src/liblzma/common/block_encoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       block_encoder.c
   4 /// \brief      Encodes .xz Blocks
   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 "block_encoder.h"
  14 #include "filter_encoder.h"
  15 #include "check.h"
  16
  17
  18 struct lzma_coder_s {
  19         /// The filters in the chain; initialized with lzma_raw_decoder_init().
  20         lzma_next_coder next;
  21
  22         /// Encoding options; we also write Unpadded Size, Compressed Size,
  23         /// and Uncompressed Size back to this structure when the encoding
  24         /// has been finished.
  25         lzma_block *block;
  26
  27         enum {
  28                 SEQ_CODE,
  29                 SEQ_PADDING,
  30                 SEQ_CHECK,
  31         } sequence;
  32
  33         /// Compressed Size calculated while encoding
  34         lzma_vli compressed_size;
  35
  36         /// Uncompressed Size calculated while encoding
  37         lzma_vli uncompressed_size;
  38
  39         /// Position in the Check field
  40         size_t pos;
  41
  42         /// Check of the uncompressed data
  43         lzma_check_state check;
  44 };
  45
  46
  47 static lzma_ret
  48 block_encode(lzma_coder *coder, lzma_allocator *allocator,
  49                 const uint8_t *restrict in, size_t *restrict in_pos,
  50                 size_t in_size, uint8_t *restrict out,
  51                 size_t *restrict out_pos, size_t out_size, lzma_action action)
  52 {
  53         // Check that our amount of input stays in proper limits.
  54         if (LZMA_VLI_MAX - coder->uncompressed_size < in_size - *in_pos)
  55                 return LZMA_DATA_ERROR;
  56
  57         switch (coder->sequence) {
  58         case SEQ_CODE: {
  59                 const size_t in_start = *in_pos;
  60                 const size_t out_start = *out_pos;
  61
  62                 const lzma_ret ret = coder->next.code(coder->next.coder,
  63                                 allocator, in, in_pos, in_size,
  64                                 out, out_pos, out_size, action);
  65
  66                 const size_t in_used = *in_pos - in_start;
  67                 const size_t out_used = *out_pos - out_start;
  68
  69                 if (COMPRESSED_SIZE_MAX - coder->compressed_size < out_used)
  70                         return LZMA_DATA_ERROR;
  71
  72                 coder->compressed_size += out_used;
  73
  74                 // No need to check for overflow because we have already
  75                 // checked it at the beginning of this function.
  76                 coder->uncompressed_size += in_used;
  77
  78                 lzma_check_update(&coder->check, coder->block->check,
  79                                 in + in_start, in_used);
  80
  81                 if (ret != LZMA_STREAM_END || action == LZMA_SYNC_FLUSH)
  82                         return ret;
  83
  84                 assert(*in_pos == in_size);
  85                 assert(action == LZMA_FINISH);
  86
  87                 // Copy the values into coder->block. The caller
  88                 // may use this information to construct Index.
  89                 coder->block->compressed_size = coder->compressed_size;
  90                 coder->block->uncompressed_size = coder->uncompressed_size;
  91
  92                 coder->sequence = SEQ_PADDING;
  93         }
  94
  95         // Fall through
  96
  97         case SEQ_PADDING:
  98                 // Pad Compressed Data to a multiple of four bytes. We can
  99                 // use coder->compressed_size for this since we don't need
 100                 // it for anything else anymore.
 101                 while (coder->compressed_size & 3) {
 102                         if (*out_pos >= out_size)
 103                                 return LZMA_OK;
 104
 105                         out[*out_pos] = 0x00;
 106                         ++*out_pos;
 107                         ++coder->compressed_size;
 108                 }
 109
 110                 if (coder->block->check == LZMA_CHECK_NONE)
 111                         return LZMA_STREAM_END;
 112
 113                 lzma_check_finish(&coder->check, coder->block->check);
 114
 115                 coder->sequence = SEQ_CHECK;
 116
 117         // Fall through
 118
 119         case SEQ_CHECK: {
 120                 const uint32_t check_size
 121                                 = lzma_check_size(coder->block->check);
 122
 123                 while (*out_pos < out_size) {
 124                         out[*out_pos] = coder->check.buffer.u8[coder->pos];
 125                         ++*out_pos;
 126
 127                         if (++coder->pos == check_size)
 128                                 return LZMA_STREAM_END;
 129                 }
 130
 131                 return LZMA_OK;
 132         }
 133         }
 134
 135         return LZMA_PROG_ERROR;
 136 }
 137
 138
 139 static void
 140 block_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
 141 {
 142         lzma_next_end(&coder->next, allocator);
 143         lzma_free(coder, allocator);
 144         return;
 145 }
 146
 147
 148 extern lzma_ret
 149 lzma_block_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 150                 lzma_block *block)
 151 {
 152         lzma_next_coder_init(lzma_block_encoder_init, next, allocator);
 153
 154         if (block->version != 0)
 155                 return LZMA_OPTIONS_ERROR;
 156
 157         // If the Check ID is not supported, we cannot calculate the check and
 158         // thus not create a proper Block.
 159         if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
 160                 return LZMA_PROG_ERROR;
 161
 162         if (!lzma_check_is_supported(block->check))
 163                 return LZMA_UNSUPPORTED_CHECK;
 164
 165         // Allocate and initialize *next->coder if needed.
 166         if (next->coder == NULL) {
 167                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
 168                 if (next->coder == NULL)
 169                         return LZMA_MEM_ERROR;
 170
 171                 next->code = &block_encode;
 172                 next->end = &block_encoder_end;
 173                 next->coder->next = LZMA_NEXT_CODER_INIT;
 174         }
 175
 176         // Basic initializations
 177         next->coder->sequence = SEQ_CODE;
 178         next->coder->block = block;
 179         next->coder->compressed_size = 0;
 180         next->coder->uncompressed_size = 0;
 181         next->coder->pos = 0;
 182
 183         // Initialize the check
 184         lzma_check_init(&next->coder->check, block->check);
 185
 186         // Initialize the requested filters.
 187         return lzma_raw_encoder_init(&next->coder->next, allocator,
 188                         block->filters);
 189 }
 190
 191
 192 extern LZMA_API(lzma_ret)
 193 lzma_block_encoder(lzma_stream *strm, lzma_block *block)
 194 {
 195         lzma_next_strm_init(lzma_block_encoder_init, strm, block);
 196
 197         strm->internal->supported_actions[LZMA_RUN] = true;
 198         strm->internal->supported_actions[LZMA_FINISH] = true;
 199
 200         return LZMA_OK;
 201 }