xref: /freebsd/contrib/xz/src/liblzma/api/lzma/base.h (revision 9e6bbe47a503137f1698232070cb4c1a4f14be10)
1 /**
2  * \file        lzma/base.h
3  * \brief       Data types and functions used in many places in liblzma API
4  */
5 
6 /*
7  * Author: 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  * See ../lzma.h for information about liblzma as a whole.
13  */
14 
15 #ifndef LZMA_H_INTERNAL
16 #	error Never include this file directly. Use <lzma.h> instead.
17 #endif
18 
19 
20 /**
21  * \brief       Boolean
22  *
23  * This is here because C89 doesn't have stdbool.h. To set a value for
24  * variables having type lzma_bool, you can use
25  *   - C99's `true' and `false' from stdbool.h;
26  *   - C++'s internal `true' and `false'; or
27  *   - integers one (true) and zero (false).
28  */
29 typedef unsigned char lzma_bool;
30 
31 
32 /**
33  * \brief       Type of reserved enumeration variable in structures
34  *
35  * To avoid breaking library ABI when new features are added, several
36  * structures contain extra variables that may be used in future. Since
37  * sizeof(enum) can be different than sizeof(int), and sizeof(enum) may
38  * even vary depending on the range of enumeration constants, we specify
39  * a separate type to be used for reserved enumeration variables. All
40  * enumeration constants in liblzma API will be non-negative and less
41  * than 128, which should guarantee that the ABI won't break even when
42  * new constants are added to existing enumerations.
43  */
44 typedef enum {
45 	LZMA_RESERVED_ENUM      = 0
46 } lzma_reserved_enum;
47 
48 
49 /**
50  * \brief       Return values used by several functions in liblzma
51  *
52  * Check the descriptions of specific functions to find out which return
53  * values they can return. With some functions the return values may have
54  * more specific meanings than described here; those differences are
55  * described per-function basis.
56  */
57 typedef enum {
58 	LZMA_OK                 = 0,
59 		/**<
60 		 * \brief       Operation completed successfully
61 		 */
62 
63 	LZMA_STREAM_END         = 1,
64 		/**<
65 		 * \brief       End of stream was reached
66 		 *
67 		 * In encoder, LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, or
68 		 * LZMA_FINISH was finished. In decoder, this indicates
69 		 * that all the data was successfully decoded.
70 		 *
71 		 * In all cases, when LZMA_STREAM_END is returned, the last
72 		 * output bytes should be picked from strm->next_out.
73 		 */
74 
75 	LZMA_NO_CHECK           = 2,
76 		/**<
77 		 * \brief       Input stream has no integrity check
78 		 *
79 		 * This return value can be returned only if the
80 		 * LZMA_TELL_NO_CHECK flag was used when initializing
81 		 * the decoder. LZMA_NO_CHECK is just a warning, and
82 		 * the decoding can be continued normally.
83 		 *
84 		 * It is possible to call lzma_get_check() immediately after
85 		 * lzma_code has returned LZMA_NO_CHECK. The result will
86 		 * naturally be LZMA_CHECK_NONE, but the possibility to call
87 		 * lzma_get_check() may be convenient in some applications.
88 		 */
89 
90 	LZMA_UNSUPPORTED_CHECK  = 3,
91 		/**<
92 		 * \brief       Cannot calculate the integrity check
93 		 *
94 		 * The usage of this return value is different in encoders
95 		 * and decoders.
96 		 *
97 		 * Encoders can return this value only from the initialization
98 		 * function. If initialization fails with this value, the
99 		 * encoding cannot be done, because there's no way to produce
100 		 * output with the correct integrity check.
101 		 *
102 		 * Decoders can return this value only from lzma_code() and
103 		 * only if the LZMA_TELL_UNSUPPORTED_CHECK flag was used when
104 		 * initializing the decoder. The decoding can still be
105 		 * continued normally even if the check type is unsupported,
106 		 * but naturally the check will not be validated, and possible
107 		 * errors may go undetected.
108 		 *
109 		 * With decoder, it is possible to call lzma_get_check()
110 		 * immediately after lzma_code() has returned
111 		 * LZMA_UNSUPPORTED_CHECK. This way it is possible to find
112 		 * out what the unsupported Check ID was.
113 		 */
114 
115 	LZMA_GET_CHECK          = 4,
116 		/**<
117 		 * \brief       Integrity check type is now available
118 		 *
119 		 * This value can be returned only by the lzma_code() function
120 		 * and only if the decoder was initialized with the
121 		 * LZMA_TELL_ANY_CHECK flag. LZMA_GET_CHECK tells the
122 		 * application that it may now call lzma_get_check() to find
123 		 * out the Check ID. This can be used, for example, to
124 		 * implement a decoder that accepts only files that have
125 		 * strong enough integrity check.
126 		 */
127 
128 	LZMA_MEM_ERROR          = 5,
129 		/**<
130 		 * \brief       Cannot allocate memory
131 		 *
132 		 * Memory allocation failed, or the size of the allocation
133 		 * would be greater than SIZE_MAX.
134 		 *
135 		 * Due to internal implementation reasons, the coding cannot
136 		 * be continued even if more memory were made available after
137 		 * LZMA_MEM_ERROR.
138 		 */
139 
140 	LZMA_MEMLIMIT_ERROR     = 6,
141 		/**
142 		 * \brief       Memory usage limit was reached
143 		 *
144 		 * Decoder would need more memory than allowed by the
145 		 * specified memory usage limit. To continue decoding,
146 		 * the memory usage limit has to be increased with
147 		 * lzma_memlimit_set().
148 		 *
149 		 * liblzma 5.2.6 and earlier had a bug in single-threaded .xz
150 		 * decoder (lzma_stream_decoder()) which made it impossible
151 		 * to continue decoding after LZMA_MEMLIMIT_ERROR even if
152 		 * the limit was increased using lzma_memlimit_set().
153 		 * Other decoders worked correctly.
154 		 */
155 
156 	LZMA_FORMAT_ERROR       = 7,
157 		/**<
158 		 * \brief       File format not recognized
159 		 *
160 		 * The decoder did not recognize the input as supported file
161 		 * format. This error can occur, for example, when trying to
162 		 * decode .lzma format file with lzma_stream_decoder,
163 		 * because lzma_stream_decoder accepts only the .xz format.
164 		 */
165 
166 	LZMA_OPTIONS_ERROR      = 8,
167 		/**<
168 		 * \brief       Invalid or unsupported options
169 		 *
170 		 * Invalid or unsupported options, for example
171 		 *  - unsupported filter(s) or filter options; or
172 		 *  - reserved bits set in headers (decoder only).
173 		 *
174 		 * Rebuilding liblzma with more features enabled, or
175 		 * upgrading to a newer version of liblzma may help.
176 		 */
177 
178 	LZMA_DATA_ERROR         = 9,
179 		/**<
180 		 * \brief       Data is corrupt
181 		 *
182 		 * The usage of this return value is different in encoders
183 		 * and decoders. In both encoder and decoder, the coding
184 		 * cannot continue after this error.
185 		 *
186 		 * Encoders return this if size limits of the target file
187 		 * format would be exceeded. These limits are huge, thus
188 		 * getting this error from an encoder is mostly theoretical.
189 		 * For example, the maximum compressed and uncompressed
190 		 * size of a .xz Stream is roughly 8 EiB (2^63 bytes).
191 		 *
192 		 * Decoders return this error if the input data is corrupt.
193 		 * This can mean, for example, invalid CRC32 in headers
194 		 * or invalid check of uncompressed data.
195 		 */
196 
197 	LZMA_BUF_ERROR          = 10,
198 		/**<
199 		 * \brief       No progress is possible
200 		 *
201 		 * This error code is returned when the coder cannot consume
202 		 * any new input and produce any new output. The most common
203 		 * reason for this error is that the input stream being
204 		 * decoded is truncated or corrupt.
205 		 *
206 		 * This error is not fatal. Coding can be continued normally
207 		 * by providing more input and/or more output space, if
208 		 * possible.
209 		 *
210 		 * Typically the first call to lzma_code() that can do no
211 		 * progress returns LZMA_OK instead of LZMA_BUF_ERROR. Only
212 		 * the second consecutive call doing no progress will return
213 		 * LZMA_BUF_ERROR. This is intentional.
214 		 *
215 		 * With zlib, Z_BUF_ERROR may be returned even if the
216 		 * application is doing nothing wrong, so apps will need
217 		 * to handle Z_BUF_ERROR specially. The above hack
218 		 * guarantees that liblzma never returns LZMA_BUF_ERROR
219 		 * to properly written applications unless the input file
220 		 * is truncated or corrupt. This should simplify the
221 		 * applications a little.
222 		 */
223 
224 	LZMA_PROG_ERROR         = 11,
225 		/**<
226 		 * \brief       Programming error
227 		 *
228 		 * This indicates that the arguments given to the function are
229 		 * invalid or the internal state of the decoder is corrupt.
230 		 *   - Function arguments are invalid or the structures
231 		 *     pointed by the argument pointers are invalid
232 		 *     e.g. if strm->next_out has been set to NULL and
233 		 *     strm->avail_out > 0 when calling lzma_code().
234 		 *   - lzma_* functions have been called in wrong order
235 		 *     e.g. lzma_code() was called right after lzma_end().
236 		 *   - If errors occur randomly, the reason might be flaky
237 		 *     hardware.
238 		 *
239 		 * If you think that your code is correct, this error code
240 		 * can be a sign of a bug in liblzma. See the documentation
241 		 * how to report bugs.
242 		 */
243 } lzma_ret;
244 
245 
246 /**
247  * \brief       The `action' argument for lzma_code()
248  *
249  * After the first use of LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, LZMA_FULL_BARRIER,
250  * or LZMA_FINISH, the same `action' must is used until lzma_code() returns
251  * LZMA_STREAM_END. Also, the amount of input (that is, strm->avail_in) must
252  * not be modified by the application until lzma_code() returns
253  * LZMA_STREAM_END. Changing the `action' or modifying the amount of input
254  * will make lzma_code() return LZMA_PROG_ERROR.
255  */
256 typedef enum {
257 	LZMA_RUN = 0,
258 		/**<
259 		 * \brief       Continue coding
260 		 *
261 		 * Encoder: Encode as much input as possible. Some internal
262 		 * buffering will probably be done (depends on the filter
263 		 * chain in use), which causes latency: the input used won't
264 		 * usually be decodeable from the output of the same
265 		 * lzma_code() call.
266 		 *
267 		 * Decoder: Decode as much input as possible and produce as
268 		 * much output as possible.
269 		 */
270 
271 	LZMA_SYNC_FLUSH = 1,
272 		/**<
273 		 * \brief       Make all the input available at output
274 		 *
275 		 * Normally the encoder introduces some latency.
276 		 * LZMA_SYNC_FLUSH forces all the buffered data to be
277 		 * available at output without resetting the internal
278 		 * state of the encoder. This way it is possible to use
279 		 * compressed stream for example for communication over
280 		 * network.
281 		 *
282 		 * Only some filters support LZMA_SYNC_FLUSH. Trying to use
283 		 * LZMA_SYNC_FLUSH with filters that don't support it will
284 		 * make lzma_code() return LZMA_OPTIONS_ERROR. For example,
285 		 * LZMA1 doesn't support LZMA_SYNC_FLUSH but LZMA2 does.
286 		 *
287 		 * Using LZMA_SYNC_FLUSH very often can dramatically reduce
288 		 * the compression ratio. With some filters (for example,
289 		 * LZMA2), fine-tuning the compression options may help
290 		 * mitigate this problem significantly (for example,
291 		 * match finder with LZMA2).
292 		 *
293 		 * Decoders don't support LZMA_SYNC_FLUSH.
294 		 */
295 
296 	LZMA_FULL_FLUSH = 2,
297 		/**<
298 		 * \brief       Finish encoding of the current Block
299 		 *
300 		 * All the input data going to the current Block must have
301 		 * been given to the encoder (the last bytes can still be
302 		 * pending in *next_in). Call lzma_code() with LZMA_FULL_FLUSH
303 		 * until it returns LZMA_STREAM_END. Then continue normally
304 		 * with LZMA_RUN or finish the Stream with LZMA_FINISH.
305 		 *
306 		 * This action is currently supported only by Stream encoder
307 		 * and easy encoder (which uses Stream encoder). If there is
308 		 * no unfinished Block, no empty Block is created.
309 		 */
310 
311 	LZMA_FULL_BARRIER = 4,
312 		/**<
313 		 * \brief       Finish encoding of the current Block
314 		 *
315 		 * This is like LZMA_FULL_FLUSH except that this doesn't
316 		 * necessarily wait until all the input has been made
317 		 * available via the output buffer. That is, lzma_code()
318 		 * might return LZMA_STREAM_END as soon as all the input
319 		 * has been consumed (avail_in == 0).
320 		 *
321 		 * LZMA_FULL_BARRIER is useful with a threaded encoder if
322 		 * one wants to split the .xz Stream into Blocks at specific
323 		 * offsets but doesn't care if the output isn't flushed
324 		 * immediately. Using LZMA_FULL_BARRIER allows keeping
325 		 * the threads busy while LZMA_FULL_FLUSH would make
326 		 * lzma_code() wait until all the threads have finished
327 		 * until more data could be passed to the encoder.
328 		 *
329 		 * With a lzma_stream initialized with the single-threaded
330 		 * lzma_stream_encoder() or lzma_easy_encoder(),
331 		 * LZMA_FULL_BARRIER is an alias for LZMA_FULL_FLUSH.
332 		 */
333 
334 	LZMA_FINISH = 3
335 		/**<
336 		 * \brief       Finish the coding operation
337 		 *
338 		 * All the input data must have been given to the encoder
339 		 * (the last bytes can still be pending in next_in).
340 		 * Call lzma_code() with LZMA_FINISH until it returns
341 		 * LZMA_STREAM_END. Once LZMA_FINISH has been used,
342 		 * the amount of input must no longer be changed by
343 		 * the application.
344 		 *
345 		 * When decoding, using LZMA_FINISH is optional unless the
346 		 * LZMA_CONCATENATED flag was used when the decoder was
347 		 * initialized. When LZMA_CONCATENATED was not used, the only
348 		 * effect of LZMA_FINISH is that the amount of input must not
349 		 * be changed just like in the encoder.
350 		 */
351 } lzma_action;
352 
353 
354 /**
355  * \brief       Custom functions for memory handling
356  *
357  * A pointer to lzma_allocator may be passed via lzma_stream structure
358  * to liblzma, and some advanced functions take a pointer to lzma_allocator
359  * as a separate function argument. The library will use the functions
360  * specified in lzma_allocator for memory handling instead of the default
361  * malloc() and free(). C++ users should note that the custom memory
362  * handling functions must not throw exceptions.
363  *
364  * Single-threaded mode only: liblzma doesn't make an internal copy of
365  * lzma_allocator. Thus, it is OK to change these function pointers in
366  * the middle of the coding process, but obviously it must be done
367  * carefully to make sure that the replacement `free' can deallocate
368  * memory allocated by the earlier `alloc' function(s).
369  *
370  * Multithreaded mode: liblzma might internally store pointers to the
371  * lzma_allocator given via the lzma_stream structure. The application
372  * must not change the allocator pointer in lzma_stream or the contents
373  * of the pointed lzma_allocator structure until lzma_end() has been used
374  * to free the memory associated with that lzma_stream. The allocation
375  * functions might be called simultaneously from multiple threads, and
376  * thus they must be thread safe.
377  */
378 typedef struct {
379 	/**
380 	 * \brief       Pointer to a custom memory allocation function
381 	 *
382 	 * If you don't want a custom allocator, but still want
383 	 * custom free(), set this to NULL and liblzma will use
384 	 * the standard malloc().
385 	 *
386 	 * \param       opaque  lzma_allocator.opaque (see below)
387 	 * \param       nmemb   Number of elements like in calloc(). liblzma
388 	 *                      will always set nmemb to 1, so it is safe to
389 	 *                      ignore nmemb in a custom allocator if you like.
390 	 *                      The nmemb argument exists only for
391 	 *                      compatibility with zlib and libbzip2.
392 	 * \param       size    Size of an element in bytes.
393 	 *                      liblzma never sets this to zero.
394 	 *
395 	 * \return      Pointer to the beginning of a memory block of
396 	 *              `size' bytes, or NULL if allocation fails
397 	 *              for some reason. When allocation fails, functions
398 	 *              of liblzma return LZMA_MEM_ERROR.
399 	 *
400 	 * The allocator should not waste time zeroing the allocated buffers.
401 	 * This is not only about speed, but also memory usage, since the
402 	 * operating system kernel doesn't necessarily allocate the requested
403 	 * memory in physical memory until it is actually used. With small
404 	 * input files, liblzma may actually need only a fraction of the
405 	 * memory that it requested for allocation.
406 	 *
407 	 * \note        LZMA_MEM_ERROR is also used when the size of the
408 	 *              allocation would be greater than SIZE_MAX. Thus,
409 	 *              don't assume that the custom allocator must have
410 	 *              returned NULL if some function from liblzma
411 	 *              returns LZMA_MEM_ERROR.
412 	 */
413 	void *(LZMA_API_CALL *alloc)(void *opaque, size_t nmemb, size_t size);
414 
415 	/**
416 	 * \brief       Pointer to a custom memory freeing function
417 	 *
418 	 * If you don't want a custom freeing function, but still
419 	 * want a custom allocator, set this to NULL and liblzma
420 	 * will use the standard free().
421 	 *
422 	 * \param       opaque  lzma_allocator.opaque (see below)
423 	 * \param       ptr     Pointer returned by lzma_allocator.alloc(),
424 	 *                      or when it is set to NULL, a pointer returned
425 	 *                      by the standard malloc().
426 	 */
427 	void (LZMA_API_CALL *free)(void *opaque, void *ptr);
428 
429 	/**
430 	 * \brief       Pointer passed to .alloc() and .free()
431 	 *
432 	 * opaque is passed as the first argument to lzma_allocator.alloc()
433 	 * and lzma_allocator.free(). This intended to ease implementing
434 	 * custom memory allocation functions for use with liblzma.
435 	 *
436 	 * If you don't need this, you should set this to NULL.
437 	 */
438 	void *opaque;
439 
440 } lzma_allocator;
441 
442 
443 /**
444  * \brief       Internal data structure
445  *
446  * The contents of this structure is not visible outside the library.
447  */
448 typedef struct lzma_internal_s lzma_internal;
449 
450 
451 /**
452  * \brief       Passing data to and from liblzma
453  *
454  * The lzma_stream structure is used for
455  *  - passing pointers to input and output buffers to liblzma;
456  *  - defining custom memory handler functions; and
457  *  - holding a pointer to coder-specific internal data structures.
458  *
459  * Typical usage:
460  *
461  *  - After allocating lzma_stream (on stack or with malloc()), it must be
462  *    initialized to LZMA_STREAM_INIT (see LZMA_STREAM_INIT for details).
463  *
464  *  - Initialize a coder to the lzma_stream, for example by using
465  *    lzma_easy_encoder() or lzma_auto_decoder(). Some notes:
466  *      - In contrast to zlib, strm->next_in and strm->next_out are
467  *        ignored by all initialization functions, thus it is safe
468  *        to not initialize them yet.
469  *      - The initialization functions always set strm->total_in and
470  *        strm->total_out to zero.
471  *      - If the initialization function fails, no memory is left allocated
472  *        that would require freeing with lzma_end() even if some memory was
473  *        associated with the lzma_stream structure when the initialization
474  *        function was called.
475  *
476  *  - Use lzma_code() to do the actual work.
477  *
478  *  - Once the coding has been finished, the existing lzma_stream can be
479  *    reused. It is OK to reuse lzma_stream with different initialization
480  *    function without calling lzma_end() first. Old allocations are
481  *    automatically freed.
482  *
483  *  - Finally, use lzma_end() to free the allocated memory. lzma_end() never
484  *    frees the lzma_stream structure itself.
485  *
486  * Application may modify the values of total_in and total_out as it wants.
487  * They are updated by liblzma to match the amount of data read and
488  * written but aren't used for anything else except as a possible return
489  * values from lzma_get_progress().
490  */
491 typedef struct {
492 	const uint8_t *next_in; /**< Pointer to the next input byte. */
493 	size_t avail_in;    /**< Number of available input bytes in next_in. */
494 	uint64_t total_in;  /**< Total number of bytes read by liblzma. */
495 
496 	uint8_t *next_out;  /**< Pointer to the next output position. */
497 	size_t avail_out;   /**< Amount of free space in next_out. */
498 	uint64_t total_out; /**< Total number of bytes written by liblzma. */
499 
500 	/**
501 	 * \brief       Custom memory allocation functions
502 	 *
503 	 * In most cases this is NULL which makes liblzma use
504 	 * the standard malloc() and free().
505 	 *
506 	 * \note        In 5.0.x this is not a const pointer.
507 	 */
508 	const lzma_allocator *allocator;
509 
510 	/** Internal state is not visible to applications. */
511 	lzma_internal *internal;
512 
513 	/*
514 	 * Reserved space to allow possible future extensions without
515 	 * breaking the ABI. Excluding the initialization of this structure,
516 	 * you should not touch these, because the names of these variables
517 	 * may change.
518 	 */
519 	void *reserved_ptr1;
520 	void *reserved_ptr2;
521 	void *reserved_ptr3;
522 	void *reserved_ptr4;
523 	uint64_t reserved_int1;
524 	uint64_t reserved_int2;
525 	size_t reserved_int3;
526 	size_t reserved_int4;
527 	lzma_reserved_enum reserved_enum1;
528 	lzma_reserved_enum reserved_enum2;
529 
530 } lzma_stream;
531 
532 
533 /**
534  * \brief       Initialization for lzma_stream
535  *
536  * When you declare an instance of lzma_stream, you can immediately
537  * initialize it so that initialization functions know that no memory
538  * has been allocated yet:
539  *
540  *     lzma_stream strm = LZMA_STREAM_INIT;
541  *
542  * If you need to initialize a dynamically allocated lzma_stream, you can use
543  * memset(strm_pointer, 0, sizeof(lzma_stream)). Strictly speaking, this
544  * violates the C standard since NULL may have different internal
545  * representation than zero, but it should be portable enough in practice.
546  * Anyway, for maximum portability, you can use something like this:
547  *
548  *     lzma_stream tmp = LZMA_STREAM_INIT;
549  *     *strm = tmp;
550  */
551 #define LZMA_STREAM_INIT \
552 	{ NULL, 0, 0, NULL, 0, 0, NULL, NULL, \
553 	NULL, NULL, NULL, NULL, 0, 0, 0, 0, \
554 	LZMA_RESERVED_ENUM, LZMA_RESERVED_ENUM }
555 
556 
557 /**
558  * \brief       Encode or decode data
559  *
560  * Once the lzma_stream has been successfully initialized (e.g. with
561  * lzma_stream_encoder()), the actual encoding or decoding is done
562  * using this function. The application has to update strm->next_in,
563  * strm->avail_in, strm->next_out, and strm->avail_out to pass input
564  * to and get output from liblzma.
565  *
566  * See the description of the coder-specific initialization function to find
567  * out what `action' values are supported by the coder.
568  */
569 extern LZMA_API(lzma_ret) lzma_code(lzma_stream *strm, lzma_action action)
570 		lzma_nothrow lzma_attr_warn_unused_result;
571 
572 
573 /**
574  * \brief       Free memory allocated for the coder data structures
575  *
576  * \param       strm    Pointer to lzma_stream that is at least initialized
577  *                      with LZMA_STREAM_INIT.
578  *
579  * After lzma_end(strm), strm->internal is guaranteed to be NULL. No other
580  * members of the lzma_stream structure are touched.
581  *
582  * \note        zlib indicates an error if application end()s unfinished
583  *              stream structure. liblzma doesn't do this, and assumes that
584  *              application knows what it is doing.
585  */
586 extern LZMA_API(void) lzma_end(lzma_stream *strm) lzma_nothrow;
587 
588 
589 /**
590  * \brief       Get progress information
591  *
592  * In single-threaded mode, applications can get progress information from
593  * strm->total_in and strm->total_out. In multi-threaded mode this is less
594  * useful because a significant amount of both input and output data gets
595  * buffered internally by liblzma. This makes total_in and total_out give
596  * misleading information and also makes the progress indicator updates
597  * non-smooth.
598  *
599  * This function gives realistic progress information also in multi-threaded
600  * mode by taking into account the progress made by each thread. In
601  * single-threaded mode *progress_in and *progress_out are set to
602  * strm->total_in and strm->total_out, respectively.
603  */
604 extern LZMA_API(void) lzma_get_progress(lzma_stream *strm,
605 		uint64_t *progress_in, uint64_t *progress_out) lzma_nothrow;
606 
607 
608 /**
609  * \brief       Get the memory usage of decoder filter chain
610  *
611  * This function is currently supported only when *strm has been initialized
612  * with a function that takes a memlimit argument. With other functions, you
613  * should use e.g. lzma_raw_encoder_memusage() or lzma_raw_decoder_memusage()
614  * to estimate the memory requirements.
615  *
616  * This function is useful e.g. after LZMA_MEMLIMIT_ERROR to find out how big
617  * the memory usage limit should have been to decode the input. Note that
618  * this may give misleading information if decoding .xz Streams that have
619  * multiple Blocks, because each Block can have different memory requirements.
620  *
621  * \return      How much memory is currently allocated for the filter
622  *              decoders. If no filter chain is currently allocated,
623  *              some non-zero value is still returned, which is less than
624  *              or equal to what any filter chain would indicate as its
625  *              memory requirement.
626  *
627  *              If this function isn't supported by *strm or some other error
628  *              occurs, zero is returned.
629  */
630 extern LZMA_API(uint64_t) lzma_memusage(const lzma_stream *strm)
631 		lzma_nothrow lzma_attr_pure;
632 
633 
634 /**
635  * \brief       Get the current memory usage limit
636  *
637  * This function is supported only when *strm has been initialized with
638  * a function that takes a memlimit argument.
639  *
640  * \return      On success, the current memory usage limit is returned
641  *              (always non-zero). On error, zero is returned.
642  */
643 extern LZMA_API(uint64_t) lzma_memlimit_get(const lzma_stream *strm)
644 		lzma_nothrow lzma_attr_pure;
645 
646 
647 /**
648  * \brief       Set the memory usage limit
649  *
650  * This function is supported only when *strm has been initialized with
651  * a function that takes a memlimit argument.
652  *
653  * liblzma 5.2.3 and earlier has a bug where memlimit value of 0 causes
654  * this function to do nothing (leaving the limit unchanged) and still
655  * return LZMA_OK. Later versions treat 0 as if 1 had been specified (so
656  * lzma_memlimit_get() will return 1 even if you specify 0 here).
657  *
658  * liblzma 5.2.6 and earlier had a bug in single-threaded .xz decoder
659  * (lzma_stream_decoder()) which made it impossible to continue decoding
660  * after LZMA_MEMLIMIT_ERROR even if the limit was increased using
661  * lzma_memlimit_set(). Other decoders worked correctly.
662  *
663  * \return      - LZMA_OK: New memory usage limit successfully set.
664  *              - LZMA_MEMLIMIT_ERROR: The new limit is too small.
665  *                The limit was not changed.
666  *              - LZMA_PROG_ERROR: Invalid arguments, e.g. *strm doesn't
667  *                support memory usage limit.
668  */
669 extern LZMA_API(lzma_ret) lzma_memlimit_set(
670 		lzma_stream *strm, uint64_t memlimit) lzma_nothrow;
671