323 lines
12 KiB
C
323 lines
12 KiB
C
/*
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* Copyright (C) 2013-2022 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2008-2013 Sourcefire, Inc.
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*
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* Authors: Alberto Wu
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*
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* Acknowledgements: Written from scratch based on specs from PKWARE:
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* http://www.pkware.com/documents/casestudies/APPNOTE.TXT
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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/*
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* Written from scratch based on specs from PKWARE:
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* see www.pkware.com/documents/casestudies/APPNOTE.TXT
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*
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* To the best of my knowledge, it's patent free:
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* http://www.unisys.com/about__unisys/lzw
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*/
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/* To Cami and Dario, the only lawyers I can stand */
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#if HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#if HAVE_STRING_H
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#include <string.h>
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#endif
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#include "clamav.h"
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#include "explode.h"
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#include "others.h"
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/* NOTE: sorting algo must be stable! */
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static void bs(uint8_t *k, uint8_t *v, unsigned int elements)
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{
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uint8_t tmp;
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unsigned int i = 0, l = 0, stop = 0, r = elements;
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while (!stop) {
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stop = 1;
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for (; i < r; i++) {
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if (v[k[i]] > v[k[i + 1]]) {
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tmp = k[i];
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k[i] = k[i + 1];
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k[i + 1] = tmp;
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stop = 0;
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}
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}
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if (stop) break;
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r--;
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i--;
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for (; i > l; i--) {
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if (v[k[i]] < v[k[i - 1]]) {
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tmp = k[i];
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k[i] = k[i - 1];
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k[i - 1] = tmp;
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stop = 0;
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}
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}
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l++;
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i++;
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}
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}
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static int unpack_tree(struct xplstate *X, uint32_t *tree, unsigned int expected)
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{
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uint8_t temptree[256], order[256], *ttree = temptree;
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uint8_t *cur = X->window;
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uint8_t packsz;
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unsigned int i;
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uint16_t code = 0, codeinc = 0, lastlen = 0;
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packsz = *cur++;
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for (i = 0; i < expected; i++) order[i] = i;
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i = expected;
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do {
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uint8_t values, len;
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values = *cur++;
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len = (values & 15) + 1;
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values = (values >> 4) + 1;
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if (values > i) return 1;
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i -= values;
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while (values--)
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*ttree++ = len;
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} while (packsz--);
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if (i) return 1;
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bs(order, temptree, expected - 1);
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i = expected - 1;
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do {
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code = code + codeinc;
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if (temptree[order[i]] != lastlen) {
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lastlen = temptree[order[i]];
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codeinc = 1 << (16 - lastlen);
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}
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tree[order[i]] = code | ((uint32_t)lastlen << 16);
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} while (i--);
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return 0;
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}
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/* bit lame of a lookup, but prolly not worth optimizing */
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static int lookup_tree(uint32_t *tree, unsigned int size, uint16_t code, uint8_t len)
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{
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uint32_t lookup = ((uint32_t)(len + 1)) << 16 | code;
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unsigned int i;
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for (i = 0; i < size; i++)
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if (tree[i] == lookup) return i;
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return -1;
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}
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int explode_init(struct xplstate *X, uint16_t flags)
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{
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X->bits = X->cur = 0;
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if (flags & 2) {
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X->largewin = 1;
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X->mask = 0x1fff;
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} else {
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X->largewin = 0;
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X->mask = 0xfff;
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}
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if (flags & 4) {
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X->state = GRABLITS;
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X->litcodes = 1;
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X->minlen = 3;
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} else {
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X->state = GRABLENS;
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X->litcodes = 0;
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X->minlen = 2;
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}
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X->got = 0;
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return EXPLODE_OK;
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}
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#define GETBIT \
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if (X->bits) { \
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X->bits--; \
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val = X->bitmap & 1; \
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X->bitmap >>= 1; \
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} else { \
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if (!X->avail_in) return EXPLODE_EBUFF; \
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if (X->avail_in >= 4) { \
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X->bitmap = cli_readint32(X->next_in); \
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X->bits = 31; \
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X->next_in += 4; \
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X->avail_in -= 4; \
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} else { \
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X->bitmap = *X->next_in; \
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X->bits = 7; \
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X->next_in++; \
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X->avail_in--; \
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} \
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val = X->bitmap & 1; \
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X->bitmap >>= 1; \
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}
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#define GETBITS(NUM) \
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if (X->bits >= (NUM)) { \
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val = X->bitmap & ((1 << (NUM)) - 1); \
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X->bitmap >>= (NUM); \
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X->bits -= (NUM); \
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} else { \
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if (X->avail_in * 8 + X->bits < (NUM)) return EXPLODE_EBUFF; \
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val = X->bitmap; \
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if (X->avail_in >= 4) { \
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X->bitmap = cli_readint32(X->next_in); \
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X->next_in += 4; \
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X->avail_in -= 4; \
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val |= (X->bitmap & ((1 << ((NUM)-X->bits)) - 1)) << X->bits; \
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X->bitmap >>= (NUM)-X->bits; \
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X->bits = 32 - ((NUM)-X->bits); \
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} else { \
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X->bitmap = *X->next_in; \
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X->next_in++; \
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X->avail_in--; \
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val |= (X->bitmap & ((1 << ((NUM)-X->bits)) - 1)) << X->bits; \
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X->bitmap >>= (NUM)-X->bits; \
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X->bits = 8 - ((NUM)-X->bits); \
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} \
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}
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#define GETCODES(CASE, WHICH, HOWMANY) \
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case CASE: { \
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if (!X->avail_in) return EXPLODE_EBUFF; \
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if (!X->got) \
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need = *X->next_in; \
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else \
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need = X->window[0]; \
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if (need > HOWMANY - 1) return EXPLODE_ESTREAM; /* too many codes */ \
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need = need + 2 - X->got; /* bytes remaining */ \
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if (need > X->avail_in) { /* if not enuff */ \
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/* just copy what's avail... */ \
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memcpy(&X->window[X->got], X->next_in, X->avail_in); \
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X->got += X->avail_in; \
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X->next_in += X->avail_in; \
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X->avail_in = 0; \
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return EXPLODE_EBUFF; /* ...and beg for more */ \
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} \
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/* else fetch what's needed */ \
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memcpy(&X->window[X->got], X->next_in, need); \
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X->avail_in -= need; \
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X->next_in += need; \
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if (unpack_tree(X, X->WHICH, HOWMANY)) return EXPLODE_ESTREAM; \
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/* and move on */ \
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X->got = 0; \
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X->state++; \
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}
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#define SETCASE(CASE) \
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X->state = (CASE); \
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case (CASE): { /* FAKE */ \
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}
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int explode(struct xplstate *X)
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{
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unsigned int val, need;
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int temp = -1;
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switch (X->state) {
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/* grab compressed coded literals, if present */
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GETCODES(GRABLITS, lit_tree, 256);
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/* grab compressed coded lens */
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GETCODES(GRABLENS, len_tree, 64);
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/* grab compressed coded dists */
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GETCODES(GRABDISTS, dist_tree, 64);
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case EXPLODE:
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while (X->avail_in || X->bits) {
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GETBIT; /* can't fail */
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if (val) {
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if (X->litcodes) {
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X->backsize = 0;
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X->state = EXPLODE_LITCODES;
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for (X->got = 0; X->got <= 15; X->got++) {
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case EXPLODE_LITCODES:
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GETBIT;
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X->backsize |= val << (15 - X->got);
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if ((temp = lookup_tree(X->lit_tree, 256, X->backsize, X->got)) != -1) break;
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}
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if (temp == -1) return EXPLODE_ESTREAM;
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X->got = temp;
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} else {
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SETCASE(EXPLODE_LITS);
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GETBITS(8);
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X->got = val;
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}
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SETCASE(EXPLODE_WBYTE);
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if (!X->avail_out) return EXPLODE_EBUFF;
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X->avail_out--;
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*X->next_out = X->window[X->cur & X->mask] = X->got;
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X->cur++;
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X->next_out++;
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} else {
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SETCASE(EXPLODE_BASEDIST);
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GETBITS(6u + X->largewin);
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X->backbytes = val;
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X->backsize = 0;
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X->state = EXPLODE_DECODEDISTS;
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for (X->got = 0; X->got <= 15; X->got++) {
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case EXPLODE_DECODEDISTS:
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GETBIT;
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X->backsize |= val << (15 - X->got);
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if ((temp = lookup_tree(X->dist_tree, 64, X->backsize, X->got)) != -1) break;
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}
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if (temp == -1) return EXPLODE_ESTREAM;
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X->backbytes |= temp << (6 + X->largewin);
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X->backbytes++;
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X->backsize = 0;
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X->state = EXPLODE_DECODELENS;
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for (X->got = 0; X->got <= 15; X->got++) {
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case EXPLODE_DECODELENS:
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GETBIT;
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X->backsize |= val << (15 - X->got);
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if ((temp = lookup_tree(X->len_tree, 64, X->backsize, X->got)) != -1) break;
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}
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if (temp == -1) return EXPLODE_ESTREAM;
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if (temp == 63) {
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SETCASE(EXPLODE_DECODEEXTRA);
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GETBITS(8);
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temp = 63 + val;
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}
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X->backsize = temp + X->minlen;
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X->state = EXPLODE_BACKCOPY;
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while (X->backsize--) {
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case EXPLODE_BACKCOPY:
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if (!X->avail_out) return EXPLODE_EBUFF;
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X->avail_out--;
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if (X->cur >= X->backbytes)
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*X->next_out = X->window[X->cur & X->mask] = X->window[(X->cur - X->backbytes) & X->mask];
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else
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*X->next_out = X->window[X->cur & X->mask] = 0;
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X->cur++;
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X->next_out++;
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}
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}
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X->state = EXPLODE;
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}
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}
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return EXPLODE_EBUFF;
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}
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void explode_shutdown(void) {}
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