private bool ReadEntries(GptHeader header)
{
_diskData.Position = header.PartitionEntriesLba * _diskGeometry.BytesPerSector;
_entryBuffer = Utilities.ReadFully(_diskData, (int)(header.PartitionEntrySize * header.PartitionEntryCount));
if (header.EntriesCrc != CalcEntriesCrc())
{
return(false);
}
return(true);
}
/// <summary>
/// Creates a new partition table on a disk.
/// </summary>
/// <param name="disk">The stream containing the disk data</param>
/// <param name="diskGeometry">The geometry of the disk</param>
/// <returns>An object to access the newly created partition table</returns>
public static GuidPartitionTable Initialize(Stream disk, Geometry diskGeometry)
{
// Create the protective MBR partition record.
BiosPartitionTable pt = BiosPartitionTable.Initialize(disk, diskGeometry);
pt.CreatePrimaryByCylinder(0, diskGeometry.Cylinders - 1, BiosPartitionTypes.GptProtective, false);
// Create the GPT headers, and blank-out the entry areas
const int EntryCount = 128;
const int EntrySize = 128;
int entrySectors = ((EntryCount * EntrySize) + diskGeometry.BytesPerSector - 1) / diskGeometry.BytesPerSector;
byte[] entriesBuffer = new byte[EntryCount * EntrySize];
// Prepare primary header
GptHeader header = new GptHeader(diskGeometry.BytesPerSector);
header.HeaderLba = 1;
header.AlternateHeaderLba = (disk.Length / diskGeometry.BytesPerSector) - 1;
header.FirstUsable = header.HeaderLba + entrySectors + 1;
header.LastUsable = header.AlternateHeaderLba - entrySectors - 1;
header.DiskGuid = Guid.NewGuid();
header.PartitionEntriesLba = 2;
header.PartitionEntryCount = EntryCount;
header.PartitionEntrySize = EntrySize;
header.EntriesCrc = CalcEntriesCrc(entriesBuffer);
// Write the primary header
byte[] headerBuffer = new byte[diskGeometry.BytesPerSector];
header.WriteTo(headerBuffer, 0);
disk.Position = header.HeaderLba * diskGeometry.BytesPerSector;
disk.Write(headerBuffer, 0, headerBuffer.Length);
// Calc alternate header
header.HeaderLba = header.AlternateHeaderLba;
header.AlternateHeaderLba = 1;
header.PartitionEntriesLba = header.HeaderLba - entrySectors;
// Write the alternate header
header.WriteTo(headerBuffer, 0);
disk.Position = header.HeaderLba * diskGeometry.BytesPerSector;
disk.Write(headerBuffer, 0, headerBuffer.Length);
return(new GuidPartitionTable(disk, diskGeometry));
}
public GptHeader(GptHeader toCopy)
{
Signature = toCopy.Signature;
Version = toCopy.Version;
HeaderSize = toCopy.HeaderSize;
Crc = toCopy.Crc;
HeaderLba = toCopy.HeaderLba;
AlternateHeaderLba = toCopy.AlternateHeaderLba;
FirstUsable = toCopy.FirstUsable;
LastUsable = toCopy.LastUsable;
DiskGuid = toCopy.DiskGuid;
PartitionEntriesLba = toCopy.PartitionEntriesLba;
PartitionEntryCount = toCopy.PartitionEntryCount;
PartitionEntrySize = toCopy.PartitionEntrySize;
EntriesCrc = toCopy.EntriesCrc;
Buffer = new byte[toCopy.Buffer.Length];
Array.Copy(toCopy.Buffer, Buffer, Buffer.Length);
}
private void Init(Stream disk, Geometry diskGeometry)
{
BiosPartitionTable bpt;
try
{
bpt = new BiosPartitionTable(disk, diskGeometry);
}
catch (IOException ioe)
{
throw new IOException("Invalid GPT disk, protective MBR table not present or invalid", ioe);
}
if (bpt.Count != 1 || bpt[0].BiosType != BiosPartitionTypes.GptProtective)
{
throw new IOException("Invalid GPT disk, protective MBR table is not valid");
}
_diskData = disk;
_diskGeometry = diskGeometry;
disk.Position = diskGeometry.BytesPerSector;
byte[] sector = Utilities.ReadFully(disk, diskGeometry.BytesPerSector);
_primaryHeader = new GptHeader(diskGeometry.BytesPerSector);
if (!_primaryHeader.ReadFrom(sector, 0) || !ReadEntries(_primaryHeader))
{
disk.Position = disk.Length - diskGeometry.BytesPerSector;
disk.Read(sector, 0, sector.Length);
_secondaryHeader = new GptHeader(diskGeometry.BytesPerSector);
if (!_secondaryHeader.ReadFrom(sector, 0) || !ReadEntries(_secondaryHeader))
{
throw new IOException("No valid GUID Partition Table found");
}
// Generate from the primary table from the secondary one
_primaryHeader = new GptHeader(_secondaryHeader);
_primaryHeader.HeaderLba = _secondaryHeader.AlternateHeaderLba;
_primaryHeader.AlternateHeaderLba = _secondaryHeader.HeaderLba;
_primaryHeader.PartitionEntriesLba = 2;
// If the disk is writeable, fix up the primary partition table based on the
// (valid) secondary table.
if (disk.CanWrite)
{
WritePrimaryHeader();
}
}
if (_secondaryHeader == null)
{
_secondaryHeader = new GptHeader(diskGeometry.BytesPerSector);
disk.Position = disk.Length - diskGeometry.BytesPerSector;
disk.Read(sector, 0, sector.Length);
if (!_secondaryHeader.ReadFrom(sector, 0) || !ReadEntries(_secondaryHeader))
{
// Generate from the secondary table from the primary one
_secondaryHeader = new GptHeader(_primaryHeader);
_secondaryHeader.HeaderLba = _secondaryHeader.AlternateHeaderLba;
_secondaryHeader.AlternateHeaderLba = _secondaryHeader.HeaderLba;
_secondaryHeader.PartitionEntriesLba = _secondaryHeader.HeaderLba - Utilities.RoundUp(_secondaryHeader.PartitionEntryCount * _secondaryHeader.PartitionEntrySize, diskGeometry.BytesPerSector);
// If the disk is writeable, fix up the secondary partition table based on the
// (valid) primary table.
if (disk.CanWrite)
{
WriteSecondaryHeader();
}
}
}
}