src/liblzma/api/lzma/index_hash.h

   1 /**
   2  * \file        lzma/index_hash.h
   3  * \brief       Validate Index by using a hash function
   4  *
   5  * Hashing makes it possible to use constant amount of memory to validate
   6  * Index of arbitrary size.
   7  */
   8
   9 /*
  10  * Author: Lasse Collin
  11  *
  12  * This file has been put into the public domain.
  13  * You can do whatever you want with this file.
  14  *
  15  * See ../lzma.h for information about liblzma as a whole.
  16  */
  17
  18 #ifndef LZMA_H_INTERNAL
  19 #       error Never include this file directly. Use <lzma.h> instead.
  20 #endif
  21
  22 /**
  23  * \brief       Opaque data type to hold the Index hash
  24  */
  25 typedef struct lzma_index_hash_s lzma_index_hash;
  26
  27
  28 /**
  29  * \brief       Allocate and initialize a new lzma_index_hash structure
  30  *
  31  * If index_hash is NULL, a new lzma_index_hash structure is allocated,
  32  * initialized, and a pointer to it returned. If allocation fails, NULL
  33  * is returned.
  34  *
  35  * If index_hash is non-NULL, it is reinitialized and the same pointer
  36  * returned. In this case, return value cannot be NULL or a different
  37  * pointer than the index_hash that was given as an argument.
  38  */
  39 extern LZMA_API(lzma_index_hash *) lzma_index_hash_init(
  40                 lzma_index_hash *index_hash, const lzma_allocator *allocator)
  41                 lzma_nothrow lzma_attr_warn_unused_result;
  42
  43
  44 /**
  45  * \brief       Deallocate lzma_index_hash structure
  46  */
  47 extern LZMA_API(void) lzma_index_hash_end(
  48                 lzma_index_hash *index_hash, const lzma_allocator *allocator)
  49                 lzma_nothrow;
  50
  51
  52 /**
  53  * \brief       Add a new Record to an Index hash
  54  *
  55  * \param       index             Pointer to a lzma_index_hash structure
  56  * \param       unpadded_size     Unpadded Size of a Block
  57  * \param       uncompressed_size Uncompressed Size of a Block
  58  *
  59  * \return      - LZMA_OK
  60  *              - LZMA_DATA_ERROR: Compressed or uncompressed size of the
  61  *                Stream or size of the Index field would grow too big.
  62  *              - LZMA_PROG_ERROR: Invalid arguments or this function is being
  63  *                used when lzma_index_hash_decode() has already been used.
  64  */
  65 extern LZMA_API(lzma_ret) lzma_index_hash_append(lzma_index_hash *index_hash,
  66                 lzma_vli unpadded_size, lzma_vli uncompressed_size)
  67                 lzma_nothrow lzma_attr_warn_unused_result;
  68
  69
  70 /**
  71  * \brief       Decode and validate the Index field
  72  *
  73  * After telling the sizes of all Blocks with lzma_index_hash_append(),
  74  * the actual Index field is decoded with this function. Specifically,
  75  * once decoding of the Index field has been started, no more Records
  76  * can be added using lzma_index_hash_append().
  77  *
  78  * This function doesn't use lzma_stream structure to pass the input data.
  79  * Instead, the input buffer is specified using three arguments. This is
  80  * because it matches better the internal APIs of liblzma.
  81  *
  82  * \param       index_hash      Pointer to a lzma_index_hash structure
  83  * \param       in              Pointer to the beginning of the input buffer
  84  * \param       in_pos          in[*in_pos] is the next byte to process
  85  * \param       in_size         in[in_size] is the first byte not to process
  86  *
  87  * \return      - LZMA_OK: So far good, but more input is needed.
  88  *              - LZMA_STREAM_END: Index decoded successfully and it matches
  89  *                the Records given with lzma_index_hash_append().
  90  *              - LZMA_DATA_ERROR: Index is corrupt or doesn't match the
  91  *                information given with lzma_index_hash_append().
  92  *              - LZMA_BUF_ERROR: Cannot progress because *in_pos >= in_size.
  93  *              - LZMA_PROG_ERROR
  94  */
  95 extern LZMA_API(lzma_ret) lzma_index_hash_decode(lzma_index_hash *index_hash,
  96                 const uint8_t *in, size_t *in_pos, size_t in_size)
  97                 lzma_nothrow lzma_attr_warn_unused_result;
  98
  99
 100 /**
 101  * \brief       Get the size of the Index field as bytes
 102  *
 103  * This is needed to verify the Backward Size field in the Stream Footer.
 104  */
 105 extern LZMA_API(lzma_vli) lzma_index_hash_size(
 106                 const lzma_index_hash *index_hash)
 107                 lzma_nothrow lzma_attr_pure;