private void runChecks()
{
// look at the position for the initial header first
byte[] buffer = new byte[i.sectorSize];
i.Seek(i.sectorSize, SeekOrigin.Begin);
i.Read(buffer, 0, buffer.Length);
int headersize = BitConverter.ToInt32(buffer, 0x0C);
uint headercheck = BitConverter.ToUInt32(buffer, 0x10);
// checksum of header is calculated with the checksum field set to zero
Array.Copy(new byte[] { 0, 0, 0, 0 }, 0x0, buffer, 0x10, 4);
// reserved field is not included
byte[] headerbuffer = new byte[headersize];
Array.Copy(buffer, headerbuffer, headerbuffer.Length);
Crc32 headercrc = new Crc32();
headercrc.ComputeHash(headerbuffer);
if (headercrc.CrcValue == headercheck)
{
this.headerFound = true;
// if the header is valid, add the header
this.headerMatchesCRC = true;
buffer = new byte[i.sectorSize];
i.Seek(i.sectorSize, SeekOrigin.Begin);
i.Read(buffer, 0, i.sectorSize);
this.header = getHeader(buffer, i, this.header);
this.tablestart = header.tablestart;
// make sure the table CRC matches as well
byte[] rawTable = new byte[tablelength];
i.Seek(header.tablestart * i.sectorSize, SeekOrigin.Begin);
i.Read(rawTable, 0, tablelength);
Crc32 tablecrc = new Crc32();
tablecrc.ComputeHash(rawTable);
if (tablecrc.CrcValue == header.tablecheck)
{
// if the table is valid, add the entries
this.tableMatchesCRC = true;
this.entries = buildTable(rawTable);
}
}
// then do the same for the backup header
buffer = new byte[i.sectorSize];
if (this.headerMatchesCRC)
{
// if the original header is valid, use the value from it to find the backup header
i.Seek(this.header.backupheader * i.sectorSize, SeekOrigin.Begin);
}
else
{
// if it is not valid, look 512 bytes from the end of the image
i.Seek(-i.sectorSize, SeekOrigin.End);
}
i.Read(buffer, 0, buffer.Length);
int backupheadersize = BitConverter.ToInt32(buffer, 0x0C);
uint backupheadercheck = BitConverter.ToUInt32(buffer, 0x10);
// checksum of header is calculated with the checksum field set to zero
Array.Copy(new byte[] { 0, 0, 0, 0 }, 0x0, buffer, 0x10, 4);
// reserved field is not included
byte[] backupheaderbuffer = new byte[headersize];
Array.Copy(buffer, backupheaderbuffer, backupheaderbuffer.Length);
Crc32 backupheadercrc = new Crc32();
backupheadercrc.ComputeHash(backupheaderbuffer);
if (backupheadercrc.CrcValue == backupheadercheck)
{
// if the header is valid, add the header
this.backupMatchesCRC = true;
this.backupFound = true;
buffer = new byte[i.sectorSize];
// go back 512 bytes because previous read incremented position by 512
i.Seek(-i.sectorSize, SeekOrigin.Current);
i.Read(buffer, 0, buffer.Length);
this.backupHeader = getHeader(buffer, i, this.backupHeader);
// make sure the table CRC matches as well
byte[] rawTable = new byte[tablelength];
i.Seek(backupHeader.tablestart * i.sectorSize, SeekOrigin.Begin);
i.Read(rawTable, 0, tablelength);
Crc32 tablecrc = new Crc32();
tablecrc.ComputeHash(rawTable);
if (tablecrc.CrcValue == backupHeader.tablecheck)
{
// if the table is valid, add the entries
this.backupTableMatchesCRC = true;
this.backupEntries = buildTable(rawTable);
}
}
i.Seek(0, SeekOrigin.Begin);
i.Read(buffer, 0, i.sectorSize);
if (buffer[buffer.Length - 2] == 0x55 && buffer[buffer.Length - 1] == 0xAA)
{
this.protectiveMBRExists = true;
}
}
private void runChecks()
{
// look at the position for the initial header first
byte[] buffer = new byte[i.sectorSize];
i.Seek(i.sectorSize, SeekOrigin.Begin);
i.Read(buffer, 0, buffer.Length);
int headersize = BitConverter.ToInt32(buffer, 0x0C);
uint headercheck = BitConverter.ToUInt32(buffer, 0x10);
// checksum of header is calculated with the checksum field set to zero
Array.Copy(new byte[] { 0, 0, 0, 0 }, 0x0, buffer, 0x10, 4);
// reserved field is not included
byte[] headerbuffer = new byte[headersize];
Array.Copy(buffer, headerbuffer, headerbuffer.Length);
Crc32 headercrc = new Crc32();
headercrc.ComputeHash(headerbuffer);
if (headercrc.CrcValue == headercheck)
{
this.headerFound = true;
// if the header is valid, add the header
this.headerMatchesCRC = true;
buffer = new byte[i.sectorSize];
i.Seek(i.sectorSize, SeekOrigin.Begin);
i.Read(buffer, 0, i.sectorSize);
this.header = getHeader(buffer, i, this.header);
this.tablestart = header.tablestart;
// make sure the table CRC matches as well
byte[] rawTable = new byte[tablelength];
i.Seek(header.tablestart * i.sectorSize, SeekOrigin.Begin);
i.Read(rawTable, 0, tablelength);
Crc32 tablecrc = new Crc32();
tablecrc.ComputeHash(rawTable);
if (tablecrc.CrcValue == header.tablecheck)
{
// if the table is valid, add the entries
this.tableMatchesCRC = true;
this.entries = buildTable(rawTable);
}
}
// then do the same for the backup header
buffer = new byte[i.sectorSize];
if (this.headerMatchesCRC)
{
// if the original header is valid, use the value from it to find the backup header
i.Seek(this.header.backupheader * i.sectorSize, SeekOrigin.Begin);
}
else
{
// if it is not valid, look 512 bytes from the end of the image
i.Seek(-i.sectorSize, SeekOrigin.End);
}
i.Read(buffer, 0, buffer.Length);
int backupheadersize = BitConverter.ToInt32(buffer, 0x0C);
uint backupheadercheck = BitConverter.ToUInt32(buffer, 0x10);
// checksum of header is calculated with the checksum field set to zero
Array.Copy(new byte[] { 0, 0, 0, 0 }, 0x0, buffer, 0x10, 4);
// reserved field is not included
byte[] backupheaderbuffer = new byte[headersize];
Array.Copy(buffer, backupheaderbuffer, backupheaderbuffer.Length);
Crc32 backupheadercrc = new Crc32();
backupheadercrc.ComputeHash(backupheaderbuffer);
if (backupheadercrc.CrcValue == backupheadercheck)
{
// if the header is valid, add the header
this.backupMatchesCRC = true;
this.backupFound = true;
buffer = new byte[i.sectorSize];
// go back 512 bytes because previous read incremented position by 512
i.Seek(-i.sectorSize, SeekOrigin.Current);
i.Read(buffer, 0, buffer.Length);
this.backupHeader = getHeader(buffer, i, this.backupHeader);
// make sure the table CRC matches as well
byte[] rawTable = new byte[tablelength];
i.Seek(backupHeader.tablestart * i.sectorSize, SeekOrigin.Begin);
i.Read(rawTable, 0, tablelength);
Crc32 tablecrc = new Crc32();
tablecrc.ComputeHash(rawTable);
if (tablecrc.CrcValue == backupHeader.tablecheck)
{
// if the table is valid, add the entries
this.backupTableMatchesCRC = true;
this.backupEntries = buildTable(rawTable);
}
}
i.Seek(0, SeekOrigin.Begin);
i.Read(buffer, 0, i.sectorSize);
if (buffer[buffer.Length - 2] == 0x55 && buffer[buffer.Length - 1] == 0xAA)
{
this.protectiveMBRExists = true;
}
}