313 lines
11 KiB
C
313 lines
11 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) 2007-2013 Sourcefire, Inc.
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*
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* Authors: Alberto Wu, Michal 'GiM' Spadlinski
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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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#if HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#include "clamav.h"
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#include "others.h"
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#include "execs.h"
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#include "pe.h"
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#include "packlibs.h"
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static int doubledl(const char **scur, uint8_t *mydlptr, const char *buffer, uint32_t buffersize)
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{
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unsigned char mydl = *mydlptr;
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unsigned char olddl = mydl;
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mydl *= 2;
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if (!(olddl & 0x7f)) {
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if (*scur < buffer || *scur >= buffer + buffersize - 1)
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return -1;
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olddl = **scur;
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mydl = olddl * 2 + 1;
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*scur = *scur + 1;
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}
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*mydlptr = mydl;
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return (olddl >> 7) & 1;
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}
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int cli_unfsg(const char *source, char *dest, int ssize, int dsize, const char **endsrc, char **enddst)
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{
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uint8_t mydl = 0x80;
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uint32_t backbytes, backsize, oldback = 0;
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const char *csrc = source;
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char *cdst = dest;
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int oob, lostbit = 1;
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if (ssize <= 0 || dsize <= 0) return -1;
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*cdst++ = *csrc++;
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while (1) {
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if ((oob = doubledl(&csrc, &mydl, source, ssize))) {
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if (oob == -1)
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return -1;
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/* 164 */
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backsize = 0;
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if ((oob = doubledl(&csrc, &mydl, source, ssize))) {
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if (oob == -1)
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return -1;
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/* 16a */
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backbytes = 0;
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if ((oob = doubledl(&csrc, &mydl, source, ssize))) {
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if (oob == -1)
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return -1;
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/* 170 */
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lostbit = 1;
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backsize++;
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backbytes = 0x10;
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while (backbytes < 0x100) {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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backbytes = backbytes * 2 + oob;
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}
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backbytes &= 0xff;
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if (!backbytes) {
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if (cdst >= dest + dsize)
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return -1;
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*cdst++ = 0x00;
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continue;
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}
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} else {
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/* 18f */
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if (csrc >= source + ssize)
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return -1;
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backbytes = *(unsigned char *)csrc;
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backsize = backsize * 2 + (backbytes & 1);
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backbytes = (backbytes & 0xff) >> 1;
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csrc++;
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if (!backbytes)
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break;
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backsize += 2;
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oldback = backbytes;
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lostbit = 0;
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}
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} else {
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/* 180 */
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backsize = 1;
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do {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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backsize = backsize * 2 + oob;
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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} while (oob);
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backsize = backsize - 1 - lostbit;
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if (!backsize) {
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/* 18a */
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backsize = 1;
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do {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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backsize = backsize * 2 + oob;
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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} while (oob);
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backbytes = oldback;
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} else {
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/* 198 */
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if (csrc >= source + ssize)
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return -1;
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backbytes = *(unsigned char *)csrc;
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backbytes += (backsize - 1) << 8;
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backsize = 1;
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csrc++;
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do {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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backsize = backsize * 2 + oob;
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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} while (oob);
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if (backbytes >= 0x7d00)
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backsize++;
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if (backbytes >= 0x500)
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backsize++;
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if (backbytes <= 0x7f)
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backsize += 2;
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oldback = backbytes;
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}
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lostbit = 0;
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}
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if (!CLI_ISCONTAINED(dest, dsize, cdst, backsize) || !CLI_ISCONTAINED(dest, dsize, cdst - backbytes, backsize))
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return -1;
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while (backsize--) {
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*cdst = *(cdst - backbytes);
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cdst++;
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}
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} else {
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/* 15d */
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if (cdst < dest || cdst >= dest + dsize || csrc < source || csrc >= source + ssize)
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return -1;
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*cdst++ = *csrc++;
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lostbit = 1;
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}
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}
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if (endsrc) *endsrc = csrc;
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if (enddst) *enddst = cdst;
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return 0;
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}
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int unmew(const char *source, char *dest, int ssize, int dsize, const char **endsrc, char **enddst)
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{
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uint8_t mydl = 0x80;
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uint32_t myeax_backbytes, myecx_backsize, oldback = 0;
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const char *csrc = source;
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char *cdst = dest;
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int oob, lostbit = 1;
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*cdst++ = *csrc++;
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while (1) {
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if ((oob = doubledl(&csrc, &mydl, source, ssize))) {
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if (oob == -1)
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return -1;
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/* 164 */
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myecx_backsize = 0;
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if ((oob = doubledl(&csrc, &mydl, source, ssize))) {
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if (oob == -1)
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return -1;
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/* 16a */
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myeax_backbytes = 0;
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if ((oob = doubledl(&csrc, &mydl, source, ssize))) {
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if (oob == -1)
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return -1;
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/* 170 */
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lostbit = 1;
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myecx_backsize++;
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myeax_backbytes = 0x10;
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while (myeax_backbytes < 0x100) {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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myeax_backbytes = myeax_backbytes * 2 + oob;
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}
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myeax_backbytes &= 0xff;
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if (!myeax_backbytes) {
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if (cdst >= dest + dsize)
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return -1;
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*cdst++ = 0x00;
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/*cli_dbgmsg("X%02x ", *(cdst-1)&0xff);*/
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continue;
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}
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} else {
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/* 18f */
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if (csrc >= source + ssize)
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return -1;
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myeax_backbytes = *(unsigned char *)csrc;
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myecx_backsize = myecx_backsize * 2 + (myeax_backbytes & 1);
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myeax_backbytes = (myeax_backbytes & 0xff) >> 1;
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csrc++;
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if (!myeax_backbytes) {
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/* cli_dbgmsg("\nBREAK \n"); */
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break;
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}
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myecx_backsize += 2;
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oldback = myeax_backbytes;
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lostbit = 0;
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}
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} else {
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/* 180 */
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myecx_backsize = 1;
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do {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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myecx_backsize = myecx_backsize * 2 + oob;
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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} while (oob);
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myecx_backsize = myecx_backsize - 1 - lostbit;
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if (!myecx_backsize) {
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/* 18a */
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myecx_backsize = 1;
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do {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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myecx_backsize = myecx_backsize * 2 + oob;
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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} while (oob);
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myeax_backbytes = oldback;
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} else {
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/* 198 */
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if (csrc >= source + ssize)
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return -1;
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myeax_backbytes = *(unsigned char *)csrc;
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myeax_backbytes += (myecx_backsize - 1) << 8;
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myecx_backsize = 1;
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csrc++;
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do {
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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myecx_backsize = myecx_backsize * 2 + oob;
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if ((oob = doubledl(&csrc, &mydl, source, ssize)) == -1)
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return -1;
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} while (oob);
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if (myeax_backbytes >= 0x7d00)
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myecx_backsize++;
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if (myeax_backbytes >= 0x500)
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myecx_backsize++;
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if (myeax_backbytes <= 0x7f)
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myecx_backsize += 2;
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oldback = myeax_backbytes;
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}
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lostbit = 0;
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}
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if (!CLI_ISCONTAINED(dest, dsize, cdst, myecx_backsize) || !CLI_ISCONTAINED(dest, dsize, cdst - myeax_backbytes, myecx_backsize)) {
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cli_dbgmsg("MEW: rete: %p %d %p %d %d || %p %d %p %d %d\n", dest, dsize, cdst, myecx_backsize,
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CLI_ISCONTAINED(dest, dsize, cdst, myecx_backsize),
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dest, dsize, cdst - myeax_backbytes, myecx_backsize,
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CLI_ISCONTAINED(dest, dsize, cdst - myeax_backbytes, myecx_backsize));
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return -1;
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}
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while (myecx_backsize--) {
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*cdst = *(cdst - myeax_backbytes);
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cdst++;
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}
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} else {
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/* 15d */
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if (cdst < dest || cdst >= dest + dsize || csrc < source || csrc >= source + ssize) {
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cli_dbgmsg("MEW: retf %p %p+%08x=%p, %p %p+%08x=%p\n",
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cdst, dest, dsize, dest + dsize, csrc, source, ssize, source + ssize);
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return -1;
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}
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*cdst++ = *csrc++;
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/* cli_dbgmsg("Z%02x ", *(cdst-1)&0xff); */
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lostbit = 1;
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}
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}
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*endsrc = csrc;
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*enddst = cdst;
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return 0;
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}
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