관리-도구

편집 파일: filter.h

/** * \file lzma/filter.h * \brief Common filter related types and functions */ /* * Author: Lasse Collin * * This file has been put into the public domain. * You can do whatever you want with this file. * * See ../lzma.h for information about liblzma as a whole. */ #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 Filter ID and a pointer 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 too small * array would make liblzma write past the end of the filters 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 * * Return true if the give Filter ID is supported for encoding by this * liblzma build. Otherwise false is returned. * * There is no way to list which filters are available in this particular * liblzma version and build. It would be useless, because the application * couldn't know what kind of options the filter would need. */ 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 * * Return true if the give Filter ID is supported for decoding by this * liblzma build. Otherwise false is returned. */ 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. * * \return - 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; /** * \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. If an error occurs, * for example due to unsupported filter chain, * UINT64_MAX is returned. */ 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. If an error occurs, * for example due to unsupported filter chain, * UINT64_MAX is returned. */ 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. * * \param strm Pointer to properly prepared lzma_stream * \param filters Array of lzma_filter structures. The end of the * array must be marked with .id = LZMA_VLI_UNKNOWN. * * The `action' with lzma_code() can be LZMA_RUN, LZMA_SYNC_FLUSH (if the * filter chain supports it), or LZMA_FINISH. * * \return - 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. * * \return - 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 is for advanced users only. This function has two slightly * different purposes: * * - After LZMA_FULL_FLUSH when using Stream encoder: Set a new filter * chain, which will be used starting from the next Block. * * - After LZMA_SYNC_FLUSH using Raw, Block, or Stream encoder: Change * the filter-specific options in the middle of encoding. The actual * filters in the chain (Filter IDs) cannot be changed. In the future, * it might become possible to change the filter options without * using LZMA_SYNC_FLUSH. * * While rarely useful, this function may be called also when no data has * been compressed yet. In that case, this function will behave as if * LZMA_FULL_FLUSH (Stream encoder) or LZMA_SYNC_FLUSH (Raw or Block * encoder) had been used right before calling this function. * * \return - 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 * * \param filters Array of lzma_filter structures. The end of the * array must be marked 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 Beginning of the output buffer * \param 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 - 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 * * \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.) */ 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 lzma_filter structures. The end of the * array must be marked 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 Beginning of the output buffer * \param 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]. */ 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. * * \param 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 - LZMA_OK * - LZMA_OPTIONS_ERROR * - LZMA_PROG_ERROR * * \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. */ extern LZMA_API(lzma_ret) lzma_properties_size( uint32_t *size, const lzma_filter *filter) lzma_nothrow; /** * \brief Encode the Filter Properties field * * \param filter Filter ID and options * \param props Buffer to hold the encoded options. The size of * buffer must have been already determined with * lzma_properties_size(). * * \return - LZMA_OK * - LZMA_OPTIONS_ERROR * - LZMA_PROG_ERROR * * \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. */ 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 to filter->options. * filter->options is set to NULL if there are no * properties or if an error occurs. * \param allocator Custom memory allocator used to allocate the * options. Set to NULL to use the default malloc(), * 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 - 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. * * \param size Pointer to integer to hold the calculated size * \param filter Filter ID and associated options whose encoded * size is to be calculated * * \return - 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 * * \note If you need to calculate size of List of Filter Flags, * you need to loop over every lzma_filter entry. */ 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 Beginning of the output buffer * \param 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 - 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. * * \return - LZMA_OK * - LZMA_OPTIONS_ERROR * - LZMA_MEM_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;