/tmp/buildd/xz-utils-5.0.0/src/liblzma/api/lzma/block.h File Reference

.xz Block handling More...

Data Structures
struct	lzma_block
	Options for the Block and Block Header encoders and decoders. More...
Defines
#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, 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, 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_buffer_decode (lzma_block *block, 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

---

Define Documentation

#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 Block Header encoder is enough for that.

Referenced by lzma_block_header_decode(), and parse_block_header().

---

Function Documentation

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.

Returns:

- 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.

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.

References lzma_filter_flags_size(), LZMA_FILTERS_MAX, lzma_vli_size(), LZMA_VLI_UNKNOWN, and return_if_error.

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:

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

Returns:

- 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.

References lzma_block_unpadded_size(), lzma_crc32(), lzma_filter_flags_encode(), LZMA_FILTERS_MAX, lzma_vli_encode(), lzma_vli_is_valid, LZMA_VLI_UNKNOWN, and return_if_error.

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

Decode Block Header.

block->version should be set to the highest value supported by the application; currently the only possible version is zero. This function will set version to the lowest value that still supports all the features required by the Block Header.

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

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

Parameters:

	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:

- 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.

References lzma_block_header_size_decode, lzma_block_unpadded_size(), LZMA_CHECK_ID_MAX, lzma_crc32(), lzma_filter_flags_decode(), LZMA_OK, lzma_vli_decode(), and return_if_error.

Referenced by parse_block_header().

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.

Returns:

- 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.

References lzma_block_unpadded_size(), lzma_check_size(), and LZMA_VLI_UNKNOWN.

Referenced by parse_block_header().

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.

Returns:

Unpadded Size on success, or zero on error.

References LZMA_CHECK_ID_MAX, lzma_check_size(), lzma_vli_is_valid, and LZMA_VLI_UNKNOWN.

Referenced by lzma_block_compressed_size(), lzma_block_header_decode(), lzma_block_header_encode(), lzma_block_total_size(), and lzma_stream_buffer_encode().

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.

Returns:

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

References lzma_block_unpadded_size(), and LZMA_VLI_UNKNOWN.

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.

Returns:

- 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 buid of liblzma. Initializing the encoder failed.
• LZMA_PROG_ERROR

References lzma_next_strm_init.

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.

Returns:

- LZMA_OK: All good, continue with lzma_code().

• LZMA_UNSUPPORTED_CHECK: Initialization was successful, but the given Check ID is not supported, thus Check will be ignored.
• LZMA_PROG_ERROR
• LZMA_MEM_ERROR

References lzma_next_strm_init.

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().

References HEADERS_BOUND, and LZMA_VLI_C.

Referenced by lzma_stream_buffer_bound().

lzma_ret lzma_block_buffer_encode	(	lzma_block *	block,
		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	Beginning of the output buffer
	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:

- 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

References lzma_check_state::buffer, check, LZMA_BUF_ERROR, lzma_check_finish(), lzma_check_init(), lzma_check_size(), lzma_check_update(), LZMA_OK, and return_if_error.

Referenced by lzma_stream_buffer_encode().

lzma_ret lzma_block_buffer_decode	(	lzma_block *	block,
		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 just like with lzma_block_decoder().
	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	Beginning of the output buffer
	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:

- 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

References lzma_next_coder_s::code, lzma_next_coder_s::coder, LZMA_FINISH, LZMA_OK, and LZMA_STREAM_END.