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 typedef struct {
  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 } lzma_block_coder;
  45
  46
  47 static lzma_ret
  48 block_encode(void *coder_ptr, const 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         lzma_block_coder *coder = coder_ptr;
  54
  55         // Check that our amount of input stays in proper limits.
  56         if (LZMA_VLI_MAX - coder->uncompressed_size < in_size - *in_pos)
  57                 return LZMA_DATA_ERROR;
  58
  59         switch (coder->sequence) {
  60         case SEQ_CODE: {
  61                 const size_t in_start = *in_pos;
  62                 const size_t out_start = *out_pos;
  63
  64                 const lzma_ret ret = coder->next.code(coder->next.coder,
  65                                 allocator, in, in_pos, in_size,
  66                                 out, out_pos, out_size, action);
  67
  68                 const size_t in_used = *in_pos - in_start;
  69                 const size_t out_used = *out_pos - out_start;
  70
  71                 if (COMPRESSED_SIZE_MAX - coder->compressed_size < out_used)
  72                         return LZMA_DATA_ERROR;
  73
  74                 coder->compressed_size += out_used;
  75
  76                 // No need to check for overflow because we have already
  77                 // checked it at the beginning of this function.
  78                 coder->uncompressed_size += in_used;
  79
  80                 // Call lzma_check_update() only if input was consumed. This
  81                 // avoids null pointer + 0 (undefined behavior) when in == 0.
  82                 if (in_used > 0)
  83                         lzma_check_update(&coder->check, coder->block->check,
  84                                         in + in_start, in_used);
  85
  86                 if (ret != LZMA_STREAM_END || action == LZMA_SYNC_FLUSH)
  87                         return ret;
  88
  89                 assert(*in_pos == in_size);
  90                 assert(action == LZMA_FINISH);
  91
  92                 // Copy the values into coder->block. The caller
  93                 // may use this information to construct Index.
  94                 coder->block->compressed_size = coder->compressed_size;
  95                 coder->block->uncompressed_size = coder->uncompressed_size;
  96
  97                 coder->sequence = SEQ_PADDING;
  98         }
  99
 100         // Fall through
 101
 102         case SEQ_PADDING:
 103                 // Pad Compressed Data to a multiple of four bytes. We can
 104                 // use coder->compressed_size for this since we don't need
 105                 // it for anything else anymore.
 106                 while (coder->compressed_size & 3) {
 107                         if (*out_pos >= out_size)
 108                                 return LZMA_OK;
 109
 110                         out[*out_pos] = 0x00;
 111                         ++*out_pos;
 112                         ++coder->compressed_size;
 113                 }
 114
 115                 if (coder->block->check == LZMA_CHECK_NONE)
 116                         return LZMA_STREAM_END;
 117
 118                 lzma_check_finish(&coder->check, coder->block->check);
 119
 120                 coder->sequence = SEQ_CHECK;
 121
 122         // Fall through
 123
 124         case SEQ_CHECK: {
 125                 const size_t check_size = lzma_check_size(coder->block->check);
 126                 lzma_bufcpy(coder->check.buffer.u8, &coder->pos, check_size,
 127                                 out, out_pos, out_size);
 128                 if (coder->pos < check_size)
 129                         return LZMA_OK;
 130
 131                 memcpy(coder->block->raw_check, coder->check.buffer.u8,
 132                                 check_size);
 133                 return LZMA_STREAM_END;
 134         }
 135         }
 136
 137         return LZMA_PROG_ERROR;
 138 }
 139
 140
 141 static void
 142 block_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
 143 {
 144         lzma_block_coder *coder = coder_ptr;
 145         lzma_next_end(&coder->next, allocator);
 146         lzma_free(coder, allocator);
 147         return;
 148 }
 149
 150
 151 static lzma_ret
 152 block_encoder_update(void *coder_ptr, const lzma_allocator *allocator,
 153                 const lzma_filter *filters lzma_attribute((__unused__)),
 154                 const lzma_filter *reversed_filters)
 155 {
 156         lzma_block_coder *coder = coder_ptr;
 157
 158         if (coder->sequence != SEQ_CODE)
 159                 return LZMA_PROG_ERROR;
 160
 161         return lzma_next_filter_update(
 162                         &coder->next, allocator, reversed_filters);
 163 }
 164
 165
 166 extern lzma_ret
 167 lzma_block_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
 168                 lzma_block *block)
 169 {
 170         lzma_next_coder_init(&lzma_block_encoder_init, next, allocator);
 171
 172         if (block == NULL)
 173                 return LZMA_PROG_ERROR;
 174
 175         // The contents of the structure may depend on the version so
 176         // check the version first.
 177         if (block->version > 1)
 178                 return LZMA_OPTIONS_ERROR;
 179
 180         // If the Check ID is not supported, we cannot calculate the check and
 181         // thus not create a proper Block.
 182         if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
 183                 return LZMA_PROG_ERROR;
 184
 185         if (!lzma_check_is_supported(block->check))
 186                 return LZMA_UNSUPPORTED_CHECK;
 187
 188         // Allocate and initialize *next->coder if needed.
 189         lzma_block_coder *coder = next->coder;
 190         if (coder == NULL) {
 191                 coder = lzma_alloc(sizeof(lzma_block_coder), allocator);
 192                 if (coder == NULL)
 193                         return LZMA_MEM_ERROR;
 194
 195                 next->coder = coder;
 196                 next->code = &block_encode;
 197                 next->end = &block_encoder_end;
 198                 next->update = &block_encoder_update;
 199                 coder->next = LZMA_NEXT_CODER_INIT;
 200         }
 201
 202         // Basic initializations
 203         coder->sequence = SEQ_CODE;
 204         coder->block = block;
 205         coder->compressed_size = 0;
 206         coder->uncompressed_size = 0;
 207         coder->pos = 0;
 208
 209         // Initialize the check
 210         lzma_check_init(&coder->check, block->check);
 211
 212         // Initialize the requested filters.
 213         return lzma_raw_encoder_init(&coder->next, allocator, block->filters);
 214 }
 215
 216
 217 extern LZMA_API(lzma_ret)
 218 lzma_block_encoder(lzma_stream *strm, lzma_block *block)
 219 {
 220         lzma_next_strm_init(lzma_block_encoder_init, strm, block);
 221
 222         strm->internal->supported_actions[LZMA_RUN] = true;
 223         strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true;
 224         strm->internal->supported_actions[LZMA_FINISH] = true;
 225
 226         return LZMA_OK;
 227 }