readdpt.cpp

计算机病毒原理最地层的读取磁盘的代码 也可以用软件读区 也可以在DOC下自己编程读取

//Read Disk Partion Table
#include<dos.h>
#include<iostream.h>
#include<stdio.h>
#include<conio.h>
#include<math.h>
#include<stdlib.h>
int  ReadSector(double Sector_Start,int Sector_Num,char * Buffer);//Read Specified sector
void ReadDPT(char * Buffer,int is_Expand);
void ReadDPTItem(char *Buffer);
int ReadExpandPartion(double Start_Position);
double HexToDec(char * cPtr,int Length);
int  DecToHex(double DecNum,char *cPtr,int Length);
struct DiskAddressPacket
{
   char  PacketSize;
   char  Reserved;
   short int BlockCount;
   void  far * BufferAd;
   unsigned char   BlockNum[8];
};
const int DPT_START=446;
const int DPT_LENGTH=16;
static int  Main_Expartion_Flag=1;
static double Main_Expartion_Start;
void main()
{
   unsigned char  Buffer[512];
   if(!ReadSector(0,1,Buffer))
   {
      cout<<"\nSome error have ocuured!";
      exit(1);
   }
   ReadDPT(Buffer+DPT_START,0);
   getch();
}
int  ReadSector(double Sector_Start,int Sector_Num,char * Buffer)//Read Specified sector
{
   union REGS in,out;
   struct SREGS sregs;
   DiskAddressPacket DAP;
   DAP.PacketSize=16;
   DAP.Reserved=0;
   DAP.BlockCount=Sector_Num;
   DAP.BufferAd=MK_FP ((char *)FP_SEG (Buffer),Buffer);
   if(!(DecToHex(Sector_Start,DAP.BlockNum,8)))
   {
      return 0;
   }
   in.h.ah=0x42;
   in.h.dl=0x80;
   in.x.si=(int)&DAP;
   sregs.ds=FP_SEG(&DAP);
   int86x(0x13,&in,&out,&sregs);
   if(!out.x.cflag)
      return 1;
   else
      return 0;
}
void ReadDPT(char * Buffer,int is_Expand)
{
   static int ExpartNum=0;
   if(!is_Expand)
      printf("\n    ******************Disk DPT****************** ");
   for ( int i=0;i<4;i++)
   {
      if(is_Expand)
      {
	 ExpartNum++;
	 printf("\nThe %d Expand partion parameter is following",ExpartNum);
      }
      else
	 printf("\nThe %d Main partion parameter is following",i+1);
      ReadDPTItem(Buffer+i*16);
      if(is_Expand&&1==i)
	 break;
   }
}
void ReadDPTItem(char *Buffer)
{
   unsigned char PartionType;
   double Total_Sectors,Start_Position;
   //Read partion state;
   printf("\n   State   Start_Position     Partion_Size     Partion Type");
   cout<<endl;
   if(Buffer[0])
      cout<<"  active";
   else
      cout<<"not active";
   //Read partion start positon
   Start_Position=HexToDec(Buffer+8,4);
   printf("%12.0f ",Start_Position);
   //Read partion size
   Total_Sectors=HexToDec(Buffer+12,4);
   printf("    %12.0f ",Total_Sectors);
   //Read partion type
   PartionType=Buffer[4];
   printf("          %x",PartionType);
   if(0xf==PartionType||0x5==PartionType)//expands partion
   {
      if(Main_Expartion_Flag)
	 Main_Expartion_Start=Start_Position;
      if(!ReadExpandPartion(Start_Position))
	 printf("\nRead Expand Partoin error!");
   }
}
int ReadExpandPartion(double Start_Position)
{
   char Buffer[512];
   if(!Main_Expartion_Flag)
   {
      Start_Position+=Main_Expartion_Start;//if not base expartion shoud add
      printf("\n Read Expartion ");
   }
   Main_Expartion_Flag=0;
   if(!ReadSector(Start_Position,1,Buffer))
      return 0;
   ReadDPT(Buffer+DPT_START,1);
   return 1;
}
double HexToDec(char * cPtr,int Length)
{
   double DecNum=0;
   unsigned char  oper1,oper2,power=0;
   double temp,powresult;
   for(int i=0;i<Length;i++)
   {
      oper1=cPtr[i];
      //oper1=oper1&0x0ff;
      oper2=oper1;
      oper1=oper1&0x0f;
      powresult=pow(16,power);
      temp=oper1*powresult;
      DecNum+=temp;
      power++;
      oper2=oper2>>4;
      oper2=oper2&0x0f;
      powresult=pow(16,power);
      temp=oper2*powresult;
      DecNum+=temp;
      power++;

   }
   return DecNum;
}
int DecToHex(double DecNum,char *cPtr,int Length)
{
   double Shang=DecNum,temp;
   int Yushu=0;
   int ActualLen=0;
   int Flag=1;
   int ByteTo;
   while (Shang>=0.00001)
   {
     temp=Shang/16;
     temp=(long int)temp;
     Yushu=Shang-temp*16;
     Shang=temp;
     if(!(Flag%2))
     {
	Yushu<<=4;
	Yushu&=0x00f0;
	cPtr[ActualLen]&=0x0f;
	ByteTo=cPtr[ActualLen];
	ByteTo|=Yushu;
	cPtr[ActualLen]=(char)ByteTo;
	ActualLen++;
     }
     else
     {
	cPtr[ActualLen]=Yushu;
     }
     if(Length==ActualLen)
     {
	return 0;
     }
     Flag++;
   }
   for(int i=ActualLen;i<Length;i++)
   {
      if(!(Flag%2))
	i++;
      if(Length==i)
	 break;
      cPtr[i]=0;
   }
   return 1;
}