--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file stream_decoder.c
+/// \brief Decodes .xz Streams
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "stream_decoder.h"
+#include "block_decoder.h"
+
+
+struct lzma_coder_s {
+ enum {
+ SEQ_STREAM_HEADER,
+ SEQ_BLOCK_HEADER,
+ SEQ_BLOCK,
+ SEQ_INDEX,
+ SEQ_STREAM_FOOTER,
+ SEQ_STREAM_PADDING,
+ } sequence;
+
+ /// Block or Metadata decoder. This takes little memory and the same
+ /// data structure can be used to decode every Block Header, so it's
+ /// a good idea to have a separate lzma_next_coder structure for it.
+ lzma_next_coder block_decoder;
+
+ /// Block options decoded by the Block Header decoder and used by
+ /// the Block decoder.
+ lzma_block block_options;
+
+ /// Stream Flags from Stream Header
+ lzma_stream_flags stream_flags;
+
+ /// Index is hashed so that it can be compared to the sizes of Blocks
+ /// with O(1) memory usage.
+ lzma_index_hash *index_hash;
+
+ /// Memory usage limit
+ uint64_t memlimit;
+
+ /// Amount of memory actually needed (only an estimate)
+ uint64_t memusage;
+
+ /// If true, LZMA_NO_CHECK is returned if the Stream has
+ /// no integrity check.
+ bool tell_no_check;
+
+ /// If true, LZMA_UNSUPPORTED_CHECK is returned if the Stream has
+ /// an integrity check that isn't supported by this liblzma build.
+ bool tell_unsupported_check;
+
+ /// If true, LZMA_GET_CHECK is returned after decoding Stream Header.
+ bool tell_any_check;
+
+ /// If true, we will tell the Block decoder to skip calculating
+ /// and verifying the integrity check.
+ bool ignore_check;
+
+ /// If true, we will decode concatenated Streams that possibly have
+ /// Stream Padding between or after them. LZMA_STREAM_END is returned
+ /// once the application isn't giving us any new input, and we aren't
+ /// in the middle of a Stream, and possible Stream Padding is a
+ /// multiple of four bytes.
+ bool concatenated;
+
+ /// When decoding concatenated Streams, this is true as long as we
+ /// are decoding the first Stream. This is needed to avoid misleading
+ /// LZMA_FORMAT_ERROR in case the later Streams don't have valid magic
+ /// bytes.
+ bool first_stream;
+
+ /// Write position in buffer[] and position in Stream Padding
+ size_t pos;
+
+ /// Buffer to hold Stream Header, Block Header, and Stream Footer.
+ /// Block Header has biggest maximum size.
+ uint8_t buffer[LZMA_BLOCK_HEADER_SIZE_MAX];
+};
+
+
+static lzma_ret
+stream_decoder_reset(lzma_coder *coder, const lzma_allocator *allocator)
+{
+ // Initialize the Index hash used to verify the Index.
+ coder->index_hash = lzma_index_hash_init(coder->index_hash, allocator);
+ if (coder->index_hash == NULL)
+ return LZMA_MEM_ERROR;
+
+ // Reset the rest of the variables.
+ coder->sequence = SEQ_STREAM_HEADER;
+ coder->pos = 0;
+
+ return LZMA_OK;
+}
+
+
+static lzma_ret
+stream_decode(lzma_coder *coder, const lzma_allocator *allocator,
+ 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)
+{
+ // When decoding the actual Block, it may be able to produce more
+ // output even if we don't give it any new input.
+ while (true)
+ switch (coder->sequence) {
+ case SEQ_STREAM_HEADER: {
+ // Copy the Stream Header to the internal buffer.
+ lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
+ LZMA_STREAM_HEADER_SIZE);
+
+ // Return if we didn't get the whole Stream Header yet.
+ if (coder->pos < LZMA_STREAM_HEADER_SIZE)
+ return LZMA_OK;
+
+ coder->pos = 0;
+
+ // Decode the Stream Header.
+ const lzma_ret ret = lzma_stream_header_decode(
+ &coder->stream_flags, coder->buffer);
+ if (ret != LZMA_OK)
+ return ret == LZMA_FORMAT_ERROR && !coder->first_stream
+ ? LZMA_DATA_ERROR : ret;
+
+ // If we are decoding concatenated Streams, and the later
+ // Streams have invalid Header Magic Bytes, we give
+ // LZMA_DATA_ERROR instead of LZMA_FORMAT_ERROR.
+ coder->first_stream = false;
+
+ // Copy the type of the Check so that Block Header and Block
+ // decoders see it.
+ coder->block_options.check = coder->stream_flags.check;
+
+ // Even if we return LZMA_*_CHECK below, we want
+ // to continue from Block Header decoding.
+ coder->sequence = SEQ_BLOCK_HEADER;
+
+ // Detect if there's no integrity check or if it is
+ // unsupported if those were requested by the application.
+ if (coder->tell_no_check && coder->stream_flags.check
+ == LZMA_CHECK_NONE)
+ return LZMA_NO_CHECK;
+
+ if (coder->tell_unsupported_check
+ && !lzma_check_is_supported(
+ coder->stream_flags.check))
+ return LZMA_UNSUPPORTED_CHECK;
+
+ if (coder->tell_any_check)
+ return LZMA_GET_CHECK;
+ }
+
+ // Fall through
+
+ case SEQ_BLOCK_HEADER: {
+ if (*in_pos >= in_size)
+ return LZMA_OK;
+
+ if (coder->pos == 0) {
+ // Detect if it's Index.
+ if (in[*in_pos] == 0x00) {
+ coder->sequence = SEQ_INDEX;
+ break;
+ }
+
+ // Calculate the size of the Block Header. Note that
+ // Block Header decoder wants to see this byte too
+ // so don't advance *in_pos.
+ coder->block_options.header_size
+ = lzma_block_header_size_decode(
+ in[*in_pos]);
+ }
+
+ // Copy the Block Header to the internal buffer.
+ lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
+ coder->block_options.header_size);
+
+ // Return if we didn't get the whole Block Header yet.
+ if (coder->pos < coder->block_options.header_size)
+ return LZMA_OK;
+
+ coder->pos = 0;
+
+ // Version 1 is needed to support the .ignore_check option.
+ coder->block_options.version = 1;
+
+ // Set up a buffer to hold the filter chain. Block Header
+ // decoder will initialize all members of this array so
+ // we don't need to do it here.
+ lzma_filter filters[LZMA_FILTERS_MAX + 1];
+ coder->block_options.filters = filters;
+
+ // Decode the Block Header.
+ return_if_error(lzma_block_header_decode(&coder->block_options,
+ allocator, coder->buffer));
+
+ // If LZMA_IGNORE_CHECK was used, this flag needs to be set.
+ // It has to be set after lzma_block_header_decode() because
+ // it always resets this to false.
+ coder->block_options.ignore_check = coder->ignore_check;
+
+ // Check the memory usage limit.
+ const uint64_t memusage = lzma_raw_decoder_memusage(filters);
+ lzma_ret ret;
+
+ if (memusage == UINT64_MAX) {
+ // One or more unknown Filter IDs.
+ ret = LZMA_OPTIONS_ERROR;
+ } else {
+ // Now we can set coder->memusage since we know that
+ // the filter chain is valid. We don't want
+ // lzma_memusage() to return UINT64_MAX in case of
+ // invalid filter chain.
+ coder->memusage = memusage;
+
+ if (memusage > coder->memlimit) {
+ // The chain would need too much memory.
+ ret = LZMA_MEMLIMIT_ERROR;
+ } else {
+ // Memory usage is OK.
+ // Initialize the Block decoder.
+ ret = lzma_block_decoder_init(
+ &coder->block_decoder,
+ allocator,
+ &coder->block_options);
+ }
+ }
+
+ // Free the allocated filter options since they are needed
+ // only to initialize the Block decoder.
+ for (size_t i = 0; i < LZMA_FILTERS_MAX; ++i)
+ lzma_free(filters[i].options, allocator);
+
+ coder->block_options.filters = NULL;
+
+ // Check if memory usage calculation and Block enocoder
+ // initialization succeeded.
+ if (ret != LZMA_OK)
+ return ret;
+
+ coder->sequence = SEQ_BLOCK;
+ }
+
+ // Fall through
+
+ case SEQ_BLOCK: {
+ const lzma_ret ret = coder->block_decoder.code(
+ coder->block_decoder.coder, allocator,
+ in, in_pos, in_size, out, out_pos, out_size,
+ action);
+
+ if (ret != LZMA_STREAM_END)
+ return ret;
+
+ // Block decoded successfully. Add the new size pair to
+ // the Index hash.
+ return_if_error(lzma_index_hash_append(coder->index_hash,
+ lzma_block_unpadded_size(
+ &coder->block_options),
+ coder->block_options.uncompressed_size));
+
+ coder->sequence = SEQ_BLOCK_HEADER;
+ break;
+ }
+
+ case SEQ_INDEX: {
+ // If we don't have any input, don't call
+ // lzma_index_hash_decode() since it would return
+ // LZMA_BUF_ERROR, which we must not do here.
+ if (*in_pos >= in_size)
+ return LZMA_OK;
+
+ // Decode the Index and compare it to the hash calculated
+ // from the sizes of the Blocks (if any).
+ const lzma_ret ret = lzma_index_hash_decode(coder->index_hash,
+ in, in_pos, in_size);
+ if (ret != LZMA_STREAM_END)
+ return ret;
+
+ coder->sequence = SEQ_STREAM_FOOTER;
+ }
+
+ // Fall through
+
+ case SEQ_STREAM_FOOTER: {
+ // Copy the Stream Footer to the internal buffer.
+ lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
+ LZMA_STREAM_HEADER_SIZE);
+
+ // Return if we didn't get the whole Stream Footer yet.
+ if (coder->pos < LZMA_STREAM_HEADER_SIZE)
+ return LZMA_OK;
+
+ coder->pos = 0;
+
+ // Decode the Stream Footer. The decoder gives
+ // LZMA_FORMAT_ERROR if the magic bytes don't match,
+ // so convert that return code to LZMA_DATA_ERROR.
+ lzma_stream_flags footer_flags;
+ const lzma_ret ret = lzma_stream_footer_decode(
+ &footer_flags, coder->buffer);
+ if (ret != LZMA_OK)
+ return ret == LZMA_FORMAT_ERROR
+ ? LZMA_DATA_ERROR : ret;
+
+ // Check that Index Size stored in the Stream Footer matches
+ // the real size of the Index field.
+ if (lzma_index_hash_size(coder->index_hash)
+ != footer_flags.backward_size)
+ return LZMA_DATA_ERROR;
+
+ // Compare that the Stream Flags fields are identical in
+ // both Stream Header and Stream Footer.
+ return_if_error(lzma_stream_flags_compare(
+ &coder->stream_flags, &footer_flags));
+
+ if (!coder->concatenated)
+ return LZMA_STREAM_END;
+
+ coder->sequence = SEQ_STREAM_PADDING;
+ }
+
+ // Fall through
+
+ case SEQ_STREAM_PADDING:
+ assert(coder->concatenated);
+
+ // Skip over possible Stream Padding.
+ while (true) {
+ if (*in_pos >= in_size) {
+ // Unless LZMA_FINISH was used, we cannot
+ // know if there's more input coming later.
+ if (action != LZMA_FINISH)
+ return LZMA_OK;
+
+ // Stream Padding must be a multiple of
+ // four bytes.
+ return coder->pos == 0
+ ? LZMA_STREAM_END
+ : LZMA_DATA_ERROR;
+ }
+
+ // If the byte is not zero, it probably indicates
+ // beginning of a new Stream (or the file is corrupt).
+ if (in[*in_pos] != 0x00)
+ break;
+
+ ++*in_pos;
+ coder->pos = (coder->pos + 1) & 3;
+ }
+
+ // Stream Padding must be a multiple of four bytes (empty
+ // Stream Padding is OK).
+ if (coder->pos != 0) {
+ ++*in_pos;
+ return LZMA_DATA_ERROR;
+ }
+
+ // Prepare to decode the next Stream.
+ return_if_error(stream_decoder_reset(coder, allocator));
+ break;
+
+ default:
+ assert(0);
+ return LZMA_PROG_ERROR;
+ }
+
+ // Never reached
+}
+
+
+static void
+stream_decoder_end(lzma_coder *coder, const lzma_allocator *allocator)
+{
+ lzma_next_end(&coder->block_decoder, allocator);
+ lzma_index_hash_end(coder->index_hash, allocator);
+ lzma_free(coder, allocator);
+ return;
+}
+
+
+static lzma_check
+stream_decoder_get_check(const lzma_coder *coder)
+{
+ return coder->stream_flags.check;
+}
+
+
+static lzma_ret
+stream_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
+ uint64_t *old_memlimit, uint64_t new_memlimit)
+{
+ *memusage = coder->memusage;
+ *old_memlimit = coder->memlimit;
+
+ if (new_memlimit != 0) {
+ if (new_memlimit < coder->memusage)
+ return LZMA_MEMLIMIT_ERROR;
+
+ coder->memlimit = new_memlimit;
+ }
+
+ return LZMA_OK;
+}
+
+
+extern lzma_ret
+lzma_stream_decoder_init(
+ lzma_next_coder *next, const lzma_allocator *allocator,
+ uint64_t memlimit, uint32_t flags)
+{
+ lzma_next_coder_init(&lzma_stream_decoder_init, next, allocator);
+
+ if (memlimit == 0)
+ return LZMA_PROG_ERROR;
+
+ if (flags & ~LZMA_SUPPORTED_FLAGS)
+ return LZMA_OPTIONS_ERROR;
+
+ if (next->coder == NULL) {
+ next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
+ if (next->coder == NULL)
+ return LZMA_MEM_ERROR;
+
+ next->code = &stream_decode;
+ next->end = &stream_decoder_end;
+ next->get_check = &stream_decoder_get_check;
+ next->memconfig = &stream_decoder_memconfig;
+
+ next->coder->block_decoder = LZMA_NEXT_CODER_INIT;
+ next->coder->index_hash = NULL;
+ }
+
+ next->coder->memlimit = memlimit;
+ next->coder->memusage = LZMA_MEMUSAGE_BASE;
+ next->coder->tell_no_check = (flags & LZMA_TELL_NO_CHECK) != 0;
+ next->coder->tell_unsupported_check
+ = (flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0;
+ next->coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0;
+ next->coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0;
+ next->coder->concatenated = (flags & LZMA_CONCATENATED) != 0;
+ next->coder->first_stream = true;
+
+ return stream_decoder_reset(next->coder, allocator);
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_stream_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
+{
+ lzma_next_strm_init(lzma_stream_decoder_init, strm, memlimit, flags);
+
+ strm->internal->supported_actions[LZMA_RUN] = true;
+ strm->internal->supported_actions[LZMA_FINISH] = true;
+
+ return LZMA_OK;
+}
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