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 /* SPDX-License-Identifier: 0BSD */
 
 /**
  * \file        lzma/base.h
  * \brief       Data types and functions used in many places in liblzma API
  * \note        Never include this file directly. Use <lzma.h> instead.
  */
 
 /*
  * Author: Lasse Collin
  */
 
 #ifndef LZMA_H_INTERNAL
 #   error Never include this file directly. Use <lzma.h> instead.
 #endif
 
 
 /**
  * \brief       Boolean
  *
  * This is here because C89 doesn't have stdbool.h. To set a value for
  * variables having type lzma_bool, you can use
  *   - C99's 'true' and 'false' from stdbool.h;
  *   - C++'s internal 'true' and 'false'; or
  *   - integers one (true) and zero (false).
  */
 typedef unsigned char lzma_bool;
 
 
 /**
  * \brief       Type of reserved enumeration variable in structures
  *
  * To avoid breaking library ABI when new features are added, several
  * structures contain extra variables that may be used in future. Since
  * sizeof(enum) can be different than sizeof(int), and sizeof(enum) may
  * even vary depending on the range of enumeration constants, we specify
  * a separate type to be used for reserved enumeration variables. All
  * enumeration constants in liblzma API will be non-negative and less
  * than 128, which should guarantee that the ABI won't break even when
  * new constants are added to existing enumerations.
  */
 typedef enum {
     LZMA_RESERVED_ENUM      = 0
 } lzma_reserved_enum;
 
 
 /**
  * \brief       Return values used by several functions in liblzma
  *
  * Check the descriptions of specific functions to find out which return
  * values they can return. With some functions the return values may have
  * more specific meanings than described here; those differences are
  * described per-function basis.
  */
 typedef enum {
     LZMA_OK                 = 0,
         /**<
          * \brief       Operation completed successfully
          */
 
     LZMA_STREAM_END         = 1,
         /**<
          * \brief       End of stream was reached
          *
          * In encoder, LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, or
          * LZMA_FINISH was finished. In decoder, this indicates
          * that all the data was successfully decoded.
          *
          * In all cases, when LZMA_STREAM_END is returned, the last
          * output bytes should be picked from strm->next_out.
          */
 
     LZMA_NO_CHECK           = 2,
         /**<
          * \brief       Input stream has no integrity check
          *
          * This return value can be returned only if the
          * LZMA_TELL_NO_CHECK flag was used when initializing
          * the decoder. LZMA_NO_CHECK is just a warning, and
          * the decoding can be continued normally.
          *
          * It is possible to call lzma_get_check() immediately after
          * lzma_code has returned LZMA_NO_CHECK. The result will
          * naturally be LZMA_CHECK_NONE, but the possibility to call
          * lzma_get_check() may be convenient in some applications.
          */
 
     LZMA_UNSUPPORTED_CHECK  = 3,
         /**<
          * \brief       Cannot calculate the integrity check
          *
          * The usage of this return value is different in encoders
          * and decoders.
          *
          * Encoders can return this value only from the initialization
          * function. If initialization fails with this value, the
          * encoding cannot be done, because there's no way to produce
          * output with the correct integrity check.
          *
          * Decoders can return this value only from lzma_code() and
          * only if the LZMA_TELL_UNSUPPORTED_CHECK flag was used when
          * initializing the decoder. The decoding can still be
          * continued normally even if the check type is unsupported,
          * but naturally the check will not be validated, and possible
          * errors may go undetected.
          *
          * With decoder, it is possible to call lzma_get_check()
          * immediately after lzma_code() has returned
          * LZMA_UNSUPPORTED_CHECK. This way it is possible to find
          * out what the unsupported Check ID was.
          */
 
     LZMA_GET_CHECK          = 4,
         /**<
          * \brief       Integrity check type is now available
          *
          * This value can be returned only by the lzma_code() function
          * and only if the decoder was initialized with the
          * LZMA_TELL_ANY_CHECK flag. LZMA_GET_CHECK tells the
          * application that it may now call lzma_get_check() to find
          * out the Check ID. This can be used, for example, to
          * implement a decoder that accepts only files that have
          * strong enough integrity check.
          */
 
     LZMA_MEM_ERROR          = 5,
         /**<
          * \brief       Cannot allocate memory
          *
          * Memory allocation failed, or the size of the allocation
          * would be greater than SIZE_MAX.
          *
          * Due to internal implementation reasons, the coding cannot
          * be continued even if more memory were made available after
          * LZMA_MEM_ERROR.
          */
 
     LZMA_MEMLIMIT_ERROR     = 6,
         /**<
          * \brief       Memory usage limit was reached
          *
          * Decoder would need more memory than allowed by the
          * specified memory usage limit. To continue decoding,
          * the memory usage limit has to be increased with
          * lzma_memlimit_set().
          *
          * liblzma 5.2.6 and earlier had a bug in single-threaded .xz
          * decoder (lzma_stream_decoder()) which made it impossible
          * to continue decoding after LZMA_MEMLIMIT_ERROR even if
          * the limit was increased using lzma_memlimit_set().
          * Other decoders worked correctly.
          */
 
     LZMA_FORMAT_ERROR       = 7,
         /**<
          * \brief       File format not recognized
          *
          * The decoder did not recognize the input as supported file
          * format. This error can occur, for example, when trying to
          * decode .lzma format file with lzma_stream_decoder,
          * because lzma_stream_decoder accepts only the .xz format.
          */
 
     LZMA_OPTIONS_ERROR      = 8,
         /**<
          * \brief       Invalid or unsupported options
          *
          * Invalid or unsupported options, for example
          *  - unsupported filter(s) or filter options; or
          *  - reserved bits set in headers (decoder only).
          *
          * Rebuilding liblzma with more features enabled, or
          * upgrading to a newer version of liblzma may help.
          */
 
     LZMA_DATA_ERROR         = 9,
         /**<
          * \brief       Data is corrupt
          *
          * The usage of this return value is different in encoders
          * and decoders. In both encoder and decoder, the coding
          * cannot continue after this error.
          *
          * Encoders return this if size limits of the target file
          * format would be exceeded. These limits are huge, thus
          * getting this error from an encoder is mostly theoretical.
          * For example, the maximum compressed and uncompressed
          * size of a .xz Stream is roughly 8 EiB (2^63 bytes).
          *
          * Decoders return this error if the input data is corrupt.
          * This can mean, for example, invalid CRC32 in headers
          * or invalid check of uncompressed data.
          */
 
     LZMA_BUF_ERROR          = 10,
         /**<
          * \brief       No progress is possible
          *
          * This error code is returned when the coder cannot consume
          * any new input and produce any new output. The most common
          * reason for this error is that the input stream being
          * decoded is truncated or corrupt.
          *
          * This error is not fatal. Coding can be continued normally
          * by providing more input and/or more output space, if
          * possible.
          *
          * Typically the first call to lzma_code() that can do no
          * progress returns LZMA_OK instead of LZMA_BUF_ERROR. Only
          * the second consecutive call doing no progress will return
          * LZMA_BUF_ERROR. This is intentional.
          *
          * With zlib, Z_BUF_ERROR may be returned even if the
          * application is doing nothing wrong, so apps will need
          * to handle Z_BUF_ERROR specially. The above hack
          * guarantees that liblzma never returns LZMA_BUF_ERROR
          * to properly written applications unless the input file
          * is truncated or corrupt. This should simplify the
          * applications a little.
          */
 
     LZMA_PROG_ERROR         = 11,
         /**<
          * \brief       Programming error
          *
          * This indicates that the arguments given to the function are
          * invalid or the internal state of the decoder is corrupt.
          *   - Function arguments are invalid or the structures
          *     pointed by the argument pointers are invalid
          *     e.g. if strm->next_out has been set to NULL and
          *     strm->avail_out > 0 when calling lzma_code().
          *   - lzma_* functions have been called in wrong order
          *     e.g. lzma_code() was called right after lzma_end().
          *   - If errors occur randomly, the reason might be flaky
          *     hardware.
          *
          * If you think that your code is correct, this error code
          * can be a sign of a bug in liblzma. See the documentation
          * how to report bugs.
          */
 
     LZMA_SEEK_NEEDED        = 12,
         /**<
          * \brief       Request to change the input file position
          *
          * Some coders can do random access in the input file. The
          * initialization functions of these coders take the file size
          * as an argument. No other coders can return LZMA_SEEK_NEEDED.
          *
          * When this value is returned, the application must seek to
          * the file position given in lzma_stream.seek_pos. This value
          * is guaranteed to never exceed the file size that was
          * specified at the coder initialization.
          *
          * After seeking the application should read new input and
          * pass it normally via lzma_stream.next_in and .avail_in.
          */
 
     /*
      * These enumerations may be used internally by liblzma
      * but they will never be returned to applications.
      */
     LZMA_RET_INTERNAL1      = 101,
     LZMA_RET_INTERNAL2      = 102,
     LZMA_RET_INTERNAL3      = 103,
     LZMA_RET_INTERNAL4      = 104,
     LZMA_RET_INTERNAL5      = 105,
     LZMA_RET_INTERNAL6      = 106,
     LZMA_RET_INTERNAL7      = 107,
     LZMA_RET_INTERNAL8      = 108
 } lzma_ret;
 
 
 /**
  * \brief       The 'action' argument for lzma_code()
  *
  * After the first use of LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, LZMA_FULL_BARRIER,
  * or LZMA_FINISH, the same 'action' must be used until lzma_code() returns
  * LZMA_STREAM_END. Also, the amount of input (that is, strm->avail_in) must
  * not be modified by the application until lzma_code() returns
  * LZMA_STREAM_END. Changing the 'action' or modifying the amount of input
  * will make lzma_code() return LZMA_PROG_ERROR.
  */
 typedef enum {
     LZMA_RUN = 0,
         /**<
          * \brief       Continue coding
          *
          * Encoder: Encode as much input as possible. Some internal
          * buffering will probably be done (depends on the filter
          * chain in use), which causes latency: the input used won't
          * usually be decodeable from the output of the same
          * lzma_code() call.
          *
          * Decoder: Decode as much input as possible and produce as
          * much output as possible.
          */
 
     LZMA_SYNC_FLUSH = 1,
         /**<
          * \brief       Make all the input available at output
          *
          * Normally the encoder introduces some latency.
          * LZMA_SYNC_FLUSH forces all the buffered data to be
          * available at output without resetting the internal
          * state of the encoder. This way it is possible to use
          * compressed stream for example for communication over
          * network.
          *
          * Only some filters support LZMA_SYNC_FLUSH. Trying to use
          * LZMA_SYNC_FLUSH with filters that don't support it will
          * make lzma_code() return LZMA_OPTIONS_ERROR. For example,
          * LZMA1 doesn't support LZMA_SYNC_FLUSH but LZMA2 does.
          *
          * Using LZMA_SYNC_FLUSH very often can dramatically reduce
          * the compression ratio. With some filters (for example,
          * LZMA2), fine-tuning the compression options may help
          * mitigate this problem significantly (for example,
          * match finder with LZMA2).
          *
          * Decoders don't support LZMA_SYNC_FLUSH.
          */
 
     LZMA_FULL_FLUSH = 2,
         /**<
          * \brief       Finish encoding of the current Block
          *
          * All the input data going to the current Block must have
          * been given to the encoder (the last bytes can still be
          * pending in *next_in). Call lzma_code() with LZMA_FULL_FLUSH
          * until it returns LZMA_STREAM_END. Then continue normally
          * with LZMA_RUN or finish the Stream with LZMA_FINISH.
          *
          * This action is currently supported only by Stream encoder
          * and easy encoder (which uses Stream encoder). If there is
          * no unfinished Block, no empty Block is created.
          */
 
     LZMA_FULL_BARRIER = 4,
         /**<
          * \brief       Finish encoding of the current Block
          *
          * This is like LZMA_FULL_FLUSH except that this doesn't
          * necessarily wait until all the input has been made
          * available via the output buffer. That is, lzma_code()
          * might return LZMA_STREAM_END as soon as all the input
          * has been consumed (avail_in == 0).
          *
          * LZMA_FULL_BARRIER is useful with a threaded encoder if
          * one wants to split the .xz Stream into Blocks at specific
          * offsets but doesn't care if the output isn't flushed
          * immediately. Using LZMA_FULL_BARRIER allows keeping
          * the threads busy while LZMA_FULL_FLUSH would make
          * lzma_code() wait until all the threads have finished
          * until more data could be passed to the encoder.
          *
          * With a lzma_stream initialized with the single-threaded
          * lzma_stream_encoder() or lzma_easy_encoder(),
          * LZMA_FULL_BARRIER is an alias for LZMA_FULL_FLUSH.
          */
 
     LZMA_FINISH = 3
         /**<
          * \brief       Finish the coding operation
          *
          * All the input data must have been given to the encoder
          * (the last bytes can still be pending in next_in).
          * Call lzma_code() with LZMA_FINISH until it returns
          * LZMA_STREAM_END. Once LZMA_FINISH has been used,
          * the amount of input must no longer be changed by
          * the application.
          *
          * When decoding, using LZMA_FINISH is optional unless the
          * LZMA_CONCATENATED flag was used when the decoder was
          * initialized. When LZMA_CONCATENATED was not used, the only
          * effect of LZMA_FINISH is that the amount of input must not
          * be changed just like in the encoder.
          */
 } lzma_action;
 
 
 /**
  * \brief       Custom functions for memory handling
  *
  * A pointer to lzma_allocator may be passed via lzma_stream structure
  * to liblzma, and some advanced functions take a pointer to lzma_allocator
  * as a separate function argument. The library will use the functions
  * specified in lzma_allocator for memory handling instead of the default
  * malloc() and free(). C++ users should note that the custom memory
  * handling functions must not throw exceptions.
  *
  * Single-threaded mode only: liblzma doesn't make an internal copy of
  * lzma_allocator. Thus, it is OK to change these function pointers in
  * the middle of the coding process, but obviously it must be done
  * carefully to make sure that the replacement 'free' can deallocate
  * memory allocated by the earlier 'alloc' function(s).
  *
  * Multithreaded mode: liblzma might internally store pointers to the
  * lzma_allocator given via the lzma_stream structure. The application
  * must not change the allocator pointer in lzma_stream or the contents
  * of the pointed lzma_allocator structure until lzma_end() has been used
  * to free the memory associated with that lzma_stream. The allocation
  * functions might be called simultaneously from multiple threads, and
  * thus they must be thread safe.
  */
 typedef struct {
     /**
      * \brief       Pointer to a custom memory allocation function
      *
      * If you don't want a custom allocator, but still want
      * custom free(), set this to NULL and liblzma will use
      * the standard malloc().
      *
      * \param       opaque  lzma_allocator.opaque (see below)
      * \param       nmemb   Number of elements like in calloc(). liblzma
      *                      will always set nmemb to 1, so it is safe to
      *                      ignore nmemb in a custom allocator if you like.
      *                      The nmemb argument exists only for
      *                      compatibility with zlib and libbzip2.
      * \param       size    Size of an element in bytes.
      *                      liblzma never sets this to zero.
      *
      * \return      Pointer to the beginning of a memory block of
      *              'size' bytes, or NULL if allocation fails
      *              for some reason. When allocation fails, functions
      *              of liblzma return LZMA_MEM_ERROR.
      *
      * The allocator should not waste time zeroing the allocated buffers.
      * This is not only about speed, but also memory usage, since the
      * operating system kernel doesn't necessarily allocate the requested
      * memory in physical memory until it is actually used. With small
      * input files, liblzma may actually need only a fraction of the
      * memory that it requested for allocation.
      *
      * \note        LZMA_MEM_ERROR is also used when the size of the
      *              allocation would be greater than SIZE_MAX. Thus,
      *              don't assume that the custom allocator must have
      *              returned NULL if some function from liblzma
      *              returns LZMA_MEM_ERROR.
      */
     void *(LZMA_API_CALL *alloc)(void *opaque, size_t nmemb, size_t size);
 
     /**
      * \brief       Pointer to a custom memory freeing function
      *
      * If you don't want a custom freeing function, but still
      * want a custom allocator, set this to NULL and liblzma
      * will use the standard free().
      *
      * \param       opaque  lzma_allocator.opaque (see below)
      * \param       ptr     Pointer returned by lzma_allocator.alloc(),
      *                      or when it is set to NULL, a pointer returned
      *                      by the standard malloc().
      */
     void (LZMA_API_CALL *free)(void *opaque, void *ptr);
 
     /**
      * \brief       Pointer passed to .alloc() and .free()
      *
      * opaque is passed as the first argument to lzma_allocator.alloc()
      * and lzma_allocator.free(). This intended to ease implementing
      * custom memory allocation functions for use with liblzma.
      *
      * If you don't need this, you should set this to NULL.
      */
     void *opaque;
 
 } lzma_allocator;
 
 
 /**
  * \brief       Internal data structure
  *
  * The contents of this structure is not visible outside the library.
  */
 typedef struct lzma_internal_s lzma_internal;
 
 
 /**
  * \brief       Passing data to and from liblzma
  *
  * The lzma_stream structure is used for
  *  - passing pointers to input and output buffers to liblzma;
  *  - defining custom memory handler functions; and
  *  - holding a pointer to coder-specific internal data structures.
  *
  * Typical usage:
  *
  *  - After allocating lzma_stream (on stack or with malloc()), it must be
  *    initialized to LZMA_STREAM_INIT (see LZMA_STREAM_INIT for details).
  *
  *  - Initialize a coder to the lzma_stream, for example by using
  *    lzma_easy_encoder() or lzma_auto_decoder(). Some notes:
  *      - In contrast to zlib, strm->next_in and strm->next_out are
  *        ignored by all initialization functions, thus it is safe
  *        to not initialize them yet.
  *      - The initialization functions always set strm->total_in and
  *        strm->total_out to zero.
  *      - If the initialization function fails, no memory is left allocated
  *        that would require freeing with lzma_end() even if some memory was
  *        associated with the lzma_stream structure when the initialization
  *        function was called.
  *
  *  - Use lzma_code() to do the actual work.
  *
  *  - Once the coding has been finished, the existing lzma_stream can be
  *    reused. It is OK to reuse lzma_stream with different initialization
  *    function without calling lzma_end() first. Old allocations are
  *    automatically freed.
  *
  *  - Finally, use lzma_end() to free the allocated memory. lzma_end() never
  *    frees the lzma_stream structure itself.
  *
  * Application may modify the values of total_in and total_out as it wants.
  * They are updated by liblzma to match the amount of data read and
  * written but aren't used for anything else except as a possible return
  * values from lzma_get_progress().
  */
 typedef struct {
     const uint8_t *next_in; /**< Pointer to the next input byte. */
     size_t avail_in;    /**< Number of available input bytes in next_in. */
     uint64_t total_in;  /**< Total number of bytes read by liblzma. */
 
     uint8_t *next_out;  /**< Pointer to the next output position. */
     size_t avail_out;   /**< Amount of free space in next_out. */
     uint64_t total_out; /**< Total number of bytes written by liblzma. */
 
     /**
      * \brief       Custom memory allocation functions
      *
      * In most cases this is NULL which makes liblzma use
      * the standard malloc() and free().
      *
      * \note        In 5.0.x this is not a const pointer.
      */
     const lzma_allocator *allocator;
 
     /** Internal state is not visible to applications. */
     lzma_internal *internal;
 
     /*
      * Reserved space to allow possible future extensions without
      * breaking the ABI. Excluding the initialization of this structure,
      * you should not touch these, because the names of these variables
      * may change.
      */
 
     /** \private     Reserved member. */
     void *reserved_ptr1;
 
     /** \private     Reserved member. */
     void *reserved_ptr2;
 
     /** \private     Reserved member. */
     void *reserved_ptr3;
 
     /** \private     Reserved member. */
     void *reserved_ptr4;
 
     /**
      * \brief       New seek input position for LZMA_SEEK_NEEDED
      *
      * When lzma_code() returns LZMA_SEEK_NEEDED, the new input position
      * needed by liblzma will be available seek_pos. The value is
      * guaranteed to not exceed the file size that was specified when
      * this lzma_stream was initialized.
      *
      * In all other situations the value of this variable is undefined.
      */
     uint64_t seek_pos;
 
     /** \private     Reserved member. */
     uint64_t reserved_int2;
 
     /** \private     Reserved member. */
     size_t reserved_int3;
 
     /** \private     Reserved member. */
     size_t reserved_int4;
 
     /** \private     Reserved member. */
     lzma_reserved_enum reserved_enum1;
 
     /** \private     Reserved member. */
     lzma_reserved_enum reserved_enum2;
 
 } lzma_stream;
 
 
 /**
  * \brief       Initialization for lzma_stream
  *
  * When you declare an instance of lzma_stream, you can immediately
  * initialize it so that initialization functions know that no memory
  * has been allocated yet:
  *
  *     lzma_stream strm = LZMA_STREAM_INIT;
  *
  * If you need to initialize a dynamically allocated lzma_stream, you can use
  * memset(strm_pointer, 0, sizeof(lzma_stream)). Strictly speaking, this
  * violates the C standard since NULL may have different internal
  * representation than zero, but it should be portable enough in practice.
  * Anyway, for maximum portability, you can use something like this:
  *
  *     lzma_stream tmp = LZMA_STREAM_INIT;
  *     *strm = tmp;
  */
 #define LZMA_STREAM_INIT \
     { NULL, 0, 0, NULL, 0, 0, NULL, NULL, \
     NULL, NULL, NULL, NULL, 0, 0, 0, 0, \
     LZMA_RESERVED_ENUM, LZMA_RESERVED_ENUM }
 
 
 /**
  * \brief       Encode or decode data
  *
  * Once the lzma_stream has been successfully initialized (e.g. with
  * lzma_stream_encoder()), the actual encoding or decoding is done
  * using this function. The application has to update strm->next_in,
  * strm->avail_in, strm->next_out, and strm->avail_out to pass input
  * to and get output from liblzma.
  *
  * See the description of the coder-specific initialization function to find
  * out what 'action' values are supported by the coder.
  *
  * \param       strm    Pointer to lzma_stream that is at least initialized
  *                      with LZMA_STREAM_INIT.
  * \param       action  Action for this function to take. Must be a valid
  *                      lzma_action enum value.
  *
  * \return      Any valid lzma_ret. See the lzma_ret enum description for more
  *              information.
  */
 extern LZMA_API(lzma_ret) lzma_code(lzma_stream *strm, lzma_action action)
         lzma_nothrow lzma_attr_warn_unused_result;
 
 
 /**
  * \brief       Free memory allocated for the coder data structures
  *
  * After lzma_end(strm), strm->internal is guaranteed to be NULL. No other
  * members of the lzma_stream structure are touched.
  *
  * \note        zlib indicates an error if application end()s unfinished
  *              stream structure. liblzma doesn't do this, and assumes that
  *              application knows what it is doing.
  *
  * \param       strm    Pointer to lzma_stream that is at least initialized
  *                      with LZMA_STREAM_INIT.
  */
 extern LZMA_API(void) lzma_end(lzma_stream *strm) lzma_nothrow;
 
 
 /**
  * \brief       Get progress information
  *
  * In single-threaded mode, applications can get progress information from
  * strm->total_in and strm->total_out. In multi-threaded mode this is less
  * useful because a significant amount of both input and output data gets
  * buffered internally by liblzma. This makes total_in and total_out give
  * misleading information and also makes the progress indicator updates
  * non-smooth.
  *
  * This function gives realistic progress information also in multi-threaded
  * mode by taking into account the progress made by each thread. In
  * single-threaded mode *progress_in and *progress_out are set to
  * strm->total_in and strm->total_out, respectively.
  *
  * \param       strm          Pointer to lzma_stream that is at least
  *                            initialized with LZMA_STREAM_INIT.
  * \param[out]  progress_in   Pointer to the number of input bytes processed.
  * \param[out]  progress_out  Pointer to the number of output bytes processed.
  */
 extern LZMA_API(void) lzma_get_progress(lzma_stream *strm,
         uint64_t *progress_in, uint64_t *progress_out) lzma_nothrow;
 
 
 /**
  * \brief       Get the memory usage of decoder filter chain
  *
  * This function is currently supported only when *strm has been initialized
  * with a function that takes a memlimit argument. With other functions, you
  * should use e.g. lzma_raw_encoder_memusage() or lzma_raw_decoder_memusage()
  * to estimate the memory requirements.
  *
  * This function is useful e.g. after LZMA_MEMLIMIT_ERROR to find out how big
  * the memory usage limit should have been to decode the input. Note that
  * this may give misleading information if decoding .xz Streams that have
  * multiple Blocks, because each Block can have different memory requirements.
  *
  * \param       strm    Pointer to lzma_stream that is at least initialized
  *                      with LZMA_STREAM_INIT.
  *
  * \return      How much memory is currently allocated for the filter
  *              decoders. If no filter chain is currently allocated,
  *              some non-zero value is still returned, which is less than
  *              or equal to what any filter chain would indicate as its
  *              memory requirement.
  *
  *              If this function isn't supported by *strm or some other error
  *              occurs, zero is returned.
  */
 extern LZMA_API(uint64_t) lzma_memusage(const lzma_stream *strm)
         lzma_nothrow lzma_attr_pure;
 
 
 /**
  * \brief       Get the current memory usage limit
  *
  * This function is supported only when *strm has been initialized with
  * a function that takes a memlimit argument.
  *
  * \param       strm    Pointer to lzma_stream that is at least initialized
  *                      with LZMA_STREAM_INIT.
  *
  * \return      On success, the current memory usage limit is returned
  *              (always non-zero). On error, zero is returned.
  */
 extern LZMA_API(uint64_t) lzma_memlimit_get(const lzma_stream *strm)
         lzma_nothrow lzma_attr_pure;
 
 
 /**
  * \brief       Set the memory usage limit
  *
  * This function is supported only when *strm has been initialized with
  * a function that takes a memlimit argument.
  *
  * liblzma 5.2.3 and earlier has a bug where memlimit value of 0 causes
  * this function to do nothing (leaving the limit unchanged) and still
  * return LZMA_OK. Later versions treat 0 as if 1 had been specified (so
  * lzma_memlimit_get() will return 1 even if you specify 0 here).
  *
  * liblzma 5.2.6 and earlier had a bug in single-threaded .xz decoder
  * (lzma_stream_decoder()) which made it impossible to continue decoding
  * after LZMA_MEMLIMIT_ERROR even if the limit was increased using
  * lzma_memlimit_set(). Other decoders worked correctly.
  *
  * \return      Possible lzma_ret values:
  *              - LZMA_OK: New memory usage limit successfully set.
  *              - LZMA_MEMLIMIT_ERROR: The new limit is too small.
  *                The limit was not changed.
  *              - LZMA_PROG_ERROR: Invalid arguments, e.g. *strm doesn't
  *                support memory usage limit.
  */
 extern LZMA_API(lzma_ret) lzma_memlimit_set(
         lzma_stream *strm, uint64_t memlimit) lzma_nothrow;

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