--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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"
+
+
+struct lzma_coder_s {
+ /// 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;
+};
+
+
+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.
+ const size_t copy_size = coder->dict.pos - dict_start;
+ assert(copy_size <= out_size - *out_pos);
+ 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(lzma_coder *coder,
+ const 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)
+{
+ 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(lzma_coder *coder, const lzma_allocator *allocator)
+{
+ 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, const void *options,
+ lzma_lz_options *lz_options))
+{
+ // Allocate the base structure if it isn't already allocated.
+ if (next->coder == NULL) {
+ next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
+ if (next->coder == NULL)
+ return LZMA_MEM_ERROR;
+
+ next->code = &lz_decode;
+ next->end = &lz_decoder_end;
+
+ next->coder->dict.buf = NULL;
+ next->coder->dict.size = 0;
+ next->coder->lz = LZMA_LZ_DECODER_INIT;
+ next->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(&next->coder->lz, allocator,
+ 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 multipe 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 (next->coder->dict.size != lz_options.dict_size) {
+ lzma_free(next->coder->dict.buf, allocator);
+ next->coder->dict.buf
+ = lzma_alloc(lz_options.dict_size, allocator);
+ if (next->coder->dict.buf == NULL)
+ return LZMA_MEM_ERROR;
+
+ next->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(next->coder->dict.buf, lz_options.preset_dict + offset,
+ copy_size);
+ next->coder->dict.pos = copy_size;
+ next->coder->dict.full = copy_size;
+ }
+
+ // Miscellaneous initializations
+ next->coder->next_finished = false;
+ next->coder->this_finished = false;
+ next->coder->temp.pos = 0;
+ next->coder->temp.size = 0;
+
+ // Initialize the next filter in the chain, if any.
+ return lzma_next_filter_init(&next->coder->next, allocator,
+ filters + 1);
+}
+
+
+extern uint64_t
+lzma_lz_decoder_memusage(size_t dictionary_size)
+{
+ return sizeof(lzma_coder) + (uint64_t)(dictionary_size);
+}
+
+
+extern void
+lzma_lz_decoder_uncompressed(lzma_coder *coder, lzma_vli uncompressed_size)
+{
+ coder->lz.set_uncompressed(coder->lz.coder, uncompressed_size);
+}
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