--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file lz_encoder.c
+/// \brief LZ in window
+///
+// Authors: Igor Pavlov
+// Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "lz_encoder.h"
+#include "lz_encoder_hash.h"
+
+// See lz_encoder_hash.h. This is a bit hackish but avoids making
+// endianness a conditional in makefiles.
+#if defined(WORDS_BIGENDIAN) && !defined(HAVE_SMALL)
+# include "lz_encoder_hash_table.h"
+#endif
+
+#include "memcmplen.h"
+
+
+struct lzma_coder_s {
+ /// LZ-based encoder e.g. LZMA
+ lzma_lz_encoder lz;
+
+ /// History buffer and match finder
+ lzma_mf mf;
+
+ /// Next coder in the chain
+ lzma_next_coder next;
+};
+
+
+/// \brief Moves the data in the input window to free space for new data
+///
+/// mf->buffer is a sliding input window, which keeps mf->keep_size_before
+/// bytes of input history available all the time. Now and then we need to
+/// "slide" the buffer to make space for the new data to the end of the
+/// buffer. At the same time, data older than keep_size_before is dropped.
+///
+static void
+move_window(lzma_mf *mf)
+{
+ // Align the move to a multiple of 16 bytes. Some LZ-based encoders
+ // like LZMA use the lowest bits of mf->read_pos to know the
+ // alignment of the uncompressed data. We also get better speed
+ // for memmove() with aligned buffers.
+ assert(mf->read_pos > mf->keep_size_before);
+ const uint32_t move_offset
+ = (mf->read_pos - mf->keep_size_before) & ~UINT32_C(15);
+
+ assert(mf->write_pos > move_offset);
+ const size_t move_size = mf->write_pos - move_offset;
+
+ assert(move_offset + move_size <= mf->size);
+
+ memmove(mf->buffer, mf->buffer + move_offset, move_size);
+
+ mf->offset += move_offset;
+ mf->read_pos -= move_offset;
+ mf->read_limit -= move_offset;
+ mf->write_pos -= move_offset;
+
+ return;
+}
+
+
+/// \brief Tries to fill the input window (mf->buffer)
+///
+/// If we are the last encoder in the chain, our input data is in in[].
+/// Otherwise we call the next filter in the chain to process in[] and
+/// write its output to mf->buffer.
+///
+/// This function must not be called once it has returned LZMA_STREAM_END.
+///
+static lzma_ret
+fill_window(lzma_coder *coder, const lzma_allocator *allocator,
+ const uint8_t *in, size_t *in_pos, size_t in_size,
+ lzma_action action)
+{
+ assert(coder->mf.read_pos <= coder->mf.write_pos);
+
+ // Move the sliding window if needed.
+ if (coder->mf.read_pos >= coder->mf.size - coder->mf.keep_size_after)
+ move_window(&coder->mf);
+
+ // Maybe this is ugly, but lzma_mf uses uint32_t for most things
+ // (which I find cleanest), but we need size_t here when filling
+ // the history window.
+ size_t write_pos = coder->mf.write_pos;
+ lzma_ret ret;
+ if (coder->next.code == NULL) {
+ // Not using a filter, simply memcpy() as much as possible.
+ lzma_bufcpy(in, in_pos, in_size, coder->mf.buffer,
+ &write_pos, coder->mf.size);
+
+ ret = action != LZMA_RUN && *in_pos == in_size
+ ? LZMA_STREAM_END : LZMA_OK;
+
+ } else {
+ ret = coder->next.code(coder->next.coder, allocator,
+ in, in_pos, in_size,
+ coder->mf.buffer, &write_pos,
+ coder->mf.size, action);
+ }
+
+ coder->mf.write_pos = write_pos;
+
+ // Silence Valgrind. lzma_memcmplen() can read extra bytes
+ // and Valgrind will give warnings if those bytes are uninitialized
+ // because Valgrind cannot see that the values of the uninitialized
+ // bytes are eventually ignored.
+ memzero(coder->mf.buffer + write_pos, LZMA_MEMCMPLEN_EXTRA);
+
+ // If end of stream has been reached or flushing completed, we allow
+ // the encoder to process all the input (that is, read_pos is allowed
+ // to reach write_pos). Otherwise we keep keep_size_after bytes
+ // available as prebuffer.
+ if (ret == LZMA_STREAM_END) {
+ assert(*in_pos == in_size);
+ ret = LZMA_OK;
+ coder->mf.action = action;
+ coder->mf.read_limit = coder->mf.write_pos;
+
+ } else if (coder->mf.write_pos > coder->mf.keep_size_after) {
+ // This needs to be done conditionally, because if we got
+ // only little new input, there may be too little input
+ // to do any encoding yet.
+ coder->mf.read_limit = coder->mf.write_pos
+ - coder->mf.keep_size_after;
+ }
+
+ // Restart the match finder after finished LZMA_SYNC_FLUSH.
+ if (coder->mf.pending > 0
+ && coder->mf.read_pos < coder->mf.read_limit) {
+ // Match finder may update coder->pending and expects it to
+ // start from zero, so use a temporary variable.
+ const uint32_t pending = coder->mf.pending;
+ coder->mf.pending = 0;
+
+ // Rewind read_pos so that the match finder can hash
+ // the pending bytes.
+ assert(coder->mf.read_pos >= pending);
+ coder->mf.read_pos -= pending;
+
+ // Call the skip function directly instead of using
+ // mf_skip(), since we don't want to touch mf->read_ahead.
+ coder->mf.skip(&coder->mf, pending);
+ }
+
+ return ret;
+}
+
+
+static lzma_ret
+lz_encode(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)
+{
+ while (*out_pos < out_size
+ && (*in_pos < in_size || action != LZMA_RUN)) {
+ // Read more data to coder->mf.buffer if needed.
+ if (coder->mf.action == LZMA_RUN && coder->mf.read_pos
+ >= coder->mf.read_limit)
+ return_if_error(fill_window(coder, allocator,
+ in, in_pos, in_size, action));
+
+ // Encode
+ const lzma_ret ret = coder->lz.code(coder->lz.coder,
+ &coder->mf, out, out_pos, out_size);
+ if (ret != LZMA_OK) {
+ // Setting this to LZMA_RUN for cases when we are
+ // flushing. It doesn't matter when finishing or if
+ // an error occurred.
+ coder->mf.action = LZMA_RUN;
+ return ret;
+ }
+ }
+
+ return LZMA_OK;
+}
+
+
+static bool
+lz_encoder_prepare(lzma_mf *mf, const lzma_allocator *allocator,
+ const lzma_lz_options *lz_options)
+{
+ // For now, the dictionary size is limited to 1.5 GiB. This may grow
+ // in the future if needed, but it needs a little more work than just
+ // changing this check.
+ if (lz_options->dict_size < LZMA_DICT_SIZE_MIN
+ || lz_options->dict_size
+ > (UINT32_C(1) << 30) + (UINT32_C(1) << 29)
+ || lz_options->nice_len > lz_options->match_len_max)
+ return true;
+
+ mf->keep_size_before = lz_options->before_size + lz_options->dict_size;
+
+ mf->keep_size_after = lz_options->after_size
+ + lz_options->match_len_max;
+
+ // To avoid constant memmove()s, allocate some extra space. Since
+ // memmove()s become more expensive when the size of the buffer
+ // increases, we reserve more space when a large dictionary is
+ // used to make the memmove() calls rarer.
+ //
+ // This works with dictionaries up to about 3 GiB. If bigger
+ // dictionary is wanted, some extra work is needed:
+ // - Several variables in lzma_mf have to be changed from uint32_t
+ // to size_t.
+ // - Memory usage calculation needs something too, e.g. use uint64_t
+ // for mf->size.
+ uint32_t reserve = lz_options->dict_size / 2;
+ if (reserve > (UINT32_C(1) << 30))
+ reserve /= 2;
+
+ reserve += (lz_options->before_size + lz_options->match_len_max
+ + lz_options->after_size) / 2 + (UINT32_C(1) << 19);
+
+ const uint32_t old_size = mf->size;
+ mf->size = mf->keep_size_before + reserve + mf->keep_size_after;
+
+ // Deallocate the old history buffer if it exists but has different
+ // size than what is needed now.
+ if (mf->buffer != NULL && old_size != mf->size) {
+ lzma_free(mf->buffer, allocator);
+ mf->buffer = NULL;
+ }
+
+ // Match finder options
+ mf->match_len_max = lz_options->match_len_max;
+ mf->nice_len = lz_options->nice_len;
+
+ // cyclic_size has to stay smaller than 2 Gi. Note that this doesn't
+ // mean limiting dictionary size to less than 2 GiB. With a match
+ // finder that uses multibyte resolution (hashes start at e.g. every
+ // fourth byte), cyclic_size would stay below 2 Gi even when
+ // dictionary size is greater than 2 GiB.
+ //
+ // It would be possible to allow cyclic_size >= 2 Gi, but then we
+ // would need to be careful to use 64-bit types in various places
+ // (size_t could do since we would need bigger than 32-bit address
+ // space anyway). It would also require either zeroing a multigigabyte
+ // buffer at initialization (waste of time and RAM) or allow
+ // normalization in lz_encoder_mf.c to access uninitialized
+ // memory to keep the code simpler. The current way is simple and
+ // still allows pretty big dictionaries, so I don't expect these
+ // limits to change.
+ mf->cyclic_size = lz_options->dict_size + 1;
+
+ // Validate the match finder ID and setup the function pointers.
+ switch (lz_options->match_finder) {
+#ifdef HAVE_MF_HC3
+ case LZMA_MF_HC3:
+ mf->find = &lzma_mf_hc3_find;
+ mf->skip = &lzma_mf_hc3_skip;
+ break;
+#endif
+#ifdef HAVE_MF_HC4
+ case LZMA_MF_HC4:
+ mf->find = &lzma_mf_hc4_find;
+ mf->skip = &lzma_mf_hc4_skip;
+ break;
+#endif
+#ifdef HAVE_MF_BT2
+ case LZMA_MF_BT2:
+ mf->find = &lzma_mf_bt2_find;
+ mf->skip = &lzma_mf_bt2_skip;
+ break;
+#endif
+#ifdef HAVE_MF_BT3
+ case LZMA_MF_BT3:
+ mf->find = &lzma_mf_bt3_find;
+ mf->skip = &lzma_mf_bt3_skip;
+ break;
+#endif
+#ifdef HAVE_MF_BT4
+ case LZMA_MF_BT4:
+ mf->find = &lzma_mf_bt4_find;
+ mf->skip = &lzma_mf_bt4_skip;
+ break;
+#endif
+
+ default:
+ return true;
+ }
+
+ // Calculate the sizes of mf->hash and mf->son and check that
+ // nice_len is big enough for the selected match finder.
+ const uint32_t hash_bytes = lz_options->match_finder & 0x0F;
+ if (hash_bytes > mf->nice_len)
+ return true;
+
+ const bool is_bt = (lz_options->match_finder & 0x10) != 0;
+ uint32_t hs;
+
+ if (hash_bytes == 2) {
+ hs = 0xFFFF;
+ } else {
+ // Round dictionary size up to the next 2^n - 1 so it can
+ // be used as a hash mask.
+ hs = lz_options->dict_size - 1;
+ hs |= hs >> 1;
+ hs |= hs >> 2;
+ hs |= hs >> 4;
+ hs |= hs >> 8;
+ hs >>= 1;
+ hs |= 0xFFFF;
+
+ if (hs > (UINT32_C(1) << 24)) {
+ if (hash_bytes == 3)
+ hs = (UINT32_C(1) << 24) - 1;
+ else
+ hs >>= 1;
+ }
+ }
+
+ mf->hash_mask = hs;
+
+ ++hs;
+ if (hash_bytes > 2)
+ hs += HASH_2_SIZE;
+ if (hash_bytes > 3)
+ hs += HASH_3_SIZE;
+/*
+ No match finder uses this at the moment.
+ if (mf->hash_bytes > 4)
+ hs += HASH_4_SIZE;
+*/
+
+ const uint32_t old_hash_count = mf->hash_count;
+ const uint32_t old_sons_count = mf->sons_count;
+ mf->hash_count = hs;
+ mf->sons_count = mf->cyclic_size;
+ if (is_bt)
+ mf->sons_count *= 2;
+
+ // Deallocate the old hash array if it exists and has different size
+ // than what is needed now.
+ if (old_hash_count != mf->hash_count
+ || old_sons_count != mf->sons_count) {
+ lzma_free(mf->hash, allocator);
+ mf->hash = NULL;
+
+ lzma_free(mf->son, allocator);
+ mf->son = NULL;
+ }
+
+ // Maximum number of match finder cycles
+ mf->depth = lz_options->depth;
+ if (mf->depth == 0) {
+ if (is_bt)
+ mf->depth = 16 + mf->nice_len / 2;
+ else
+ mf->depth = 4 + mf->nice_len / 4;
+ }
+
+ return false;
+}
+
+
+static bool
+lz_encoder_init(lzma_mf *mf, const lzma_allocator *allocator,
+ const lzma_lz_options *lz_options)
+{
+ // Allocate the history buffer.
+ if (mf->buffer == NULL) {
+ // lzma_memcmplen() is used for the dictionary buffer
+ // so we need to allocate a few extra bytes to prevent
+ // it from reading past the end of the buffer.
+ mf->buffer = lzma_alloc(mf->size + LZMA_MEMCMPLEN_EXTRA,
+ allocator);
+ if (mf->buffer == NULL)
+ return true;
+
+ // Keep Valgrind happy with lzma_memcmplen() and initialize
+ // the extra bytes whose value may get read but which will
+ // effectively get ignored.
+ memzero(mf->buffer + mf->size, LZMA_MEMCMPLEN_EXTRA);
+ }
+
+ // Use cyclic_size as initial mf->offset. This allows
+ // avoiding a few branches in the match finders. The downside is
+ // that match finder needs to be normalized more often, which may
+ // hurt performance with huge dictionaries.
+ mf->offset = mf->cyclic_size;
+ mf->read_pos = 0;
+ mf->read_ahead = 0;
+ mf->read_limit = 0;
+ mf->write_pos = 0;
+ mf->pending = 0;
+
+#if UINT32_MAX >= SIZE_MAX / 4
+ // Check for integer overflow. (Huge dictionaries are not
+ // possible on 32-bit CPU.)
+ if (mf->hash_count > SIZE_MAX / sizeof(uint32_t)
+ || mf->sons_count > SIZE_MAX / sizeof(uint32_t))
+ return true;
+#endif
+
+ // Allocate and initialize the hash table. Since EMPTY_HASH_VALUE
+ // is zero, we can use lzma_alloc_zero() or memzero() for mf->hash.
+ //
+ // We don't need to initialize mf->son, but not doing that may
+ // make Valgrind complain in normalization (see normalize() in
+ // lz_encoder_mf.c). Skipping the initialization is *very* good
+ // when big dictionary is used but only small amount of data gets
+ // actually compressed: most of the mf->son won't get actually
+ // allocated by the kernel, so we avoid wasting RAM and improve
+ // initialization speed a lot.
+ if (mf->hash == NULL) {
+ mf->hash = lzma_alloc_zero(mf->hash_count * sizeof(uint32_t),
+ allocator);
+ mf->son = lzma_alloc(mf->sons_count * sizeof(uint32_t),
+ allocator);
+
+ if (mf->hash == NULL || mf->son == NULL) {
+ lzma_free(mf->hash, allocator);
+ mf->hash = NULL;
+
+ lzma_free(mf->son, allocator);
+ mf->son = NULL;
+
+ return true;
+ }
+ } else {
+/*
+ for (uint32_t i = 0; i < mf->hash_count; ++i)
+ mf->hash[i] = EMPTY_HASH_VALUE;
+*/
+ memzero(mf->hash, mf->hash_count * sizeof(uint32_t));
+ }
+
+ mf->cyclic_pos = 0;
+
+ // Handle preset dictionary.
+ if (lz_options->preset_dict != NULL
+ && lz_options->preset_dict_size > 0) {
+ // If the preset dictionary is bigger than the actual
+ // dictionary, use only the tail.
+ mf->write_pos = my_min(lz_options->preset_dict_size, mf->size);
+ memcpy(mf->buffer, lz_options->preset_dict
+ + lz_options->preset_dict_size - mf->write_pos,
+ mf->write_pos);
+ mf->action = LZMA_SYNC_FLUSH;
+ mf->skip(mf, mf->write_pos);
+ }
+
+ mf->action = LZMA_RUN;
+
+ return false;
+}
+
+
+extern uint64_t
+lzma_lz_encoder_memusage(const lzma_lz_options *lz_options)
+{
+ // Old buffers must not exist when calling lz_encoder_prepare().
+ lzma_mf mf = {
+ .buffer = NULL,
+ .hash = NULL,
+ .son = NULL,
+ .hash_count = 0,
+ .sons_count = 0,
+ };
+
+ // Setup the size information into mf.
+ if (lz_encoder_prepare(&mf, NULL, lz_options))
+ return UINT64_MAX;
+
+ // Calculate the memory usage.
+ return ((uint64_t)(mf.hash_count) + mf.sons_count) * sizeof(uint32_t)
+ + mf.size + sizeof(lzma_coder);
+}
+
+
+static void
+lz_encoder_end(lzma_coder *coder, const lzma_allocator *allocator)
+{
+ lzma_next_end(&coder->next, allocator);
+
+ lzma_free(coder->mf.son, allocator);
+ lzma_free(coder->mf.hash, allocator);
+ lzma_free(coder->mf.buffer, 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;
+}
+
+
+static lzma_ret
+lz_encoder_update(lzma_coder *coder, const lzma_allocator *allocator,
+ const lzma_filter *filters_null lzma_attribute((__unused__)),
+ const lzma_filter *reversed_filters)
+{
+ if (coder->lz.options_update == NULL)
+ return LZMA_PROG_ERROR;
+
+ return_if_error(coder->lz.options_update(
+ coder->lz.coder, reversed_filters));
+
+ return lzma_next_filter_update(
+ &coder->next, allocator, reversed_filters + 1);
+}
+
+
+extern lzma_ret
+lzma_lz_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+ const lzma_filter_info *filters,
+ lzma_ret (*lz_init)(lzma_lz_encoder *lz,
+ const lzma_allocator *allocator, const void *options,
+ lzma_lz_options *lz_options))
+{
+#ifdef HAVE_SMALL
+ // We need that the CRC32 table has been initialized.
+ lzma_crc32_init();
+#endif
+
+ // Allocate and initialize the base data structure.
+ if (next->coder == NULL) {
+ next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
+ if (next->coder == NULL)
+ return LZMA_MEM_ERROR;
+
+ next->code = &lz_encode;
+ next->end = &lz_encoder_end;
+ next->update = &lz_encoder_update;
+
+ next->coder->lz.coder = NULL;
+ next->coder->lz.code = NULL;
+ next->coder->lz.end = NULL;
+
+ // mf.size is initialized to silence Valgrind
+ // when used on optimized binaries (GCC may reorder
+ // code in a way that Valgrind gets unhappy).
+ next->coder->mf.buffer = NULL;
+ next->coder->mf.size = 0;
+ next->coder->mf.hash = NULL;
+ next->coder->mf.son = NULL;
+ next->coder->mf.hash_count = 0;
+ next->coder->mf.sons_count = 0;
+
+ next->coder->next = LZMA_NEXT_CODER_INIT;
+ }
+
+ // Initialize the LZ-based encoder.
+ lzma_lz_options lz_options;
+ return_if_error(lz_init(&next->coder->lz, allocator,
+ filters[0].options, &lz_options));
+
+ // Setup the size information into next->coder->mf and deallocate
+ // old buffers if they have wrong size.
+ if (lz_encoder_prepare(&next->coder->mf, allocator, &lz_options))
+ return LZMA_OPTIONS_ERROR;
+
+ // Allocate new buffers if needed, and do the rest of
+ // the initialization.
+ if (lz_encoder_init(&next->coder->mf, allocator, &lz_options))
+ return LZMA_MEM_ERROR;
+
+ // Initialize the next filter in the chain, if any.
+ return lzma_next_filter_init(&next->coder->next, allocator,
+ filters + 1);
+}
+
+
+extern LZMA_API(lzma_bool)
+lzma_mf_is_supported(lzma_match_finder mf)
+{
+ bool ret = false;
+
+#ifdef HAVE_MF_HC3
+ if (mf == LZMA_MF_HC3)
+ ret = true;
+#endif
+
+#ifdef HAVE_MF_HC4
+ if (mf == LZMA_MF_HC4)
+ ret = true;
+#endif
+
+#ifdef HAVE_MF_BT2
+ if (mf == LZMA_MF_BT2)
+ ret = true;
+#endif
+
+#ifdef HAVE_MF_BT3
+ if (mf == LZMA_MF_BT3)
+ ret = true;
+#endif
+
+#ifdef HAVE_MF_BT4
+ if (mf == LZMA_MF_BT4)
+ ret = true;
+#endif
+
+ return ret;
+}
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