2 * \file lzma/index_hash.h
3 * \brief Validates Index by using a hash function
5 * Instead of constructing complete Index while decoding Blocks, Index hash
6 * calculates a hash of the Block sizes and Index, and then compares the
7 * hashes. This way memory usage is constant even with large number of
8 * Blocks and huge Index.
10 * \author Copyright (C) 2008 Lasse Collin
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
17 * This library is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
23 #ifndef LZMA_H_INTERNAL
24 # error Never include this file directly. Use <lzma.h> instead.
28 * \brief Opaque data type to hold the Index hash
30 typedef struct lzma_index_hash_s lzma_index_hash;
34 * \brief Allocate and initialize a new lzma_index_hash structure
36 * If index_hash is NULL, a new lzma_index_hash structure is allocated,
37 * initialized, and a pointer to it returned. If allocation fails, NULL
40 * If index_hash is non-NULL, it is reinitialized and the same pointer
41 * returned. In this case, return value cannot be NULL or a different
42 * pointer than the index_hash that was given as an argument.
44 extern LZMA_API(lzma_index_hash *) lzma_index_hash_init(
45 lzma_index_hash *index_hash, lzma_allocator *allocator)
46 lzma_attr_warn_unused_result;
50 * \brief Deallocate lzma_index_hash structure
52 extern LZMA_API(void) lzma_index_hash_end(
53 lzma_index_hash *index_hash, lzma_allocator *allocator);
57 * \brief Add a new Record to an Index hash
59 * \param index Pointer to a lzma_index_hash structure
60 * \param unpadded_size Unpadded Size of a Block
61 * \param uncompressed_size Uncompressed Size of a Block
64 * - LZMA_DATA_ERROR: Compressed or uncompressed size of the
65 * Stream or size of the Index field would grow too big.
66 * - LZMA_PROG_ERROR: Invalid arguments or this function is being
67 * used when lzma_index_hash_decode() has already been used.
69 extern LZMA_API(lzma_ret) lzma_index_hash_append(lzma_index_hash *index_hash,
70 lzma_vli unpadded_size, lzma_vli uncompressed_size)
71 lzma_attr_warn_unused_result;
75 * \brief Decode and validate the Index field
77 * After telling the sizes of all Blocks with lzma_index_hash_append(),
78 * the actual Index field is decoded with this function. Specifically,
79 * once decoding of the Index field has been started, no more Records
80 * can be added using lzma_index_hash_append().
82 * This function doesn't use lzma_stream structure to pass the input data.
83 * Instead, the input buffer is specified using three arguments. This is
84 * because it matches better the internal APIs of liblzma.
86 * \param index_hash Pointer to a lzma_index_hash structure
87 * \param in Pointer to the beginning of the input buffer
88 * \param in_pos in[*in_pos] is the next byte to process
89 * \param in_size in[in_size] is the first byte not to process
91 * \return - LZMA_OK: So far good, but more input is needed.
92 * - LZMA_STREAM_END: Index decoded successfully and it matches
93 * the Records given with lzma_index_hash_append().
94 * - LZMA_DATA_ERROR: Index is corrupt or doesn't match the
95 * information given with lzma_index_hash_append().
96 * - LZMA_BUF_ERROR: Cannot progress because *in_pos >= in_size.
99 extern LZMA_API(lzma_ret) lzma_index_hash_decode(lzma_index_hash *index_hash,
100 const uint8_t *in, size_t *in_pos, size_t in_size)
101 lzma_attr_warn_unused_result;
105 * \brief Get the size of the Index field as bytes
107 * This is needed to verify the Backward Size field in the Stream Footer.
109 extern LZMA_API(lzma_vli) lzma_index_hash_size(
110 const lzma_index_hash *index_hash)