lzma_block Struct Reference

Options for the Block and Block Header encoders and decoders. More...

#include <block.h>

Data Fields
uint32_t	version
	Block format version.
uint32_t	header_size
	Size of the Block Header field.
lzma_check	check
	Type of integrity Check.
lzma_vli	compressed_size
	Size of the Compressed Data in bytes.
lzma_vli	uncompressed_size
	Uncompressed Size in bytes.
lzma_filter *	filters
	Array of filters.
uint8_t	raw_check [LZMA_CHECK_SIZE_MAX]
	Raw value stored in the Check field.
void *	reserved_ptr1
void *	reserved_ptr2
void *	reserved_ptr3
uint32_t	reserved_int1
uint32_t	reserved_int2
lzma_vli	reserved_int3
lzma_vli	reserved_int4
lzma_vli	reserved_int5
lzma_vli	reserved_int6
lzma_vli	reserved_int7
lzma_vli	reserved_int8
lzma_reserved_enum	reserved_enum1
lzma_reserved_enum	reserved_enum2
lzma_reserved_enum	reserved_enum3
lzma_reserved_enum	reserved_enum4
lzma_bool	ignore_check
	A flag to Block decoder to not verify the Check field.
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

Detailed Description

Options for the Block and Block Header encoders and decoders.

Different Block handling functions use different parts of this structure. Some read some members, other functions write, and some do both. Only the members listed for reading need to be initialized when the specified functions are called. The members marked for writing will be assigned new values at some point either by calling the given function or by later calls to lzma_code().

Field Documentation

check

lzma_check check

Type of integrity Check.

The Check ID is not stored into the Block Header, thus its value must be provided also when decoding.

Read by:

• lzma_block_header_encode()
• lzma_block_header_decode()
• lzma_block_compressed_size()
• lzma_block_unpadded_size()
• lzma_block_total_size()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_buffer_decode()

compressed_size

lzma_vli compressed_size

Size of the Compressed Data in bytes.

Encoding: If this is not LZMA_VLI_UNKNOWN, Block Header encoder will store this value to the Block Header. Block encoder doesn't care about this value, but will set it once the encoding has been finished.

Decoding: If this is not LZMA_VLI_UNKNOWN, Block decoder will verify that the size of the Compressed Data field matches compressed_size.

Usually you don't know this value when encoding in streamed mode, and thus cannot write this field into the Block Header.

In non-streamed mode you can reserve space for this field before encoding the actual Block. After encoding the data, finish the Block by encoding the Block Header. Steps in detail:

• Set compressed_size to some big enough value. If you don't know better, use LZMA_VLI_MAX, but remember that bigger values take more space in Block Header.
• Call lzma_block_header_size() to see how much space you need to reserve for the Block Header.
• Encode the Block using lzma_block_encoder() and lzma_code(). It sets compressed_size to the correct value.
• Use lzma_block_header_encode() to encode the Block Header. Because space was reserved in the first step, you don't need to call lzma_block_header_size() anymore, because due to reserving, header_size has to be big enough. If it is "too big", lzma_block_header_encode() will add enough Header Padding to make Block Header to match the size specified by header_size.

Read by:

• lzma_block_header_size()
• lzma_block_header_encode()
• lzma_block_compressed_size()
• lzma_block_unpadded_size()
• lzma_block_total_size()
• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_decode()
• lzma_block_compressed_size()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_buffer_decode()

Encoding: If this is not LZMA_VLI_UNKNOWN, Block Header encoder will store this value to the Block Header. Block encoder doesn't care about this value, but will set it once the encoding has been finished.

Decoding: If this is not LZMA_VLI_UNKNOWN, Block decoder will verify that the size of the Compressed Data field matches compressed_size.

Usually you don't know this value when encoding in streamed mode, and thus cannot write this field into the Block Header.

In non-streamed mode you can reserve space for this field before encoding the actual Block. After encoding the data, finish the Block by encoding the Block Header. Steps in detail:

• Set compressed_size to some big enough value. If you don't know better, use LZMA_VLI_MAX, but remember that bigger values take more space in Block Header.
• Call lzma_block_header_size() to see how much space you need to reserve for the Block Header.
• Encode the Block using lzma_block_encoder() and lzma_code(). It sets compressed_size to the correct value.
• Use lzma_block_header_encode() to encode the Block Header. Because space was reserved in the first step, you don't need to call lzma_block_header_size() anymore, because due to reserving, header_size has to be big enough. If it is "too big", lzma_block_header_encode() will add enough Header Padding to make Block Header to match the size specified by header_size.

Read by:

• lzma_block_header_size()
• lzma_block_header_encode()
• lzma_block_compressed_size()
• lzma_block_unpadded_size()
• lzma_block_total_size()
• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_decode()
• lzma_block_compressed_size()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_uncomp_encode()
• lzma_block_buffer_decode()

filters

lzma_filter * filters

Array of filters.

There can be 1-4 filters. The end of the array is marked with .id = LZMA_VLI_UNKNOWN.

Read by:

• lzma_block_header_size()
• lzma_block_header_encode()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_decode(): Note that this does NOT free() the old filter options structures. All unused filters[] will have .id == LZMA_VLI_UNKNOWN and .options == NULL. If decoding fails, all filters[] are guaranteed to be LZMA_VLI_UNKNOWN and NULL.

Note

Because of the array is terminated with .id = LZMA_VLI_UNKNOWN, the actual array must have LZMA_FILTERS_MAX + 1 members or the Block Header decoder will overflow the buffer.

header_size

uint32_t header_size

Size of the Block Header field.

Size of the Block Header field in bytes.

This is always a multiple of four.

Read by:

• lzma_block_header_encode()
• lzma_block_header_decode()
• lzma_block_compressed_size()
• lzma_block_unpadded_size()
• lzma_block_total_size()
• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_size()
• lzma_block_buffer_encode()

This is always a multiple of four.

Read by:

• lzma_block_header_encode()
• lzma_block_header_decode()
• lzma_block_compressed_size()
• lzma_block_unpadded_size()
• lzma_block_total_size()
• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_size()
• lzma_block_buffer_encode()
• lzma_block_uncomp_encode()

ignore_check

lzma_bool ignore_check

A flag to Block decoder to not verify the Check field.

This field is supported by liblzma >= 5.1.4beta if .version >= 1.

If this is set to true, the integrity check won't be calculated and verified. Unless you know what you are doing, you should leave this to false. (A reason to set this to true is when the file integrity is verified externally anyway and you want to speed up the decompression, which matters mostly when using SHA-256 as the integrity check.)

If .version >= 1, read by:

• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by (.version is ignored):

• lzma_block_header_decode() always sets this to false

This member is supported by liblzma >= 5.1.4beta if .version >= 1.

If this is set to true, the integrity check won't be calculated and verified. Unless you know what you are doing, you should leave this to false. (A reason to set this to true is when the file integrity is verified externally anyway and you want to speed up the decompression, which matters mostly when using SHA-256 as the integrity check.)

If .version >= 1, read by:

• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by (.version is ignored):

• lzma_block_header_decode() always sets this to false

raw_check

uint8_t raw_check

Raw value stored in the Check field.

After successful coding, the first lzma_check_size(check) bytes of this array contain the raw value stored in the Check field.

Note that CRC32 and CRC64 are stored in little endian byte order. Take it into account if you display the Check values to the user.

Written by:

• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_buffer_decode()

After successful coding, the first lzma_check_size(check) bytes of this array contain the raw value stored in the Check field.

Note that CRC32 and CRC64 are stored in little endian byte order. Take it into account if you display the Check values to the user.

Written by:

• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_uncomp_encode()
• lzma_block_buffer_decode()

reserved_bool2

lzma_bool reserved_bool2

Reserved member.

reserved_bool3

lzma_bool reserved_bool3

Reserved member.

reserved_bool4

lzma_bool reserved_bool4

Reserved member.

reserved_bool5

lzma_bool reserved_bool5

Reserved member.

reserved_bool6

lzma_bool reserved_bool6

Reserved member.

reserved_bool7

lzma_bool reserved_bool7

Reserved member.

reserved_bool8

lzma_bool reserved_bool8

Reserved member.

reserved_enum1

lzma_reserved_enum reserved_enum1

Reserved member.

reserved_enum2

lzma_reserved_enum reserved_enum2

Reserved member.

reserved_enum3

lzma_reserved_enum reserved_enum3

Reserved member.

reserved_enum4

lzma_reserved_enum reserved_enum4

Reserved member.

reserved_int1

uint32_t reserved_int1

Reserved member.

reserved_int2

uint32_t reserved_int2

Reserved member.

reserved_int3

lzma_vli reserved_int3

Reserved member.

reserved_int4

lzma_vli reserved_int4

Reserved member.

reserved_int5

lzma_vli reserved_int5

Reserved member.

reserved_int6

lzma_vli reserved_int6

Reserved member.

reserved_int7

lzma_vli reserved_int7

Reserved member.

reserved_int8

lzma_vli reserved_int8

Reserved member.

reserved_ptr1

void * reserved_ptr1

Reserved member.

reserved_ptr2

void * reserved_ptr2

Reserved member.

reserved_ptr3

void * reserved_ptr3

Reserved member.

uncompressed_size

lzma_vli uncompressed_size

Uncompressed Size in bytes.

This is handled very similarly to compressed_size above.

uncompressed_size is needed by fewer functions than compressed_size. This is because uncompressed_size isn't needed to validate that Block stays within proper limits.

Read by:

• lzma_block_header_size()
• lzma_block_header_encode()
• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_decode()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_buffer_decode()

This is handled very similarly to compressed_size above.

uncompressed_size is needed by fewer functions than compressed_size. This is because uncompressed_size isn't needed to validate that Block stays within proper limits.

Read by:

• lzma_block_header_size()
• lzma_block_header_encode()
• lzma_block_decoder()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_decode()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_uncomp_encode()
• lzma_block_buffer_decode()

version

uint32_t version

Block format version.

To prevent API and ABI breakages when new features are needed, a version number is used to indicate which fields in this structure are in use:

• liblzma >= 5.0.0: version = 0 is supported.
• liblzma >= 5.1.4beta: Support for version = 1 was added, which adds the ignore_check field.

If version is greater than one, most Block related functions will return LZMA_OPTIONS_ERROR (lzma_block_header_decode() works with any version value).

Read by:

• All functions that take pointer to lzma_block as argument, including lzma_block_header_decode().

Written by:

• lzma_block_header_decode()

To prevent API and ABI breakages when new features are needed, a version number is used to indicate which members in this structure are in use:

• liblzma >= 5.0.0: version = 0 is supported.
• liblzma >= 5.1.4beta: Support for version = 1 was added, which adds the ignore_check member.

If version is greater than one, most Block related functions will return LZMA_OPTIONS_ERROR (lzma_block_header_decode() works with any version value).

Read by:

• lzma_block_header_size()
• lzma_block_header_encode()
• lzma_block_header_decode()
• lzma_block_compressed_size()
• lzma_block_unpadded_size()
• lzma_block_total_size()
• lzma_block_encoder()
• lzma_block_decoder()
• lzma_block_buffer_encode()
• lzma_block_uncomp_encode()
• lzma_block_buffer_decode()

Written by:

• lzma_block_header_decode()

---

The documentation for this struct was generated from the following files:

• C:/Pereira/Dua/source forge files my love/tar_dll/val/xcx_xz/xz-5.4.0/lzma/block.h
• C:/Pereira/Dua/source forge files my love/tar_dll/val/xcx_xz/xz-5.4.0/xz-5.4.0/src/liblzma/api/lzma/block.h
• C:/Pereira/Dua/source forge files my love/tar_dll/val/xcx_xz/xz-5.4.1/lzma/block.h
• C:/Pereira/Dua/source forge files my love/tar_dll/val/xcx_xz/xz-5.4.1/xz-5.4.1/src/liblzma/api/lzma/block.h
• C:/Pereira/Dua/source forge files my love/tar_dll/val/xcx_xz/xz-5.6.2/lzma/block.h
• C:/Pereira/Dua/source forge files my love/tar_dll/val/xcx_xz/xz-5.6.2/xz-5.6.2/src/liblzma/api/lzma/block.h