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xz/src/liblzma/api/lzma/filter.h

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/**
* \file lzma/filter.h
* \brief Common filter related types and functions
* \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 Maximum number of filters in a chain
*
* A filter chain can have 1-4 filters, of which three are allowed to change
* the size of the data. Usually only one or two filters are needed.
*/
#define LZMA_FILTERS_MAX 4
/**
* \brief Filter options
*
* This structure is used to pass a Filter ID and a pointer to the filter's
* options to liblzma. A few functions work with a single lzma_filter
* structure, while most functions expect a filter chain.
*
* A filter chain is indicated with an array of lzma_filter structures.
* The array is terminated with .id = LZMA_VLI_UNKNOWN. Thus, the filter
* array must have LZMA_FILTERS_MAX + 1 elements (that is, five) to
* be able to hold any arbitrary filter chain. This is important when
* using lzma_block_header_decode() from block.h, because a filter array
* that is too small would make liblzma write past the end of the array.
*/
typedef struct {
/**
* \brief Filter ID
*
* Use constants whose name begin with 'LZMA_FILTER_' to specify
* different filters. In an array of lzma_filter structures, use
* LZMA_VLI_UNKNOWN to indicate end of filters.
*
* \note This is not an enum, because on some systems enums
* cannot be 64-bit.
*/
lzma_vli id;
/**
* \brief Pointer to filter-specific options structure
*
* If the filter doesn't need options, set this to NULL. If id is
* set to LZMA_VLI_UNKNOWN, options is ignored, and thus
* doesn't need be initialized.
*/
void *options;
} lzma_filter;
/**
* \brief Test if the given Filter ID is supported for encoding
*
* \param id Filter ID
*
* \return lzma_bool:
* - true if the Filter ID is supported for encoding by this
* liblzma build.
* - false otherwise.
*/
extern LZMA_API(lzma_bool) lzma_filter_encoder_is_supported(lzma_vli id)
lzma_nothrow lzma_attr_const;
/**
* \brief Test if the given Filter ID is supported for decoding
*
* \param id Filter ID
*
* \return lzma_bool:
* - true if the Filter ID is supported for decoding by this
* liblzma build.
* - false otherwise.
*/
extern LZMA_API(lzma_bool) lzma_filter_decoder_is_supported(lzma_vli id)
lzma_nothrow lzma_attr_const;
/**
* \brief Copy the filters array
*
* Copy the Filter IDs and filter-specific options from src to dest.
* Up to LZMA_FILTERS_MAX filters are copied, plus the terminating
* .id == LZMA_VLI_UNKNOWN. Thus, dest should have at least
* LZMA_FILTERS_MAX + 1 elements space unless the caller knows that
* src is smaller than that.
*
* Unless the filter-specific options is NULL, the Filter ID has to be
* supported by liblzma, because liblzma needs to know the size of every
* filter-specific options structure. The filter-specific options are not
* validated. If options is NULL, any unsupported Filter IDs are copied
* without returning an error.
*
* Old filter-specific options in dest are not freed, so dest doesn't
* need to be initialized by the caller in any way.
*
* If an error occurs, memory possibly already allocated by this function
* is always freed. liblzma versions older than 5.2.7 may modify the dest
* array and leave its contents in an undefined state if an error occurs.
* liblzma 5.2.7 and newer only modify the dest array when returning LZMA_OK.
*
* \param src Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
* \param[out] dest Destination filter array
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_MEM_ERROR
* - LZMA_OPTIONS_ERROR: Unsupported Filter ID and its options
* is not NULL.
* - LZMA_PROG_ERROR: src or dest is NULL.
*/
extern LZMA_API(lzma_ret) lzma_filters_copy(
const lzma_filter *src, lzma_filter *dest,
const lzma_allocator *allocator)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Free the options in the array of lzma_filter structures
*
* This frees the filter chain options. The filters array itself is not freed.
*
* The filters array must have at most LZMA_FILTERS_MAX + 1 elements
* including the terminating element which must have .id = LZMA_VLI_UNKNOWN.
* For all elements before the terminating element:
* - options will be freed using the given lzma_allocator or,
* if allocator is NULL, using free().
* - options will be set to NULL.
* - id will be set to LZMA_VLI_UNKNOWN.
*
* If filters is NULL, this does nothing. Again, this never frees the
* filters array itself.
*
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
*/
extern LZMA_API(void) lzma_filters_free(
lzma_filter *filters, const lzma_allocator *allocator)
lzma_nothrow;
/**
* \brief Calculate approximate memory requirements for raw encoder
*
* This function can be used to calculate the memory requirements for
* Block and Stream encoders too because Block and Stream encoders don't
* need significantly more memory than raw encoder.
*
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
*
* \return Number of bytes of memory required for the given
* filter chain when encoding or UINT64_MAX on error.
*/
extern LZMA_API(uint64_t) lzma_raw_encoder_memusage(const lzma_filter *filters)
lzma_nothrow lzma_attr_pure;
/**
* \brief Calculate approximate memory requirements for raw decoder
*
* This function can be used to calculate the memory requirements for
* Block and Stream decoders too because Block and Stream decoders don't
* need significantly more memory than raw decoder.
*
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
*
* \return Number of bytes of memory required for the given
* filter chain when decoding or UINT64_MAX on error.
*/
extern LZMA_API(uint64_t) lzma_raw_decoder_memusage(const lzma_filter *filters)
lzma_nothrow lzma_attr_pure;
/**
* \brief Initialize raw encoder
*
* This function may be useful when implementing custom file formats.
*
* The 'action' with lzma_code() can be LZMA_RUN, LZMA_SYNC_FLUSH (if the
* filter chain supports it), or LZMA_FINISH.
*
* \param strm Pointer to lzma_stream that is at least
* initialized with LZMA_STREAM_INIT.
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_MEM_ERROR
* - LZMA_OPTIONS_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_raw_encoder(
lzma_stream *strm, const lzma_filter *filters)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Initialize raw decoder
*
* The initialization of raw decoder goes similarly to raw encoder.
*
* The 'action' with lzma_code() can be LZMA_RUN or LZMA_FINISH. Using
* LZMA_FINISH is not required, it is supported just for convenience.
*
* \param strm Pointer to lzma_stream that is at least
* initialized with LZMA_STREAM_INIT.
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_MEM_ERROR
* - LZMA_OPTIONS_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_raw_decoder(
lzma_stream *strm, const lzma_filter *filters)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Update the filter chain in the encoder
*
* This function may be called after lzma_code() has returned LZMA_STREAM_END
* when LZMA_FULL_BARRIER, LZMA_FULL_FLUSH, or LZMA_SYNC_FLUSH was used:
*
* - After LZMA_FULL_BARRIER or LZMA_FULL_FLUSH: Single-threaded .xz Stream
* encoder (lzma_stream_encoder()) and (since liblzma 5.4.0) multi-threaded
* Stream encoder (lzma_stream_encoder_mt()) allow setting a new filter
* chain to be used for the next Block(s).
*
* - After LZMA_SYNC_FLUSH: Raw encoder (lzma_raw_encoder()),
* Block encoder (lzma_block_encoder()), and single-threaded .xz Stream
* encoder (lzma_stream_encoder()) allow changing certain filter-specific
* options in the middle of encoding. The actual filters in the chain
* (Filter IDs) must not be changed! Currently only the lc, lp, and pb
* options of LZMA2 (not LZMA1) can be changed this way.
*
* - In the future some filters might allow changing some of their options
* without any barrier or flushing but currently such filters don't exist.
*
* This function may also be called when no data has been compressed yet
* although this is rarely useful. In that case, this function will behave
* as if LZMA_FULL_FLUSH (Stream encoders) or LZMA_SYNC_FLUSH (Raw or Block
* encoder) had been used right before calling this function.
*
* \param strm Pointer to lzma_stream that is at least
* initialized with LZMA_STREAM_INIT.
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_MEM_ERROR
* - LZMA_MEMLIMIT_ERROR
* - LZMA_OPTIONS_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_filters_update(
lzma_stream *strm, const lzma_filter *filters) lzma_nothrow;
/**
* \brief Single-call raw encoder
*
* \note There is no function to calculate how big output buffer
* would surely be big enough. (lzma_stream_buffer_bound()
* works only for lzma_stream_buffer_encode(); raw encoder
* won't necessarily meet that bound.)
*
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
* \param in Beginning of the input buffer
* \param in_size Size of the input buffer
* \param[out] out Beginning of the output buffer
* \param[out] out_pos The next byte will be written to out[*out_pos].
* *out_pos is updated only if encoding succeeds.
* \param out_size Size of the out buffer; the first byte into
* which no data is written to is out[out_size].
*
* \return Possible lzma_ret values:
* - LZMA_OK: Encoding was successful.
* - LZMA_BUF_ERROR: Not enough output buffer space.
* - LZMA_OPTIONS_ERROR
* - LZMA_MEM_ERROR
* - LZMA_DATA_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_raw_buffer_encode(
const lzma_filter *filters, const lzma_allocator *allocator,
const uint8_t *in, size_t in_size, uint8_t *out,
size_t *out_pos, size_t out_size) lzma_nothrow;
/**
* \brief Single-call raw decoder
*
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
* \param in Beginning of the input buffer
* \param in_pos The next byte will be read from in[*in_pos].
* *in_pos is updated only if decoding succeeds.
* \param in_size Size of the input buffer; the first byte that
* won't be read is in[in_size].
* \param[out] out Beginning of the output buffer
* \param[out] out_pos The next byte will be written to out[*out_pos].
* *out_pos is updated only if encoding succeeds.
* \param out_size Size of the out buffer; the first byte into
* which no data is written to is out[out_size].
*
* \return Possible lzma_ret values:
* - LZMA_OK: Decoding was successful.
* - LZMA_BUF_ERROR: Not enough output buffer space.
* - LZMA_OPTIONS_ERROR
* - LZMA_MEM_ERROR
* - LZMA_DATA_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_raw_buffer_decode(
const lzma_filter *filters, const lzma_allocator *allocator,
const uint8_t *in, size_t *in_pos, size_t in_size,
uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow;
/**
* \brief Get the size of the Filter Properties field
*
* This function may be useful when implementing custom file formats
* using the raw encoder and decoder.
*
* \note This function validates the Filter ID, but does not
* necessarily validate the options. Thus, it is possible
* that this returns LZMA_OK while the following call to
* lzma_properties_encode() returns LZMA_OPTIONS_ERROR.
*
* \param[out] size Pointer to uint32_t to hold the size of the properties
* \param filter Filter ID and options (the size of the properties may
* vary depending on the options)
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_OPTIONS_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_properties_size(
uint32_t *size, const lzma_filter *filter) lzma_nothrow;
/**
* \brief Encode the Filter Properties field
*
* \note Even this function won't validate more options than actually
* necessary. Thus, it is possible that encoding the properties
* succeeds but using the same options to initialize the encoder
* will fail.
*
* \note If lzma_properties_size() indicated that the size
* of the Filter Properties field is zero, calling
* lzma_properties_encode() is not required, but it
* won't do any harm either.
*
* \param filter Filter ID and options
* \param[out] props Buffer to hold the encoded options. The size of
* the buffer must have been already determined with
* lzma_properties_size().
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_properties_encode(
const lzma_filter *filter, uint8_t *props) lzma_nothrow;
/**
* \brief Decode the Filter Properties field
*
* \param filter filter->id must have been set to the correct
* Filter ID. filter->options doesn't need to be
* initialized (it's not freed by this function). The
* decoded options will be stored in filter->options;
* it's application's responsibility to free it when
* appropriate. filter->options is set to NULL if
* there are no properties or if an error occurs.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
* and in case of an error, also free().
* \param props Input buffer containing the properties.
* \param props_size Size of the properties. This must be the exact
* size; giving too much or too little input will
* return LZMA_OPTIONS_ERROR.
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_OPTIONS_ERROR
* - LZMA_MEM_ERROR
*/
extern LZMA_API(lzma_ret) lzma_properties_decode(
lzma_filter *filter, const lzma_allocator *allocator,
const uint8_t *props, size_t props_size) lzma_nothrow;
/**
* \brief Calculate encoded size of a Filter Flags field
*
* Knowing the size of Filter Flags is useful to know when allocating
* memory to hold the encoded Filter Flags.
*
* \note If you need to calculate size of List of Filter Flags,
* you need to loop over every lzma_filter entry.
*
* \param[out] size Pointer to integer to hold the calculated size
* \param filter Filter ID and associated options whose encoded
* size is to be calculated
*
* \return Possible lzma_ret values:
* - LZMA_OK: *size set successfully. Note that this doesn't
* guarantee that filter->options is valid, thus
* lzma_filter_flags_encode() may still fail.
* - LZMA_OPTIONS_ERROR: Unknown Filter ID or unsupported options.
* - LZMA_PROG_ERROR: Invalid options
*/
extern LZMA_API(lzma_ret) lzma_filter_flags_size(
uint32_t *size, const lzma_filter *filter)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Encode Filter Flags into given buffer
*
* In contrast to some functions, this doesn't allocate the needed buffer.
* This is due to how this function is used internally by liblzma.
*
* \param filter Filter ID and options to be encoded
* \param[out] out Beginning of the output buffer
* \param[out] out_pos out[*out_pos] is the next write position. This
* is updated by the encoder.
* \param out_size out[out_size] is the first byte to not write.
*
* \return Possible lzma_ret values:
* - LZMA_OK: Encoding was successful.
* - LZMA_OPTIONS_ERROR: Invalid or unsupported options.
* - LZMA_PROG_ERROR: Invalid options or not enough output
* buffer space (you should have checked it with
* lzma_filter_flags_size()).
*/
extern LZMA_API(lzma_ret) lzma_filter_flags_encode(const lzma_filter *filter,
uint8_t *out, size_t *out_pos, size_t out_size)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Decode Filter Flags from given buffer
*
* The decoded result is stored into *filter. The old value of
* filter->options is not free()d. If anything other than LZMA_OK
* is returned, filter->options is set to NULL.
*
* \param[out] filter Destination filter. The decoded Filter ID will
* be stored in filter->id. If options are needed
* they will be allocated and the pointer will be
* stored in filter->options.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
* \param in Beginning of the input buffer
* \param[out] in_pos The next byte will be read from in[*in_pos].
* *in_pos is updated only if decoding succeeds.
* \param in_size Size of the input buffer; the first byte that
* won't be read is in[in_size].
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_OPTIONS_ERROR
* - LZMA_MEM_ERROR
* - LZMA_DATA_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_filter_flags_decode(
lzma_filter *filter, const lzma_allocator *allocator,
const uint8_t *in, size_t *in_pos, size_t in_size)
lzma_nothrow lzma_attr_warn_unused_result;
/***********
* Strings *
***********/
/**
* \brief Allow or show all filters
*
* By default only the filters supported in the .xz format are accept by
* lzma_str_to_filters() or shown by lzma_str_list_filters().
*/
#define LZMA_STR_ALL_FILTERS UINT32_C(0x01)
/**
* \brief Do not validate the filter chain in lzma_str_to_filters()
*
* By default lzma_str_to_filters() can return an error if the filter chain
* as a whole isn't usable in the .xz format or in the raw encoder or decoder.
* With this flag, this validation is skipped. This flag doesn't affect the
* handling of the individual filter options. To allow non-.xz filters also
* LZMA_STR_ALL_FILTERS is needed.
*/
#define LZMA_STR_NO_VALIDATION UINT32_C(0x02)
/**
* \brief Stringify encoder options
*
* Show the filter-specific options that the encoder will use.
* This may be useful for verbose diagnostic messages.
*
* Note that if options were decoded from .xz headers then the encoder options
* may be undefined. This flag shouldn't be used in such a situation.
*/
#define LZMA_STR_ENCODER UINT32_C(0x10)
/**
* \brief Stringify decoder options
*
* Show the filter-specific options that the decoder will use.
* This may be useful for showing what filter options were decoded
* from file headers.
*/
#define LZMA_STR_DECODER UINT32_C(0x20)
/**
* \brief Produce xz-compatible getopt_long() syntax
*
* That is, "delta:dist=2 lzma2:dict=4MiB,pb=1,lp=1" becomes
* "--delta=dist=2 --lzma2=dict=4MiB,pb=1,lp=1".
*
* This syntax is compatible with xz 5.0.0 as long as the filters and
* their options are supported too.
*/
#define LZMA_STR_GETOPT_LONG UINT32_C(0x40)
/**
* \brief Use two dashes "--" instead of a space to separate filters
*
* That is, "delta:dist=2 lzma2:pb=1,lp=1" becomes
* "delta:dist=2--lzma2:pb=1,lp=1". This looks slightly odd but this
* kind of strings should be usable on the command line without quoting.
* However, it is possible that future versions with new filter options
* might produce strings that require shell quoting anyway as the exact
* set of possible characters isn't frozen for now.
*
* It is guaranteed that the single quote (') will never be used in
* filter chain strings (even if LZMA_STR_NO_SPACES isn't used).
*/
#define LZMA_STR_NO_SPACES UINT32_C(0x80)
/**
* \brief Convert a string to a filter chain
*
* This tries to make it easier to write applications that allow users
* to set custom compression options. This only handles the filter
* configuration (including presets) but not the number of threads,
* block size, check type, or memory limits.
*
* The input string can be either a preset or a filter chain. Presets
* begin with a digit 0-9 and may be followed by zero or more flags
* which are lower-case letters. Currently only "e" is supported, matching
* LZMA_PRESET_EXTREME. For partial xz command line syntax compatibility,
* a preset string may start with a single dash "-".
*
* A filter chain consists of one or more "filtername:opt1=value1,opt2=value2"
* strings separated by one or more spaces. Leading and trailing spaces are
* ignored. All names and values must be lower-case. Extra commas in the
* option list are ignored. The order of filters is significant: when
* encoding, the uncompressed input data goes to the leftmost filter first.
* Normally "lzma2" is the last filter in the chain.
*
* If one wishes to avoid spaces, for example, to avoid shell quoting,
* it is possible to use two dashes "--" instead of spaces to separate
* the filters.
*
* For xz command line compatibility, each filter may be prefixed with
* two dashes "--" and the colon ":" separating the filter name from
* the options may be replaced with an equals sign "=".
*
* By default, only filters that can be used in the .xz format are accepted.
* To allow all filters (LZMA1) use the flag LZMA_STR_ALL_FILTERS.
*
* By default, very basic validation is done for the filter chain as a whole,
* for example, that LZMA2 is only used as the last filter in the chain.
* The validation isn't perfect though and it's possible that this function
* succeeds but using the filter chain for encoding or decoding will still
* result in LZMA_OPTIONS_ERROR. To disable this validation, use the flag
* LZMA_STR_NO_VALIDATION.
*
* The available filter names and their options are available via
* lzma_str_list_filters(). See the xz man page for the description
* of filter names and options.
*
* For command line applications, below is an example how an error message
* can be displayed. Note the use of an empty string for the field width.
* If "^" was used there it would create an off-by-one error except at
* the very beginning of the line.
*
* \code{.c}
* const char *str = ...; // From user
* lzma_filter filters[LZMA_FILTERS_MAX + 1];
* int pos;
* const char *msg = lzma_str_to_filters(str, &pos, filters, 0, NULL);
* if (msg != NULL) {
* printf("%s: Error in XZ compression options:\n", argv[0]);
* printf("%s: %s\n", argv[0], str);
* printf("%s: %*s^\n", argv[0], errpos, "");
* printf("%s: %s\n", argv[0], msg);
* }
* \endcode
*
* \param str User-supplied string describing a preset or
* a filter chain. If a default value is needed and
* you don't know what would be good, use "6" since
* that is the default preset in xz too.
* \param[out] error_pos If this isn't NULL, this value will be set on
* both success and on all errors. This tells the
* location of the error in the string. This is
* an int to make it straightforward to use this
* as printf() field width. The value is guaranteed
* to be in the range [0, INT_MAX] even if strlen(str)
* somehow was greater than INT_MAX.
* \param[out] filters An array of lzma_filter structures. There must
* be LZMA_FILTERS_MAX + 1 (that is, five) elements
* in the array. The old contents are ignored so it
* doesn't need to be initialized. This array is
* modified only if this function returns NULL.
* Once the allocated filter options are no longer
* needed, lzma_filters_free() can be used to free the
* options (it doesn't free the filters array itself).
* \param flags Bitwise-or of zero or more of the flags
* LZMA_STR_ALL_FILTERS and LZMA_STR_NO_VALIDATION.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
*
* \return On success, NULL is returned. On error, a statically-allocated
* error message is returned which together with the error_pos
* should give some idea what is wrong.
*/
extern LZMA_API(const char *) lzma_str_to_filters(
const char *str, int *error_pos, lzma_filter *filters,
uint32_t flags, const lzma_allocator *allocator)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Convert a filter chain to a string
*
* Use cases:
*
* - Verbose output showing the full encoder options to the user
* (use LZMA_STR_ENCODER in flags)
*
* - Showing the filters and options that are required to decode a file
* (use LZMA_STR_DECODER in flags)
*
* - Showing the filter names without any options in informational messages
* where the technical details aren't important (no flags). In this case
* the .options in the filters array are ignored and may be NULL even if
* a filter has a mandatory options structure.
*
* Note that even if the filter chain was specified using a preset,
* the resulting filter chain isn't reversed to a preset. So if you
* specify "6" to lzma_str_to_filters() then lzma_str_from_filters()
* will produce a string containing "lzma2".
*
* \param[out] str On success *str will be set to point to an
* allocated string describing the given filter
* chain. Old value is ignored. On error *str is
* always set to NULL.
* \param filters Array of filters terminated with
* .id == LZMA_VLI_UNKNOWN.
* \param flags Bitwise-or of zero or more of the flags
* LZMA_STR_ENCODER, LZMA_STR_DECODER,
* LZMA_STR_GETOPT_LONG, and LZMA_STR_NO_SPACES.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_OPTIONS_ERROR: Empty filter chain
* (filters[0].id == LZMA_VLI_UNKNOWN) or the filter chain
* includes a Filter ID that is not supported by this function.
* - LZMA_MEM_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_str_from_filters(
char **str, const lzma_filter *filters, uint32_t flags,
const lzma_allocator *allocator)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief List available filters and/or their options (for help message)
*
* If a filter_id is given then only one line is created which contains the
* filter name. If LZMA_STR_ENCODER or LZMA_STR_DECODER is used then the
* options read by the encoder or decoder are printed on the same line.
*
* If filter_id is LZMA_VLI_UNKNOWN then all supported .xz-compatible filters
* are listed:
*
* - If neither LZMA_STR_ENCODER nor LZMA_STR_DECODER is used then
* the supported filter names are listed on a single line separated
* by spaces.
*
* - If LZMA_STR_ENCODER or LZMA_STR_DECODER is used then filters and
* the supported options are listed one filter per line. There won't
* be a newline after the last filter.
*
* - If LZMA_STR_ALL_FILTERS is used then the list will include also
* those filters that cannot be used in the .xz format (LZMA1).
*
* \param str On success *str will be set to point to an
* allocated string listing the filters and options.
* Old value is ignored. On error *str is always set
* to NULL.
* \param filter_id Filter ID or LZMA_VLI_UNKNOWN.
* \param flags Bitwise-or of zero or more of the flags
* LZMA_STR_ALL_FILTERS, LZMA_STR_ENCODER,
* LZMA_STR_DECODER, and LZMA_STR_GETOPT_LONG.
* \param allocator lzma_allocator for custom allocator functions.
* Set to NULL to use malloc() and free().
*
* \return Possible lzma_ret values:
* - LZMA_OK
* - LZMA_OPTIONS_ERROR: Unsupported filter_id or flags
* - LZMA_MEM_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_str_list_filters(
char **str, lzma_vli filter_id, uint32_t flags,
const lzma_allocator *allocator)
lzma_nothrow lzma_attr_warn_unused_result;
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