contrib/xz/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 size_t check_size = lzma_check_size(coder->block->check);
 121                 lzma_bufcpy(coder->check.buffer.u8, &coder->pos, check_size,
 122                                 out, out_pos, out_size);
 123                 if (coder->pos < check_size)
 124                         return LZMA_OK;
 125
 126                 memcpy(coder->block->raw_check, coder->check.buffer.u8,
 127                                 check_size);
 128                 return LZMA_STREAM_END;
 129         }
 130         }
 131
 132         return LZMA_PROG_ERROR;
 133 }
 134
 135
 136 static void
 137 block_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
 138 {
 139         lzma_next_end(&coder->next, allocator);
 140         lzma_free(coder, allocator);
 141         return;
 142 }
 143
 144
 145 static lzma_ret
 146 block_encoder_update(lzma_coder *coder, lzma_allocator *allocator,
 147                 const lzma_filter *filters lzma_attribute((unused)),
 148                 const lzma_filter *reversed_filters)
 149 {
 150         if (coder->sequence != SEQ_CODE)
 151                 return LZMA_PROG_ERROR;
 152
 153         return lzma_next_filter_update(
 154                         &coder->next, allocator, reversed_filters);
 155 }
 156
 157
 158 extern lzma_ret
 159 lzma_block_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 160                 lzma_block *block)
 161 {
 162         lzma_next_coder_init(&lzma_block_encoder_init, next, allocator);
 163
 164         if (block->version != 0)
 165                 return LZMA_OPTIONS_ERROR;
 166
 167         // If the Check ID is not supported, we cannot calculate the check and
 168         // thus not create a proper Block.
 169         if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
 170                 return LZMA_PROG_ERROR;
 171
 172         if (!lzma_check_is_supported(block->check))
 173                 return LZMA_UNSUPPORTED_CHECK;
 174
 175         // Allocate and initialize *next->coder if needed.
 176         if (next->coder == NULL) {
 177                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
 178                 if (next->coder == NULL)
 179                         return LZMA_MEM_ERROR;
 180
 181                 next->code = &block_encode;
 182                 next->end = &block_encoder_end;
 183                 next->update = &block_encoder_update;
 184                 next->coder->next = LZMA_NEXT_CODER_INIT;
 185         }
 186
 187         // Basic initializations
 188         next->coder->sequence = SEQ_CODE;
 189         next->coder->block = block;
 190         next->coder->compressed_size = 0;
 191         next->coder->uncompressed_size = 0;
 192         next->coder->pos = 0;
 193
 194         // Initialize the check
 195         lzma_check_init(&next->coder->check, block->check);
 196
 197         // Initialize the requested filters.
 198         return lzma_raw_encoder_init(&next->coder->next, allocator,
 199                         block->filters);
 200 }
 201
 202
 203 extern LZMA_API(lzma_ret)
 204 lzma_block_encoder(lzma_stream *strm, lzma_block *block)
 205 {
 206         lzma_next_strm_init(lzma_block_encoder_init, strm, block);
 207
 208         strm->internal->supported_actions[LZMA_RUN] = true;
 209         strm->internal->supported_actions[LZMA_FINISH] = true;
 210
 211         return LZMA_OK;
 212 }