/*
  *  msexpand: Microsoft "compress.exe/expand.exe" compatible decompressor
  *
  *  Copyright (c) 2000 Martin Hinner <mhi@penguin.cz>
  *  Algorithm & data structures by M. Winterhoff <100326.2776@compuserve.com>
  *
  *  Corrected and adapted to ClamAV by Tomasz Kojm <tkojm@clamav.net>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2, or (at your option)
  *  any later version.
  *
  *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 
 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif
 #include "cltypes.h"
 #include "others.h"
 
 int cli_msexpand(FILE *in, FILE *out)
 {
 	int bits, ch, i, j, len, mask;
 	unsigned char *buffer;
 	uint32_t magic1, magic2, magic3, filesize;
 	uint16_t reserved;
 
 
     if(fread(&magic1, sizeof(magic1), 1, in) != 1) {
 	return -1;
     }
 
 #if WORDS_BIGENDIAN == 1
     if(magic1 == 0x535A4444L)
 #else
     if(magic1 == 0x44445A53L)
 #endif
     {
 	if(fread(&magic2, sizeof(magic2), 1, in) != 1) {
 	    return -1;
 	}
 
 	if(fread(&reserved, sizeof(reserved), 1, in) != 1) {
 	    return -1;
 	}
 
 	if(fread(&filesize, sizeof(filesize), 1, in) != 1) {
 	    return -1;
 	}
 
 #if WORDS_BIGENDIAN == 1
 	if(magic2 != 0x88F02733L)
 #else
 	if(magic2 != 0x3327F088L)
 #endif
 	{
 	    cli_warnmsg("msexpand: Not a MS-compressed file\n");
 	    return -1;
 	}
 
     } else
 #if WORDS_BIGENDIAN == 1
     if(magic1 == 0x4B57414AL)
 #else
     if(magic1 == 0x4A41574BL)
 #endif
     {
 	if(fread(&magic2, sizeof(magic2), 1, in) != 1) {
 	    return -1;
 	}
 
 	if(fread(&magic3, sizeof(magic3), 1, in) != 1) {
 	    return -1;
 	}
 
 	if(fread(&reserved, sizeof(reserved), 1, in) != 1) {
 	    return -1;
 	}
 
 #if WORDS_BIGENDIAN == 1
 	if(magic2 != 0x88F027D1L || magic3 != 0x03001200L)
 #else
 	if(magic2 != 0xD127F088L || magic3 != 0x00120003L)
 #endif
 	{
 	    cli_warnmsg("msexpand: Not a MS-compressed file\n");
 	    return -1;
 	}
 
 	cli_warnmsg("msexpand: unsupported version 6.22\n");
 	return -1;
 
     } else {
 	cli_warnmsg("msexpand: Not a MS-compressed file\n");
 	return -1;
     }
 
     if((buffer = (unsigned char *) cli_calloc(4096, sizeof(char))) == NULL) {
 	cli_errmsg("msexpand: Can't allocate memory\n");
 	return -1;
     }
 
     i = 4096 - 16;
 
     while (1) {
 	if((bits = fgetc(in)) == EOF)
 	    break;
 
 	for(mask = 0x01; mask & 0xFF; mask <<= 1) {
 	    if(!(bits & mask)) {
 		if((j = fgetc(in)) == EOF)
 		    break;
 		len = fgetc(in);
 		j += (len & 0xF0) << 4;
 		len = (len & 15) + 3;
 		while(len--) {
 		    buffer[i] = buffer[j];
 		    if(fwrite(&buffer[i], sizeof(unsigned char), 1, out) != 1) {
 			free(buffer);
 			return -1;
 		    }
 		    j++;
 		    j %= 4096;
 		    i++;
 		    i %= 4096;
 		}
 	    } else {
 		if((ch = fgetc(in)) == EOF)
 		    break;
 
 		buffer[i] = ch;
 		if(fwrite(&buffer[i], sizeof(unsigned char), 1, out) != 1) {
 		    free(buffer);
 		    return -1;
 		}
 		i++;
 		i %= 4096;
 	    }
 	}
     }
 
     free(buffer);
     return 0;
 }