src/liblzma/common/alone_encoder.c

   1 // SPDX-License-Identifier: 0BSD
   2
   3 ///////////////////////////////////////////////////////////////////////////////
   4 //
   5 /// \file       alone_encoder.c
   6 /// \brief      Encoder for LZMA_Alone files
   7 //
   8 //  Author:     Lasse Collin
   9 //
  10 ///////////////////////////////////////////////////////////////////////////////
  11
  12 #include "common.h"
  13 #include "lzma_encoder.h"
  14
  15
  16 #define ALONE_HEADER_SIZE (1 + 4 + 8)
  17
  18
  19 typedef struct {
  20         lzma_next_coder next;
  21
  22         enum {
  23                 SEQ_HEADER,
  24                 SEQ_CODE,
  25         } sequence;
  26
  27         size_t header_pos;
  28         uint8_t header[ALONE_HEADER_SIZE];
  29 } lzma_alone_coder;
  30
  31
  32 static lzma_ret
  33 alone_encode(void *coder_ptr, const lzma_allocator *allocator,
  34                 const uint8_t *restrict in, size_t *restrict in_pos,
  35                 size_t in_size, uint8_t *restrict out,
  36                 size_t *restrict out_pos, size_t out_size,
  37                 lzma_action action)
  38 {
  39         lzma_alone_coder *coder = coder_ptr;
  40
  41         while (*out_pos < out_size)
  42         switch (coder->sequence) {
  43         case SEQ_HEADER:
  44                 lzma_bufcpy(coder->header, &coder->header_pos,
  45                                 ALONE_HEADER_SIZE,
  46                                 out, out_pos, out_size);
  47                 if (coder->header_pos < ALONE_HEADER_SIZE)
  48                         return LZMA_OK;
  49
  50                 coder->sequence = SEQ_CODE;
  51                 break;
  52
  53         case SEQ_CODE:
  54                 return coder->next.code(coder->next.coder,
  55                                 allocator, in, in_pos, in_size,
  56                                 out, out_pos, out_size, action);
  57
  58         default:
  59                 assert(0);
  60                 return LZMA_PROG_ERROR;
  61         }
  62
  63         return LZMA_OK;
  64 }
  65
  66
  67 static void
  68 alone_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
  69 {
  70         lzma_alone_coder *coder = coder_ptr;
  71         lzma_next_end(&coder->next, allocator);
  72         lzma_free(coder, allocator);
  73         return;
  74 }
  75
  76
  77 static lzma_ret
  78 alone_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
  79                 const lzma_options_lzma *options)
  80 {
  81         lzma_next_coder_init(&alone_encoder_init, next, allocator);
  82
  83         lzma_alone_coder *coder = next->coder;
  84
  85         if (coder == NULL) {
  86                 coder = lzma_alloc(sizeof(lzma_alone_coder), allocator);
  87                 if (coder == NULL)
  88                         return LZMA_MEM_ERROR;
  89
  90                 next->coder = coder;
  91                 next->code = &alone_encode;
  92                 next->end = &alone_encoder_end;
  93                 coder->next = LZMA_NEXT_CODER_INIT;
  94         }
  95
  96         // Basic initializations
  97         coder->sequence = SEQ_HEADER;
  98         coder->header_pos = 0;
  99
 100         // Encode the header:
 101         // - Properties (1 byte)
 102         if (lzma_lzma_lclppb_encode(options, coder->header))
 103                 return LZMA_OPTIONS_ERROR;
 104
 105         // - Dictionary size (4 bytes)
 106         if (options->dict_size < LZMA_DICT_SIZE_MIN)
 107                 return LZMA_OPTIONS_ERROR;
 108
 109         // Round up to the next 2^n or 2^n + 2^(n - 1) depending on which
 110         // one is the next unless it is UINT32_MAX. While the header would
 111         // allow any 32-bit integer, we do this to keep the decoder of liblzma
 112         // accepting the resulting files.
 113         uint32_t d = options->dict_size - 1;
 114         d |= d >> 2;
 115         d |= d >> 3;
 116         d |= d >> 4;
 117         d |= d >> 8;
 118         d |= d >> 16;
 119         if (d != UINT32_MAX)
 120                 ++d;
 121
 122         write32le(coder->header + 1, d);
 123
 124         // - Uncompressed size (always unknown and using EOPM)
 125         memset(coder->header + 1 + 4, 0xFF, 8);
 126
 127         // Initialize the LZMA encoder.
 128         const lzma_filter_info filters[2] = {
 129                 {
 130                         .id = LZMA_FILTER_LZMA1,
 131                         .init = &lzma_lzma_encoder_init,
 132                         .options = (void *)(options),
 133                 }, {
 134                         .init = NULL,
 135                 }
 136         };
 137
 138         return lzma_next_filter_init(&coder->next, allocator, filters);
 139 }
 140
 141
 142 extern LZMA_API(lzma_ret)
 143 lzma_alone_encoder(lzma_stream *strm, const lzma_options_lzma *options)
 144 {
 145         lzma_next_strm_init(alone_encoder_init, strm, options);
 146
 147         strm->internal->supported_actions[LZMA_RUN] = true;
 148         strm->internal->supported_actions[LZMA_FINISH] = true;
 149
 150         return LZMA_OK;
 151 }