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-rw-r--r--src/liblzma/common/alone_decoder.c197
1 files changed, 197 insertions, 0 deletions
diff --git a/src/liblzma/common/alone_decoder.c b/src/liblzma/common/alone_decoder.c
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+++ b/src/liblzma/common/alone_decoder.c
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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;
+}