/// <summary>
/// Initialises a new GPT and attempts to read its information from the specified disk.
/// </summary>
/// <param name="disk">The disk to read the GPT from.</param>
public GPT(Hardware.Devices.DiskDevice disk)
{
#if GPT_TRACE
BasicConsole.WriteLine("Checking for GPT...");
BasicConsole.DelayOutput(1);
#endif
//Assumed block size of 512.
uint blockSize = 512;
//Note: The GPT format specifies a protective MBR entry (1 partition
// covering the entire disk) immediately followed (byte-wise)
// by the GPT. Thus the GPT must come at 512th byte.
// However, some disks can have 4096 bytes per sector (/block)
// so the code below might break as reading LBA 1 (2nd LBA) would
// return the wrong data. We probably ought to find some way to
// check the block size and just load the required amount of data.
//Check for single MBR partition with 0xEE system ID
byte[] blockData = new byte[blockSize];
//Read the first sector of data.
disk.ReadBlock(0UL, 1U, blockData);
//Attempt to read the MBR
MBR TheMBR = new MBR(blockData);
//If the MBR isn't valid, the protective MBR partition specified as part of GPT
// isn't present / valid so this isn't a valid GPT.
if (!TheMBR.IsValid)
{
#if GPT_TRACE
BasicConsole.WriteLine("MBR invalid.");
BasicConsole.DelayOutput(1);
#endif
return;
}
//Or, if there is not one and only one partition in the MBR then the
// protective MBR isn't valid so this isn't a valid GPT
else if (TheMBR.NumPartitions != 1)
{
#if GPT_TRACE
BasicConsole.WriteLine("No partitions in MBR.");
BasicConsole.DelayOutput(1);
#endif
return;
}
//Or, the first (/only) partition entry has the wrong ID. 0xEE is the partition
// ID for a GOT formatted MBR partition.
else if (TheMBR.Partitions[0].SystemID != 0xEE)
{
#if GPT_TRACE
BasicConsole.WriteLine(((FOS_System.String)"MBR partition 0 system ID not GPT. ") + TheMBR.Partitions[0].SystemID);
BasicConsole.DelayOutput(1);
#endif
return;
}
#if GPT_TRACE
BasicConsole.WriteLine("GPT MBR partition detected.");
BasicConsole.DelayOutput(1);
#endif
//Now we know this is very-likely to be GPT formatted.
// But we must check the GPT header for signature etc.
//Read the GPT block
disk.ReadBlock(1UL, 1U, blockData);
//Check for GPT signature: 0x45 0x46 0x49 0x20 0x50 0x41 0x52 0x54
bool OK = blockData[0] == 0x45;
OK = OK && blockData[1] == 0x46;
OK = OK && blockData[2] == 0x49;
OK = OK && blockData[3] == 0x20;
OK = OK && blockData[4] == 0x50;
OK = OK && blockData[5] == 0x41;
OK = OK && blockData[6] == 0x52;
OK = OK && blockData[7] == 0x54;
//If any part of the ID was wrong, this is not a valid GPT.
if (!OK)
{
#if GPT_TRACE
BasicConsole.WriteLine("GPT signature invalid.");
BasicConsole.DelayOutput(1);
#endif
return;
}
//Now we know, this is a valid GPT. Whether or not the actual entries are valid
// is yet to be determined. There is of course the small chance that some other
// data has conflicted with GPT data and that this isn't a GPT, it just looks
// like it. If that is the case, what idiot formatted the disk we are reading
// because a conflict like that is impossible to detect without user input!
IsValid = true;
#if GPT_TRACE
BasicConsole.WriteLine("Valid GPT detected.");
BasicConsole.DelayOutput(5);
#endif
//Load-in GPT global data
Revision = ByteConverter.ToUInt32(blockData, 8);
HeaderSize = ByteConverter.ToUInt32(blockData, 12);
HeaderCRC32 = ByteConverter.ToUInt32(blockData, 16);
HeaderLBA = ByteConverter.ToUInt64(blockData, 24);
HeaderBackupLBA = ByteConverter.ToUInt64(blockData, 32);
FirstUsableLBAForPartitions = ByteConverter.ToUInt64(blockData, 40);
LastUsableLBAForPartitions = ByteConverter.ToUInt64(blockData, 48);
#if GPT_TRACE
BasicConsole.WriteLine(((FOS_System.String)"Revision : ") + Revision);
BasicConsole.WriteLine(((FOS_System.String)"Header size : ") + HeaderSize);
BasicConsole.WriteLine(((FOS_System.String)"Header CRC32 : ") + HeaderCRC32);
BasicConsole.WriteLine(((FOS_System.String)"Header LBA : ") + HeaderLBA);
BasicConsole.WriteLine(((FOS_System.String)"Header Backup LBA : ") + HeaderBackupLBA);
BasicConsole.WriteLine(((FOS_System.String)"First usable LBA for partitions : ") + FirstUsableLBAForPartitions);
BasicConsole.WriteLine(((FOS_System.String)"Last usable LBA for partitions : ") + LastUsableLBAForPartitions);
BasicConsole.DelayOutput(5);
#endif
//Load the disk ID
DiskGUID = new byte[16];
DiskGUID[0] = blockData[56];
DiskGUID[1] = blockData[57];
DiskGUID[2] = blockData[58];
DiskGUID[3] = blockData[59];
DiskGUID[4] = blockData[60];
DiskGUID[5] = blockData[61];
DiskGUID[6] = blockData[62];
DiskGUID[7] = blockData[63];
DiskGUID[8] = blockData[64];
DiskGUID[9] = blockData[65];
DiskGUID[10] = blockData[66];
DiskGUID[11] = blockData[67];
DiskGUID[12] = blockData[68];
DiskGUID[13] = blockData[69];
DiskGUID[14] = blockData[70];
DiskGUID[15] = blockData[71];
//Load more global GPT data
StartingLBAOfPartitionArray = ByteConverter.ToUInt64(blockData, 72);
NumPartitionEntries = ByteConverter.ToUInt32(blockData, 80);
SizeOfPartitionEntry = ByteConverter.ToUInt32(blockData, 84);
PartitionArrayCRC32 = ByteConverter.ToUInt32(blockData, 88);
#if GPT_TRACE
BasicConsole.WriteLine(((FOS_System.String)"Start LBA of part arrray : ") + StartingLBAOfPartitionArray);
BasicConsole.WriteLine(((FOS_System.String)"Num part entries : ") + NumPartitionEntries);
BasicConsole.WriteLine(((FOS_System.String)"Size of part entry : ") + SizeOfPartitionEntry);
BasicConsole.WriteLine(((FOS_System.String)"Part array CRC32 : ") + PartitionArrayCRC32);
BasicConsole.DelayOutput(5);
#endif
ulong blockNum = StartingLBAOfPartitionArray;
uint entriesPerBlock = blockSize / SizeOfPartitionEntry;
#if GPT_TRACE
BasicConsole.WriteLine("Reading partition entries...");
BasicConsole.WriteLine(((FOS_System.String)"blockNum=") + blockNum);
BasicConsole.WriteLine(((FOS_System.String)"entriesPerBlock=") + entriesPerBlock);
BasicConsole.DelayOutput(1);
#endif
//TODO: Check the CRC32 values of the header and partition table
// are correct.
//Note: By not checking the CRCs, we have the option to manually edit
// the GPT without rejecting it if CRCs end up incorrect.
//TODO: Add an override option to ignore the CRCs
//TODO: Add a method to update / correct the CRCs
//Read partition infos
for(uint i = 0; i < NumPartitionEntries; i++)
{
//If we're on a block boundary, we need to load the next block
// of data to parse.
if (i % entriesPerBlock == 0)
{
#if GPT_TRACE
BasicConsole.WriteLine("Reading block data...");
BasicConsole.WriteLine(((FOS_System.String)"blockNum=") + blockNum);
BasicConsole.DelayOutput(1);
#endif
//Load the next block of data
disk.ReadBlock(blockNum++, 1u, blockData);
}
//Calculate the offset into the current data block
uint offset = (i % entriesPerBlock) * SizeOfPartitionEntry;
#if GPT_TRACE
BasicConsole.WriteLine("Reading entry...");
BasicConsole.WriteLine(((FOS_System.String)"offset=") + offset);
#endif
//Attempt to load the partition info
PartitionInfo inf = new PartitionInfo(blockData, offset, SizeOfPartitionEntry);
//Partitions are marked as empty by an all-zero type ID. If the partition is empty,
// there is no point adding it.
if (!inf.Empty)
{
#if GPT_TRACE
BasicConsole.WriteLine("Entry not empty.");
#endif
//Add the non-empty partition
Partitions.Add(inf);
}
#if GPT_TRACE
else
{
BasicConsole.WriteLine("Entry empty.");
}
#endif
}
}
/// <summary>
/// Attempts to initialise a disk treating it as MBR formatted.
/// </summary>
/// <param name="aDiskDevice">The disk to initialise.</param>
/// <returns>True if a valid MBR was detected and the disk was successfully initialised. Otherwise, false.</returns>
private static bool InitAsMBR(DiskDevice aDiskDevice)
{
#if FSM_TRACE
BasicConsole.WriteLine("Attempting to read MBR...");
#endif
byte[] MBRData = new byte[512];
aDiskDevice.ReadBlock(0UL, 1U, MBRData);
#if FSM_TRACE
BasicConsole.WriteLine("Read potential MBR data. Attempting to init MBR...");
#endif
MBR TheMBR = new MBR(MBRData);
if (!TheMBR.IsValid)
{
return false;
}
else
{
#if FSM_TRACE
BasicConsole.WriteLine("Valid MBR found.");
#endif
ProcessMBR(TheMBR, aDiskDevice);
return true;
}
}
/// <summary>
/// Processes a valid master boot record to initialize its partitions.
/// </summary>
/// <param name="anMBR">The MBR to process.</param>
/// <param name="aDiskDevice">The disk device from which the MBR was read.</param>
private static void ProcessMBR(MBR anMBR, DiskDevice aDiskDevice)
{
for (int i = 0; i < anMBR.NumPartitions; i++)
{
MBR.PartitionInfo aPartInfo = anMBR.Partitions[i];
if (aPartInfo.EBRLocation != 0)
{
byte[] EBRData = new byte[512];
aDiskDevice.ReadBlock(aPartInfo.EBRLocation, 1U, EBRData);
EBR newEBR = new EBR(EBRData);
ProcessMBR(newEBR, aDiskDevice);
}
else
{
Partitions.Add(new Partition(aDiskDevice, aPartInfo.StartSector, aPartInfo.SectorCount));
}
}
}
/// <summary>
/// Initialises a new GPT and attempts to read its information from the specified disk.
/// </summary>
/// <param name="disk">The disk to read the GPT from.</param>
public GPT(Hardware.Devices.DiskDevice disk)
{
#if GPT_TRACE
BasicConsole.WriteLine("Checking for GPT...");
BasicConsole.DelayOutput(1);
#endif
//Assumed block size of 512.
uint blockSize = 512;
//Note: The GPT format specifies a protective MBR entry (1 partition
// covering the entire disk) immediately followed (byte-wise)
// by the GPT. Thus the GPT must come at 512th byte.
// However, some disks can have 4096 bytes per sector (/block)
// so the code below might break as reading LBA 1 (2nd LBA) would
// return the wrong data. We probably ought to find some way to
// check the block size and just load the required amount of data.
//Check for single MBR partition with 0xEE system ID
byte[] blockData = new byte[blockSize];
//Read the first sector of data.
disk.ReadBlock(0UL, 1U, blockData);
//Attempt to read the MBR
MBR TheMBR = new MBR(blockData);
//If the MBR isn't valid, the protective MBR partition specified as part of GPT
// isn't present / valid so this isn't a valid GPT.
if (!TheMBR.IsValid)
{
#if GPT_TRACE
BasicConsole.WriteLine("MBR invalid.");
BasicConsole.DelayOutput(1);
#endif
return;
}
//Or, if there is not one and only one partition in the MBR then the
// protective MBR isn't valid so this isn't a valid GPT
else if (TheMBR.NumPartitions != 1)
{
#if GPT_TRACE
BasicConsole.WriteLine("No partitions in MBR.");
BasicConsole.DelayOutput(1);
#endif
return;
}
//Or, the first (/only) partition entry has the wrong ID. 0xEE is the partition
// ID for a GOT formatted MBR partition.
else if (TheMBR.Partitions[0].SystemID != 0xEE)
{
#if GPT_TRACE
BasicConsole.WriteLine(((FOS_System.String) "MBR partition 0 system ID not GPT. ") + TheMBR.Partitions[0].SystemID);
BasicConsole.DelayOutput(1);
#endif
return;
}
#if GPT_TRACE
BasicConsole.WriteLine("GPT MBR partition detected.");
BasicConsole.DelayOutput(1);
#endif
//Now we know this is very-likely to be GPT formatted.
// But we must check the GPT header for signature etc.
//Read the GPT block
disk.ReadBlock(1UL, 1U, blockData);
//Check for GPT signature: 0x45 0x46 0x49 0x20 0x50 0x41 0x52 0x54
bool OK = blockData[0] == 0x45;
OK = OK && blockData[1] == 0x46;
OK = OK && blockData[2] == 0x49;
OK = OK && blockData[3] == 0x20;
OK = OK && blockData[4] == 0x50;
OK = OK && blockData[5] == 0x41;
OK = OK && blockData[6] == 0x52;
OK = OK && blockData[7] == 0x54;
//If any part of the ID was wrong, this is not a valid GPT.
if (!OK)
{
#if GPT_TRACE
BasicConsole.WriteLine("GPT signature invalid.");
BasicConsole.DelayOutput(1);
#endif
return;
}
//Now we know, this is a valid GPT. Whether or not the actual entries are valid
// is yet to be determined. There is of course the small chance that some other
// data has conflicted with GPT data and that this isn't a GPT, it just looks
// like it. If that is the case, what idiot formatted the disk we are reading
// because a conflict like that is impossible to detect without user input!
IsValid = true;
#if GPT_TRACE
BasicConsole.WriteLine("Valid GPT detected.");
BasicConsole.DelayOutput(5);
#endif
//Load-in GPT global data
Revision = ByteConverter.ToUInt32(blockData, 8);
HeaderSize = ByteConverter.ToUInt32(blockData, 12);
HeaderCRC32 = ByteConverter.ToUInt32(blockData, 16);
HeaderLBA = ByteConverter.ToUInt64(blockData, 24);
HeaderBackupLBA = ByteConverter.ToUInt64(blockData, 32);
FirstUsableLBAForPartitions = ByteConverter.ToUInt64(blockData, 40);
LastUsableLBAForPartitions = ByteConverter.ToUInt64(blockData, 48);
#if GPT_TRACE
BasicConsole.WriteLine(((FOS_System.String) "Revision : ") + Revision);
BasicConsole.WriteLine(((FOS_System.String) "Header size : ") + HeaderSize);
BasicConsole.WriteLine(((FOS_System.String) "Header CRC32 : ") + HeaderCRC32);
BasicConsole.WriteLine(((FOS_System.String) "Header LBA : ") + HeaderLBA);
BasicConsole.WriteLine(((FOS_System.String) "Header Backup LBA : ") + HeaderBackupLBA);
BasicConsole.WriteLine(((FOS_System.String) "First usable LBA for partitions : ") + FirstUsableLBAForPartitions);
BasicConsole.WriteLine(((FOS_System.String) "Last usable LBA for partitions : ") + LastUsableLBAForPartitions);
BasicConsole.DelayOutput(5);
#endif
//Load the disk ID
DiskGUID = new byte[16];
DiskGUID[0] = blockData[56];
DiskGUID[1] = blockData[57];
DiskGUID[2] = blockData[58];
DiskGUID[3] = blockData[59];
DiskGUID[4] = blockData[60];
DiskGUID[5] = blockData[61];
DiskGUID[6] = blockData[62];
DiskGUID[7] = blockData[63];
DiskGUID[8] = blockData[64];
DiskGUID[9] = blockData[65];
DiskGUID[10] = blockData[66];
DiskGUID[11] = blockData[67];
DiskGUID[12] = blockData[68];
DiskGUID[13] = blockData[69];
DiskGUID[14] = blockData[70];
DiskGUID[15] = blockData[71];
//Load more global GPT data
StartingLBAOfPartitionArray = ByteConverter.ToUInt64(blockData, 72);
NumPartitionEntries = ByteConverter.ToUInt32(blockData, 80);
SizeOfPartitionEntry = ByteConverter.ToUInt32(blockData, 84);
PartitionArrayCRC32 = ByteConverter.ToUInt32(blockData, 88);
#if GPT_TRACE
BasicConsole.WriteLine(((FOS_System.String) "Start LBA of part arrray : ") + StartingLBAOfPartitionArray);
BasicConsole.WriteLine(((FOS_System.String) "Num part entries : ") + NumPartitionEntries);
BasicConsole.WriteLine(((FOS_System.String) "Size of part entry : ") + SizeOfPartitionEntry);
BasicConsole.WriteLine(((FOS_System.String) "Part array CRC32 : ") + PartitionArrayCRC32);
BasicConsole.DelayOutput(5);
#endif
ulong blockNum = StartingLBAOfPartitionArray;
uint entriesPerBlock = blockSize / SizeOfPartitionEntry;
#if GPT_TRACE
BasicConsole.WriteLine("Reading partition entries...");
BasicConsole.WriteLine(((FOS_System.String) "blockNum=") + blockNum);
BasicConsole.WriteLine(((FOS_System.String) "entriesPerBlock=") + entriesPerBlock);
BasicConsole.DelayOutput(1);
#endif
//TODO: Check the CRC32 values of the header and partition table
// are correct.
//Note: By not checking the CRCs, we have the option to manually edit
// the GPT without rejecting it if CRCs end up incorrect.
//TODO: Add an override option to ignore the CRCs
//TODO: Add a method to update / correct the CRCs
//Read partition infos
for (uint i = 0; i < NumPartitionEntries; i++)
{
//If we're on a block boundary, we need to load the next block
// of data to parse.
if (i % entriesPerBlock == 0)
{
#if GPT_TRACE
BasicConsole.WriteLine("Reading block data...");
BasicConsole.WriteLine(((FOS_System.String) "blockNum=") + blockNum);
BasicConsole.DelayOutput(1);
#endif
//Load the next block of data
disk.ReadBlock(blockNum++, 1u, blockData);
}
//Calculate the offset into the current data block
uint offset = (i % entriesPerBlock) * SizeOfPartitionEntry;
#if GPT_TRACE
BasicConsole.WriteLine("Reading entry...");
BasicConsole.WriteLine(((FOS_System.String) "offset=") + offset);
#endif
//Attempt to load the partition info
PartitionInfo inf = new PartitionInfo(blockData, offset, SizeOfPartitionEntry);
//Partitions are marked as empty by an all-zero type ID. If the partition is empty,
// there is no point adding it.
if (!inf.Empty)
{
#if GPT_TRACE
BasicConsole.WriteLine("Entry not empty.");
#endif
//Add the non-empty partition
Partitions.Add(inf);
}
#if GPT_TRACE
else
{
BasicConsole.WriteLine("Entry empty.");
}
#endif
}
}
