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269 lines
8.0 KiB
269 lines
8.0 KiB
/*
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* Copyright (C) 2015, 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2010 Sourcefire, Inc.
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*
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* Authors: aCaB <acab@clamav.net>
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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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#if HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#include <string.h>
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#include "scanners.h"
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#include "cltypes.h"
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#include "others.h"
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#include "clamav.h"
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#include "fmap.h"
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#include "binhex.h"
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static const uint8_t hqxtbl[] = {
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/* 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f */
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/* 00-0f */ 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
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/* 10-1f */ 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
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/* 20-2f */ 0xff,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0xff,0xff,
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/* 30-3f */ 0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0xff,0x14,0x15,0xff,0xff,0xff,0xff,0xff,0xff,
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/* 40-4f */ 0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0xff,
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/* 50-5f */ 0x25,0x26,0x27,0x28,0x29,0x2a,0x2b,0xff,0x2c,0x2d,0x2e,0x2f,0xff,0xff,0xff,0xff,
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/* 60-6f */ 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0xff,0x37,0x38,0x39,0x3a,0x3b,0x3c,0xff,0xff,
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/* 70-7f */ 0x3d,0x3e,0x3f,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
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};
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#define BH_FLUSH_SZ (BUFSIZ - 256)
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int cli_binhex(cli_ctx *ctx) {
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fmap_t *map = *ctx->fmap;
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const uint8_t *encoded = NULL;
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uint8_t decoded[BUFSIZ], spare_bits = 0, last_byte = 0, this_byte = 0, offset = 0;
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size_t enc_done=0, enc_todo=map->len;
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unsigned int dec_done=0, chunksz = 0, chunkoff=0;
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uint32_t datalen = 0, reslen = 0;
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int in_data = 0, in_run = 0, datafd, resfd, ret = CL_CLEAN;
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enum binhex_phase { IN_BANNER, IN_HEADER, IN_DATA, IN_LIMBO1, IN_LIMBO2, IN_RES } write_phase = IN_BANNER;
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char *dname, *rname;
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cli_dbgmsg("in cli_binhex\n");
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if(!map->len) return CL_CLEAN;
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if((ret = cli_gentempfd(ctx->engine->tmpdir, &dname, &datafd)) != CL_SUCCESS)
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return ret;
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if((ret = cli_gentempfd(ctx->engine->tmpdir, &rname, &resfd)) != CL_SUCCESS) {
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close(datafd);
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if(cli_unlink(dname)) ret = CL_EUNLINK;
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free(dname);
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return ret;
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}
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memset(decoded, 0, 24);
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while(1) {
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uint8_t b;
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if(!enc_todo || dec_done >= BH_FLUSH_SZ) {
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if(write_phase == IN_HEADER) {
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uint32_t namelen = (uint32_t)decoded[0], hdrlen = 1 + namelen + 1 + 4 + 4 + 2;
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if(!dec_done) {
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cli_dbgmsg("cli_binhex: file is empty\n");
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break;
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}
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datalen = (decoded[hdrlen]<<24) | (decoded[hdrlen+1]<<16) | (decoded[hdrlen+2]<<8) | decoded[hdrlen+3];
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hdrlen += 4;
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reslen = (decoded[hdrlen]<<24) | (decoded[hdrlen+1]<<16) | (decoded[hdrlen+2]<<8) | decoded[hdrlen+3];
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hdrlen += 4 + 2;
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decoded[namelen+1] = 0;
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if(dec_done <= hdrlen) {
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cli_dbgmsg("cli_binhex: file too short for header\n");
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break;
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}
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if((ret = cli_checklimits("cli_binhex(data)", ctx, datalen, 0, 0)) != CL_CLEAN)
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break;
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if(cli_checklimits("cli_binhex(resources)", ctx, reslen, 0, 0) != CL_CLEAN)
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reslen = 0;
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cli_dbgmsg("cli_binhex: decoding '%s' - %u bytes of data to %s - %u bytes or resources to %s\n", decoded+1, datalen, dname, reslen, rname);
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memmove(decoded, &decoded[hdrlen], dec_done - hdrlen);
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dec_done -= hdrlen;
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write_phase++;
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}
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if(dec_done && write_phase == IN_DATA) {
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unsigned int todo = MIN(dec_done, datalen);
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datalen -= todo;
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dec_done -= todo;
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if(cli_writen(datafd, decoded, todo)!=(int)todo) {
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ret = CL_EWRITE;
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break;
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}
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if(!datalen) {
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write_phase++;
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if (lseek(datafd, 0, SEEK_SET) == -1) {
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cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
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ret = CL_ESEEK;
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break;
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}
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ret = cli_magic_scandesc(datafd, dname, ctx);
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if(ret == CL_VIRUS) break;
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}
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if(dec_done)
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memmove(decoded, &decoded[todo], dec_done);
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}
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if(dec_done && write_phase == IN_LIMBO1) {
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if(dec_done > 1) {
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if(reslen<5) {
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cli_dbgmsg("cli_binhex: skipping resources (too small)\n");
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break;
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}
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dec_done-=2;
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write_phase+=2;
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if(dec_done)
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memmove(decoded, &decoded[2], dec_done);
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} else {
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dec_done--;
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write_phase++;
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if(dec_done)
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memmove(decoded, &decoded[1], dec_done);
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}
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}
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if(dec_done && write_phase == IN_LIMBO2) {
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if(reslen<5) {
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cli_dbgmsg("cli_binhex: skipping resources (too small)\n");
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break;
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}
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write_phase++;
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if(--dec_done)
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memmove(decoded, &decoded[1], dec_done);
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}
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if(dec_done && write_phase == IN_RES) {
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unsigned int todo = MIN(dec_done, reslen);
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reslen -= todo;
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dec_done -= todo;
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if(cli_writen(resfd, decoded, todo)!=(int)todo) {
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ret = CL_EWRITE;
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break;
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}
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if(!reslen) {
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if (lseek(resfd, 0, SEEK_SET) == -1) {
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cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
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ret = CL_ESEEK;
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break;
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}
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ret = cli_magic_scandesc(resfd, rname, ctx);
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break;
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}
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}
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if(!enc_todo) {
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if(write_phase == IN_DATA) {
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cli_dbgmsg("cli_binhex: scanning partially extracted data fork\n");
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if (lseek(datafd, 0, SEEK_SET) == -1) {
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cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
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ret = CL_ESEEK;
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break;
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}
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ret = cli_magic_scandesc(datafd, dname, ctx);
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} else if(write_phase == IN_RES) {
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cli_dbgmsg("cli_binhex: scanning partially extracted resource fork\n");
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if (lseek(resfd, 0, SEEK_SET) == -1) {
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cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
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ret = CL_ESEEK;
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break;
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}
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ret = cli_magic_scandesc(resfd, rname, ctx);
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}
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break;
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}
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}
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// 'chunksz' must be 0 the first iteration,
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// so that 'encoded' will be initialized before first dereference.
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if(!chunksz)
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{
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chunksz = MIN(enc_todo, map->pgsz);
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encoded = fmap_need_off_once(map, enc_done, chunksz);
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if(!encoded) {
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ret = CL_EREAD;
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break;
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}
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chunkoff = 0;
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}
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chunksz--;
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b = encoded[chunkoff++];
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enc_done++;
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enc_todo--;
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if((char)b == '\r' || (char)b == '\n') {
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in_data = 1;
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continue;
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}
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if(!in_data) continue;
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if(write_phase == IN_BANNER) {
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if((char)b != ':') {
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cli_dbgmsg("cli_binhex: broken file (missing stream start identifier)\n");
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break;
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}
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write_phase++;
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}
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if((char)b == ':')
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continue;
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if(b > 0x7f || (b = hqxtbl[b]) == 0xff) {
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cli_dbgmsg("cli_binhex: Invalid character (%02x)\n", encoded[chunkoff-1]);
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break;
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}
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switch((offset++) & 3) { /* 6 bits per char */
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case 0: /* left-6h */
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spare_bits = b<<2;
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continue;
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case 1: /* left-2l + middle-4h */
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this_byte = spare_bits | (b>>4);
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spare_bits = b<<4;
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break;
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case 2: /* middle-4l + right-2h */
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this_byte = spare_bits | (b>>2);
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spare_bits = b<<6;
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break;
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case 3: /* right-6l */
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this_byte = spare_bits | b;
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}
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if(in_run) {
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in_run = 0;
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if(!this_byte)
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this_byte = 0x90;
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else {
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while(--this_byte)
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decoded[dec_done++] = last_byte;
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continue;
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}
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} else if(this_byte == 0x90) {
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in_run = 1;
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continue;
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}
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decoded[dec_done++] = this_byte;
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last_byte = this_byte;
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}
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close(datafd);
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close(resfd);
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if(!ctx->engine->keeptmp) {
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if(cli_unlink(dname) && ret != CL_VIRUS) ret = CL_EUNLINK;
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if(cli_unlink(rname) && ret != CL_VIRUS) ret = CL_EUNLINK;
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}
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free(dname);
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free(rname);
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return ret;
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}
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