public static bool TryGetMbrInfo(DiskImage hdd, out MbrPartitioningInfo info)
{
info = default;
Debug.Assert(Unsafe.SizeOf <MbrHeader>() == MBR_SIZE);
var headerBytes = hdd.ReadBytes(0, MBR_SIZE);
MbrHeader header = MemoryMarshal.Cast <byte, MbrHeader>(new Span <byte>(headerBytes))[0];
if (header.BootSig != MbrHeader.MbrMagic)
{
return(false);
}
bool hasGpt = false;
for (int i = 0; i < 4; i++)
{
var part = header.GetPartition(i);
hasGpt |= part.Type == MbrPartitionType.GptProtective;
}
//MBR paritioned disks often contain boot loaders in non-paritioned space.
//So to be safe copy all the data.
List <FileExtent> partitions = new List <FileExtent>()
{
new FileExtent(MBR_SIZE, hdd.Length - MBR_SIZE),
};
info = new MbrPartitioningInfo(headerBytes, partitions, hasGpt);
return(true);
}
static bool getParitionInfo(DiskImage image, out IPartitioningInfo info)
{
GptPartitioningInfo gpt;
if (GptPartitioningInfo.TryGetGptInfo(image, out gpt))
{
info = gpt;
return(true);
}
MbrPartitioningInfo mbr;
if (MbrPartitioningInfo.TryGetMbrInfo(image, out mbr))
{
info = mbr;
return(true);
}
info = null;
return(false);
}
public static bool TryGetGptInfo(DiskImage hdd, out GptPartitioningInfo info)
{
Debug.Assert(Unsafe.SizeOf <GptHeader>() == CurrentHeaderSize);
Debug.Assert(Unsafe.SizeOf <PartitionEntry>() == PartitionEntrySize);
info = null;
MbrPartitioningInfo mbr;
if (!MbrPartitioningInfo.TryGetMbrInfo(hdd, out mbr))
{
return(false);
}
if (!mbr.HasGpt)
{
return(false);
}
var primaryHeader = LoadHeader(hdd, SectorSize);
var backupHeader = LoadHeader(hdd, hdd.Length - SectorSize);
//Make sure the headers agree on each other's locations
if (primaryHeader.BackupLba != (hdd.Length / SectorSize) - 1)
{
throw new Exception("Location of backup LBA in primary header is wrong.");
}
if (backupHeader.BackupLba != 1)
{
throw new Exception("Location of primary LBA in backup header is wrong.");
}
//make sure the headers match
if (primaryHeader.NumberOfPartitions != backupHeader.NumberOfPartitions)
{
throw new Exception("Primary and backup GPT headers do not agree on the number of partitions.");
}
if (primaryHeader.FirstUsableLba != backupHeader.FirstUsableLba || primaryHeader.LastUsableLba != backupHeader.LastUsableLba)
{
throw new Exception("Primary and backup GPT headers do not agree on the usable area of the disk.");
}
if (primaryHeader.DiskGuid != backupHeader.DiskGuid)
{
throw new Exception("Primary and backup GPT headers do not agree on the disk GUID.");
}
//TODO: Make sure the partition entries do not intersect with the usable area of the disk or the GptHeader.
//at this point we have varified that the header for both the primary and backup
//GPT are correct. We are only going to load paritions from the primary header.
//Make sure the minimum space for partition entries was reserved
if (primaryHeader.FirstUsableLba < (Program.RoundUp(MinimumSizeForParitionEntriesArea, SectorSize) / SectorSize + 2)) //extra two sectors for protective MBR and GPT header
{
throw new Exception("Not enough space for primary parition entries was reserved.");
}
if (primaryHeader.LastUsableLba >= Program.RoundDown(hdd.Length - MinimumSizeForParitionEntriesArea - SectorSize, SectorSize) / SectorSize)
{
throw new Exception("Not enough space for backup parition entries was reserved.");
}
byte[] partitionEntriesBytes = new byte[primaryHeader.NumberOfPartitions * PartitionEntrySize];
hdd.ReadBytes(new Span <byte>(partitionEntriesBytes), primaryHeader.StartingLbaOfPartitionEntries * SectorSize);
uint actualEntriesCrc = Crc32Algorithm.Compute(partitionEntriesBytes);
if (primaryHeader.CrcOfPartitionEntry != actualEntriesCrc)
{
throw new Exception("CRC of partition entries not correct.");
}
var partitions = new List <PartitionEntry>();
foreach (PartitionEntry part in MemoryMarshal.Cast <byte, PartitionEntry>(new ReadOnlySpan <byte>(partitionEntriesBytes)))
{
if (part.Type == Guid.Empty)
{
continue;
}
if (part.FirstLba < primaryHeader.FirstUsableLba || part.LastLba > primaryHeader.LastUsableLba)
{
throw new Exception($"Parition '{part.Name}' is outside the usable space.");
}
partitions.Add(part);
}
partitions.Sort((a, b) => a.FirstLba.CompareTo(b.FirstLba));
//TODO: make sure the paritions do not intersect with each other
info = new GptPartitioningInfo(mbr, partitions);
return(true);
}
private GptPartitioningInfo(MbrPartitioningInfo protectiveMbr, List <PartitionEntry> partitions)
{
this.mProtectiveMbr = protectiveMbr;
this.mPartitions = partitions;
}