src/liblzma/common/block_encoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       block_encoder.c
   4 /// \brief      Encodes .xz Blocks
   5 //
   6 //  Copyright (C) 2007 Lasse Collin
   7 //
   8 //  This library is free software; you can redistribute it and/or
   9 //  modify it under the terms of the GNU Lesser General Public
  10 //  License as published by the Free Software Foundation; either
  11 //  version 2.1 of the License, or (at your option) any later version.
  12 //
  13 //  This library is distributed in the hope that it will be useful,
  14 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 //  Lesser General Public License for more details.
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #include "block_encoder.h"
  21 #include "filter_encoder.h"
  22 #include "check.h"
  23
  24
  25 struct lzma_coder_s {
  26         /// The filters in the chain; initialized with lzma_raw_decoder_init().
  27         lzma_next_coder next;
  28
  29         /// Encoding options; we also write Unpadded Size, Compressed Size,
  30         /// and Uncompressed Size back to this structure when the encoding
  31         /// has been finished.
  32         lzma_block *block;
  33
  34         enum {
  35                 SEQ_CODE,
  36                 SEQ_PADDING,
  37                 SEQ_CHECK,
  38         } sequence;
  39
  40         /// Compressed Size calculated while encoding
  41         lzma_vli compressed_size;
  42
  43         /// Uncompressed Size calculated while encoding
  44         lzma_vli uncompressed_size;
  45
  46         /// Position in the Check field
  47         size_t pos;
  48
  49         /// Check of the uncompressed data
  50         lzma_check_state check;
  51 };
  52
  53
  54 static lzma_ret
  55 block_encode(lzma_coder *coder, lzma_allocator *allocator,
  56                 const uint8_t *restrict in, size_t *restrict in_pos,
  57                 size_t in_size, uint8_t *restrict out,
  58                 size_t *restrict out_pos, size_t out_size, lzma_action action)
  59 {
  60         // Check that our amount of input stays in proper limits.
  61         if (LZMA_VLI_MAX - coder->uncompressed_size < in_size - *in_pos)
  62                 return LZMA_DATA_ERROR;
  63
  64         switch (coder->sequence) {
  65         case SEQ_CODE: {
  66                 const size_t in_start = *in_pos;
  67                 const size_t out_start = *out_pos;
  68
  69                 const lzma_ret ret = coder->next.code(coder->next.coder,
  70                                 allocator, in, in_pos, in_size,
  71                                 out, out_pos, out_size, action);
  72
  73                 const size_t in_used = *in_pos - in_start;
  74                 const size_t out_used = *out_pos - out_start;
  75
  76                 if (COMPRESSED_SIZE_MAX - coder->compressed_size < out_used)
  77                         return LZMA_DATA_ERROR;
  78
  79                 coder->compressed_size += out_used;
  80
  81                 // No need to check for overflow because we have already
  82                 // checked it at the beginning of this function.
  83                 coder->uncompressed_size += in_used;
  84
  85                 lzma_check_update(&coder->check, coder->block->check,
  86                                 in + in_start, in_used);
  87
  88                 if (ret != LZMA_STREAM_END || action == LZMA_SYNC_FLUSH)
  89                         return ret;
  90
  91                 assert(*in_pos == in_size);
  92                 assert(action == LZMA_FINISH);
  93
  94                 // Copy the values into coder->block. The caller
  95                 // may use this information to construct Index.
  96                 coder->block->compressed_size = coder->compressed_size;
  97                 coder->block->uncompressed_size = coder->uncompressed_size;
  98
  99                 coder->sequence = SEQ_PADDING;
 100         }
 101
 102         // Fall through
 103
 104         case SEQ_PADDING:
 105                 // Pad Compressed Data to a multiple of four bytes. We can
 106                 // use coder->compressed_size for this since we don't need
 107                 // it for anything else anymore.
 108                 while (coder->compressed_size & 3) {
 109                         if (*out_pos >= out_size)
 110                                 return LZMA_OK;
 111
 112                         out[*out_pos] = 0x00;
 113                         ++*out_pos;
 114                         ++coder->compressed_size;
 115                 }
 116
 117                 if (coder->block->check == LZMA_CHECK_NONE)
 118                         return LZMA_STREAM_END;
 119
 120                 lzma_check_finish(&coder->check, coder->block->check);
 121
 122                 coder->sequence = SEQ_CHECK;
 123
 124         // Fall through
 125
 126         case SEQ_CHECK: {
 127                 const uint32_t check_size
 128                                 = lzma_check_size(coder->block->check);
 129
 130                 while (*out_pos < out_size) {
 131                         out[*out_pos] = coder->check.buffer.u8[coder->pos];
 132                         ++*out_pos;
 133
 134                         if (++coder->pos == check_size)
 135                                 return LZMA_STREAM_END;
 136                 }
 137
 138                 return LZMA_OK;
 139         }
 140         }
 141
 142         return LZMA_PROG_ERROR;
 143 }
 144
 145
 146 static void
 147 block_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
 148 {
 149         lzma_next_end(&coder->next, allocator);
 150         lzma_free(coder, allocator);
 151         return;
 152 }
 153
 154
 155 extern lzma_ret
 156 lzma_block_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 157                 lzma_block *block)
 158 {
 159         lzma_next_coder_init(lzma_block_encoder_init, next, allocator);
 160
 161         if (block->version != 0)
 162                 return LZMA_OPTIONS_ERROR;
 163
 164         // If the Check ID is not supported, we cannot calculate the check and
 165         // thus not create a proper Block.
 166         if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
 167                 return LZMA_PROG_ERROR;
 168
 169         if (!lzma_check_is_supported(block->check))
 170                 return LZMA_UNSUPPORTED_CHECK;
 171
 172         // Allocate and initialize *next->coder if needed.
 173         if (next->coder == NULL) {
 174                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
 175                 if (next->coder == NULL)
 176                         return LZMA_MEM_ERROR;
 177
 178                 next->code = &block_encode;
 179                 next->end = &block_encoder_end;
 180                 next->coder->next = LZMA_NEXT_CODER_INIT;
 181         }
 182
 183         // Basic initializations
 184         next->coder->sequence = SEQ_CODE;
 185         next->coder->block = block;
 186         next->coder->compressed_size = 0;
 187         next->coder->uncompressed_size = 0;
 188         next->coder->pos = 0;
 189
 190         // Initialize the check
 191         lzma_check_init(&next->coder->check, block->check);
 192
 193         // Initialize the requested filters.
 194         return lzma_raw_encoder_init(&next->coder->next, allocator,
 195                         block->filters);
 196 }
 197
 198
 199 extern LZMA_API(lzma_ret)
 200 lzma_block_encoder(lzma_stream *strm, lzma_block *block)
 201 {
 202         lzma_next_strm_init(lzma_block_encoder_init, strm, block);
 203
 204         strm->internal->supported_actions[LZMA_RUN] = true;
 205         strm->internal->supported_actions[LZMA_FINISH] = true;
 206
 207         return LZMA_OK;
 208 }