1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file lz_encoder.c
4 /// \brief LZ in window
5 ///
6 // Authors: Igor Pavlov
7 // Lasse Collin
8 //
9 // This file has been put into the public domain.
10 // You can do whatever you want with this file.
11 //
12 ///////////////////////////////////////////////////////////////////////////////
13
14 #include "lz_encoder.h"
15 #include "lz_encoder_hash.h"
16
17 // See lz_encoder_hash.h. This is a bit hackish but avoids making
18 // endianness a conditional in makefiles.
19 #if defined(WORDS_BIGENDIAN) && !defined(HAVE_SMALL)
20 # include "lz_encoder_hash_table.h"
21 #endif
22
23 #include "memcmplen.h"
24
25
26 typedef struct {
27 /// LZ-based encoder e.g. LZMA
28 lzma_lz_encoder lz;
29
30 /// History buffer and match finder
31 lzma_mf mf;
32
33 /// Next coder in the chain
34 lzma_next_coder next;
35 } lzma_coder;
36
37
38 /// \brief Moves the data in the input window to free space for new data
39 ///
40 /// mf->buffer is a sliding input window, which keeps mf->keep_size_before
41 /// bytes of input history available all the time. Now and then we need to
42 /// "slide" the buffer to make space for the new data to the end of the
43 /// buffer. At the same time, data older than keep_size_before is dropped.
44 ///
45 static void
46 move_window(lzma_mf *mf)
47 {
48 // Align the move to a multiple of 16 bytes. Some LZ-based encoders
49 // like LZMA use the lowest bits of mf->read_pos to know the
50 // alignment of the uncompressed data. We also get better speed
51 // for memmove() with aligned buffers.
52 assert(mf->read_pos > mf->keep_size_before);
53 const uint32_t move_offset
54 = (mf->read_pos - mf->keep_size_before) & ~UINT32_C(15);
55
56 assert(mf->write_pos > move_offset);
57 const size_t move_size = mf->write_pos - move_offset;
58
59 assert(move_offset + move_size <= mf->size);
60
61 memmove(mf->buffer, mf->buffer + move_offset, move_size);
62
63 mf->offset += move_offset;
64 mf->read_pos -= move_offset;
65 mf->read_limit -= move_offset;
66 mf->write_pos -= move_offset;
67
68 return;
69 }
70
71
72 /// \brief Tries to fill the input window (mf->buffer)
73 ///
74 /// If we are the last encoder in the chain, our input data is in in[].
75 /// Otherwise we call the next filter in the chain to process in[] and
76 /// write its output to mf->buffer.
77 ///
78 /// This function must not be called once it has returned LZMA_STREAM_END.
79 ///
80 static lzma_ret
81 fill_window(lzma_coder *coder, const lzma_allocator *allocator,
82 const uint8_t *in, size_t *in_pos, size_t in_size,
83 lzma_action action)
84 {
85 assert(coder->mf.read_pos <= coder->mf.write_pos);
86
87 // Move the sliding window if needed.
88 if (coder->mf.read_pos >= coder->mf.size - coder->mf.keep_size_after)
89 move_window(&coder->mf);
90
91 // Maybe this is ugly, but lzma_mf uses uint32_t for most things
92 // (which I find cleanest), but we need size_t here when filling
93 // the history window.
94 size_t write_pos = coder->mf.write_pos;
95 lzma_ret ret;
96 if (coder->next.code == NULL) {
97 // Not using a filter, simply memcpy() as much as possible.
98 lzma_bufcpy(in, in_pos, in_size, coder->mf.buffer,
99 &write_pos, coder->mf.size);
100
101 ret = action != LZMA_RUN && *in_pos == in_size
102 ? LZMA_STREAM_END : LZMA_OK;
103
104 } else {
105 ret = coder->next.code(coder->next.coder, allocator,
106 in, in_pos, in_size,
107 coder->mf.buffer, &write_pos,
108 coder->mf.size, action);
109 }
110
111 coder->mf.write_pos = write_pos;
112
113 // Silence Valgrind. lzma_memcmplen() can read extra bytes
114 // and Valgrind will give warnings if those bytes are uninitialized
115 // because Valgrind cannot see that the values of the uninitialized
116 // bytes are eventually ignored.
117 memzero(coder->mf.buffer + write_pos, LZMA_MEMCMPLEN_EXTRA);
118
119 // If end of stream has been reached or flushing completed, we allow
120 // the encoder to process all the input (that is, read_pos is allowed
121 // to reach write_pos). Otherwise we keep keep_size_after bytes
122 // available as prebuffer.
123 if (ret == LZMA_STREAM_END) {
124 assert(*in_pos == in_size);
125 ret = LZMA_OK;
126 coder->mf.action = action;
127 coder->mf.read_limit = coder->mf.write_pos;
128
129 } else if (coder->mf.write_pos > coder->mf.keep_size_after) {
130 // This needs to be done conditionally, because if we got
131 // only little new input, there may be too little input
132 // to do any encoding yet.
133 coder->mf.read_limit = coder->mf.write_pos
134 - coder->mf.keep_size_after;
135 }
136
137 // Restart the match finder after finished LZMA_SYNC_FLUSH.
138 if (coder->mf.pending > 0
139 && coder->mf.read_pos < coder->mf.read_limit) {
140 // Match finder may update coder->pending and expects it to
141 // start from zero, so use a temporary variable.
142 const uint32_t pending = coder->mf.pending;
143 coder->mf.pending = 0;
144
145 // Rewind read_pos so that the match finder can hash
146 // the pending bytes.
147 assert(coder->mf.read_pos >= pending);
148 coder->mf.read_pos -= pending;
149
150 // Call the skip function directly instead of using
151 // mf_skip(), since we don't want to touch mf->read_ahead.
152 coder->mf.skip(&coder->mf, pending);
153 }
154
155 return ret;
156 }
157
158
159 static lzma_ret
160 lz_encode(void *coder_ptr, const lzma_allocator *allocator,
161 const uint8_t *restrict in, size_t *restrict in_pos,
162 size_t in_size,
163 uint8_t *restrict out, size_t *restrict out_pos,
164 size_t out_size, lzma_action action)
165 {
166 lzma_coder *coder = coder_ptr;
167
168 while (*out_pos < out_size
169 && (*in_pos < in_size || action != LZMA_RUN)) {
170 // Read more data to coder->mf.buffer if needed.
171 if (coder->mf.action == LZMA_RUN && coder->mf.read_pos
172 >= coder->mf.read_limit)
173 return_if_error(fill_window(coder, allocator,
174 in, in_pos, in_size, action));
175
176 // Encode
177 const lzma_ret ret = coder->lz.code(coder->lz.coder,
178 &coder->mf, out, out_pos, out_size);
179 if (ret != LZMA_OK) {
180 // Setting this to LZMA_RUN for cases when we are
181 // flushing. It doesn't matter when finishing or if
182 // an error occurred.
183 coder->mf.action = LZMA_RUN;
184 return ret;
185 }
186 }
187
188 return LZMA_OK;
189 }
190
191
192 static bool
193 lz_encoder_prepare(lzma_mf *mf, const lzma_allocator *allocator,
194 const lzma_lz_options *lz_options)
195 {
196 // For now, the dictionary size is limited to 1.5 GiB. This may grow
197 // in the future if needed, but it needs a little more work than just
198 // changing this check.
199 if (lz_options->dict_size < LZMA_DICT_SIZE_MIN
200 || lz_options->dict_size
201 > (UINT32_C(1) << 30) + (UINT32_C(1) << 29)
202 || lz_options->nice_len > lz_options->match_len_max)
203 return true;
204
205 mf->keep_size_before = lz_options->before_size + lz_options->dict_size;
206
207 mf->keep_size_after = lz_options->after_size
208 + lz_options->match_len_max;
209
210 // To avoid constant memmove()s, allocate some extra space. Since
211 // memmove()s become more expensive when the size of the buffer
212 // increases, we reserve more space when a large dictionary is
213 // used to make the memmove() calls rarer.
214 //
215 // This works with dictionaries up to about 3 GiB. If bigger
216 // dictionary is wanted, some extra work is needed:
217 // - Several variables in lzma_mf have to be changed from uint32_t
218 // to size_t.
219 // - Memory usage calculation needs something too, e.g. use uint64_t
220 // for mf->size.
221 uint32_t reserve = lz_options->dict_size / 2;
222 if (reserve > (UINT32_C(1) << 30))
223 reserve /= 2;
224
225 reserve += (lz_options->before_size + lz_options->match_len_max
226 + lz_options->after_size) / 2 + (UINT32_C(1) << 19);
227
228 const uint32_t old_size = mf->size;
229 mf->size = mf->keep_size_before + reserve + mf->keep_size_after;
230
231 // Deallocate the old history buffer if it exists but has different
232 // size than what is needed now.
233 if (mf->buffer != NULL && old_size != mf->size) {
234 lzma_free(mf->buffer, allocator);
235 mf->buffer = NULL;
236 }
237
238 // Match finder options
239 mf->match_len_max = lz_options->match_len_max;
240 mf->nice_len = lz_options->nice_len;
241
242 // cyclic_size has to stay smaller than 2 Gi. Note that this doesn't
243 // mean limiting dictionary size to less than 2 GiB. With a match
244 // finder that uses multibyte resolution (hashes start at e.g. every
245 // fourth byte), cyclic_size would stay below 2 Gi even when
246 // dictionary size is greater than 2 GiB.
247 //
248 // It would be possible to allow cyclic_size >= 2 Gi, but then we
249 // would need to be careful to use 64-bit types in various places
250 // (size_t could do since we would need bigger than 32-bit address
251 // space anyway). It would also require either zeroing a multigigabyte
252 // buffer at initialization (waste of time and RAM) or allow
253 // normalization in lz_encoder_mf.c to access uninitialized
254 // memory to keep the code simpler. The current way is simple and
255 // still allows pretty big dictionaries, so I don't expect these
256 // limits to change.
257 mf->cyclic_size = lz_options->dict_size + 1;
258
259 // Validate the match finder ID and setup the function pointers.
260 switch (lz_options->match_finder) {
261 #ifdef HAVE_MF_HC3
262 case LZMA_MF_HC3:
263 mf->find = &lzma_mf_hc3_find;
264 mf->skip = &lzma_mf_hc3_skip;
265 break;
266 #endif
267 #ifdef HAVE_MF_HC4
268 case LZMA_MF_HC4:
269 mf->find = &lzma_mf_hc4_find;
270 mf->skip = &lzma_mf_hc4_skip;
271 break;
272 #endif
273 #ifdef HAVE_MF_BT2
274 case LZMA_MF_BT2:
275 mf->find = &lzma_mf_bt2_find;
276 mf->skip = &lzma_mf_bt2_skip;
277 break;
278 #endif
279 #ifdef HAVE_MF_BT3
280 case LZMA_MF_BT3:
281 mf->find = &lzma_mf_bt3_find;
282 mf->skip = &lzma_mf_bt3_skip;
283 break;
284 #endif
285 #ifdef HAVE_MF_BT4
286 case LZMA_MF_BT4:
287 mf->find = &lzma_mf_bt4_find;
288 mf->skip = &lzma_mf_bt4_skip;
289 break;
290 #endif
291
292 default:
293 return true;
294 }
295
296 // Calculate the sizes of mf->hash and mf->son.
297 //
298 // NOTE: Since 5.3.5beta the LZMA encoder ensures that nice_len
299 // is big enough for the selected match finder. This makes it
300 // easier for applications as nice_len = 2 will always be accepted
301 // even though the effective value can be slightly bigger.
302 const uint32_t hash_bytes
303 = mf_get_hash_bytes(lz_options->match_finder);
304 assert(hash_bytes <= mf->nice_len);
305
306 const bool is_bt = (lz_options->match_finder & 0x10) != 0;
307 uint32_t hs;
308
309 if (hash_bytes == 2) {
310 hs = 0xFFFF;
311 } else {
312 // Round dictionary size up to the next 2^n - 1 so it can
313 // be used as a hash mask.
314 hs = lz_options->dict_size - 1;
315 hs |= hs >> 1;
316 hs |= hs >> 2;
317 hs |= hs >> 4;
318 hs |= hs >> 8;
319 hs >>= 1;
320 hs |= 0xFFFF;
321
322 if (hs > (UINT32_C(1) << 24)) {
323 if (hash_bytes == 3)
324 hs = (UINT32_C(1) << 24) - 1;
325 else
326 hs >>= 1;
327 }
328 }
329
330 mf->hash_mask = hs;
331
332 ++hs;
333 if (hash_bytes > 2)
334 hs += HASH_2_SIZE;
335 if (hash_bytes > 3)
336 hs += HASH_3_SIZE;
337 /*
338 No match finder uses this at the moment.
339 if (mf->hash_bytes > 4)
340 hs += HASH_4_SIZE;
341 */
342
343 const uint32_t old_hash_count = mf->hash_count;
344 const uint32_t old_sons_count = mf->sons_count;
345 mf->hash_count = hs;
346 mf->sons_count = mf->cyclic_size;
347 if (is_bt)
348 mf->sons_count *= 2;
349
350 // Deallocate the old hash array if it exists and has different size
351 // than what is needed now.
352 if (old_hash_count != mf->hash_count
353 || old_sons_count != mf->sons_count) {
354 lzma_free(mf->hash, allocator);
355 mf->hash = NULL;
356
357 lzma_free(mf->son, allocator);
358 mf->son = NULL;
359 }
360
361 // Maximum number of match finder cycles
362 mf->depth = lz_options->depth;
363 if (mf->depth == 0) {
364 if (is_bt)
365 mf->depth = 16 + mf->nice_len / 2;
366 else
367 mf->depth = 4 + mf->nice_len / 4;
368 }
369
370 return false;
371 }
372
373
374 static bool
375 lz_encoder_init(lzma_mf *mf, const lzma_allocator *allocator,
376 const lzma_lz_options *lz_options)
377 {
378 // Allocate the history buffer.
379 if (mf->buffer == NULL) {
380 // lzma_memcmplen() is used for the dictionary buffer
381 // so we need to allocate a few extra bytes to prevent
382 // it from reading past the end of the buffer.
383 mf->buffer = lzma_alloc(mf->size + LZMA_MEMCMPLEN_EXTRA,
384 allocator);
385 if (mf->buffer == NULL)
386 return true;
387
388 // Keep Valgrind happy with lzma_memcmplen() and initialize
389 // the extra bytes whose value may get read but which will
390 // effectively get ignored.
391 memzero(mf->buffer + mf->size, LZMA_MEMCMPLEN_EXTRA);
392 }
393
394 // Use cyclic_size as initial mf->offset. This allows
395 // avoiding a few branches in the match finders. The downside is
396 // that match finder needs to be normalized more often, which may
397 // hurt performance with huge dictionaries.
398 mf->offset = mf->cyclic_size;
399 mf->read_pos = 0;
400 mf->read_ahead = 0;
401 mf->read_limit = 0;
402 mf->write_pos = 0;
403 mf->pending = 0;
404
405 #if UINT32_MAX >= SIZE_MAX / 4
406 // Check for integer overflow. (Huge dictionaries are not
407 // possible on 32-bit CPU.)
408 if (mf->hash_count > SIZE_MAX / sizeof(uint32_t)
409 || mf->sons_count > SIZE_MAX / sizeof(uint32_t))
410 return true;
411 #endif
412
413 // Allocate and initialize the hash table. Since EMPTY_HASH_VALUE
414 // is zero, we can use lzma_alloc_zero() or memzero() for mf->hash.
415 //
416 // We don't need to initialize mf->son, but not doing that may
417 // make Valgrind complain in normalization (see normalize() in
418 // lz_encoder_mf.c). Skipping the initialization is *very* good
419 // when big dictionary is used but only small amount of data gets
420 // actually compressed: most of the mf->son won't get actually
421 // allocated by the kernel, so we avoid wasting RAM and improve
422 // initialization speed a lot.
423 if (mf->hash == NULL) {
424 mf->hash = lzma_alloc_zero(mf->hash_count * sizeof(uint32_t),
425 allocator);
426 mf->son = lzma_alloc(mf->sons_count * sizeof(uint32_t),
427 allocator);
428
429 if (mf->hash == NULL || mf->son == NULL) {
430 lzma_free(mf->hash, allocator);
431 mf->hash = NULL;
432
433 lzma_free(mf->son, allocator);
434 mf->son = NULL;
435
436 return true;
437 }
438 } else {
439 /*
440 for (uint32_t i = 0; i < mf->hash_count; ++i)
441 mf->hash[i] = EMPTY_HASH_VALUE;
442 */
443 memzero(mf->hash, mf->hash_count * sizeof(uint32_t));
444 }
445
446 mf->cyclic_pos = 0;
447
448 // Handle preset dictionary.
449 if (lz_options->preset_dict != NULL
450 && lz_options->preset_dict_size > 0) {
451 // If the preset dictionary is bigger than the actual
452 // dictionary, use only the tail.
453 mf->write_pos = my_min(lz_options->preset_dict_size, mf->size);
454 memcpy(mf->buffer, lz_options->preset_dict
455 + lz_options->preset_dict_size - mf->write_pos,
456 mf->write_pos);
457 mf->action = LZMA_SYNC_FLUSH;
458 mf->skip(mf, mf->write_pos);
459 }
460
461 mf->action = LZMA_RUN;
462
463 return false;
464 }
465
466
467 extern uint64_t
468 lzma_lz_encoder_memusage(const lzma_lz_options *lz_options)
469 {
470 // Old buffers must not exist when calling lz_encoder_prepare().
471 lzma_mf mf = {
472 .buffer = NULL,
473 .hash = NULL,
474 .son = NULL,
475 .hash_count = 0,
476 .sons_count = 0,
477 };
478
479 // Setup the size information into mf.
480 if (lz_encoder_prepare(&mf, NULL, lz_options))
481 return UINT64_MAX;
482
483 // Calculate the memory usage.
484 return ((uint64_t)(mf.hash_count) + mf.sons_count) * sizeof(uint32_t)
485 + mf.size + sizeof(lzma_coder);
486 }
487
488
489 static void
490 lz_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
491 {
492 lzma_coder *coder = coder_ptr;
493
494 lzma_next_end(&coder->next, allocator);
495
496 lzma_free(coder->mf.son, allocator);
497 lzma_free(coder->mf.hash, allocator);
498 lzma_free(coder->mf.buffer, allocator);
499
500 if (coder->lz.end != NULL)
501 coder->lz.end(coder->lz.coder, allocator);
502 else
503 lzma_free(coder->lz.coder, allocator);
504
505 lzma_free(coder, allocator);
506 return;
507 }
508
509
510 static lzma_ret
511 lz_encoder_update(void *coder_ptr, const lzma_allocator *allocator,
512 const lzma_filter *filters_null lzma_attribute((__unused__)),
513 const lzma_filter *reversed_filters)
514 {
515 lzma_coder *coder = coder_ptr;
516
517 if (coder->lz.options_update == NULL)
518 return LZMA_PROG_ERROR;
519
520 return_if_error(coder->lz.options_update(
521 coder->lz.coder, reversed_filters));
522
523 return lzma_next_filter_update(
524 &coder->next, allocator, reversed_filters + 1);
525 }
526
527
528 static lzma_ret
529 lz_encoder_set_out_limit(void *coder_ptr, uint64_t *uncomp_size,
530 uint64_t out_limit)
531 {
532 lzma_coder *coder = coder_ptr;
533
534 // This is supported only if there are no other filters chained.
535 if (coder->next.code == NULL && coder->lz.set_out_limit != NULL)
536 return coder->lz.set_out_limit(
537 coder->lz.coder, uncomp_size, out_limit);
538
539 return LZMA_OPTIONS_ERROR;
540 }
541
542
543 extern lzma_ret
544 lzma_lz_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
545 const lzma_filter_info *filters,
546 lzma_ret (*lz_init)(lzma_lz_encoder *lz,
547 const lzma_allocator *allocator,
548 lzma_vli id, const void *options,
549 lzma_lz_options *lz_options))
550 {
551 #if defined(HAVE_SMALL) && !defined(HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR)
552 // We need that the CRC32 table has been initialized.
553 lzma_crc32_init();
554 #endif
555
556 // Allocate and initialize the base data structure.
557 lzma_coder *coder = next->coder;
558 if (coder == NULL) {
559 coder = lzma_alloc(sizeof(lzma_coder), allocator);
560 if (coder == NULL)
561 return LZMA_MEM_ERROR;
562
563 next->coder = coder;
564 next->code = &lz_encode;
565 next->end = &lz_encoder_end;
566 next->update = &lz_encoder_update;
567 next->set_out_limit = &lz_encoder_set_out_limit;
568
569 coder->lz.coder = NULL;
570 coder->lz.code = NULL;
571 coder->lz.end = NULL;
572
573 // mf.size is initialized to silence Valgrind
574 // when used on optimized binaries (GCC may reorder
575 // code in a way that Valgrind gets unhappy).
576 coder->mf.buffer = NULL;
577 coder->mf.size = 0;
578 coder->mf.hash = NULL;
579 coder->mf.son = NULL;
580 coder->mf.hash_count = 0;
581 coder->mf.sons_count = 0;
582
583 coder->next = LZMA_NEXT_CODER_INIT;
584 }
585
586 // Initialize the LZ-based encoder.
587 lzma_lz_options lz_options;
588 return_if_error(lz_init(&coder->lz, allocator,
589 filters[0].id, filters[0].options, &lz_options));
590
591 // Setup the size information into coder->mf and deallocate
592 // old buffers if they have wrong size.
593 if (lz_encoder_prepare(&coder->mf, allocator, &lz_options))
594 return LZMA_OPTIONS_ERROR;
595
596 // Allocate new buffers if needed, and do the rest of
597 // the initialization.
598 if (lz_encoder_init(&coder->mf, allocator, &lz_options))
599 return LZMA_MEM_ERROR;
600
601 // Initialize the next filter in the chain, if any.
602 return lzma_next_filter_init(&coder->next, allocator, filters + 1);
603 }
604
605
606 extern LZMA_API(lzma_bool)
607 lzma_mf_is_supported(lzma_match_finder mf)
608 {
609 switch (mf) {
610 #ifdef HAVE_MF_HC3
611 case LZMA_MF_HC3:
612 return true;
613 #endif
614 #ifdef HAVE_MF_HC4
615 case LZMA_MF_HC4:
616 return true;
617 #endif
618 #ifdef HAVE_MF_BT2
619 case LZMA_MF_BT2:
620 return true;
621 #endif
622 #ifdef HAVE_MF_BT3
623 case LZMA_MF_BT3:
624 return true;
625 #endif
626 #ifdef HAVE_MF_BT4
627 case LZMA_MF_BT4:
628 return true;
629 #endif
630 default:
631 return false;
632 }
633 }