index_hash.h File Reference

Validate Index by using a hash function. More...

Go to the source code of this file.

Typedefs
typedef struct lzma_index_hash_s	lzma_index_hash
	Opaque data type to hold the Index hash. More...

Functions
	LZMA_API (lzma_index_hash *) lzma_index_hash_init(lzma_index_hash *index_hash
	Allocate and initialize a new lzma_index_hash structure. More...
	LZMA_API (void) lzma_index_hash_end(lzma_index_hash *index_hash
	Deallocate lzma_index_hash structure. More...
	LZMA_API (lzma_ret) lzma_index_hash_append(lzma_index_hash *index_hash
	Add a new Record to an Index hash. More...
	LZMA_API (lzma_vli) lzma_index_hash_size(const lzma_index_hash *index_hash) lzma_nothrow lzma_attr_pure
	Get the size of the Index field as bytes. More...

Variables
const lzma_allocator *allocator lzma_nothrow	lzma_attr_warn_unused_result
const lzma_allocator *allocator	lzma_nothrow
lzma_vli	unpadded_size
const uint8_t *	in
const uint8_t size_t *	in_pos

Detailed Description

Validate Index by using a hash function.

Hashing makes it possible to use constant amount of memory to validate Index of arbitrary size.

Definition in file index_hash.h.

Typedef Documentation

lzma_index_hash

typedef struct lzma_index_hash_s lzma_index_hash

Opaque data type to hold the Index hash.

Definition at line 1 of file index_hash.h.

Function Documentation

LZMA_API() [1/4]

LZMA_API

(

lzma_index_hash *

)

Allocate and initialize a new lzma_index_hash structure.

If index_hash is NULL, a new lzma_index_hash structure is allocated, initialized, and a pointer to it returned. If allocation fails, NULL is returned.

If index_hash is non-NULL, it is reinitialized and the same pointer returned. In this case, return value cannot be NULL or a different pointer than the index_hash that was given as an argument.

LZMA_API() [2/4]

LZMA_API

(

lzma_ret

)

Add a new Record to an Index hash.

Decode and validate the Index field.

Parameters

index	Pointer to a lzma_index_hash structure
unpadded_size	Unpadded Size of a Block
uncompressed_size	Uncompressed Size of a Block

Returns

- LZMA_OK

• LZMA_DATA_ERROR: Compressed or uncompressed size of the Stream or size of the Index field would grow too big.
• LZMA_PROG_ERROR: Invalid arguments or this function is being used when lzma_index_hash_decode() has already been used.

After telling the sizes of all Blocks with lzma_index_hash_append(), the actual Index field is decoded with this function. Specifically, once decoding of the Index field has been started, no more Records can be added using lzma_index_hash_append().

This function doesn't use lzma_stream structure to pass the input data. Instead, the input buffer is specified using three arguments. This is because it matches better the internal APIs of liblzma.

Parameters

index_hash	Pointer to a lzma_index_hash structure
in	Pointer to the beginning of the input buffer
in_pos	in[*in_pos] is the next byte to process
in_size	in[in_size] is the first byte not to process

Returns

- LZMA_OK: So far good, but more input is needed.

• LZMA_STREAM_END: Index decoded successfully and it matches the Records given with lzma_index_hash_append().
• LZMA_DATA_ERROR: Index is corrupt or doesn't match the information given with lzma_index_hash_append().
• LZMA_BUF_ERROR: Cannot progress because *in_pos >= in_size.
• LZMA_PROG_ERROR

LZMA_API() [3/4]

LZMA_API

(

uint64_t

)

const

Get the size of the Index field as bytes.

This is needed to verify the Backward Size field in the Stream Footer.

Get the size of the Index field as bytes.

Calculate approximate memory requirements for raw encoder.

Calculate Unpadded Size.

Get the memory usage of decoder filter chain.

Calculate CRC64 using the polynomial from the ECMA-182 standard.

This function is used similarly to lzma_crc32(). See its documentation.

Definition at line 131 of file block_util.c.

{
    lzma_vli unpadded_size = lzma_block_unpadded_size(block);
 
    if (unpadded_size != LZMA_VLI_UNKNOWN)
        unpadded_size = vli_ceil4(unpadded_size);
 
    return unpadded_size;
}

LZMA_API() [4/4]

LZMA_API

(

void

)

Deallocate lzma_index_hash structure.

Variable Documentation

in

const uint8_t* in

Definition at line 96 of file index_hash.h.

in_pos

const uint8_t size_t* in_pos

Definition at line 96 of file index_hash.h.

lzma_attr_warn_unused_result

const uint8_t size_t size_t in_size lzma_nothrow lzma_attr_warn_unused_result

Definition at line 41 of file index_hash.h.

lzma_nothrow

const lzma_allocator* allocator lzma_nothrow

Definition at line 49 of file index_hash.h.

unpadded_size

lzma_vli unpadded_size

Definition at line 66 of file index_hash.h.