| liblzma (XZ Utils) 5.6.1

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block.h File Reference

.xz Block handling More...

## Data Structures
struct | lzma_block
| Options for the Block and Block Header encoders and decoders. More...

## Macros
#define | LZMA_BLOCK_HEADER_SIZE_MIN 8
#define | LZMA_BLOCK_HEADER_SIZE_MAX 1024
#define | lzma_block_header_size_decode(b) (((uint32_t)(b) + 1) * 4)
| Decode the Block Header Size field.

## Functions
lzma_ret | lzma_block_header_size (lzma_block *block) lzma_nothrow lzma_attr_warn_unused_result
| Calculate Block Header Size.
lzma_ret | lzma_block_header_encode (const lzma_block *block, uint8_t *out) lzma_nothrow lzma_attr_warn_unused_result
| Encode Block Header.
lzma_ret | lzma_block_header_decode (lzma_block *block, const lzma_allocator *allocator, const uint8_t *in) lzma_nothrow lzma_attr_warn_unused_result
| Decode Block Header.
lzma_ret | lzma_block_compressed_size (lzma_block *block, lzma_vli unpadded_size) lzma_nothrow lzma_attr_warn_unused_result
| Validate and set Compressed Size according to Unpadded Size.
lzma_vli | lzma_block_unpadded_size (const lzma_block *block) lzma_nothrow lzma_attr_pure
| Calculate Unpadded Size.
lzma_vli | lzma_block_total_size (const lzma_block *block) lzma_nothrow lzma_attr_pure
| Calculate the total encoded size of a Block.
lzma_ret | lzma_block_encoder (lzma_stream *strm, lzma_block *block) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .xz Block encoder.
lzma_ret | lzma_block_decoder (lzma_stream *strm, lzma_block *block) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .xz Block decoder.
size_t | lzma_block_buffer_bound (size_t uncompressed_size) lzma_nothrow
| Calculate maximum output size for single-call Block encoding.
lzma_ret | lzma_block_buffer_encode (lzma_block *block, 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 lzma_attr_warn_unused_result
| Single-call .xz Block encoder.
lzma_ret | lzma_block_uncomp_encode (lzma_block *block, const uint8_t *in, size_t in_size, uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow lzma_attr_warn_unused_result
| Single-call uncompressed .xz Block encoder.
lzma_ret | lzma_block_buffer_decode (lzma_block *block, 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
| Single-call .xz Block decoder.

## Detailed Description

.xz Block handling

Note
  Never include this file directly. Use <lzma.h> instead.

## Macro Definition Documentation

## ◆ lzma_block_header_size_decode

#define lzma_block_header_size_decode | ( |  | b | ) | (((uint32_t)(b) + 1) * 4)

Decode the Block Header Size field.

To decode Block Header using lzma_block_header_decode(), the size of the Block Header has to be known and stored into lzma_block.header_size. The size can be calculated from the first byte of a Block using this macro. Note that if the first byte is 0x00, it indicates beginning of Index; use this macro only when the byte is not 0x00.

There is no encoding macro because lzma_block_header_size() and lzma_block_header_encode() should be used.

## Function Documentation

## ◆ lzma_block_header_size()

lzma_ret lzma_block_header_size | ( | lzma_block * | block | ) |

Calculate Block Header Size.

Calculate the minimum size needed for the Block Header field using the settings specified in the lzma_block structure. Note that it is OK to increase the calculated header_size value as long as it is a multiple of four and doesn't exceed LZMA_BLOCK_HEADER_SIZE_MAX. Increasing header_size just means that lzma_block_header_encode() will add Header Padding.

Note
  This doesn't check that all the options are valid i.e. this may return LZMA_OK even if lzma_block_header_encode() or lzma_block_encoder() would fail. If you want to validate the filter chain, consider using lzma_memlimit_encoder() which as a side-effect validates the filter chain.

Parameters

  block | Block options

Returns
  Possible lzma_ret values:
  - LZMA_OK: Size calculated successfully and stored to block->header_size.
  - LZMA_OPTIONS_ERROR: Unsupported version, filters or filter options.
  - LZMA_PROG_ERROR: Invalid values like compressed_size == 0.

## ◆ lzma_block_header_encode()

lzma_ret lzma_block_header_encode | ( | const lzma_block * | block,
|  | uint8_t * | out
| ) |  |

Encode Block Header.

The caller must have calculated the size of the Block Header already with lzma_block_header_size(). If a value larger than the one calculated by lzma_block_header_size() is used, the Block Header will be padded to the specified size.

Parameters

  | block | Block options to be encoded.
  [out] | out | Beginning of the output buffer. This must be at least block->header_size bytes.

Returns
  Possible lzma_ret values:
  - LZMA_OK: Encoding was successful. block->header_size bytes were written to output buffer.
  - LZMA_OPTIONS_ERROR: Invalid or unsupported options.
  - LZMA_PROG_ERROR: Invalid arguments, for example block->header_size is invalid or block->filters is NULL.

## ◆ lzma_block_header_decode()

lzma_ret lzma_block_header_decode | ( | lzma_block * | block,
|  | const lzma_allocator * | allocator,
|  | const uint8_t * | in
| ) |  |

Decode Block Header.

block->version should (usually) be set to the highest value supported by the application. If the application sets block->version to a value higher than supported by the current liblzma version, this function will downgrade block->version to the highest value supported by it. Thus one should check the value of block->version after calling this function if block->version was set to a non-zero value and the application doesn't otherwise know that the liblzma version being used is new enough to support the specified block->version.

The size of the Block Header must have already been decoded with lzma_block_header_size_decode() macro and stored to block->header_size.

The integrity check type from Stream Header must have been stored to block->check.

block->filters must have been allocated, but they don't need to be initialized (possible existing filter options are not freed).

Parameters

  [out] | block | Destination for Block options
  | allocator | lzma_allocator for custom allocator functions. Set to NULL to use malloc() (and also free() if an error occurs).
  | in | Beginning of the input buffer. This must be at least block->header_size bytes.

Returns
  Possible lzma_ret values:
  - LZMA_OK: Decoding was successful. block->header_size bytes were read from the input buffer.
  - LZMA_OPTIONS_ERROR: The Block Header specifies some unsupported options such as unsupported filters. This can happen also if block->version was set to a too low value compared to what would be required to properly represent the information stored in the Block Header.
  - LZMA_DATA_ERROR: Block Header is corrupt, for example, the CRC32 doesn't match.
  - LZMA_PROG_ERROR: Invalid arguments, for example block->header_size is invalid or block->filters is NULL.

## ◆ lzma_block_compressed_size()

lzma_ret lzma_block_compressed_size | ( | lzma_block * | block,
|  | lzma_vli | unpadded_size
| ) |  |

Validate and set Compressed Size according to Unpadded Size.

Block Header stores Compressed Size, but Index has Unpadded Size. If the application has already parsed the Index and is now decoding Blocks, it can calculate Compressed Size from Unpadded Size. This function does exactly that with error checking:

- Compressed Size calculated from Unpadded Size must be positive integer, that is, Unpadded Size must be big enough that after Block Header and Check fields there's still at least one byte for Compressed Size.
- If Compressed Size was present in Block Header, the new value calculated from Unpadded Size is compared against the value from Block Header.

Note
  This function must be called _after_ decoding the Block Header field so that it can properly validate Compressed Size if it was present in Block Header.

Parameters

  block | Block options: block->header_size must already be set with lzma_block_header_size().
  unpadded_size | Unpadded Size from the Index field in bytes

Returns
  Possible lzma_ret values:
  - LZMA_OK: block->compressed_size was set successfully.
  - LZMA_DATA_ERROR: unpadded_size is too small compared to block->header_size and lzma_check_size(block->check).
  - LZMA_PROG_ERROR: Some values are invalid. For example, block->header_size must be a multiple of four and between 8 and 1024 inclusive.

## ◆ lzma_block_unpadded_size()

lzma_vli lzma_block_unpadded_size | ( | const lzma_block * | block | ) |

Calculate Unpadded Size.

The Index field stores Unpadded Size and Uncompressed Size. The latter can be taken directly from the lzma_block structure after coding a Block, but Unpadded Size needs to be calculated from Block Header Size, Compressed Size, and size of the Check field. This is where this function is needed.

Parameters

  block | Block options: block->header_size must already be set with lzma_block_header_size().

Returns
  Unpadded Size on success, or zero on error.

## ◆ lzma_block_total_size()

lzma_vli lzma_block_total_size | ( | const lzma_block * | block | ) |

Calculate the total encoded size of a Block.

This is equivalent to lzma_block_unpadded_size() except that the returned value includes the size of the Block Padding field.

Parameters

  block | Block options: block->header_size must already be set with lzma_block_header_size().

Returns
  On success, total encoded size of the Block. On error, zero is returned.

## ◆ lzma_block_encoder()

lzma_ret lzma_block_encoder | ( | lzma_stream * | strm,
|  | lzma_block * | block
| ) |  |

Initialize .xz Block encoder.

Valid actions for lzma_code() are LZMA_RUN, LZMA_SYNC_FLUSH (only if the filter chain supports it), and LZMA_FINISH.

The Block encoder encodes the Block Data, Block Padding, and Check value. It does NOT encode the Block Header which can be encoded with lzma_block_header_encode().

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  block | Block options: block->version, block->check, and block->filters must have been initialized.

Returns
  Possible lzma_ret values:
  - LZMA_OK: All good, continue with lzma_code().
  - LZMA_MEM_ERROR
  - LZMA_OPTIONS_ERROR
  - LZMA_UNSUPPORTED_CHECK: block->check specifies a Check ID that is not supported by this build of liblzma. Initializing the encoder failed.
  - LZMA_PROG_ERROR

## ◆ lzma_block_decoder()

lzma_ret lzma_block_decoder | ( | lzma_stream * | strm,
|  | lzma_block * | block
| ) |  |

Initialize .xz Block decoder.

Valid actions for lzma_code() are LZMA_RUN and LZMA_FINISH. Using LZMA_FINISH is not required. It is supported only for convenience.

The Block decoder decodes the Block Data, Block Padding, and Check value. It does NOT decode the Block Header which can be decoded with lzma_block_header_decode().

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  block | Block options

Returns
  Possible lzma_ret values:
  - LZMA_OK: All good, continue with lzma_code().
  - LZMA_PROG_ERROR
  - LZMA_MEM_ERROR

## ◆ lzma_block_buffer_bound()

size_t lzma_block_buffer_bound | ( | size_t | uncompressed_size | ) |

Calculate maximum output size for single-call Block encoding.

This is equivalent to lzma_stream_buffer_bound() but for .xz Blocks. See the documentation of lzma_stream_buffer_bound().

Parameters

  uncompressed_size | Size of the data to be encoded with the single-call Block encoder.

Returns
  Maximum output size in bytes for single-call Block encoding.

## ◆ lzma_block_buffer_encode()

lzma_ret lzma_block_buffer_encode | ( | lzma_block * | block,
|  | const lzma_allocator * | allocator,
|  | const uint8_t * | in,
|  | size_t | in_size,
|  | uint8_t * | out,
|  | size_t * | out_pos,
|  | size_t | out_size
| ) |  |

Single-call .xz Block encoder.

In contrast to the multi-call encoder initialized with lzma_block_encoder(), this function encodes also the Block Header. This is required to make it possible to write appropriate Block Header also in case the data isn't compressible, and different filter chain has to be used to encode the data in uncompressed form using uncompressed chunks of the LZMA2 filter.

When the data isn't compressible, header_size, compressed_size, and uncompressed_size are set just like when the data was compressible, but it is possible that header_size is too small to hold the filter chain specified in block->filters, because that isn't necessarily the filter chain that was actually used to encode the data. lzma_block_unpadded_size() still works normally, because it doesn't read the filters array.

Parameters

  | block | Block options: block->version, block->check, and block->filters must have been initialized.
  | allocator | lzma_allocator for custom allocator functions. Set to NULL to use malloc() and free().
  | in | Beginning of the input buffer
  | in_size | Size of the input buffer
  [out] | out | Beginning of the output buffer
  [out] | out_pos | The next byte will be written to out[*out_pos]. *out_pos is updated only if encoding succeeds.
  | out_size | Size of the out buffer; the first byte into which no data is written to is out[out_size].

Returns
  Possible lzma_ret values:
  - LZMA_OK: Encoding was successful.
  - LZMA_BUF_ERROR: Not enough output buffer space.
  - LZMA_UNSUPPORTED_CHECK
  - LZMA_OPTIONS_ERROR
  - LZMA_MEM_ERROR
  - LZMA_DATA_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_block_uncomp_encode()

lzma_ret lzma_block_uncomp_encode | ( | lzma_block * | block,
|  | const uint8_t * | in,
|  | size_t | in_size,
|  | uint8_t * | out,
|  | size_t * | out_pos,
|  | size_t | out_size
| ) |  |

Single-call uncompressed .xz Block encoder.

This is like lzma_block_buffer_encode() except this doesn't try to compress the data and instead encodes the data using LZMA2 uncompressed chunks. The required output buffer size can be determined with lzma_block_buffer_bound().

Since the data won't be compressed, this function ignores block->filters. This function doesn't take lzma_allocator because this function doesn't allocate any memory from the heap.

Parameters

  | block | Block options: block->version, block->check, and block->filters must have been initialized.
  | in | Beginning of the input buffer
  | in_size | Size of the input buffer
  [out] | out | Beginning of the output buffer
  [out] | out_pos | The next byte will be written to out[*out_pos]. *out_pos is updated only if encoding succeeds.
  | out_size | Size of the out buffer; the first byte into which no data is written to is out[out_size].

Returns
  Possible lzma_ret values:
  - LZMA_OK: Encoding was successful.
  - LZMA_BUF_ERROR: Not enough output buffer space.
  - LZMA_UNSUPPORTED_CHECK
  - LZMA_OPTIONS_ERROR
  - LZMA_MEM_ERROR
  - LZMA_DATA_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_block_buffer_decode()

lzma_ret lzma_block_buffer_decode | ( | lzma_block * | block,
|  | 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
| ) |  |

Single-call .xz Block decoder.

This is single-call equivalent of lzma_block_decoder(), and requires that the caller has already decoded Block Header and checked its memory usage.

Parameters

  | block | Block options
  | allocator | lzma_allocator for custom allocator functions. Set to NULL to use malloc() and free().
  | in | Beginning of the input buffer
  | in_pos | The next byte will be read from in[*in_pos]. *in_pos is updated only if decoding succeeds.
  | in_size | Size of the input buffer; the first byte that won't be read is in[in_size].
  [out] | out | Beginning of the output buffer
  [out] | out_pos | The next byte will be written to out[*out_pos]. *out_pos is updated only if encoding succeeds.
  | out_size | Size of the out buffer; the first byte into which no data is written to is out[out_size].

Returns
  Possible lzma_ret values:
  - LZMA_OK: Decoding was successful.
  - LZMA_OPTIONS_ERROR
  - LZMA_DATA_ERROR
  - LZMA_MEM_ERROR
  - LZMA_BUF_ERROR: Output buffer was too small.
  - LZMA_PROG_ERROR

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