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Diffstat (limited to 'src/liblzma/common/alone_decoder.c')
| -rw-r--r-- | src/liblzma/common/alone_decoder.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/src/liblzma/common/alone_decoder.c b/src/liblzma/common/alone_decoder.c new file mode 100644 index 00000000..092047b4 --- /dev/null +++ b/src/liblzma/common/alone_decoder.c @@ -0,0 +1,197 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file alone_decoder.c +/// \brief Decoder for LZMA_Alone files +// +// Copyright (C) 2007 Lasse Collin +// +// This library is free software; you can redistribute it and/or +// modify it under the terms of the GNU Lesser General Public +// License as published by the Free Software Foundation; either +// version 2.1 of the License, or (at your option) any later version. +// +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Lesser General Public License for more details. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "alone_decoder.h" +#include "lzma_decoder.h" + + +struct lzma_coder_s { + lzma_next_coder next; + + enum { + SEQ_PROPERTIES, + SEQ_DICTIONARY_SIZE, + SEQ_UNCOMPRESSED_SIZE, + SEQ_CODER_INIT, + SEQ_CODE, + } sequence; + + size_t pos; + + lzma_options_alone options; +}; + + +static lzma_ret +alone_decode(lzma_coder *coder, + lzma_allocator *allocator lzma_attribute((unused)), + const uint8_t *restrict in, size_t *restrict in_pos, + size_t in_size, uint8_t *restrict out, + size_t *restrict out_pos, size_t out_size, + lzma_action action) +{ + while (*out_pos < out_size + && (coder->sequence == SEQ_CODE || *in_pos < in_size)) + switch (coder->sequence) { + case SEQ_PROPERTIES: + if (lzma_lzma_decode_properties( + &coder->options.lzma, in[*in_pos])) + return LZMA_DATA_ERROR; + + coder->sequence = SEQ_DICTIONARY_SIZE; + ++*in_pos; + break; + + case SEQ_DICTIONARY_SIZE: + coder->options.lzma.dictionary_size + |= (size_t)(in[*in_pos]) << (coder->pos * 8); + + if (++coder->pos == 4) { + // A hack to ditch tons of false positives: We allow + // only dictionary sizes that are a power of two. + // LZMA_Alone didn't create other kinds of files, + // although it's not impossible that files with + // other dictionary sizes exist. Well, if someone + // complains, this will be reconsidered. + size_t count = 0; + for (size_t i = 0; i < 32; ++i) + if (coder->options.lzma.dictionary_size + & (UINT32_C(1) << i)) + ++count; + + if (count > 1) + return LZMA_DATA_ERROR; + + coder->pos = 0; + coder->sequence = SEQ_UNCOMPRESSED_SIZE; + } + + ++*in_pos; + break; + + case SEQ_UNCOMPRESSED_SIZE: + coder->options.uncompressed_size + |= (lzma_vli)(in[*in_pos]) << (coder->pos * 8); + + if (++coder->pos == 8) { + // Another hack to ditch false positives: Assume that + // if the uncompressed size is known, it must be less + // than 256 GiB. Again, if someone complains, this + // will be reconsidered. + if (coder->options.uncompressed_size + != LZMA_VLI_VALUE_UNKNOWN + && coder->options.uncompressed_size + >= (LZMA_VLI_C(1) << 38)) + return LZMA_DATA_ERROR; + + coder->pos = 0; + coder->sequence = SEQ_CODER_INIT; + } + + ++*in_pos; + break; + + case SEQ_CODER_INIT: { + // Two is enough because there won't be implicit filters. + lzma_filter_info filters[2] = { + { + .init = &lzma_lzma_decoder_init, + .options = &coder->options.lzma, + .uncompressed_size = coder->options + .uncompressed_size, + }, { + .init = NULL, + } + }; + + const lzma_ret ret = lzma_next_filter_init(&coder->next, + allocator, filters); + if (ret != LZMA_OK) + return ret; + + coder->sequence = SEQ_CODE; + } + + // Fall through + + case SEQ_CODE: { + return coder->next.code(coder->next.coder, + allocator, in, in_pos, in_size, + out, out_pos, out_size, action); + } + + default: + return LZMA_PROG_ERROR; + } + + return LZMA_OK; +} + + +static void +alone_decoder_end(lzma_coder *coder, lzma_allocator *allocator) +{ + lzma_next_coder_end(&coder->next, allocator); + lzma_free(coder, allocator); + return; +} + + +static lzma_ret +alone_decoder_init(lzma_next_coder *next, lzma_allocator *allocator) +{ + if (next->coder == NULL) { + next->coder = lzma_alloc(sizeof(lzma_coder), allocator); + if (next->coder == NULL) + return LZMA_MEM_ERROR; + + next->code = &alone_decode; + next->end = &alone_decoder_end; + next->coder->next = LZMA_NEXT_CODER_INIT; + } + + next->coder->sequence = SEQ_PROPERTIES; + next->coder->pos = 0; + next->coder->options.lzma.dictionary_size = 0; + next->coder->options.uncompressed_size = 0; + + return LZMA_OK; +} + + +extern lzma_ret +lzma_alone_decoder_init(lzma_next_coder *next, lzma_allocator *allocator) +{ + // We need to use _init2 because we don't pass any varadic args. + lzma_next_coder_init2(next, allocator, alone_decoder_init, + alone_decoder_init, allocator); +} + + +extern LZMA_API lzma_ret +lzma_alone_decoder(lzma_stream *strm) +{ + lzma_next_strm_init2(strm, alone_decoder_init, + alone_decoder_init, strm->allocator); + + strm->internal->supported_actions[LZMA_RUN] = true; + strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true; + + return LZMA_OK; +} |