/*

  *  Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
  *  Copyright (C) 2007-2013 Sourcefire, Inc.

  *
  *  Authors: Tomasz Kojm

  * 
  *  Acknowledgements: Decompression scheme by M. Winterhoff.

  *
  *  This program is free software; you can redistribute it and/or modify

  *  it under the terms of the GNU General Public License version 2 as
  *  published by the Free Software Foundation.

  *
  *  This program 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 details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software

  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  *  MA 02110-1301, USA.

  */
 

 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif
 

 #include <stdio.h>

 #include <stddef.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>

 #include <string.h>

 #include "clamav.h"

 #include "others.h"

 #include "msexpand.h"

 #include "fmap.h"

 #ifndef HAVE_ATTRIB_PACKED
 #define __attribute__(x)
 #endif

 #ifdef HAVE_PRAGMA_PACK
 #pragma pack(1)
 #endif
 
 #ifdef HAVE_PRAGMA_PACK_HPPA
 #pragma pack 1
 #endif
 

 #define EC32(x) le32_to_host(x)
 #define EC16(x) le16_to_host(x)
 
 #define MAGIC1	0x44445a53
 #define MAGIC2	0x3327f088
 #define MAGIC3	0x0041
 
 struct msexp_hdr {
     uint32_t magic1;
     uint32_t magic2;
     uint16_t magic3;
     uint32_t fsize;

 } __attribute__((packed));
 
 #ifdef HAVE_PRAGMA_PACK
 #pragma pack()
 #endif
 
 #ifdef HAVE_PRAGMA_PACK_HPPA
 #pragma pack
 #endif

 #define B_SIZE 4096
 #define RW_SIZE 2048

 
 #define READBYTES				\

     rbytes = MIN(RW_SIZE, map->len - cur_off);  \
     if(!rbytes)					\

 	break;					\

     rbuff = fmap_need_off_once(map, cur_off, rbytes); \
     if(!rbuff)					\
 	return CL_EREAD;			\
     cur_off += rbytes;				\

     r = 0;
 
 #define WRITEBYTES				\
     ret = cli_writen(ofd, wbuff, w);		\
     if(ret == -1 || (unsigned int) ret != w)	\

 	return CL_EWRITE;			\

     wbytes += w;				\

     if(wbytes >= fsize)				\

 	return CL_SUCCESS;			\
     w = 0;
 
 

 int cli_msexpand(cli_ctx *ctx, int ofd)

 {

 	const struct msexp_hdr *hdr;

 	uint8_t i, mask, bits;

 	unsigned char buff[B_SIZE], wbuff[RW_SIZE];

 	const unsigned char *rbuff = NULL; 	// rbuff will be set to a real address by READBYTES
 										// in the first iteration of the loop.

 	unsigned int j = B_SIZE - 16, k, l, r = 0, w = 0, rbytes = 0, wbytes = 0;

 	fmap_t *map = *ctx->fmap;
 	off_t cur_off = sizeof(*hdr);
 	unsigned int fsize;

 	int ret;

     if(!(hdr = fmap_need_off_once(map, 0, sizeof(*hdr))))

 	return CL_EREAD;

     if(EC32(hdr->magic1) != MAGIC1 || EC32(hdr->magic2) != MAGIC2 || EC16(hdr->magic3) != MAGIC3) {

 	cli_dbgmsg("MSEXPAND: Not supported file format\n");
 	return CL_EFORMAT;
     }

     fsize = EC32(hdr->fsize);
     cli_dbgmsg("MSEXPAND: File size from header: %u\n", fsize);

     if(cli_checklimits("MSEXPAND", ctx, fsize, 0, 0)!=CL_CLEAN)

         return CL_SUCCESS;

     memset(buff, 0, B_SIZE);

     while(1) {

 	if(!rbytes || (r == rbytes)) {
 	    READBYTES;

 	}
 

 	bits = rbuff[r]; r++;

 	mask = 1;
 	for(i = 0; i < 8; i++) {
 	    if(bits & mask) {
 		if(r == rbytes) {
 		    READBYTES;
 		}

 		if(w == RW_SIZE) {

 		    WRITEBYTES;
 		}

 		wbuff[w] = buff[j] = rbuff[r];
 		r++; w++;

 		j++; j %= B_SIZE;

 	    } else {
 		if(r == rbytes) {
 		    READBYTES;
 		}
 		k = rbuff[r]; r++;

 		if(r == rbytes) {
 		    READBYTES;

 		}

 		l = rbuff[r]; r++;

 		k += (l & 0xf0) << 4;
 		l = (l & 0x0f) + 3;
 		while(l--) {

 		    if(w == RW_SIZE) {

 			WRITEBYTES;
 		    }
 		    wbuff[w] = buff[j] = buff[k];
 		    w++;

 		    k++; k %= B_SIZE;
 		    j++; j %= B_SIZE;

 		}
 	    }

 	    mask *= 2;

 	}
     }
 

     if(w) {
 	WRITEBYTES;
     }
 
     return CL_SUCCESS;

 }