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* going to change even if a newer version of the .xz file format is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