src/liblzma/common/stream_buffer_encoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       stream_buffer_encoder.c
   4 /// \brief      Single-call .xz Stream encoder
   5 //
   6 //  Author:     Lasse Collin
   7 //
   8 //  This file has been put into the public domain.
   9 //  You can do whatever you want with this file.
  10 //
  11 ///////////////////////////////////////////////////////////////////////////////
  12
  13 #include "common.h"
  14 #include "index.h"
  15
  16
  17 /// Maximum size of Index that has exactly one Record.
  18 /// Index Indicator + Number of Records + Record + CRC32 rounded up to
  19 /// the next multiple of four.
  20 #define INDEX_BOUND ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3)
  21
  22 /// Stream Header, Stream Footer, and Index
  23 #define HEADERS_BOUND (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND)
  24
  25
  26 extern LZMA_API(size_t)
  27 lzma_stream_buffer_bound(size_t uncompressed_size)
  28 {
  29         // Get the maximum possible size of a Block.
  30         const size_t block_bound = lzma_block_buffer_bound(uncompressed_size);
  31         if (block_bound == 0)
  32                 return 0;
  33
  34         // Catch the possible integer overflow and also prevent the size of
  35         // the Stream exceeding LZMA_VLI_MAX (theoretically possible on
  36         // 64-bit systems).
  37         if (my_min(SIZE_MAX, LZMA_VLI_MAX) - block_bound < HEADERS_BOUND)
  38                 return 0;
  39
  40         return block_bound + HEADERS_BOUND;
  41 }
  42
  43
  44 extern LZMA_API(lzma_ret)
  45 lzma_stream_buffer_encode(lzma_filter *filters, lzma_check check,
  46                 const lzma_allocator *allocator,
  47                 const uint8_t *in, size_t in_size,
  48                 uint8_t *out, size_t *out_pos_ptr, size_t out_size)
  49 {
  50         // Sanity checks
  51         if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX
  52                         || (in == NULL && in_size != 0) || out == NULL
  53                         || out_pos_ptr == NULL || *out_pos_ptr > out_size)
  54                 return LZMA_PROG_ERROR;
  55
  56         if (!lzma_check_is_supported(check))
  57                 return LZMA_UNSUPPORTED_CHECK;
  58
  59         // Note for the paranoids: Index encoder prevents the Stream from
  60         // getting too big and still being accepted with LZMA_OK, and Block
  61         // encoder catches if the input is too big. So we don't need to
  62         // separately check if the buffers are too big.
  63
  64         // Use a local copy. We update *out_pos_ptr only if everything
  65         // succeeds.
  66         size_t out_pos = *out_pos_ptr;
  67
  68         // Check that there's enough space for both Stream Header and
  69         // Stream Footer.
  70         if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
  71                 return LZMA_BUF_ERROR;
  72
  73         // Reserve space for Stream Footer so we don't need to check for
  74         // available space again before encoding Stream Footer.
  75         out_size -= LZMA_STREAM_HEADER_SIZE;
  76
  77         // Encode the Stream Header.
  78         lzma_stream_flags stream_flags = {
  79                 .version = 0,
  80                 .check = check,
  81         };
  82
  83         if (lzma_stream_header_encode(&stream_flags, out + out_pos)
  84                         != LZMA_OK)
  85                 return LZMA_PROG_ERROR;
  86
  87         out_pos += LZMA_STREAM_HEADER_SIZE;
  88
  89         // Encode a Block but only if there is at least one byte of input.
  90         lzma_block block = {
  91                 .version = 0,
  92                 .check = check,
  93                 .filters = filters,
  94         };
  95
  96         if (in_size > 0)
  97                 return_if_error(lzma_block_buffer_encode(&block, allocator,
  98                                 in, in_size, out, &out_pos, out_size));
  99
 100         // Index
 101         {
 102                 // Create an Index. It will have one Record if there was
 103                 // at least one byte of input to encode. Otherwise the
 104                 // Index will be empty.
 105                 lzma_index *i = lzma_index_init(allocator);
 106                 if (i == NULL)
 107                         return LZMA_MEM_ERROR;
 108
 109                 lzma_ret ret = LZMA_OK;
 110
 111                 if (in_size > 0)
 112                         ret = lzma_index_append(i, allocator,
 113                                         lzma_block_unpadded_size(&block),
 114                                         block.uncompressed_size);
 115
 116                 // If adding the Record was successful, encode the Index
 117                 // and get its size which will be stored into Stream Footer.
 118                 if (ret == LZMA_OK) {
 119                         ret = lzma_index_buffer_encode(
 120                                         i, out, &out_pos, out_size);
 121
 122                         stream_flags.backward_size = lzma_index_size(i);
 123                 }
 124
 125                 lzma_index_end(i, allocator);
 126
 127                 if (ret != LZMA_OK)
 128                         return ret;
 129         }
 130
 131         // Stream Footer. We have already reserved space for this.
 132         if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
 133                         != LZMA_OK)
 134                 return LZMA_PROG_ERROR;
 135
 136         out_pos += LZMA_STREAM_HEADER_SIZE;
 137
 138         // Everything went fine, make the new output position available
 139         // to the application.
 140         *out_pos_ptr = out_pos;
 141         return LZMA_OK;
 142 }