224 lines
8.1 KiB
C
224 lines
8.1 KiB
C
/**
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* \file lzma/stream_flags.h
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* \brief .xz Stream Header and Stream Footer encoder and decoder
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*/
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/*
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* Author: Lasse Collin
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*
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* This file has been put into the public domain.
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* You can do whatever you want with this file.
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*
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* See ../lzma.h for information about liblzma as a whole.
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*/
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#ifndef LZMA_H_INTERNAL
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# error Never include this file directly. Use <lzma.h> instead.
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#endif
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/**
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* \brief Size of Stream Header and Stream Footer
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*
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* Stream Header and Stream Footer have the same size and they are not
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* going to change even if a newer version of the .xz file format is
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* developed in future.
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*/
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#define LZMA_STREAM_HEADER_SIZE 12
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/**
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* \brief Options for encoding/decoding Stream Header and Stream Footer
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*/
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typedef struct {
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/**
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* \brief Stream Flags format version
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*
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* To prevent API and ABI breakages if new features are needed in
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* Stream Header or Stream Footer, a version number is used to
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* indicate which fields in this structure are in use. For now,
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* version must always be zero. With non-zero version, the
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* lzma_stream_header_encode() and lzma_stream_footer_encode()
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* will return LZMA_OPTIONS_ERROR.
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*
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* lzma_stream_header_decode() and lzma_stream_footer_decode()
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* will always set this to the lowest value that supports all the
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* features indicated by the Stream Flags field. The application
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* must check that the version number set by the decoding functions
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* is supported by the application. Otherwise it is possible that
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* the application will decode the Stream incorrectly.
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*/
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uint32_t version;
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/**
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* \brief Backward Size
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*
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* Backward Size must be a multiple of four bytes. In this Stream
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* format version, Backward Size is the size of the Index field.
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*
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* Backward Size isn't actually part of the Stream Flags field, but
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* it is convenient to include in this structure anyway. Backward
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* Size is present only in the Stream Footer. There is no need to
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* initialize backward_size when encoding Stream Header.
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*
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* lzma_stream_header_decode() always sets backward_size to
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* LZMA_VLI_UNKNOWN so that it is convenient to use
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* lzma_stream_flags_compare() when both Stream Header and Stream
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* Footer have been decoded.
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*/
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lzma_vli backward_size;
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# define LZMA_BACKWARD_SIZE_MIN 4
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# define LZMA_BACKWARD_SIZE_MAX (LZMA_VLI_C(1) << 34)
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/**
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* \brief Check ID
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*
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* This indicates the type of the integrity check calculated from
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* uncompressed data.
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*/
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lzma_check check;
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/*
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* Reserved space to allow possible future extensions without
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* breaking the ABI. You should not touch these, because the
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* names of these variables may change.
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*
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* (We will never be able to use all of these since Stream Flags
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* is just two bytes plus Backward Size of four bytes. But it's
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* nice to have the proper types when they are needed.)
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*/
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lzma_reserved_enum reserved_enum1;
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lzma_reserved_enum reserved_enum2;
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lzma_reserved_enum reserved_enum3;
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lzma_reserved_enum reserved_enum4;
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lzma_bool reserved_bool1;
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lzma_bool reserved_bool2;
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lzma_bool reserved_bool3;
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lzma_bool reserved_bool4;
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lzma_bool reserved_bool5;
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lzma_bool reserved_bool6;
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lzma_bool reserved_bool7;
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lzma_bool reserved_bool8;
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uint32_t reserved_int1;
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uint32_t reserved_int2;
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} lzma_stream_flags;
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/**
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* \brief Encode Stream Header
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*
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* \param options Stream Header options to be encoded.
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* options->backward_size is ignored and doesn't
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* need to be initialized.
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* \param out Beginning of the output buffer of
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* LZMA_STREAM_HEADER_SIZE bytes.
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*
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* \return - LZMA_OK: Encoding was successful.
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* - LZMA_OPTIONS_ERROR: options->version is not supported by
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* this liblzma version.
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* - LZMA_PROG_ERROR: Invalid options.
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*/
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extern LZMA_API(lzma_ret) lzma_stream_header_encode(
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const lzma_stream_flags *options, uint8_t *out)
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lzma_nothrow lzma_attr_warn_unused_result;
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/**
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* \brief Encode Stream Footer
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*
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* \param options Stream Footer options to be encoded.
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* \param out Beginning of the output buffer of
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* LZMA_STREAM_HEADER_SIZE bytes.
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*
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* \return - LZMA_OK: Encoding was successful.
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* - LZMA_OPTIONS_ERROR: options->version is not supported by
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* this liblzma version.
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* - LZMA_PROG_ERROR: Invalid options.
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*/
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extern LZMA_API(lzma_ret) lzma_stream_footer_encode(
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const lzma_stream_flags *options, uint8_t *out)
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lzma_nothrow lzma_attr_warn_unused_result;
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/**
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* \brief Decode Stream Header
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*
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* \param options Target for the decoded Stream Header options.
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* \param in Beginning of the input buffer of
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* LZMA_STREAM_HEADER_SIZE bytes.
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*
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* options->backward_size is always set to LZMA_VLI_UNKNOWN. This is to
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* help comparing Stream Flags from Stream Header and Stream Footer with
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* lzma_stream_flags_compare().
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*
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* \return - LZMA_OK: Decoding was successful.
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* - LZMA_FORMAT_ERROR: Magic bytes don't match, thus the given
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* buffer cannot be Stream Header.
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* - LZMA_DATA_ERROR: CRC32 doesn't match, thus the header
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* is corrupt.
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* - LZMA_OPTIONS_ERROR: Unsupported options are present
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* in the header.
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*
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* \note When decoding .xz files that contain multiple Streams, it may
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* make sense to print "file format not recognized" only if
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* decoding of the Stream Header of the _first_ Stream gives
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* LZMA_FORMAT_ERROR. If non-first Stream Header gives
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* LZMA_FORMAT_ERROR, the message used for LZMA_DATA_ERROR is
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* probably more appropriate.
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*
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* For example, Stream decoder in liblzma uses LZMA_DATA_ERROR if
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* LZMA_FORMAT_ERROR is returned by lzma_stream_header_decode()
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* when decoding non-first Stream.
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*/
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extern LZMA_API(lzma_ret) lzma_stream_header_decode(
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lzma_stream_flags *options, const uint8_t *in)
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lzma_nothrow lzma_attr_warn_unused_result;
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/**
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* \brief Decode Stream Footer
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*
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* \param options Target for the decoded Stream Header options.
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* \param in Beginning of the input buffer of
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* LZMA_STREAM_HEADER_SIZE bytes.
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*
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* \return - LZMA_OK: Decoding was successful.
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* - LZMA_FORMAT_ERROR: Magic bytes don't match, thus the given
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* buffer cannot be Stream Footer.
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* - LZMA_DATA_ERROR: CRC32 doesn't match, thus the Stream Footer
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* is corrupt.
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* - LZMA_OPTIONS_ERROR: Unsupported options are present
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* in Stream Footer.
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*
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* \note If Stream Header was already decoded successfully, but
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* decoding Stream Footer returns LZMA_FORMAT_ERROR, the
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* application should probably report some other error message
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* than "file format not recognized", since the file more likely
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* is corrupt (possibly truncated). Stream decoder in liblzma
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* uses LZMA_DATA_ERROR in this situation.
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*/
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extern LZMA_API(lzma_ret) lzma_stream_footer_decode(
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lzma_stream_flags *options, const uint8_t *in)
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lzma_nothrow lzma_attr_warn_unused_result;
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/**
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* \brief Compare two lzma_stream_flags structures
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*
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* backward_size values are compared only if both are not
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* LZMA_VLI_UNKNOWN.
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*
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* \return - LZMA_OK: Both are equal. If either had backward_size set
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* to LZMA_VLI_UNKNOWN, backward_size values were not
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* compared or validated.
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* - LZMA_DATA_ERROR: The structures differ.
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* - LZMA_OPTIONS_ERROR: version in either structure is greater
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* than the maximum supported version (currently zero).
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* - LZMA_PROG_ERROR: Invalid value, e.g. invalid check or
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* backward_size.
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*/
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extern LZMA_API(lzma_ret) lzma_stream_flags_compare(
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const lzma_stream_flags *a, const lzma_stream_flags *b)
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lzma_nothrow lzma_attr_pure;
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