X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcommon%2Findex_encoder.c;fp=lzma%2Fcommon%2Findex_encoder.c;h=d25ac7d3372b546bd2d925d0c273ee20214155dc;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage diff --git a/lzma/common/index_encoder.c b/lzma/common/index_encoder.c new file mode 100644 index 0000000..d25ac7d --- /dev/null +++ b/lzma/common/index_encoder.c @@ -0,0 +1,254 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file index_encoder.c +/// \brief Encodes the Index field +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "index_encoder.h" +#include "index.h" +#include "check.h" + + +struct lzma_coder_s { + enum { + SEQ_INDICATOR, + SEQ_COUNT, + SEQ_UNPADDED, + SEQ_UNCOMPRESSED, + SEQ_NEXT, + SEQ_PADDING, + SEQ_CRC32, + } sequence; + + /// Index being encoded + const lzma_index *index; + + /// Iterator for the Index being encoded + lzma_index_iter iter; + + /// Position in integers + size_t pos; + + /// CRC32 of the List of Records field + uint32_t crc32; +}; + + +static lzma_ret +index_encode(lzma_coder *coder, + const lzma_allocator *allocator lzma_attribute((__unused__)), + const uint8_t *restrict in lzma_attribute((__unused__)), + size_t *restrict in_pos lzma_attribute((__unused__)), + size_t in_size lzma_attribute((__unused__)), + uint8_t *restrict out, size_t *restrict out_pos, + size_t out_size, + lzma_action action lzma_attribute((__unused__))) +{ + // Position where to start calculating CRC32. The idea is that we + // need to call lzma_crc32() only once per call to index_encode(). + const size_t out_start = *out_pos; + + // Return value to use if we return at the end of this function. + // We use "goto out" to jump out of the while-switch construct + // instead of returning directly, because that way we don't need + // to copypaste the lzma_crc32() call to many places. + lzma_ret ret = LZMA_OK; + + while (*out_pos < out_size) + switch (coder->sequence) { + case SEQ_INDICATOR: + out[*out_pos] = 0x00; + ++*out_pos; + coder->sequence = SEQ_COUNT; + break; + + case SEQ_COUNT: { + const lzma_vli count = lzma_index_block_count(coder->index); + ret = lzma_vli_encode(count, &coder->pos, + out, out_pos, out_size); + if (ret != LZMA_STREAM_END) + goto out; + + ret = LZMA_OK; + coder->pos = 0; + coder->sequence = SEQ_NEXT; + break; + } + + case SEQ_NEXT: + if (lzma_index_iter_next( + &coder->iter, LZMA_INDEX_ITER_BLOCK)) { + // Get the size of the Index Padding field. + coder->pos = lzma_index_padding_size(coder->index); + assert(coder->pos <= 3); + coder->sequence = SEQ_PADDING; + break; + } + + coder->sequence = SEQ_UNPADDED; + + // Fall through + + case SEQ_UNPADDED: + case SEQ_UNCOMPRESSED: { + const lzma_vli size = coder->sequence == SEQ_UNPADDED + ? coder->iter.block.unpadded_size + : coder->iter.block.uncompressed_size; + + ret = lzma_vli_encode(size, &coder->pos, + out, out_pos, out_size); + if (ret != LZMA_STREAM_END) + goto out; + + ret = LZMA_OK; + coder->pos = 0; + + // Advance to SEQ_UNCOMPRESSED or SEQ_NEXT. + ++coder->sequence; + break; + } + + case SEQ_PADDING: + if (coder->pos > 0) { + --coder->pos; + out[(*out_pos)++] = 0x00; + break; + } + + // Finish the CRC32 calculation. + coder->crc32 = lzma_crc32(out + out_start, + *out_pos - out_start, coder->crc32); + + coder->sequence = SEQ_CRC32; + + // Fall through + + case SEQ_CRC32: + // We don't use the main loop, because we don't want + // coder->crc32 to be touched anymore. + do { + if (*out_pos == out_size) + return LZMA_OK; + + out[*out_pos] = (coder->crc32 >> (coder->pos * 8)) + & 0xFF; + ++*out_pos; + + } while (++coder->pos < 4); + + return LZMA_STREAM_END; + + default: + assert(0); + return LZMA_PROG_ERROR; + } + +out: + // Update the CRC32. + coder->crc32 = lzma_crc32(out + out_start, + *out_pos - out_start, coder->crc32); + + return ret; +} + + +static void +index_encoder_end(lzma_coder *coder, const lzma_allocator *allocator) +{ + lzma_free(coder, allocator); + return; +} + + +static void +index_encoder_reset(lzma_coder *coder, const lzma_index *i) +{ + lzma_index_iter_init(&coder->iter, i); + + coder->sequence = SEQ_INDICATOR; + coder->index = i; + coder->pos = 0; + coder->crc32 = 0; + + return; +} + + +extern lzma_ret +lzma_index_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator, + const lzma_index *i) +{ + lzma_next_coder_init(&lzma_index_encoder_init, next, allocator); + + if (i == NULL) + return LZMA_PROG_ERROR; + + if (next->coder == NULL) { + next->coder = lzma_alloc(sizeof(lzma_coder), allocator); + if (next->coder == NULL) + return LZMA_MEM_ERROR; + + next->code = &index_encode; + next->end = &index_encoder_end; + } + + index_encoder_reset(next->coder, i); + + return LZMA_OK; +} + + +extern LZMA_API(lzma_ret) +lzma_index_encoder(lzma_stream *strm, const lzma_index *i) +{ + lzma_next_strm_init(lzma_index_encoder_init, strm, i); + + strm->internal->supported_actions[LZMA_RUN] = true; + strm->internal->supported_actions[LZMA_FINISH] = true; + + return LZMA_OK; +} + + +extern LZMA_API(lzma_ret) +lzma_index_buffer_encode(const lzma_index *i, + uint8_t *out, size_t *out_pos, size_t out_size) +{ + // Validate the arguments. + if (i == NULL || out == NULL || out_pos == NULL || *out_pos > out_size) + return LZMA_PROG_ERROR; + + // Don't try to encode if there's not enough output space. + if (out_size - *out_pos < lzma_index_size(i)) + return LZMA_BUF_ERROR; + + // The Index encoder needs just one small data structure so we can + // allocate it on stack. + lzma_coder coder; + index_encoder_reset(&coder, i); + + // Do the actual encoding. This should never fail, but store + // the original *out_pos just in case. + const size_t out_start = *out_pos; + lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0, + out, out_pos, out_size, LZMA_RUN); + + if (ret == LZMA_STREAM_END) { + ret = LZMA_OK; + } else { + // We should never get here, but just in case, restore the + // output position and set the error accordingly if something + // goes wrong and debugging isn't enabled. + assert(0); + *out_pos = out_start; + ret = LZMA_PROG_ERROR; + } + + return ret; +}