770 : : do {
771 : : } while (*(ush*)(scan+=2) == *(ush*)(match+=2) &&
772 : : *(ush*)(scan+=2) == *(ush*)(match+=2) &&
773 : : *(ush*)(scan+=2) == *(ush*)(match+=2) &&
774 : : *(ush*)(scan+=2) == *(ush*)(match+=2) &&
775 : : scan < strend);
776 : : /* The funny "do {}" generates better code on most compilers */
777 : :
778 : : /* Here, scan <= window+strstart+257 */
779 : : Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
780 : : if (*scan == *match) scan++;
781 : :
782 : : len = (MAX_MATCH - 1) - (int)(strend-scan);
783 : : scan = strend - (MAX_MATCH-1);
784 : :
785 : : #else /* UNALIGNED_OK */
786 : :
787 [ # # ][ # # ]: 0 : if (match[best_len] != scan_end ||
788 [ # # ]: 0 : match[best_len-1] != scan_end1 ||
789 [ # # ]: 0 : *match != *scan ||
790 : 0 : *++match != scan[1]) continue;
791 : :
792 : : /* The check at best_len-1 can be removed because it will be made
793 : : * again later. (This heuristic is not always a win.)
794 : : * It is not necessary to compare scan[2] and match[2] since they
795 : : * are always equal when the other bytes match, given that
796 : : * the hash keys are equal and that HASH_BITS >= 8.
797 : : */
798 : 0 : scan += 2, match++;
799 : : Assert(*scan == *match, "match[2]?");
800 : :
801 : : /* We check for insufficient lookahead only every 8th comparison;
802 : : * the 256th check will be made at strstart+258.
803 : : */
804 : : do {
805 [ # # ][ # # ]: 0 : } while (*++scan == *++match && *++scan == *++match &&
806 [ # # ][ # # ]: 0 : *++scan == *++match && *++scan == *++match &&
807 [ # # ][ # # ]: 0 : *++scan == *++match && *++scan == *++match &&
808 [ # # ][ # # ]: 0 : *++scan == *++match && *++scan == *++match &&
809 [ # # ]: 0 : scan < strend);
810 : :
811 : : Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
812 : :
813 : 0 : len = MAX_MATCH - (int)(strend - scan);
814 : 0 : scan = strend - MAX_MATCH;
815 : :
816 : : #endif /* UNALIGNED_OK */
817 : :
818 [ # # ]: 0 : if (len > best_len) {
819 : 0 : s->match_start = cur_match;
820 : : best_len = len;
821 [ # # ]: 0 : if (len >= nice_match) break;
822 : : #ifdef UNALIGNED_OK
823 : : scan_end = *(ush*)(scan+best_len-1);
824 : : #else
825 : 0 : scan_end1 = scan[best_len-1];
826 : 0 : scan_end = scan[best_len];
827 : : #endif
828 : : }
829 : 0 : } while ((cur_match = prev[cur_match & wmask]) > limit
830 [ # # ][ # # ]: 0 : && --chain_length != 0);
831 : :
832 [ # # ]: 0 : if ((uInt)best_len <= s->lookahead) return best_len;
833 : 0 : return s->lookahead;
834 : : }
835 : :
836 : : #ifdef DEBUG_ZLIB
837 : : /* ===========================================================================
838 : : * Check that the match at match_start is indeed a match.
839 : : */
840 : : static void check_match(
841 : : deflate_state *s,
842 : : IPos start,
843 : : IPos match,
844 : : int length
845 : : )
846 : : {
847 : : /* check that the match is indeed a match */
848 : : if (memcmp((char *)s->window + match,
849 : : (char *)s->window + start, length) != EQUAL) {
850 : : fprintf(stderr, " start %u, match %u, length %d\n",
851 : : start, match, length);
852 : : do {
853 : : fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
854 : : } while (--length != 0);
855 : : z_error("invalid match");
856 : : }
857 : : if (z_verbose > 1) {
858 : : fprintf(stderr,"\\[%d,%d]", start-match, length);
859 : : do { putc(s->window[start++], stderr); } while (--length != 0);
860 : : }
861 : : }
862 : : #else
863 : : # define check_match(s, start, match, length)
864 : : #endif
865 : :
866 : : /* ===========================================================================
867 : : * Fill the window when the lookahead becomes insufficient.
868 : : * Updates strstart and lookahead.
869 : : *
870 : : * IN assertion: lookahead < MIN_LOOKAHEAD
871 : : * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
872 : : * At least one byte has been read, or avail_in == 0; reads are
873 : : * performed for at least two bytes (required for the zip translate_eol
874 : : * option -- not supported here).
875 : : */
876 : 0 : static void fill_window(
877 : : deflate_state *s
878 : : )
879 : : {
880 : : register unsigned n, m;
881 : : register Pos *p;
882 : : unsigned more; /* Amount of free space at the end of the window. */
883 : 0 : uInt wsize = s->w_size;
884 : :
885 : : do {
886 : 0 : more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
887 : :
888 : : /* Deal with !@#$% 64K limit: */
889 [ # # ][ # # ]: 0 : if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
[ # # ]
890 : : more = wsize;
891 : :
892 [ # # ]: 0 : } else if (more == (unsigned)(-1)) {
893 : : /* Very unlikely, but possible on 16 bit machine if strstart == 0
894 : : * and lookahead == 1 (input done one byte at time)
895 : : */
896 : 0 : more--;
897 : :
898 : : /* If the window is almost full and there is insufficient lookahead,
899 : : * move the upper half to the lower one to make room in the upper half.
900 : : */
901 [ # # ]: 0 : } else if (s->strstart >= wsize+MAX_DIST(s)) {
902 : :
903 : 0 : memcpy((char *)s->window, (char *)s->window+wsize,
904 : : (unsigned)wsize);
905 : 0 : s->match_start -= wsize;
906 : 0 : s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
907 : 0 : s->block_start -= (long) wsize;
908 : :
909 : : /* Slide the hash table (could be avoided with 32 bit values
910 : : at the expense of memory usage). We slide even when level == 0
911 : : to keep the hash table consistent if we switch back to level > 0
912 : : later. (Using level 0 permanently is not an optimal usage of
913 : : zlib, so we don't care about this pathological case.)
914 : : */
915 : 0 : n = s->hash_size;
916 : 0 : p = &s->head[n];
917 : : do {
918 : 0 : m = *--p;
919 [ # # ]: 0 : *p = (Pos)(m >= wsize ? m-wsize : NIL);
920 [ # # ]: 0 : } while (--n);
921 : :
922 : : n = wsize;
923 : 0 : p = &s->prev[n];
924 : : do {
925 : 0 : m = *--p;
926 [ # # ]: 0 : *p = (Pos)(m >= wsize ? m-wsize : NIL);
927 : : /* If n is not on any hash chain, prev[n] is garbage but
928 : : * its value will never be used.
929 : : */
930 [ # # ]: 0 : } while (--n);
931 : 0 : more += wsize;
932 : : }
933 [ # # ]: 0 : if (s->strm->avail_in == 0) return;
934 : :
935 : : /* If there was no sliding:
936 : : * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
937 : : * more == window_size - lookahead - strstart
938 : : * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
939 : : * => more >= window_size - 2*WSIZE + 2
940 : : * In the BIG_MEM or MMAP case (not yet supported),
941 : : * window_size == input_size + MIN_LOOKAHEAD &&
942 : : * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
943 : : * Otherwise, window_size == 2*WSIZE so more >= 2.
944 : : * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
945 : : */
946 : : Assert(more >= 2, "more < 2");
947 : :
948 : 0 : n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
949 : 0 : s->lookahead += n;
950 : :
951 : : /* Initialize the hash value now that we have some input: */
952 [ # # ]: 0 : if (s->lookahead >= MIN_MATCH) {
953 : 0 : s->ins_h = s->window[s->strstart];
954 : 0 : UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
955 : : #if MIN_MATCH != 3
956 : : Call UPDATE_HASH() MIN_MATCH-3 more times
957 : : #endif
958 : : }
959 : : /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
960 : : * but this is not important since only literal bytes will be emitted.
961 : : */
962 : :
963 [ # # ][ # # ]: 0 : } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
964 : : }
965 : :
966 : : /* ===========================================================================
967 : : * Flush the current block, with given end-of-file flag.
968 : : * IN assertion: strstart is set to the end of the current match.
969 : : */
970 : : #define FLUSH_BLOCK_ONLY(s, eof) { \
971 : : zlib_tr_flush_block(s, (s->block_start >= 0L ? \
972 : : (char *)&s->window[(unsigned)s->block_start] : \
973 : : NULL), \
974 : : (ulg)((long)s->strstart - s->block_start), \
975 : : (eof)); \
976 : : s->block_start = s->strstart; \
977 : : flush_pending(s->strm); \
978 : : Tracev((stderr,"[FLUSH]")); \
979 : : }
980 : :
981 : : /* Same but force premature exit if necessary. */
982 : : #define FLUSH_BLOCK(s, eof) { \
983 : : FLUSH_BLOCK_ONLY(s, eof); \
984 : : if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
985 : : }
986 : :
987 : : /* ===========================================================================
988 : : * Copy without compression as much as possible from the input stream, return
989 : : * the current block state.
990 : : * This function does not insert new strings in the dictionary since
991 : : * uncompressible data is probably not useful. This function is used
992 : : * only for the level=0 compression option.
993 : : * NOTE: this function should be optimized to avoid extra copying from
994 : : * window to pending_buf.
995 : : */
996 : 0 : static block_state deflate_stored(
997 : : deflate_state *s,
998 : : int flush
999 : : )
1000 : : {
1001 : : /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1002 : : * to pending_buf_size, and each stored block has a 5 byte header:
1003 : : */
1004 : : ulg max_block_size = 0xffff;
1005 : : ulg max_start;
1006 : :
1007 [ # # ]: 0 : if (max_block_size > s->pending_buf_size - 5) {
1008 : : max_block_size = s->pending_buf_size - 5;
1009 : : }
1010 : :
1011 : : /* Copy as much as possible from input to output: */
1012 : : for (;;) {
1013 : : /* Fill the window as much as possible: */
1014 [ # # ]: 0 : if (s->lookahead <= 1) {
1015 : :
1016 : : Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1017 : : s->block_start >= (long)s->w_size, "slide too late");
1018 : :
1019 : 0 : fill_window(s);
1020 [ # # ][ # # ]: 0 : if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1021 : :
1022 [ # # ]: 0 : if (s->lookahead == 0) break; /* flush the current block */
1023 : : }
1024 : : Assert(s->block_start >= 0L, "block gone");
1025 : :
1026 : 0 : s->strstart += s->lookahead;
1027 : 0 : s->lookahead = 0;
1028 : :
1029 : : /* Emit a stored block if pending_buf will be full: */
1030 : 0 : max_start = s->block_start + max_block_size;
1031 [ # # ][ # # ]: 0 : if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1032 : : /* strstart == 0 is possible when wraparound on 16-bit machine */
1033 : 0 : s->lookahead = (uInt)(s->strstart - max_start);
1034 : 0 : s->strstart = (uInt)max_start;
1035 [ # # ][ # # ]: 0 : FLUSH_BLOCK(s, 0);
1036 : : }
1037 : : /* Flush if we may have to slide, otherwise block_start may become
1038 : : * negative and the data will be gone:
1039 : : */
1040 [ # # ]: 0 : if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1041 [ # # ][ # # ]: 0 : FLUSH_BLOCK(s, 0);
1042 : : }
1043 : : }
1044 [ # # ][ # # ]: 0 : FLUSH_BLOCK(s, flush == Z_FINISH);
[ # # ]
1045 [ # # ]: 0 : return flush == Z_FINISH ? finish_done : block_done;
1046 : : }
1047 : :
1048 : : /* ===========================================================================
1049 : : * Compress as much as possible from the input stream, return the current
1050 : : * block state.
1051 : : * This function does not perform lazy evaluation of matches and inserts
1052 : : * new strings in the dictionary only for unmatched strings or for short
1053 : : * matches. It is used only for the fast compression options.
1054 : : */
1055 : 0 : static block_state deflate_fast(
1056 : : deflate_state *s,
1057 : : int flush
1058 : : )
1059 : : {
1060 : : IPos hash_head = NIL; /* head of the hash chain */
1061 : : int bflush; /* set if current block must be flushed */
1062 : :
1063 : : for (;;) {
1064 : : /* Make sure that we always have enough lookahead, except
1065 : : * at the end of the input file. We need MAX_MATCH bytes
1066 : : * for the next match, plus MIN_MATCH bytes to insert the
1067 : : * string following the next match.
1068 : : */
1069 [ # # ]: 0 : if (s->lookahead < MIN_LOOKAHEAD) {
1070 : 0 : fill_window(s);
1071 [ # # ][ # # ]: 0 : if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1072 : : return need_more;
1073 : : }
1074 [ # # ]: 0 : if (s->lookahead == 0) break; /* flush the current block */
1075 : : }
1076 : :
1077 : : /* Insert the string window[strstart .. strstart+2] in the
1078 : : * dictionary, and set hash_head to the head of the hash chain:
1079 : : */
1080 [ # # ]: 0 : if (s->lookahead >= MIN_MATCH) {
1081 : 0 : INSERT_STRING(s, s->strstart, hash_head);
1082 : : }
1083 : :
1084 : : /* Find the longest match, discarding those <= prev_length.
1085 : : * At this point we have always match_length < MIN_MATCH
1086 : : */
1087 [ # # ][ # # ]: 0 : if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1088 : : /* To simplify the code, we prevent matches with the string
1089 : : * of window index 0 (in particular we have to avoid a match
1090 : : * of the string with itself at the start of the input file).
1091 : : */
1092 [ # # ]: 0 : if (s->strategy != Z_HUFFMAN_ONLY) {
1093 : 0 : s->match_length = longest_match (s, hash_head);
1094 : : }
1095 : : /* longest_match() sets match_start */
1096 : : }
1097 [ # # ]: 0 : if (s->match_length >= MIN_MATCH) {
1098 : : check_match(s, s->strstart, s->match_start, s->match_length);
1099 : :
1100 : 0 : bflush = zlib_tr_tally(s, s->strstart - s->match_start,
1101 : : s->match_length - MIN_MATCH);
1102 : :
1103 : 0 : s->lookahead -= s->match_length;
1104 : :
1105 : : /* Insert new strings in the hash table only if the match length
1106 : : * is not too large. This saves time but degrades compression.
1107 : : */
1108 [ # # ][ # # ]: 0 : if (s->match_length <= s->max_insert_length &&
1109 : : s->lookahead >= MIN_MATCH) {
1110 : 0 : s->match_length--; /* string at strstart already in hash table */
1111 : : do {
1112 : 0 : s->strstart++;
1113 : 0 : INSERT_STRING(s, s->strstart, hash_head);
1114 : : /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1115 : : * always MIN_MATCH bytes ahead.
1116 : : */
1117 [ # # ]: 0 : } while (--s->match_length != 0);
1118 : 0 : s->strstart++;
1119 : : } else {
1120 : 0 : s->strstart += s->match_length;
1121 : 0 : s->match_length = 0;
1122 : 0 : s->ins_h = s->window[s->strstart];
1123 : 0 : UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1124 : : #if MIN_MATCH != 3
1125 : : Call UPDATE_HASH() MIN_MATCH-3 more times
1126 : : #endif
1127 : : /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1128 : : * matter since it will be recomputed at next deflate call.
1129 : : */
1130 : : }
1131 : : } else {
1132 : : /* No match, output a literal byte */
1133 : : Tracevv((stderr,"%c", s->window[s->strstart]));
1134 : 0 : bflush = zlib_tr_tally (s, 0, s->window[s->strstart]);
1135 : 0 : s->lookahead--;
1136 : 0 : s->strstart++;
1137 : : }
1138 [ # # ][ # # ]: 0 : if (bflush) FLUSH_BLOCK(s, 0);
[ # # ]
1139 : : }
1140 [ # # ][ # # ]: 0 : FLUSH_BLOCK(s, flush == Z_FINISH);
[ # # ]
1141 [ # # ]: 0 : return flush == Z_FINISH ? finish_done : block_done;
1142 : : }
1143 : :
1144 : : /* ===========================================================================
1145 : : * Same as above, but achieves better compression. We use a lazy
1146 : : * evaluation for matches: a match is finally adopted only if there is
1147 : : * no better match at the next window position.
1148 : : */
1149 : 0 : static block_state deflate_slow(
1150 : : deflate_state *s,
1151 : : int flush
1152 : : )
1153 : : {
1154 : : IPos hash_head = NIL; /* head of hash chain */
1155 : : int bflush; /* set if current block must be flushed */
1156 : :
1157 : : /* Process the input block. */
1158 : : for (;;) {
1159 : : /* Make sure that we always have enough lookahead, except
1160 : : * at the end of the input file. We need MAX_MATCH bytes
1161 : : * for the next match, plus MIN_MATCH bytes to insert the
1162 : : * string following the next match.
1163 : : */
1164 [ # # ]: 0 : if (s->lookahead < MIN_LOOKAHEAD) {
1165 : 0 : fill_window(s);
1166 [ # # ][ # # ]: 0 : if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1167 : : return need_more;
1168 : : }
1169 [ # # ]: 0 : if (s->lookahead == 0) break; /* flush the current block */
1170 : : }
1171 : :
1172 : : /* Insert the string window[strstart .. strstart+2] in the
1173 : : * dictionary, and set hash_head to the head of the hash chain:
1174 : : */
1175 [ # # ]: 0 : if (s->lookahead >= MIN_MATCH) {
1176 : 0 : INSERT_STRING(s, s->strstart, hash_head);
1177 : : }
1178 : :
1179 : : /* Find the longest match, discarding those <= prev_length.
1180 : : */
1181 : 0 : s->prev_length = s->match_length, s->prev_match = s->match_start;
1182 : 0 : s->match_length = MIN_MATCH-1;
1183 : :
1184 [ # # ][ # # ]: 0 : if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
[ # # ]
1185 : 0 : s->strstart - hash_head <= MAX_DIST(s)) {
1186 : : /* To simplify the code, we prevent matches with the string
1187 : : * of window index 0 (in particular we have to avoid a match
1188 : : * of the string with itself at the start of the input file).
1189 : : */
1190 [ # # ]: 0 : if (s->strategy != Z_HUFFMAN_ONLY) {
1191 : 0 : s->match_length = longest_match (s, hash_head);
1192 : : }
1193 : : /* longest_match() sets match_start */
1194 : :
1195 [ # # ][ # # ]: 0 : if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
[ # # ]
1196 [ # # ]: 0 : (s->match_length == MIN_MATCH &&
1197 : 0 : s->strstart - s->match_start > TOO_FAR))) {
1198 : :
1199 : : /* If prev_match is also MIN_MATCH, match_start is garbage
1200 : : * but we will ignore the current match anyway.
1201 : : */
1202 : 0 : s->match_length = MIN_MATCH-1;
1203 : : }
1204 : : }
1205 : : /* If there was a match at the previous step and the current
1206 : : * match is not better, output the previous match:
1207 : : */
1208 [ # # ][ # # ]: 0 : if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1209 : 0 : uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1210 : : /* Do not insert strings in hash table beyond this. */
1211 : :
1212 : : check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1213 : :
1214 : 0 : bflush = zlib_tr_tally(s, s->strstart -1 - s->prev_match,
1215 : : s->prev_length - MIN_MATCH);
1216 : :
1217 : : /* Insert in hash table all strings up to the end of the match.
1218 : : * strstart-1 and strstart are already inserted. If there is not
1219 : : * enough lookahead, the last two strings are not inserted in
1220 : : * the hash table.
1221 : : */
1222 : 0 : s->lookahead -= s->prev_length-1;
1223 : 0 : s->prev_length -= 2;
1224 : : do {
1225 [ # # ]: 0 : if (++s->strstart <= max_insert) {
1226 : 0 : INSERT_STRING(s, s->strstart, hash_head);
1227 : : }
1228 [ # # ]: 0 : } while (--s->prev_length != 0);
1229 : 0 : s->match_available = 0;
1230 : 0 : s->match_length = MIN_MATCH-1;
1231 : 0 : s->strstart++;
1232 : :
1233 [ # # ][ # # ]: 0 : if (bflush) FLUSH_BLOCK(s, 0);
[ # # ]
1234 : :
1235 [ # # ]: 0 : } else if (s->match_available) {
1236 : : /* If there was no match at the previous position, output a
1237 : : * single literal. If there was a match but the current match
1238 : : * is longer, truncate the previous match to a single literal.
1239 : : */
1240 : : Tracevv((stderr,"%c", s->window[s->strstart-1]));
1241 [ # # ]: 0 : if (zlib_tr_tally (s, 0, s->window[s->strstart-1])) {
1242 [ # # ]: 0 : FLUSH_BLOCK_ONLY(s, 0);
1243 : : }
1244 : 0 : s->strstart++;
1245 : 0 : s->lookahead--;
1246 [ # # ]: 0 : if (s->strm->avail_out == 0) return need_more;
1247 : : } else {
1248 : : /* There is no previous match to compare with, wait for
1249 : : * the next step to decide.
1250 : : */
1251 : 0 : s->match_available = 1;
1252 : 0 : s->strstart++;
1253 : 0 : s->lookahead--;
1254 : : }
1255 : : }
1256 : : Assert (flush != Z_NO_FLUSH, "no flush?");
1257 [ # # ]: 0 : if (s->match_available) {
1258 : : Tracevv((stderr,"%c", s->window[s->strstart-1]));
1259 : 0 : zlib_tr_tally (s, 0, s->window[s->strstart-1]);
1260 : 0 : s->match_available = 0;
1261 : : }
1262 [ # # ][ # # ]: 0 : FLUSH_BLOCK(s, flush == Z_FINISH);
[ # # ]
1263 [ # # ]: 0 : return flush == Z_FINISH ? finish_done : block_done;
1264 : : }
1265 : :
1266 : 0 : int zlib_deflate_workspacesize(int windowBits, int memLevel)
1267 : : {
1268 [ # # ]: 0 : if (windowBits < 0) /* undocumented feature: suppress zlib header */
1269 : 0 : windowBits = -windowBits;
1270 : :
1271 : : /* Since the return value is typically passed to vmalloc() unchecked... */
1272 [ # # ][ # # ]: 0 : BUG_ON(memLevel < 1 || memLevel > MAX_MEM_LEVEL || windowBits < 9 ||
1273 : : windowBits > 15);
1274 : :
1275 : 0 : return sizeof(deflate_workspace)
1276 : 0 : + zlib_deflate_window_memsize(windowBits)
1277 : 0 : + zlib_deflate_prev_memsize(windowBits)
1278 : 0 : + zlib_deflate_head_memsize(memLevel)
1279 : 0 : + zlib_deflate_overlay_memsize(memLevel);
1280 : : }
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