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diff --git a/src/liblzma/lz/lz_decoder.c b/src/liblzma/lz/lz_decoder.c
new file mode 100644
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+++ b/src/liblzma/lz/lz_decoder.c
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       lz_decoder.c
+/// \brief      LZ out window
+///
+//  Authors:    Igor Pavlov
+//              Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+// liblzma supports multiple LZ77-based filters. The LZ part is shared
+// between these filters. The LZ code takes care of dictionary handling
+// and passing the data between filters in the chain. The filter-specific
+// part decodes from the input buffer to the dictionary.
+
+
+#include "lz_decoder.h"
+
+
+typedef struct {
+	/// Dictionary (history buffer)
+	lzma_dict dict;
+
+	/// The actual LZ-based decoder e.g. LZMA
+	lzma_lz_decoder lz;
+
+	/// Next filter in the chain, if any. Note that LZMA and LZMA2 are
+	/// only allowed as the last filter, but the long-range filter in
+	/// future can be in the middle of the chain.
+	lzma_next_coder next;
+
+	/// True if the next filter in the chain has returned LZMA_STREAM_END.
+	bool next_finished;
+
+	/// True if the LZ decoder (e.g. LZMA) has detected end of payload
+	/// marker. This may become true before next_finished becomes true.
+	bool this_finished;
+
+	/// Temporary buffer needed when the LZ-based filter is not the last
+	/// filter in the chain. The output of the next filter is first
+	/// decoded into buffer[], which is then used as input for the actual
+	/// LZ-based decoder.
+	struct {
+		size_t pos;
+		size_t size;
+		uint8_t buffer[LZMA_BUFFER_SIZE];
+	} temp;
+} lzma_coder;
+
+
+static void
+lz_decoder_reset(lzma_coder *coder)
+{
+	coder->dict.pos = 0;
+	coder->dict.full = 0;
+	coder->dict.buf[coder->dict.size - 1] = '\0';
+	coder->dict.need_reset = false;
+	return;
+}
+
+
+static lzma_ret
+decode_buffer(lzma_coder *coder,
+		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)
+{
+	while (true) {
+		// Wrap the dictionary if needed.
+		if (coder->dict.pos == coder->dict.size)
+			coder->dict.pos = 0;
+
+		// Store the current dictionary position. It is needed to know
+		// where to start copying to the out[] buffer.
+		const size_t dict_start = coder->dict.pos;
+
+		// Calculate how much we allow coder->lz.code() to decode.
+		// It must not decode past the end of the dictionary
+		// buffer, and we don't want it to decode more than is
+		// actually needed to fill the out[] buffer.
+		coder->dict.limit = coder->dict.pos
+				+ my_min(out_size - *out_pos,
+					coder->dict.size - coder->dict.pos);
+
+		// Call the coder->lz.code() to do the actual decoding.
+		const lzma_ret ret = coder->lz.code(
+				coder->lz.coder, &coder->dict,
+				in, in_pos, in_size);
+
+		// Copy the decoded data from the dictionary to the out[]
+		// buffer. Do it conditionally because out can be NULL
+		// (in which case copy_size is always 0). Calling memcpy()
+		// with a null-pointer is undefined even if the third
+		// argument is 0.
+		const size_t copy_size = coder->dict.pos - dict_start;
+		assert(copy_size <= out_size - *out_pos);
+
+		if (copy_size > 0)
+			memcpy(out + *out_pos, coder->dict.buf + dict_start,
+					copy_size);
+
+		*out_pos += copy_size;
+
+		// Reset the dictionary if so requested by coder->lz.code().
+		if (coder->dict.need_reset) {
+			lz_decoder_reset(coder);
+
+			// Since we reset dictionary, we don't check if
+			// dictionary became full.
+			if (ret != LZMA_OK || *out_pos == out_size)
+				return ret;
+		} else {
+			// Return if everything got decoded or an error
+			// occurred, or if there's no more data to decode.
+			//
+			// Note that detecting if there's something to decode
+			// is done by looking if dictionary become full
+			// instead of looking if *in_pos == in_size. This
+			// is because it is possible that all the input was
+			// consumed already but some data is pending to be
+			// written to the dictionary.
+			if (ret != LZMA_OK || *out_pos == out_size
+					|| coder->dict.pos < coder->dict.size)
+				return ret;
+		}
+	}
+}
+
+
+static lzma_ret
+lz_decode(void *coder_ptr, 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)
+{
+	lzma_coder *coder = coder_ptr;
+
+	if (coder->next.code == NULL)
+		return decode_buffer(coder, in, in_pos, in_size,
+				out, out_pos, out_size);
+
+	// We aren't the last coder in the chain, we need to decode
+	// our input to a temporary buffer.
+	while (*out_pos < out_size) {
+		// Fill the temporary buffer if it is empty.
+		if (!coder->next_finished
+				&& coder->temp.pos == coder->temp.size) {
+			coder->temp.pos = 0;
+			coder->temp.size = 0;
+
+			const lzma_ret ret = coder->next.code(
+					coder->next.coder,
+					allocator, in, in_pos, in_size,
+					coder->temp.buffer, &coder->temp.size,
+					LZMA_BUFFER_SIZE, action);
+
+			if (ret == LZMA_STREAM_END)
+				coder->next_finished = true;
+			else if (ret != LZMA_OK || coder->temp.size == 0)
+				return ret;
+		}
+
+		if (coder->this_finished) {
+			if (coder->temp.size != 0)
+				return LZMA_DATA_ERROR;
+
+			if (coder->next_finished)
+				return LZMA_STREAM_END;
+
+			return LZMA_OK;
+		}
+
+		const lzma_ret ret = decode_buffer(coder, coder->temp.buffer,
+				&coder->temp.pos, coder->temp.size,
+				out, out_pos, out_size);
+
+		if (ret == LZMA_STREAM_END)
+			coder->this_finished = true;
+		else if (ret != LZMA_OK)
+			return ret;
+		else if (coder->next_finished && *out_pos < out_size)
+			return LZMA_DATA_ERROR;
+	}
+
+	return LZMA_OK;
+}
+
+
+static void
+lz_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
+{
+	lzma_coder *coder = coder_ptr;
+
+	lzma_next_end(&coder->next, allocator);
+	lzma_free(coder->dict.buf, allocator);
+
+	if (coder->lz.end != NULL)
+		coder->lz.end(coder->lz.coder, allocator);
+	else
+		lzma_free(coder->lz.coder, allocator);
+
+	lzma_free(coder, allocator);
+	return;
+}
+
+
+extern lzma_ret
+lzma_lz_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+		const lzma_filter_info *filters,
+		lzma_ret (*lz_init)(lzma_lz_decoder *lz,
+			const lzma_allocator *allocator,
+			lzma_vli id, const void *options,
+			lzma_lz_options *lz_options))
+{
+	// Allocate the base structure if it isn't already allocated.
+	lzma_coder *coder = next->coder;
+	if (coder == NULL) {
+		coder = lzma_alloc(sizeof(lzma_coder), allocator);
+		if (coder == NULL)
+			return LZMA_MEM_ERROR;
+
+		next->coder = coder;
+		next->code = &lz_decode;
+		next->end = &lz_decoder_end;
+
+		coder->dict.buf = NULL;
+		coder->dict.size = 0;
+		coder->lz = LZMA_LZ_DECODER_INIT;
+		coder->next = LZMA_NEXT_CODER_INIT;
+	}
+
+	// Allocate and initialize the LZ-based decoder. It will also give
+	// us the dictionary size.
+	lzma_lz_options lz_options;
+	return_if_error(lz_init(&coder->lz, allocator,
+			filters[0].id, filters[0].options, &lz_options));
+
+	// If the dictionary size is very small, increase it to 4096 bytes.
+	// This is to prevent constant wrapping of the dictionary, which
+	// would slow things down. The downside is that since we don't check
+	// separately for the real dictionary size, we may happily accept
+	// corrupt files.
+	if (lz_options.dict_size < 4096)
+		lz_options.dict_size = 4096;
+
+	// Make dictionary size a multiple of 16. Some LZ-based decoders like
+	// LZMA use the lowest bits lzma_dict.pos to know the alignment of the
+	// data. Aligned buffer is also good when memcpying from the
+	// dictionary to the output buffer, since applications are
+	// recommended to give aligned buffers to liblzma.
+	//
+	// Avoid integer overflow.
+	if (lz_options.dict_size > SIZE_MAX - 15)
+		return LZMA_MEM_ERROR;
+
+	lz_options.dict_size = (lz_options.dict_size + 15) & ~((size_t)(15));
+
+	// Allocate and initialize the dictionary.
+	if (coder->dict.size != lz_options.dict_size) {
+		lzma_free(coder->dict.buf, allocator);
+		coder->dict.buf
+				= lzma_alloc(lz_options.dict_size, allocator);
+		if (coder->dict.buf == NULL)
+			return LZMA_MEM_ERROR;
+
+		coder->dict.size = lz_options.dict_size;
+	}
+
+	lz_decoder_reset(next->coder);
+
+	// Use the preset dictionary if it was given to us.
+	if (lz_options.preset_dict != NULL
+			&& lz_options.preset_dict_size > 0) {
+		// If the preset dictionary is bigger than the actual
+		// dictionary, copy only the tail.
+		const size_t copy_size = my_min(lz_options.preset_dict_size,
+				lz_options.dict_size);
+		const size_t offset = lz_options.preset_dict_size - copy_size;
+		memcpy(coder->dict.buf, lz_options.preset_dict + offset,
+				copy_size);
+		coder->dict.pos = copy_size;
+		coder->dict.full = copy_size;
+	}
+
+	// Miscellaneous initializations
+	coder->next_finished = false;
+	coder->this_finished = false;
+	coder->temp.pos = 0;
+	coder->temp.size = 0;
+
+	// Initialize the next filter in the chain, if any.
+	return lzma_next_filter_init(&coder->next, allocator, filters + 1);
+}
+
+
+extern uint64_t
+lzma_lz_decoder_memusage(size_t dictionary_size)
+{
+	return sizeof(lzma_coder) + (uint64_t)(dictionary_size);
+}