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/**
* \file lzma/index_hash.h
* \brief Validates Index by using a hash function
*
* Instead of constructing complete Index while decoding Blocks, Index hash
* calculates a hash of the Block sizes and Index, and then compares the
* hashes. This way memory usage is constant even with large number of
* Blocks and huge Index.
*
* \author Copyright (C) 2008 Lasse Collin
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
#ifndef LZMA_H_INTERNAL
# error Never include this file directly. Use <lzma.h> instead.
#endif
/**
* \brief Opaque data type to hold the Index hash
*/
typedef struct lzma_index_hash_s lzma_index_hash;
/**
* \brief 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.
*/
extern LZMA_API lzma_index_hash *lzma_index_hash_init(
lzma_index_hash *index_hash, lzma_allocator *allocator)
lzma_attr_warn_unused_result;
/**
* \brief Deallocate lzma_index_hash structure
*/
extern LZMA_API void lzma_index_hash_end(
lzma_index_hash *index_hash, lzma_allocator *allocator);
/**
* \brief Add a new Record to an Index hash
*
* \param index Pointer to a lzma_index_hash structure
* \param unpadded_size Unpadded Size of a Block
* \param uncompressed_size Uncompressed Size of a Block
*
* \return - 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.
*/
extern LZMA_API lzma_ret lzma_index_hash_append(lzma_index_hash *index_hash,
lzma_vli unpadded_size, lzma_vli uncompressed_size)
lzma_attr_warn_unused_result;
/**
* \brief 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.
*
* \param index_hash Pointer to a lzma_index_hash structure
* \param in Pointer to the beginning of the input buffer
* \param in_pos in[*in_pos] is the next byte to process
* \param in_size in[in_size] is the first byte not to process
*
* \return - 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
*/
extern LZMA_API lzma_ret lzma_index_hash_decode(lzma_index_hash *index_hash,
const uint8_t *in, size_t *in_pos, size_t in_size)
lzma_attr_warn_unused_result;
/**
* \brief Get the size of the Index field as bytes
*
* This is needed to verify the Backward Size field in the Stream Footer.
*/
extern LZMA_API lzma_vli lzma_index_hash_size(
const lzma_index_hash *index_hash)
lzma_attr_pure;
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