/*

  *  Copyright (C) 2007-2008 Sourcefire, Inc.
  *
  *  Authors: Tomasz Kojm

  *
  *  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 "clamav.h"

 #include "cltypes.h"
 #include "others.h"

 #include "msexpand.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 BSIZE 4096
 #define RWBUFF 2048
 
 #define READBYTES				\
     ret = cli_readn(fd, rbuff, RWBUFF);		\
     if(ret == -1)				\

 	return CL_EREAD;			\

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

 	return CL_EWRITE;			\

     wbytes += w;				\

     if(wbytes >= EC32(hdr.fsize))		\

 	return CL_SUCCESS;			\
     w = 0;
 
 
 int cli_msexpand(int fd, int ofd, cli_ctx *ctx)
 {
 	struct msexp_hdr hdr;
 	uint8_t i, mask, bits;
 	unsigned char buff[BSIZE], rbuff[RWBUFF], wbuff[RWBUFF];
 	unsigned int j = BSIZE - 16, k, l, r = 0, w = 0, rbytes = 0, wbytes = 0;
 	int ret;

     if(cli_readn(fd, &hdr, sizeof(hdr)) == -1)

 	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;
     }

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

     if(cli_checklimits("MSEXPAND", ctx, EC32(hdr.fsize), 0, 0)!=CL_CLEAN)

         return CL_SUCCESS;

     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 == RWBUFF) {
 		    WRITEBYTES;
 		}

 		wbuff[w] = buff[j] = rbuff[r];
 		r++; w++;
 		j++; j %= BSIZE;
 	    } 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 == RWBUFF) {
 			WRITEBYTES;
 		    }
 		    wbuff[w] = buff[j] = buff[k];
 		    w++;
 		    k++; k %= BSIZE;
 		    j++; j %= BSIZE;

 		}
 	    }

 	    mask *= 2;

 	}
     }
 

     if(w) {
 	WRITEBYTES;
     }
 
     return CL_SUCCESS;

 }