1 ///////////////////////////////////////////////////////////////////////////////
3 /// \file index_encoder.c
4 /// \brief Encodes the Index field
6 // Author: Lasse Collin
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
11 ///////////////////////////////////////////////////////////////////////////////
13 #include "index_encoder.h"
29 /// Index being encoded
30 const lzma_index *index;
32 /// Iterator for the Index being encoded
35 /// Position in integers
38 /// CRC32 of the List of Records field
44 index_encode(void *coder_ptr,
45 const lzma_allocator *allocator lzma_attribute((__unused__)),
46 const uint8_t *restrict in lzma_attribute((__unused__)),
47 size_t *restrict in_pos lzma_attribute((__unused__)),
48 size_t in_size lzma_attribute((__unused__)),
49 uint8_t *restrict out, size_t *restrict out_pos,
51 lzma_action action lzma_attribute((__unused__)))
53 lzma_index_coder *coder = coder_ptr;
55 // Position where to start calculating CRC32. The idea is that we
56 // need to call lzma_crc32() only once per call to index_encode().
57 const size_t out_start = *out_pos;
59 // Return value to use if we return at the end of this function.
60 // We use "goto out" to jump out of the while-switch construct
61 // instead of returning directly, because that way we don't need
62 // to copypaste the lzma_crc32() call to many places.
63 lzma_ret ret = LZMA_OK;
65 while (*out_pos < out_size)
66 switch (coder->sequence) {
70 coder->sequence = SEQ_COUNT;
74 const lzma_vli count = lzma_index_block_count(coder->index);
75 ret = lzma_vli_encode(count, &coder->pos,
76 out, out_pos, out_size);
77 if (ret != LZMA_STREAM_END)
82 coder->sequence = SEQ_NEXT;
87 if (lzma_index_iter_next(
88 &coder->iter, LZMA_INDEX_ITER_BLOCK)) {
89 // Get the size of the Index Padding field.
90 coder->pos = lzma_index_padding_size(coder->index);
91 assert(coder->pos <= 3);
92 coder->sequence = SEQ_PADDING;
96 coder->sequence = SEQ_UNPADDED;
101 case SEQ_UNCOMPRESSED: {
102 const lzma_vli size = coder->sequence == SEQ_UNPADDED
103 ? coder->iter.block.unpadded_size
104 : coder->iter.block.uncompressed_size;
106 ret = lzma_vli_encode(size, &coder->pos,
107 out, out_pos, out_size);
108 if (ret != LZMA_STREAM_END)
114 // Advance to SEQ_UNCOMPRESSED or SEQ_NEXT.
120 if (coder->pos > 0) {
122 out[(*out_pos)++] = 0x00;
126 // Finish the CRC32 calculation.
127 coder->crc32 = lzma_crc32(out + out_start,
128 *out_pos - out_start, coder->crc32);
130 coder->sequence = SEQ_CRC32;
135 // We don't use the main loop, because we don't want
136 // coder->crc32 to be touched anymore.
138 if (*out_pos == out_size)
141 out[*out_pos] = (coder->crc32 >> (coder->pos * 8))
145 } while (++coder->pos < 4);
147 return LZMA_STREAM_END;
151 return LZMA_PROG_ERROR;
156 coder->crc32 = lzma_crc32(out + out_start,
157 *out_pos - out_start, coder->crc32);
164 index_encoder_end(void *coder, const lzma_allocator *allocator)
166 lzma_free(coder, allocator);
172 index_encoder_reset(lzma_index_coder *coder, const lzma_index *i)
174 lzma_index_iter_init(&coder->iter, i);
176 coder->sequence = SEQ_INDICATOR;
186 lzma_index_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
189 lzma_next_coder_init(&lzma_index_encoder_init, next, allocator);
192 return LZMA_PROG_ERROR;
194 if (next->coder == NULL) {
195 next->coder = lzma_alloc(sizeof(lzma_index_coder), allocator);
196 if (next->coder == NULL)
197 return LZMA_MEM_ERROR;
199 next->code = &index_encode;
200 next->end = &index_encoder_end;
203 index_encoder_reset(next->coder, i);
209 extern LZMA_API(lzma_ret)
210 lzma_index_encoder(lzma_stream *strm, const lzma_index *i)
212 lzma_next_strm_init(lzma_index_encoder_init, strm, i);
214 strm->internal->supported_actions[LZMA_RUN] = true;
215 strm->internal->supported_actions[LZMA_FINISH] = true;
221 extern LZMA_API(lzma_ret)
222 lzma_index_buffer_encode(const lzma_index *i,
223 uint8_t *out, size_t *out_pos, size_t out_size)
225 // Validate the arguments.
226 if (i == NULL || out == NULL || out_pos == NULL || *out_pos > out_size)
227 return LZMA_PROG_ERROR;
229 // Don't try to encode if there's not enough output space.
230 if (out_size - *out_pos < lzma_index_size(i))
231 return LZMA_BUF_ERROR;
233 // The Index encoder needs just one small data structure so we can
234 // allocate it on stack.
235 lzma_index_coder coder;
236 index_encoder_reset(&coder, i);
238 // Do the actual encoding. This should never fail, but store
239 // the original *out_pos just in case.
240 const size_t out_start = *out_pos;
241 lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0,
242 out, out_pos, out_size, LZMA_RUN);
244 if (ret == LZMA_STREAM_END) {
247 // We should never get here, but just in case, restore the
248 // output position and set the error accordingly if something
249 // goes wrong and debugging isn't enabled.
251 *out_pos = out_start;
252 ret = LZMA_PROG_ERROR;