XZ Utils  5.2.9
Typedefs | Functions
index_hash.h File Reference

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

Typedefs

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

Functions

lzma_index_hashlzma_index_hash_init (lzma_index_hash *index_hash, const lzma_allocator *allocator) lzma_nothrow lzma_attr_warn_unused_result
 Allocate and initialize a new lzma_index_hash structure. More...
 
void lzma_index_hash_end (lzma_index_hash *index_hash, const lzma_allocator *allocator) lzma_nothrow
 Deallocate lzma_index_hash structure. More...
 
lzma_ret lzma_index_hash_append (lzma_index_hash *index_hash, lzma_vli unpadded_size, lzma_vli uncompressed_size) lzma_nothrow lzma_attr_warn_unused_result
 Add a new Record to an Index hash. More...
 
lzma_ret lzma_index_hash_decode (lzma_index_hash *index_hash, const uint8_t *in, size_t *in_pos, size_t in_size) lzma_nothrow lzma_attr_warn_unused_result
 Decode and validate the Index field. More...
 
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...
 

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.

Typedef Documentation

◆ lzma_index_hash

Opaque data type to hold the Index hash.

Function Documentation

◆ lzma_index_hash_init()

lzma_index_hash* lzma_index_hash_init ( lzma_index_hash index_hash,
const lzma_allocator allocator 
)

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_index_hash_end()

void lzma_index_hash_end ( lzma_index_hash index_hash,
const lzma_allocator allocator 
)

Deallocate lzma_index_hash structure.

◆ lzma_index_hash_append()

lzma_ret lzma_index_hash_append ( lzma_index_hash index_hash,
lzma_vli  unpadded_size,
lzma_vli  uncompressed_size 
)

Add a new Record to an Index hash.

Parameters
index_hashPointer to a lzma_index_hash structure
unpadded_sizeUnpadded Size of a Block
uncompressed_sizeUncompressed 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.

◆ lzma_index_hash_decode()

lzma_ret lzma_index_hash_decode ( lzma_index_hash index_hash,
const uint8_t *  in,
size_t *  in_pos,
size_t  in_size 
)

Decode and validate the Index field.

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_hashPointer to a lzma_index_hash structure
inPointer to the beginning of the input buffer
in_posin[*in_pos] is the next byte to process
in_sizein[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

References hash_append(), index_size_unpadded(), LZMA_BUF_ERROR, lzma_check_finish(), LZMA_DATA_ERROR, LZMA_OK, LZMA_STREAM_END, LZMA_VLI_C, lzma_vli_decode(), UNPADDED_SIZE_MAX, and UNPADDED_SIZE_MIN.

◆ lzma_index_hash_size()

lzma_vli lzma_index_hash_size ( const lzma_index_hash index_hash)

Get the size of the Index field as bytes.

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

References index_size().