X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Fdecompress.c;h=d79865b898d19e9409f47569531aa0ef5f38454b;hp=68ab495dac0cabc3aeb60844b55da40aa2f4b3dd;hb=a8d148d9b2a765ba7fcbce927ea2546f917afe53;hpb=a6f5add5e9811584ebd75591a6a25cb9686da9a8 diff --git a/src/decompress.c b/src/decompress.c index 68ab495d..d79865b8 100644 --- a/src/decompress.c +++ b/src/decompress.c @@ -1,344 +1,110 @@ /* * decompress.c * - * Functions used for decompression. + * Generic functions for decompression, wrapping around actual decompression + * implementations. */ /* - * Copyright (C) 2012 Eric Biggers + * Copyright (C) 2013, 2014 Eric Biggers * - * This file is part of wimlib, a library for working with WIM files. + * This file 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 3 of the License, or (at your option) any + * later version. * - * wimlib is free software; you can redistribute it and/or modify it under the - * terms of the GNU General Public License as published by the Free - * Software Foundation; either version 3 of the License, or (at your option) - * any later version. - * - * wimlib 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 General Public License for more + * This file 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. * - * You should have received a copy of the GNU General Public License - * along with wimlib; if not, see http://www.gnu.org/licenses/. + * You should have received a copy of the GNU Lesser General Public License + * along with this file; if not, see http://www.gnu.org/licenses/. */ -#include "decompress.h" -#include - -/* Reads @n bytes from the bitstream @stream into the location pointed to by @dest. - * The bitstream must be 16-bit aligned. */ -int bitstream_read_bytes(struct input_bitstream *stream, size_t n, void *dest) -{ - /* Precondition: The bitstream is 16-byte aligned. */ - wimlib_assert2(stream->bitsleft % 16 == 0); +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif - u8 *p = dest; +#include "wimlib.h" +#include "wimlib/decompressor_ops.h" +#include "wimlib/util.h" - /* Get the bytes currently in the buffer variable. */ - while (stream->bitsleft != 0) { - if (n-- == 0) - return 0; - *p++ = bitstream_peek_bits(stream, 8); - bitstream_remove_bits(stream, 8); - } +struct wimlib_decompressor { + const struct decompressor_ops *ops; + size_t max_block_size; + void *private; +}; - /* Get the rest directly from the pointer to the data. Of course, it's - * necessary to check there are really n bytes available. */ - if (n > stream->data_bytes_left) { - ERROR("Unexpected end of input when reading %zu bytes from " - "bitstream (only have %u bytes left)", - n, stream->data_bytes_left); - return 1; - } - memcpy(p, stream->data, n); - stream->data += n; - stream->data_bytes_left -= n; +static const struct decompressor_ops *decompressor_ops[] = { + [WIMLIB_COMPRESSION_TYPE_XPRESS] = &xpress_decompressor_ops, + [WIMLIB_COMPRESSION_TYPE_LZX] = &lzx_decompressor_ops, + [WIMLIB_COMPRESSION_TYPE_LZMS] = &lzms_decompressor_ops, +}; - /* It's possible to copy an odd number of bytes and leave the stream in - * an inconsistent state. Fix it by reading the next byte, if it is - * there. */ - if ((n & 1) && stream->data_bytes_left != 0) { - stream->bitsleft = 8; - stream->data_bytes_left--; - stream->bitbuf |= (input_bitbuf_t)(*stream->data) << - (sizeof(input_bitbuf_t) * 8 - 8); - stream->data++; - } - return 0; +static bool +decompressor_ctype_valid(int ctype) +{ + return (ctype >= 0 && + ctype < ARRAY_LEN(decompressor_ops) && + decompressor_ops[ctype] != NULL); } -/* - * Builds a fast huffman decoding table from a canonical huffman code lengths - * table. Based on code written by David Tritscher. - * - * @decode_table: The array in which to create the fast huffman decoding - * table. It must have a length of at least - * (2**num_bits) + 2 * num_syms to guarantee - * that there is enough space. - * - * @num_syms: Total number of symbols in the Huffman tree. - * - * @num_bits: Any symbols with a code length of num_bits or less can be - * decoded in one lookup of the table. 2**num_bits - * must be greater than or equal to @num_syms if there are - * any Huffman codes longer than @num_bits. - * - * @lens: An array of length @num_syms, indexable by symbol, that - * gives the length of that symbol. Because the Huffman - * tree is in canonical form, it can be reconstructed by - * only knowing the length of the code for each symbol. - * - * @make_codeword_len: An integer that gives the longest possible codeword - * length. - * - * Returns 0 on success; returns 1 if the length values do not correspond to a - * valid Huffman tree, or if there are codes of length greater than @num_bits - * but 2**num_bits < num_syms. - * - * What exactly is the format of the fast Huffman decoding table? The first - * (1 << num_bits) entries of the table are indexed by chunks of the input of - * size @num_bits. If the next Huffman code in the input happens to have a - * length of exactly @num_bits, the symbol is simply read directly from the - * decoding table. Alternatively, if the next Huffman code has length _less - * than_ @num_bits, the symbol is also read directly from the decode table; this - * is possible because every entry in the table that is indexed by an integer - * that has the shorter code as a binary prefix is filled in with the - * appropriate symbol. If a code has length n <= num_bits, it will have - * 2**(num_bits - n) possible suffixes, and thus that many entries in the - * decoding table. - * - * It's a bit more complicated if the next Huffman code has length of more than - * @num_bits. The table entry indexed by the first @num_bits of that code - * cannot give the appropriate symbol directly, because that entry is guaranteed - * to be referenced by the Huffman codes for multiple symbols. And while the - * LZX compression format does not allow codes longer than 16 bits, a table of - * size (2 ** 16) = 65536 entries would be too slow to create. - * - * There are several different ways to make it possible to look up the symbols - * for codes longer than @num_bits. A common way is to make the entries for the - * prefixes of length @num_bits of those entries be pointers to additional - * decoding tables that are indexed by some number of additional bits of the - * code symbol. The technique used here is a bit simpler, however. We just - * store the needed subtrees of the Huffman tree in the decoding table after the - * lookup entries, beginning at index (2**num_bits). Real pointers are - * replaced by indices into the decoding table, and we distinguish symbol - * entries from pointers by the fact that values less than @num_syms must be - * symbol values. - */ -int make_huffman_decode_table(u16 decode_table[], unsigned num_syms, - unsigned num_bits, const u8 lens[], - unsigned max_code_len) +WIMLIBAPI int +wimlib_create_decompressor(enum wimlib_compression_type ctype, + size_t max_block_size, + struct wimlib_decompressor **dec_ret) { - /* Number of entries in the decode table. */ - u32 table_num_entries = 1 << num_bits; - - /* Current position in the decode table. */ - u32 decode_table_pos = 0; - - /* Fill entries for codes short enough for a direct mapping. Here we - * are taking advantage of the ordering of the codes, since they are for - * a canonical Huffman tree. It must be the case that all the codes of - * some length @code_length, zero-extended or one-extended, numerically - * precede all the codes of length @code_length + 1. Furthermore, if we - * have 2 symbols A and B, such that A is listed before B in the lens - * array, and both symbols have the same code length, then we know that - * the code for A numerically precedes the code for B. - * */ - for (unsigned code_len = 1; code_len <= num_bits; code_len++) { - - /* Number of entries that a code of length @code_length would - * need. */ - u32 code_num_entries = 1 << (num_bits - code_len); - - - /* For each symbol of length @code_len, fill in its entries in - * the decode table. */ - for (unsigned sym = 0; sym < num_syms; sym++) { - - if (lens[sym] != code_len) - continue; - - - /* Check for table overrun. This can only happen if the - * given lengths do not correspond to a valid Huffman - * tree. */ - if (decode_table_pos >= table_num_entries) { - ERROR("Huffman decoding table overrun: " - "pos = %u, num_entries = %u", - decode_table_pos, table_num_entries); - return 1; - } - - /* Fill all possible lookups of this symbol with - * the symbol itself. */ - for (unsigned i = 0; i < code_num_entries; i++) - decode_table[decode_table_pos + i] = sym; - - /* Increment the position in the decode table by - * the number of entries that were just filled - * in. */ - decode_table_pos += code_num_entries; - } - } - - /* If all entries of the decode table have been filled in, there are no - * codes longer than num_bits, so we are done filling in the decode - * table. */ - if (decode_table_pos == table_num_entries) - return 0; - - /* Otherwise, fill in the remaining entries, which correspond to codes longer - * than @num_bits. */ - - - /* First, zero out the rest of the entries; this is necessary so - * that the entries appear as "unallocated" in the next part. */ - for (unsigned i = decode_table_pos; i < table_num_entries; i++) - decode_table[i] = 0; - - /* Assert that 2**num_bits is at least num_syms. If this wasn't the - * case, we wouldn't be able to distinguish pointer entries from symbol - * entries. */ - wimlib_assert((1 << num_bits) >= num_syms); - - - /* The current Huffman code. */ - unsigned current_code = decode_table_pos; - - /* The tree nodes are allocated starting at - * decode_table[table_num_entries]. Remember that the full size of the - * table, including the extra space for the tree nodes, is actually - * 2**num_bits + 2 * num_syms slots, while table_num_entries is only - * 2**num_bits. */ - unsigned next_free_tree_slot = table_num_entries; - - /* Go through every codeword of length greater than @num_bits. Note: - * the LZX format guarantees that the codeword length can be at most 16 - * bits. */ - for (unsigned code_len = num_bits + 1; code_len <= max_code_len; - code_len++) - { - current_code <<= 1; - for (unsigned sym = 0; sym < num_syms; sym++) { - if (lens[sym] != code_len) - continue; - - - /* i is the index of the current node; find it from the - * prefix of the current Huffman code. */ - unsigned i = current_code >> (code_len - num_bits); - - if (i >= (1 << num_bits)) { - ERROR("Invalid canonical Huffman code"); - return 1; - } - - /* Go through each bit of the current Huffman code - * beyond the prefix of length num_bits and walk the - * tree, "allocating" slots that have not yet been - * allocated. */ - for (int bit_num = num_bits + 1; bit_num <= code_len; bit_num++) { - - /* If the current tree node points to nowhere - * but we need to follow it, allocate a new node - * for it to point to. */ - if (decode_table[i] == 0) { - decode_table[i] = next_free_tree_slot; - decode_table[next_free_tree_slot++] = 0; - decode_table[next_free_tree_slot++] = 0; - } - - i = decode_table[i]; - - /* Is the next bit 0 or 1? If 0, go left; - * otherwise, go right (by incrementing i by 1) */ - int bit_pos = code_len - bit_num; - - int bit = (current_code & (1 << bit_pos)) >> - bit_pos; - i += bit; - } - - /* i is now the index of the leaf entry into which the - * actual symbol will go. */ - decode_table[i] = sym; - - /* Increment decode_table_pos only if the prefix of the - * Huffman code changes. */ - if (current_code >> (code_len - num_bits) != - (current_code + 1) >> (code_len - num_bits)) - decode_table_pos++; - - /* current_code is always incremented because this is - * how canonical Huffman codes are generated (add 1 for - * each code, then left shift whenever the code length - * increases) */ - current_code++; - } - } - - - /* If the lengths really represented a valid Huffman tree, all - * @table_num_entries in the table will have been filled. However, it - * is also possible that the tree is completely empty (as noted - * earlier) with all 0 lengths, and this is expected to succeed. */ - - if (decode_table_pos != table_num_entries) { - - for (unsigned i = 0; i < num_syms; i++) { - if (lens[i] != 0) { - ERROR("Lengths do not form a valid canonical " - "Huffman tree (only filled %u of %u " - "decode table slots)", - decode_table_pos, table_num_entries); - return 1; - } + struct wimlib_decompressor *dec; + + if (!decompressor_ctype_valid(ctype)) + return WIMLIB_ERR_INVALID_COMPRESSION_TYPE; + + if (dec_ret == NULL) + return WIMLIB_ERR_INVALID_PARAM; + + if (max_block_size == 0) + return WIMLIB_ERR_INVALID_PARAM; + + dec = MALLOC(sizeof(*dec)); + if (dec == NULL) + return WIMLIB_ERR_NOMEM; + dec->ops = decompressor_ops[ctype]; + dec->max_block_size = max_block_size; + dec->private = NULL; + if (dec->ops->create_decompressor) { + int ret; + + ret = dec->ops->create_decompressor(max_block_size, + &dec->private); + if (ret) { + FREE(dec); + return ret; } } + *dec_ret = dec; return 0; } -/* Reads a Huffman-encoded symbol when it is known there are less than - * MAX_CODE_LEN bits remaining in the bitstream. */ -int read_huffsym_near_end_of_input(struct input_bitstream *istream, - const u16 decode_table[], - const u8 lens[], - unsigned num_syms, - unsigned table_bits, - unsigned *n) +WIMLIBAPI int +wimlib_decompress(const void *compressed_data, size_t compressed_size, + void *uncompressed_data, size_t uncompressed_size, + struct wimlib_decompressor *dec) { - unsigned bitsleft = istream->bitsleft; - unsigned key_size; - u16 sym; - u16 key_bits; + if (unlikely(uncompressed_size > dec->max_block_size)) + return -2; - if (table_bits > bitsleft) { - key_size = bitsleft; - bitsleft = 0; - key_bits = bitstream_peek_bits(istream, key_size) << - (table_bits - key_size); - } else { - key_size = table_bits; - bitsleft -= table_bits; - key_bits = bitstream_peek_bits(istream, table_bits); - } + return dec->ops->decompress(compressed_data, compressed_size, + uncompressed_data, uncompressed_size, + dec->private); +} - sym = decode_table[key_bits]; - if (sym >= num_syms) { - bitstream_remove_bits(istream, key_size); - do { - if (bitsleft == 0) { - ERROR("Input stream exhausted"); - return 1; - } - key_bits = sym + bitstream_peek_bits(istream, 1); - bitstream_remove_bits(istream, 1); - bitsleft--; - } while ((sym = decode_table[key_bits]) >= num_syms); - } else { - bitstream_remove_bits(istream, lens[sym]); +WIMLIBAPI void +wimlib_free_decompressor(struct wimlib_decompressor *dec) +{ + if (dec) { + if (dec->ops->free_decompressor) + dec->ops->free_decompressor(dec->private); + FREE(dec); } - *n = sym; - return 0; }